Search

This study presents a design for an absorber used in a solar air collector for an indirect solar dryer. The absorber comprises two aluminium plates corrugated and joined together to form parallel cylinders, enabling airflow within the collector. This research aims to experimentally examine the drying process of two types of bananas, one from Morocco and the other from abroad, using the designed solar air collector. Additionally, the study aims to investigate the peculiarities of the drying process and the performance of the solar dryer employed. The experiments were conducted by subjecting the bananas to the designed solar air collector, and the evolution of drying was monitored. The initial mass of the bananas used was 631.6 g for the Moroccan banana and 713.6 g for the Export banana. After the drying process, the mass of the Moroccan banana reduced to 77.5 g, while the Export banana reduced to 137.3 g, indicating significant moisture removal. The percentage of the amount of water extracted (Q) from the bananas was found to be 87.7% for the Moroccan banana and 80.8% for the Export banana. These results demonstrate the effectiveness of the corrugated aluminium plate absorber in facilitating the drying process in the solar air collector. The significant reduction in the mass of the bananas and the high percentage of water extraction highlight the efficiency of the solar dryer in removing moisture from the agricultural produce. The findings of this study contribute to the understanding of the drying process of bananas and offer valuable insights for the design and optimization of solar drying systems for agricultural applications. [ABSTRACT FROM AUTHOR]

Achieving food security in Mozambique is critical, since 80% of the population cannot afford an adequate diet. While increasing agricultural production is a necessary effort to address this challenge, inadequate post-harvest treatment leads to storage losses and quality degradation, with repercussions for food security. The use of solar drying is promoted as a solution to provide efficient and reliable access to food preservation that improves the food security situation in rural communities. However, there is a lack of clear evidence on how the use or access to solar drying affects food security. This study identifies the determinants of farmers' choice to use solar drying and evaluates the effect of a passive solar dryer on food security using survey data from 634 households. We allocated solar dryers to selected communities and all interested individuals belonging to these communities were eligible to use it. Propensity score matching and endogenous switching poisson regression are used to estimate the average effect. The use of solar drying with associated training significantly increases the food security status of participants by increasing household food availability, women's dietary diversity, and months of adequate household food provision and by decreasing the household food insecurity access scale. [ABSTRACT FROM AUTHOR]

Preservation of food and vegetable products is an age-old practice for the retention of flavor, appearance, and quality. From ancient times, driers for drying food grains work on direct sun rays, firewood, fossil fuels, and coals causing carbon release. These available methods are expensive, unreliable, and unhygienic; thereby the use of a solar dryer working on free and clean energy is better for higher value addition to food preservation. The objective of this exploration is to study the recent developments in the use of different types of solar dryers for drying foods, vegetables, seafood, etc. There exist many studies on the effects of the parameters such as temperature, relative humidity, and speed of air, turbulence effect, sun irradiation, and the latitude of the location in the solar drying process. The findings show that the climate conditions such as solar radiation and atmospheric air play an important role in the drying efficiency of the solar dryer. A phase change material stores thermal energy during the daytime and releases heat during the nighttime. This process improves thermal efficiency and reduces heat loss during the drying period. On the one hand, a hybrid dryer integrated with a solar panel produces electricity for the operation of a DC blower circulating hot air inside the drying chamber for better drying. In addition, a critical review has been performed on the usage of different absorbing plates increasing heat transfer rate, use of various phase change materials for heat storage, and analysis of CFD simulation. [ABSTRACT FROM AUTHOR]

Conventional hot air and solar energy processes have been used for apricot. These processes had adverse effects on the quality due to the longer process times, and this indicates the need for an innovative approach. Radio frequency (RF) processing has innovation potential for drying with its volumetric heating feature, but an optimal process should be designed for process efficiency in industrial‐scale applications. Therefore, the objective of this study was to confirm the RF process for industrial‐scale apricot drying. For this purpose, a mathematical model was developed to predict temperature and moisture content change of apricots during drying, and experimental validation study was carried out. For the RF drying process, pre‐dried apricots (0.58–0.75 kg water/kg dry matter, db) by solar energy were used. The purpose was to start the RF process at a suitable moisture content level as this process was not feasible to apply directly due to the high initial moisture content of apricots (up to 4 kg water/kg dry matter, db). RF drying experiments were carried out in a 10 kW hot air‐assisted (50–60°C) staggered through electrode system. Optimum electrode gap was 81 mm with 2500 V potential of the charged electrode. Final moisture content of the dried apricots was 0.25–0.33 kg water/kg dry matter (db). Following the model validation for temperature and moisture content change, industrial‐scale apricot drying scenarios were demonstrated to confirm the RF process for feasibility and process design. Practical Application: A comprehensive mathematical model was developed for radio frequency (RF) drying of apricots. This model was experimentally validated with respect to the temperature and moisture content change. Various process design studies were carried out for an industrial‐scale apricot drying process to confirm the process feasibility. With this background, the results of this study can be directly used in an industrial drying for an optimal process design and energy efficiency. [ABSTRACT FROM AUTHOR]

• This study examines the drying kinetics of food waste and its impact on biogas production. • Temperature and airflow play a crucial role in the drying kinetics of food waste. • Drying reduces biogas production, minimizing methane emissions and environmental impact. • For sustainability reasons, solar drying can be easily integrated into existing food waste management systems. The present work analyzes the drying kinetics of food waste, focusing on the effects of temperature, airflow and drying on biogas production. The work involves the experimental determination of food waste drying kinetics under controlled environmental conditions, including modeling the curves using a mathematical model. Indirect solar drying experiments of food waste have been performed at different air flow rates (300 m3.h-1 and 150 m3.h-1) and temperature values (40, 50, 60, and 70 °C). The temperature in the drying room was adjusted to the desired level using an auxiliary electric heating system. Energetic and environmental performance metrics of different air flow rate and temperature configurations have also been investigated and presented within the scope of this work. Additionally, an experimental investigation to measure the biogas generated by the fermentation of dried food waste was conducted. It was established that a logarithmic model best captures the drying kinetics, and the temperature and airflow are crucial variables. Increasing the drying temperature from 40 °C to 70 °C for the tests that performed in lower and higher flow rates improved the specific moisture extraction rate as 45.02 % and 130.65 %, respectively. It can also be observed that only phase 2 is present in the drying curve, phases 0 and 1 are absent. Furthermore, drying decreases the generation of biogas, which is primarily composed of methane, a potent greenhouse gas, according to experimental studies. [ABSTRACT FROM AUTHOR]

• Shrinkage, effective diffusion coefficient (D e), surface transfer coefficients on solar drying are reviewed. • Their influencing factors were thoroughly discussed. • The main factors volume of water, moisture content, air temperature, air velocity are discussed. • Different mathematical models involved in the above parameters are reviewed. • Important results are listed and recommendations are given. Drying of food materials leads to an increase in shelf-life and gives quality end products. Drying with solar energy is an economical and environmentally friendly method than other drying methods. The food products are dried using solar energy in different methods such as open sun drying, direct, indirect, mixed-mode and hybrid solar drying. There are some parameters such as shrinkage, effective diffusion coefficient (D e), surface transfer coefficients, etc. majorly influence the solar drying of food products and these elements are extensively reviewed in this work. The shrinkage of food products affects the drying rate and quality of the food products as it involves surface cracking, volume, porosity and hardness changes. The D e gives the moisture transfer rate in the food products during solar drying. The values of surface transfer coefficients including mass transfer coefficient (h m) and heat transfer coefficient (h) give the mass and heat transfer rate from the surface of the food product as these parameters are surface parameters. The parameters such as shrinkage, D e , h m, and h of food products and their influencing factors need to be analyzed to understand more about the physics of the solar drying process. An extensive review is made on the factors of shrinkage, D e , h m and h such as volume of water, moisture content, air temperature, air velocity, the thickness of product and geometry of food. The values of shrinkage, D e , h m and h of different solar drying processes are tabulated and discussed. A brief review was performed on different mathematical models used to determine the values of shrinkage, D e , h m, and h during solar drying of food products. The influencing factors such as moisture content, air temperature, velocity, thickness and geometry of the product on these three factors shrinkage, D e , h m, and h were discussed. Important results and recommendations of this topic are mentioned at the final because it is an innovative review trial in the solar drying area. [ABSTRACT FROM AUTHOR]

Recently, the quality of food solar dried has been associated to solar irradiance, irradiation and UV-light. Different materials used as covering materials in direct solar dryers had different optical properties, thus, different quality should be expected in solar food drying. The objective of this study was to compare two direct solar dryers builder with different covering materials: Direct Solar Drying with Poly (methyl methacrylate) (DSD), and Greenhouse Solar Drying with polyethylene (SGD), based on their three aspects: chemical composition, heat-mass transference, economic-environmental effect. Chemical composition was evaluated as the total phenolic compounds (TPC), flavonoids (TF) anthocyanins (TA) and antioxidant activity (AA) of blackberry pulp (Rubus spp). Dehydrated blackberry pulp contains lower TA than raw samples because TA is sensitive to solar irradiation and UV solar irradiation. TPC, TF and AA averages do not show significant differences among all the drying processes. Evaluation of energy and heat transfer in the evaporative and diffusive periods of the drying technologies led to an assessment of the return of investment period for DSD and SGD technologies for different power sources. The results suggest payback periods between 39 and 121 months, considering only the 6 months of harvest duration without using the solar dryers the rest of the year. [ABSTRACT FROM AUTHOR]

• Polyethylene cover favored the retention of bioactive compounds during solar drying. • Cellular polycarbonate cover provided a suitable drying temperature. • Bioactive compounds in dried strawberry followed a first order degradation kinetics. • Drying temperature and UV radiation influenced on bioactive compounds concentration. Cover material of solar dryers influences on fruit properties due to the temperature and ultraviolet radiation (UV) during drying. Polyethylene (P) is the most used material for covering solar dryers. Cellular polycarbonate (CP) is a material that promotes UV protection; hence, it has recently been proposed as a covering material for greenhouse dryers. However, it is unknown whether CP cover will have any effect on bioactive compounds of foods treated by solar drying. Especially, if CP has advantages in preserving sensitive compounds compared to traditional materials as P. In this work the effect of CP and P covers on anthocyanins (TA) and total phenolic compounds (TPC) of strawberries during solar drying was evaluated. Open sun drying was used as a reference. Drying temperature, solar radiation, external and internal UV radiation was measured. The results indicated that the drying temperature and UV radiation influenced the moisture content and bioactive compounds. Direct radiation increased the drying temperature and reduced the final moisture content, while the partial incidence of UV radiation in the dried samples with P covers favored the remaining 40.7% of TA and 42.5% of TPC. With CP covers, where the ultraviolet radiation was zero, the 15.5% of TA and 14.4% of TPC were retained. Activation energy indicated that bioactives were more stable in the solar dryer with P and transparent cellular polycarbonate covers, demonstrated that they can be used as coatings in solar dryers destined for drying fruits, producing high-quality dehydrated products and efficient solar drying processes. [ABSTRACT FROM AUTHOR]

Solar drying is a sustainable process that may impact the quality of dried food. This is because, pigments contained in food are sensitive to sunlight, and exposure to ultraviolet radiation can affect them. We applied biopolymer-based coatings on strawberry, from hydro-colloidal solutions of Opuntia ficus indica-mucilage, fenugreek, xanthan gum, gum Arabic, and guar gum to evaluate their potential use as UV filters for solar drying of food. Thermal properties and the optical transmittance, absorbance and reflectance of the coatings were measured to assess their influence on food-sunlight interaction. During the drying experiments, the moisture content, total anthocyanins (TA), and total phenolic compounds (TPC) were measured. Optical and thermal properties are influenced by the biopolymer-based coatings. Also, the optical properties are influenced by the coating thickness. The differences in optical and thermal properties influence the drying process. Differences exist in the drying rate for strawberry slices with coating, compared with those without the coatings. In general, the TA and TPC content in the product are better preserved under solar drying than in control experiments done in a drying oven. A partial transmittance of solar UV radiation is recommended to obtain increased TA and TPC contents in the dried product. [ABSTRACT FROM AUTHOR]

• Solar drying of foods holds huge potential in on-farm food processing. • Dryer designs and selection of components significantly affect drying characteristics. • The use of energy storage materials in solar dryers can be of great benefit to food samples. • Computer applications and modeling can be integrated for improved process control. • Hybrid drying techniques to assist solar drying provide better quality end-products. Considering the growing energy crisis, the need for green-energy alternatives is inevitable. Food processing must consider the application of renewable energy for replacing conventional and energy-intensive unit operations; drying in particular. The utilization of solar energy for drying of foods remains to be attractive in terms of energy efficiency, cost-effectiveness, and rural applicability. However, a huge technological gap exists; developing low-cost and energy-efficient dryers for the production of high-quality foods is a challenge. Proper design and selection of components for a solar dryer are mandatory for the effective utilization of thermal energy. Considering these aspects, this review focuses on providing an exhaustive report on the available dryer designs and other critical considerations, along with a summary of diverse applications for different foods. Besides, various recent advancements, challenges, and limitations for implementing large-scale solar drying of foods are presented in terms of technology, energy considerations, and other socio-economic aspects. Thus, this review provides valuable insights into the state of the art of solar dryers, to assist the progress of this green and sustainable technology for food applications. [ABSTRACT FROM AUTHOR]

In this research, the objective was to determine the drying rate of aguaymanto (Physalis Peruviana L.) in three different solar dryers. To accomplish this aim three prototypes were designed and built direct, indirect, and mixed dryer. The drying process went through solar radiation and natural hot air convection generated by solar collectors. During rehearsals, weather conditions were recorded: average wind speed of 1.11 m/s, the relative air humidity (RH) ranged from 16% to 52%, and the minimum and maximum ambient temperature were 14.7 °C (287.8 K) and 26.4 °C (299.5 K). The initial moisture (bs) was 4.53 and the final moisture of 0.07; 0.12 and 0.10 (kg water/kg dry solid), respectively. Drying rates reached values: 0.0287; 0.0208 and 0.0407 (kg water/hour·m2). Drying time: 41 h for direct type, 56 h for indirect 56 h, and 29 h mixed. Solar drying is a viable, natural, economical, and easy alternative to use for food de-hydration. [ABSTRACT FROM AUTHOR]

Emergency situation caused people having difficulties in fulfilling their daily nutritional needs through ready-to-eat foods. The aim of this research was to utilize white oyster mushroom in the making of biscuit as emergency food product. White oyster mushroom powders were obtained by drying of fresh white oyster mushroom using cabinet dryer, sun drying, and oven. Cabinet dryer was chosen as the best drying method to produce white oyster mushroom powder based on yield and nutritional content. Biscuit emergency food products were formulated by using 25%, 30%, 35% of white oyster mushroom powder and using the different types of fat (palm oil, margarine, and shortening). Each formulation were analyzed for physical, chemical and sensory characteristics. The results showed that the higher white oyster mushroom powder's added, the moisture, protein, fat, ash and hardness of biscuit increased, but the lightness decreased. The different type of fat used, gave the different characteristics of products. The best formulation chosen were 25% of white oyster mushroom powder added and palm oil as fat source. The chosen biscuit's formulation had 241.58 kcal which was 10.86% of energy given by protein, 42.14% from fat, and 47.00% from carbohydrate. The comparison analysis with the emergency food commercial product (NEO's brand) showed that the chosen biscuit had higher energy from protein and lower energy from fat and carbohydrate. So, this biscuit product could be consumed as an emergency food product because it was ready to fulfill the daily nutritional needs. [ABSTRACT FROM AUTHOR]

In the present work, the use of automatic temperature controllers based on embedded systems for solar dryers is proposed, in order to improve the product quality in small scale drying operations. With this aim, from a scientific literature review, it was determined the temperature influence over the quality of the dried product, like spices, in solar drying operations for food conservation. Then, it was established the use of temperature controllers as a way to decrease the quality loses in the drying operation in solar installations. Finally, it was proposed the use of embedded systems, like microcontroller based systems, for the development of economical temperature control systems fitted to small scale solar drying productions. [ABSTRACT FROM AUTHOR]

Abstract Cassava processing practices vary among communities and countries with implications for food safety. The study examined the microbiota and microbial metabolite profiles of 126 samples of sun-dried cassava products: grits, improved chips, improved flour, kivunde , and makopa from Tanzania, and mangahazo maina from Madagascar. All samples were free of Salmonella spp. Only 12.5% makopa , 6.7% of mechanically processed flour, and 25% of chips conformed to yeast/mold regulatory limits (103 cfu/g). Among the most agriculturally important mycotoxins, aflatoxins (B1, B2, G1, and M1) were detected in 6.3–11.9%, fumonisins (B1, B2 and B3) in 3.2–41.3%, and zearalenone in 41.3% of the samples. A few samples of improved chips, improved flour, and makopa contained high aflatoxin B1 content. Some emerging mycotoxins: emodin, beauvericin, moniliformin, sterigmatocystin, alternariol methyl ether, nivalenol, mycophenolic acid, enniatin B, and enniatin B1 were detected. The most prevalent microbial metabolites were emodin (75.4%), tryptophol (67.5%), equisetin (61.9%), and beauvericin (51.6%), at mean concentrations of 8.8 μg/kg, 794.1 μg/kg, 277.2 μg/kg, and 29.5 μg/kg, respectively. Emodin and Beauvericin are the only emerging mycotoxins in this group and the mean concentrations are the lowest. Nevertheless, regular surveillance along the cassava food chain is recommended for early detection of emerging mycotoxins to prevent health problems associated with ingestion of unexpected toxins in foods. Highlights • Yeast/mold was a common contaminant in sun-dried cassava products. • Fusarium is a common mycotoxin producer in the sun-dried cassava products. • Sporadic presence of aflatoxins may occur in some sun-dried cassava products. • Processing with machines did not guarantee absence of mycotoxins in cassava products. • Strict hygiene measures are needed to guarantee conformity of products to standards. [ABSTRACT FROM AUTHOR]

In this article, an experimental estimation of thermal efficiency of horizontal and vertical-finned double-pass solar air collectors integrated with drying chamber has been carried out. The rig consists of two main parts as solar collector and dryer. The system was installed in the laboratory of Szent István University, Gödöllő, Hungary. The absorbers were made from a copper integrated fins in horizontal and vertical directions. The test results showed that the daily efficiency increased by10% when the direction of fins have been changed from vertical to horizontal. After 5 h drying of 2 kg apple slices, the final weights were 1.16 and 1.37 kg by using horizontal and vertical-finned collectors, respectively. [ABSTRACT FROM AUTHOR]

Solar food drying is a well-established food-conserving process in India. Various researchers had developed solar dryer models which were usually validated using experimental observations and numerical simulation processes that are time-consuming and money-consuming. Computational fluid dynamics (CFD) simulation software facilitates the simulation of the models and gives same results in a comparatively small frame of time. This research paper is focused on CFD simulation, validation of design, energy analysis and numerical computation for domestic direct-type solar dryer for which experimental observations were performed at Ludhiana in November 2006. The design and simulation of the domestic direct-type multi-shelf dryer at no load condition are performed using ANSYS Fluent 14.0 software. The temperature of the air inside the dryer is found to be 326 K, which validates the design and purpose of the domestic direct-type multi-shelf dryer. The embodied energy of the constituents used in the construction of dryer is obtained as 339.015 kWh, and the energy payback time and carbon credit are found to be 7.57 years and INR 2055, respectively. The convective heat transfer coefficient for the dryer varies from 2.4 to 2.8 W m−2 °C−1. Coefficient of determination is estimated to be 0.98 under no load condition which shows the fare agreement between predicted and experimental value. [ABSTRACT FROM AUTHOR]

Abstract Algeria industry fruit processing generates a huge amount of waste which causes a serious environmental problem. Thereby, the use of solar drying as a clean energy process seems to be a promising solution. This will enhance the value of fruit waste by reusing it in a dry form, and will also contribute to the protection of the environment. For this purpose, an innovative greenhouse solar dryer has been designed at the Solar Equipment Development Unit in Bou Ismail. An experimental study of solar drying kinetics of industrial tomato pomace was conducted to test the performance of the new solar dryer as a waste processing dryer. The drying temperature of the tomato waste, using this type of dryer, varies between 40 and 58 °C. The duration of the drying operation for a final product is only 5 h. Five new universal and dimensionless models and five different drying models chosen from the literature were evaluated in order to select the model that better fits the experimental data generated during the drying process. Among the different models tested, it emerged that the new model2 was the most suitable to describe the drying process of tomato waste. Also, the diffusion coefficient and the activate energy were studied and determined. The effective diffusivity varies between 3.2E-9 and 4.7E-10 m2/s with activation energy is 75.6 kJ/mol. Highlights • A new greenhouse solar dryer was used to dry tomato waste from fruit and vegetable processing plants. • The tomato waste lost 86% of its original weight and the time of the drying process is 5 h. • Five new universal and dimensionless models were used. • The new model2 characterizes well the drying curves of tomato waste and different agricultural products. • There is a direct liaison between temperature and the effective diffusion coefficient. [ABSTRACT FROM AUTHOR]

Abstract Mycotoxins are a variety of metabolic products produced by fungi, which can cause various damages to other organisms. The aim of this study was to figure out the effect of new drying methods namely "drying in oven under magnetic field" and "drying under the sun and magnetic field" on the mycotoxin formation for some food samples. In this system, a fixed magnetic field of 300 μT was used for the drying process. The amounts of moisture in the samples dried with the new developed methods were measured in hazelnut (Corylus L.), fig (Ficus carica L.), chili pepper (Capsicum annuum L.) and grape (Vitis vinifera L.) depending on time. Mycotoxin species within different foodstuffs were determined at trace levels by using LC-MS/MS device under the optimum conditions, and the results obtained from the samples dried with the new methods were compared with each other and results of food samples dried by traditional method. The results indicated that the new developed drying methods cause decrease in the drying periods, and the dried samples did not contain any mycotoxin. This study suggested new drying strategies to eliminate the mycotoxin formation. For the analysis of the results, different statistical tests were used. In order to determine which technique works faster in drying the samples, box plots were obtained using descriptive statistics. Mann Whitney tests were also applied to determine if there was a statistical difference between the drying methods. Highlights • This study offers new drying methods for both effective drying and elimination of mycotoxin formation. • Drying under the sun and magnetic field and drying in oven under the magnetic field were applied to hazelnut, fig, chili pepper and grape samples. • LOD values were found to be between 1.8 and 321 µg/L for the analytes of interest. • None of the mycotoxin species were observed in the samples dried with the new developed methods. • The most contaminated food sample is chili pepper when traditional drying is used. [ABSTRACT FROM AUTHOR]

Highlights • Shrinkage and microstructural changes of solar dried dates was investigated. • GTD had the lowest drying time for khalal, rutab and tamr stages of date. • FCSD dried dates had the lowest percentage of shrinkage. • Quadratic equation is proposed as the best model to describe the volumetric shrinkage. • FCSD dried date tissue had the least structural deformation. Abstract The effect of solar drying methods on shrinkage and the corresponding influence on microstructural changes of dates at three ripening stages (khalal, rutab and tamr) were investigated and evaluated shrinkage models that are best describing the shrinkage behavior. Drying was accomplished by forced convective solar dryer, greenhouse tunnel dryer and open sun drying. It was observed that, the greenhouse tunnel dryer had 37, 38 and 38% lower drying time for khalal, rutab and tamr stage dates, respectively compared to open sun drying, whereas the drying time was lower by 15, 29 and 30%, respectively in forced convective solar dryer. The drying methods and ripening stages had significant effect on shrinkage attributes of dates. Dates dried in the forced convective solar dryer had the lowest percentage of shrinkage in length (7–9%), diameter (10–27%) and volume (25–51%) at the three ripening stages followed by greenhouse tunnel dryer (7–13%, 12–27% and 29–53%, respectively) and open sun drying (8–13%, 17–32% and 37–60%, respectively). The quadratic equation was proposed as the best model to describe the volumetric shrinkage of dates as a function of moisture content or moisture ratio at the three ripening stages for all the three drying methods. Microstructural analysis of date tissue revealed that forced convective solar dryer had the least structural deformation at the three ripening stages. Overall, forced convective solar dryer produced the best quality of dried dates. [ABSTRACT FROM AUTHOR]

Abstract The quality of Theobroma cacao L. is influenced by different variables both in the crop and in the processes of postharvest, the latter it includes the fermentation and the drying, fundamental for the formation of aroma and flavor precursors, determinants in the characteristics of quality and differentiation of cocoa in the chocolate industry. The objective of the present research was to evaluate the effect of the solar drying process using a plastic roof solar dryer on the sensory and chemical quality of a mixture of cocoa cultivated in a region of Antioquia, Colombia. The content of total polyphenols, anthocyanins, sugars, mannitol, pH, total acidity, humidity, ethereal extract, ash, crude fiber and odor and flavor descriptors were analyzed. For analyzing the data, we used the methodology of longitudinal data analysis and repeated measurements, a Principal Component Analysis (PCA), and a principal factor analysis. The analyzed sensory characteristics are statistically different over time (p < 0.05). There was a decrease in the content of anthocyanins, total polyphenols and sucrose, and an increase in glucose and fructose during fermentation and drying. The analysis of factors allowed to define a series of groupings as indexes of quality according to the chemical and sensory properties analyzed in the drying process. Overall, the mixture of cocoa clones evaluated in the solar drying process presented indicators of sensory and chemical quality associated with descriptions of odor (spicy, dairy, nut, fruity, sweet cane), flavor (floral and spicy), ethereal extract, and pH that indicate a good benefit of cocoa and show the potential that Colombia has as a producer of fine aroma cocoa in high demand in premium markets. Graphical abstract Unlabelled Image Highlights • Anthocyanins were a key indicator to determine the quality of the fermentation process. • Fermentation and drying process showed that 132 hours were enough to produce desirable descriptors in cocoa. • Principal component analysis can distinguish the chemical and sensory characteristics that influence the quality of cocoa. [ABSTRACT FROM AUTHOR]

The hazelnut (Corylus avellana L.) is one of the most popular tree nuts in the world. The proper selection of drying methods is necessary to prevent oil oxidation which will influence the overall nut quality during storage. The aim of this study was to determine the effects of sun drying (SD) and artificial dryingied (AD) on the chemical traits of hazelnuts during long-term storage. Protein, lipid and moisture contents, water activity, fatty acid composition, sum of fatty acids, and oil oxidation properties were determined over 24 months' storage (2015-2017) at 20-25 °C and 70-90% relative humidity. The results showed that monounsaturated fatty acids (MUFA) was the main fatty acid group (81.55-83.38%) followed by polyunsaturated (PUFA; 10.39-11.57%) and saturated fatty acids (SFA; 5.75-6.60%). The samples dried by AD had more SFA (5.86%) and MUFA (83.11%) than the SD samples. At the end of storage, the lowest free fatty acid, and peroxide value (0.52%-1.45 meqO2⋅kg-1, respectively), and the highest oleic/linoleic acidity ratio (7.76) were found from AD. Therefore, AD appears to be more promising for hazelnut drying. [ABSTRACT FROM AUTHOR]

Combined practice of sulfuration and drying is widely applied for extending shelf life of fruits. The differences in fruit size are not taken into consideration during these applications and during fresh fruit consumption. In this study, effect of fruit size and drying methods (hot air-drying and sun drying) on the chemical composition of fresh and sulfurated apricot was investigated. Total drying times for sun drying and hot air-drying were 11 d and 51 h, respectively. A temperature gradient was applied during hot air-drying. The fruit size substantially affects the composition of both fresh and dried apricots. The results were subjected to principal component analysis. The small-sized fresh apricots discriminate themselves from large ones with higher amounts of phenolic compounds, whereas the large-sized fresh apricots contain more sugar and organic acids. Size classification and hot air-drying are advisable for high-quality dried apricot production. [ABSTRACT FROM AUTHOR]

Kiln-dried fruit drying time is readily predicted from initial moisture content since the environment is tightly controlled. For uncontrolled environments, such as a greenhouse solar dryer, a product's drying time varies depending on ambient conditions and is thus more difficult to predict. Prediction of the drying time is needed to better schedule dryer use. Data was obtained from a set of wireless scales that weigh the waste during solar drying after initial moisture content measurement of a sample. A set of linear and quadratic models for drying rate are tested with the best yielding a 39% reduction in RMSE over traditional models. The results indicate that the modelling approach is likely to be useful for open solar dryers where the temperature, and thus the drying rate, is not controlled. [ABSTRACT FROM AUTHOR]

Grape pomace is an agro-industrial by-product from the production of must (grape juice) by pressing whole grapes. In order to evaluate the seeds and skins of the grape pomace, it must first be dried and then separated in a screen machine. The drying of pomace is an important and necessary process for the optimum separation of seeds. The main purpose of this study was to determine the optimum drying process for obtaining high-quality grape seed oil. In this research, open air and solar energy drying methods were compared in terms of water activity, total bacterial and mold-yeast count, along with the chemical and fatty acid compositions of pressed grape residues. Oleic acid and linoleic acid contents ranged from 16.56-16.96% and 71.45-71.96%, respectively. Antioxidant activities ranged from 2.33-2.80 μmol trolox/g. The results showed that the drying methods did not decrease the nutritional quality of grape residues and prevented microbial growth by decreasing water activity to below 0.60. [ABSTRACT FROM AUTHOR]

Highlights • Study the drying kinetics of two cherry cultivar in a convective solar dryer. • Determine the effect of drying air temperature and the drying air flow rate on the drying kinetics of the cherry. • Determine the characteristic drying curve of sweet cherry (CDC). Abstract This study presents the convectional drying process of two types of Moroccan sweet cherry, namely, Burlat and Van. 40 g of cherries were taken, pitted, cut in two halves, and were dried using a partially indirect solar convective dryer, which has an area of 2.5 m2. The thin-layer drying of sweet cherry were carried out in July 2017 at three air temperatures of 60, 70 and 80 °C and for two drying air flow rate 150 and 300 m3/h. Moreover, the cherry fruits are sufficiently dried in the ranges between 34 and 40 °C of ambient air temperature, 17–27% of relative humidity, and 200–900 W/m2 of solar radiation. The evolution of the moisture dry content and the drying rate as a function of drying time for different temperatures are shown graphically. Experience shows that as the air drying temperature increases the drying time decreases. During the experiments, pitted cherries were dried and the moisture content was decreased from 82.12 for Burlat and 85.45 for Van to 23 ± 3% (w.b). The drying temperature of 80 °C and air velocity of 300 m3/h were the optimum values for cherry fruit drying in a minimum time of 240 min. The characteristic drying curve (CDC) applicable to both types of cherry has been established as a polynomial of order 3 in reduced moisture content. [ABSTRACT FROM AUTHOR]

The influence of air-drying (AD), convection oven (CO) and solar drying (SOD) on the physical and chemical properties of Ilex guayusa leaves is discussed. Total ash (%), acid-insoluble ash (%), watersoluble ash (%), residual moisture (%) and caffeine content (%) were estimated. Additionally, alkaloids, flavonoids, reducing sugars, saponins, steroids, quinones, fats, phenols and tannins detection of dry leaves extracts were assessed. The results revealed that parameters of physical analysis were not affected by the drying techniques. The highest amount of secondary metabolites in ethanol and aqueous extracts were detected. In general, convection oven dried leaves showed the highest caffeine content (3.71%) and the lowest drying time (13 h) compared to other drying methods. The results revealed a fast method to dry Ilex guayusa leaves and indicate that this species possess a variety of bioactive compounds beneficial for health. Our results revealed an effective quick method to dry Ilex guayusa leaves without altering the content of beneficial bioactive components. [ABSTRACT FROM AUTHOR]

In this paper, a review on solar drying is presented. The review comprises the main components, classifications and affecting parameters. Advantages, disadvantages and limitations of such technology are also investigated. That said, solar dryers are assessed according to three key-elements: way of air movement (passive and active), mode of transferring heat (direct and indirect, hybrid and mixed) and type of drying chamber (cabinet, greenhouse and tent). Moreover, economic and environmental studies are performed for the Lebanese case in order to assess the Payback Period (PP) and the amount of CO 2 reduction. The examined parameters are the percentage of time where solar dryer is utilized (Pr), the mass of dried food and food type. Results show that for Pr equals to 0.6, when drying 120 kg of carrots using solar dryer the amount of Saved Money (SM) is 780 $/month, PP is 10 months and the amount of CO2 emissions decreases by 6400 kg/month. [ABSTRACT FROM AUTHOR]

Cassava sour starch is a naturally-fermented, sun-dried product. It allows obtaining less dense bakery products than the native starch, being an appreciated gluten-free ingredient. The aim of this work was to study the effect of fermentation and drying method on the physicochemical and technological characteristics of cassava sour starch and to identify the relationships among those distinctive features that may condition their potential food applications. Natural fermentation following starch extraction could not be replaced by the use of a starter. Sour starches pastes showed lower apparent viscosities related to their lactic and/or butyric acid content, and a higher retrogradation tendency, mainly associated to sun-drying. The fermentation combined with the solar exposition represent a complex process that induce changes not easily observed on starch powders but clearly evidenced after gelatinization of the starch suspensions. [ABSTRACT FROM AUTHOR]

This work aimed at modeling thin-layer solar drying of cassava noodles (tapioca). The selection of good drying models for dryers helps to improve their efficiency. Drying data of tapioca was obtained using a forced convection solar dryer. The treatment combinations of the experiment comprise of air flow velocities (V) of 1.5, 2.5, and 3.5 m s-1; drying layer thicknesses (B) of 0.48 and 0.72 cm; and initial moisture contents (Mi) of 297%, 186%, and 122% (dry basis). Eleven thin-layer drying models from literature, in addition to a new model developed in this work were all fitted to the solar drying data of tapioca. Least square regression analysis was carried out and comparison between drying models was made using goodness of fit statistical parameters. Drying kinetics of the tapioca was determined. Effective moisture diffusivity and activation energy of the tapioca were also determined. The results obtained from the analysis show that the new model (Modified Aghbashlo model) was the best fitted to the drying data of tapioca. The determined effective moisture diffusivity of the tapioca samples varied from 4.93×10-11 to 8.82×10-11 m2 s-1. Also, the activation energy of the tapioca samples was determined as 28 kJ mol-1. [ABSTRACT FROM AUTHOR]

An integrated solar system was examined and worked for drying chamomile during the summer season 2013 in Germany. The system consisted of collector, heat exchanger, reflector, main drying chamber below collector, additional drying chamber and supplementary electric heaters immersed in water tank. It could also storage of solar energy into water during the time of sun-shine and reuse this energy at cloudy weather or off sunshine time to raise the temperature of drying air inside the system. The capacity of main drying chamber ranged 32–35 kg of fresh chamomile and 10–12 kg for the other separate drying chamber. Air temperature inside the dryer could be maintained as desired range for drying chamomile using a temperature controller. The integrated dryer was operated about 30–33 h to reduce the moisture contents of chamomile from 72-75%–6% (wb) compared to 60 h to reduce it to 9–10% (wb) using open sun drying method. Nine mathematical models for drying kinetics of chamomile were tested to determine the parameters of the best suitable models for those plants. It is found Midili model was the best model to define drying kinetics of chamomile for the main and additional drying chambers in solar system. [ABSTRACT FROM AUTHOR]

This study focuses on the drying of the same quantity of a food product, cut in three different shapes (cylindrical, cubical and rectangular parallelepipedic). The experiments were carried out, considering the solar drying of potatoes. The results show that, the drying kinetics depend, on the shape and the size of items, which constitute each quantity. Using the diffusion model and experimental curves of the drying kinetics, the internal coefficient of diffusion, is identified for each case. Results show that, due to the shrinkage effect, the calculation of this coefficients modified, between the beginning and the end of drying. Relations between these coefficients and the characteristic dimension, are established. The analysis assesses the geometrical factors, which influence the drying parameters. The objective of this work is to propose recommendations for a wide use of solar dryers and to study the feasibility and the exploitation of these clean systems, especially in the Maghreb region. [ABSTRACT FROM AUTHOR]

Field drying trials were conducted using both field baskets as well as grab sampling techniques to study drying behaviour of switchgrass and maize (corn) stover (CS). Environmental conditions such as hourly solar radiation, vapour pressure deficit (VPD), average wind speed, rainfall amount, harvesting method, and field operations such as swath density were used as variables for model development. A powerful classification-based algorithm, which uses a collection of decision trees called random forest (RF) was utilised to predict moisture content (MC) of switchgrass and CS on wet basis. RF predicted the MC of switchgrass and CS with a coefficient of determination of 0.77 and 0.79, respectively. Rainfall, hours after harvest, average change in solar radiation in past 12 h, average solar radiation in past 12 h, and swath density were found to be the important variables affecting the MC of CS. Drying CS in low density (LD) and medium density (MD) swaths facilitated quick drying even in moderate drying conditions. Rainfall events ranging from 1.5 to 7.5 mm were experienced during the switchgrass drying period which delayed crop drying by one day to several days depending on the weather conditions after rainfall. Several rewetting events were also observed due to dew at night which increased the MC in LD switchgrass and CS by 5–15%. The models developed in the current study will help in decision-making of switchgrass and CS collection after harvest, based on forecast weather conditions in lower Midwestern states. [ABSTRACT FROM AUTHOR]

Abstract: The effect of two passive drying methods on the degradation of ascorbic acid (vitamin C),  α‐tocopherol (vitamin E), and β‐carotene (provitamin A) in ripe mango and tomato was determined. Samples of both commodities were dried outdoors in a solar drying cabinet or indoors in sealed plastic boxes containing ceramic zeolite drying beads in a bead‐to‐fruit ratio of 1:10. Nutrient content of the dried samples was compared to fresh samples (undried control) obtained from the same batch of fruit. Mango samples tended to reach an equilibrium weight of approximately 18% of their initial weight after 28 to 30 hr of drying in both drying methods, while tomatoes equilibrated at 5% to 6% of their initial weight after 8 to 10 hr of drying in the solar drying cabinet and after approximately 30 hr using drying beads. The content of all three nutrients in solar dried tomato, and of β‐carotene in mango were significantly (P < 0.05) lower than the control. α‐Tocopherol and β‐carotene content in tomato and β‐carotene content in mango were significantly lower than the control in samples dried using drying beads. Drying method had a significant (P < 0.05) effect on nutrient content; ascorbic acid and β‐carotene content were lower in solar dried tomato than in tomato dried with drying beads. For mango, β‐carotene content was lower after solar drying as compared to drying with drying beads. Drying fruit at lower temperatures using drying beads resulted in higher overall nutrient content of the dried fruit. Practical Application: Agriculturalists in developing countries still depend largely on solar drying methods as a means of extending the shelf life and increasing the value of fruit and vegetable products. Zeolite drying beads are reusable and are capable of drying fruit relatively quickly in a controlled environment, and may reduce the degradation of certain nutrients due to heat during solar drying. [ABSTRACT FROM AUTHOR]

Processed fish and fish products have high nutritional value, longer shelf life and fetch better prices on the market in contrast to freshly caught fish which are highly perishable. Processing, however, alters nutrient composition of a product underpinning the need for caution when consuming processed products. The study analyzed the effect of traditional smoking and sun drying on proximate composition (moisture, protein, fat and ash) of Diplotaxodon species locally known as Ndunduma. This is an important commercial cichlid species harvested across the entire Lake Malawi by both artisanal and commercial fishers. Fresh Diplotaxodon fish samples were collected from fishers' boats in the southwestern part of Lake Malawi, Malawi immediately after catch early in the morning. The fish were washed then weighed and thereafter, smoked in a traditional smoking kiln and sun dried on reed mats. Determined percent moisture, protein, fat and ash content for smoked fish were: 12.22±0.05, 55.30±1.67, 25.31±2.78 and 12.96±0.72, respectively, while corresponding values for fish that were sun dried were: 24.28±0.14, 52.80±1.28, 22.36±0.26 and 13.81±0.14, respectively. Overall, results show reduced protein content in processed fish (smoked and sun dried) (P<0.05) although not significantly different in smoked fish (P>0.05). Significantly low moisture content in smoked fish is indicative of a product with longer shelf life since moisture favours rapid microbial growth causing freshness quality deterioration. Although not significantly different, high fat (P>0.05) and ash (P<0.05) in smoked fish is consistent with a nutrient rich product. The study concludes that smoked Diplotaxodon species is more nutritious and may present better storage qualities than sun dried due to relatively low moisture. Caution should, nevertheless, be considered due to the high fat levels to prevent spoilage caused by breakdown of fats. Since smoked products are of high commercial value, fish processors should be encouraged to smoke fresh Diplotaxodon species other than sun drying. [ABSTRACT FROM AUTHOR]

A computational fluid dynamics model was developed to simulate the corn drying process in a solar cabinet dryer. Incident solar radiation was modeled using a dual-band spectrum to simulate the absorption of shortwave radiation by corn and account for the greenhouse effect caused by glazing materials. The performance of the dryer was simulated at fair and overcast weather conditions. The model allowed visualization of temperature, humidity, and air velocity profiles in the dryer. The model was validated with experimental results, which showed an overprediction of temperature (8.5%) and humidity (21.4%). The experimental humidity profile suggests that there was stagnation in the airflow of the dryer, which was accurately predicted by the model. The model was used to simulate the dryer’s performance under overcast conditions, and the predicted moisture removal was 32% less than the simulated fair-weather case. [ABSTRACT FROM AUTHOR]

This study aims to share experience in designing, building, and testing of a portable and energetically autonomous food dehydration system based on the air type building integrated photovoltaic thermal (BIPVT) roof and to perform simulations of drying system performance under different climates. The drying system is based on air-type BIPVT collectors as main heat and electricity sources. BIPVT collectors are metal sheet integrated photovoltaic (PV) modules with the air gap organized under PV modules. The total power of PV panels is 1 kW. In addition, the system comprises a piping system, a fan, batteries, dampers, heat recovery unit, a drying chamber, and an electrical heater for auxiliary heating. The system can work in three operational modes depending on weather conditions. During indoor experiments, the irradiance to heat conversion ratio was obtained, which is the ratio of irradiance power solar on top of the roof to heating power produced by the system. It was about 0.4 kW/kW in mode 1 and 0.5 kW/kW in mode 2. However, the results of the simulations showed that it is possible to achieve the irradiance to heat conversion ratio between 0.3 and 1.2 kW/kW depending on the air flow rate and the operational mode. The results of the simulations during the period June – September showed that the total heat energy produced by the system is 3223 and 3479 kWh in Tallinn and Provence, respectively. However, for autonomous operation for 24/7, the system requires additional electricities of 355 and 142 kWh in Tallinn and Provence, respectively. When the irradiance level is higher than 300 W/m2 in Provence and 400 W/m2 in Tallinn, the system is fully autonomous. [ABSTRACT FROM AUTHOR]

Abstract: The effect of microwave blanching time (0–3 min), followed by dipping in brine solution (sample to solution ratio 0–4) prior to drying of carrot slices and shreds in solar‐biomass hybrid dryer on the final moisture content of the samples, drying rate, rehydration ratio, color change, textural firmness change, and beta carotene content was studied using two‐factor 3 level factorial design. Pretreatment parameters were optimized using response surface methodology. As the microwave blanching time increased, there was an increase in the drying rate, rehydration ratio, and beta carotene content, with minimum changes in textural firmness, color, and final moisture content. Increase in brine solution to sample ratio impacted the drying rate and beta‐carotene content in the samples, positively. Microwave blanching time of 3 min and brine solution to sample ratio of 2 were found to be the optimum pretreatment parameters for drying of carrot slices and shreds. Practical applications: Solar energy is abundantly available in tropical countries like India and this renewable energy can be utilized to preserve food materials, economically. Carrots being seasonal in nature require be drying and preserving for further use during off seasons, and potential of a solar‐biomass hybrid dryer can be tapped to reduce the energy requirement for a high energy requiring processing operation like drying. The study recommends pretreatments to carrot slices and shreds like dry microwave blanching, followed by brine solution dipping of carrot slices and shreds for better quality in terms of faster moisture removal leading to lower drying period, beta‐carotene retention, better rehydration characteristics as compared to control samples, where no such pretreatments were given. This recommendation can be very well be utilized to reduce the energy demand in food processing industry. [ABSTRACT FROM AUTHOR]

Abstract: The physicochemical and antioxidant properties of whole hihatsumodoki (Piper retrofractum Vahl) pepper fruits were evaluated before and after solar‐ and oven‐drying. Desirable dry matter (24% relative mass) and aw (0.50) values were obtained after solar‐drying for 18 hr, and oven‐drying for 24, 6, and 4 hr at 50, 70, and 90 °C, respectively. The color parameters (Hunter a* and b* values) of the fruits were affected by their drying conditions. Principal component analysis was used to determine suitable drying conditions to obtain dried pepper fruits with desirable food and color properties. The piperine contents of the dried pepper fruits were maintained under all of the drying conditions tested. However, solar‐drying for 18 hr and oven‐drying at 90 °C for 6 hr resulted in significant reductions in their total phenol contents and DPPH radical scavenging activities. The results of this study may be useful for optimizing the drying of whole hihatsumodoki fruits. Practical applications: This work aimed to study the effects of solar‐ and oven‐drying processes on the physicochemical properties of an economically important species of pepper fruits, hihatsumodoki. A range of drying conditions was examined, and the optimal conditions were determined to maintain pungency and antioxidant activity while achieving a sufficiently low water activity to prevent microbial growth and spoilage. The present study serves as an important work in providing insights into how the thermal and UV stabilities of piperine and phenolic compounds in hihatsumodoki pepper fruits affect the physicochemical and antioxidant properties when the fruits are subjected to different drying conditions. The work described in this paper will be of use to a wide range of readers interested in optimizing drying processes based on experimental data, and may be applicable to a variety of Piperaceae. [ABSTRACT FROM AUTHOR]

The application of solar drying (SD) and heat pump-assisted solar drying (HPSD) on the retention of flavonoid components, total color changes, and water activity ofClinacanthus nutansLindau leaves were investigated. Analysis of data shows significantly higher extractable yield and flavonoid (orientin and vitexin) percentage during the drying with HPSD. The same drying technique also revealed optimum color values and low water activity. Thin-layer models fitted to the experimental data show that Hii and Law model is suitable for SD, while logarithmic model is able to give a good fit to HPSD. [ABSTRACT FROM AUTHOR]

Solar crops drying as a process has currently become a decisive factor to improve the efficiency in the industrial, residential and farm sectors. Given its considerable importance, different researchers have proposed and developed a great number of theoretical and experimental models to predict the drying kinetics of the process, including the machine and the product. In the use of solar thermic driers, there have been great advances on developing models; however, the major part of these works has concentrated in driers of industrial scale. The unified models that allow predicting temperature profiles and moisture content for many types of crops, using handmade driers to small scales have been less applied. It has been mainly due to the wide diversity of products and the big differences between the existing processes. The purpose of this research is offering a panoramic about the state of the art related to models and present the basic theoretical foundations to develop a model for solar seed drying. [ABSTRACT FROM AUTHOR]

Abstract: The presence of fungi in our foods poses serious health risks as some genera of fungi may produce certain mycotoxins which have carcinogenic, mutagenic, teratogenic, and immunosuppressive effect on humans and animals alike. Fruitbodies of Pleurotus ostreatus were solar dried at a moisture content of 12.5 ± 0.2% and stored in polythene and polypropylene packs, gamma irradiated at doses of 0 (control), 1, 2, 3, 4, and 5 kGy at a dose rate of 1.7 kGy/hr from a Cobalt 60 source (SLL, 515, Hungary) and stored at room temperature 28–30°C for a period of 12 months. Mycological analyses were done at intervals of 0, 3, 6, and 12 months. A total of eleven (11) fungi belonging to eight fungal genera were isolated on both Cooke's and DRBC media; Aspergillus (A. niger, A. flavus, A. fumigatus, A. tamarii), Rhizopus (R. oligosporus), Mucor (M. racemosus), Fusarium (F. oxysporum), Penicillium (Penicillium sp.), Trichoderma (T. viride), and Rhodotorula sp. were recorded. There was a significant (p < .05) reduction in initial mycofloral population by an average of 2.2 log cycles as well as in species numbers with increasing doses of radiation. Radiation sensitivity (D10 values) also ranged between 1.68–2.78 kGy. Gamma irradiation treatment is one way which can enhance food safety through the reduction in potential pathogens and has been recommended as part of a comprehensive program to enhance food safety. [ABSTRACT FROM AUTHOR]

Solar crops drying as a process has currently become a decisive factor to improve the efficiency in the industrial, residential and farm sectors. Given its considerable importance, different researchers have proposed and developed a great number of theoretical and experimental models to predict the drying kinetics of the process, including the machine and the product. In the use of solar thermic driers, there have been great advances on developing models; however, the major part of these works has concentrated in driers of industrial scale. The unified models that allow predicting temperature profiles and moisture content for many types of crops, using handmade driers to small scales have been less applied. It has been mainly due to the wide diversity of products and the big differences between the existing processes. The purpose of this research is offering a panoramic about the state of the art related to models and present the basic theoretical foundations to develop a model for solar seed drying. [ABSTRACT FROM AUTHOR]

The main objective of this investigation was carried out to study the ability of utilizing greenhouse solar dryers for drying of corn in order to obtain the best quality of dried grains for using it as seeds with the least drying time, and comparing with the natural sun drying method. Thus, contributing to increase the productivity. Corn cv. (Giza 168) was used for the experimental work at initial moisture content of 31.73% on dry basis (d.b). Two different drying methods of corn were tested for drying of ear and shelled corn. The two methods were natural sun drying and solar drying using greenhouse type solar dryers at different air velocities (0.5, 1.0 and 1.5 m/s). The experiments were carried out in rice mechanization center at Meet El- Dyba, Kafr El-Sheikh Governorate, Egypt during September 2016. Experiment included the flowing variables 1. Two different drying methods (Solar drying method using greenhouse type solar dryer and natural sun drying method). 2. Two different conditions of corn (complete earshelled corn). 3. Three different air velocity (0.5, 1.0 and 1.5 m/s). High moisture ear and shelled corn was dried by using solar energy for heating air inside a greenhouse and compared with natural sun drying method. The results of quality tests that included standard germination test, vigor test and tetrazolium test for both drying methods for ear and shelled corn recorded high percentages for all treatments except solar drying of ear corn at air velocities 0.5 and 1.0 m/s. The average air temperature inside the solar dryer at air velocities 0.5 and 1.0 m/s reached to 43.9 and 42.4 ˚C respectively. High temperatures killed the germ of corn so the quality tests were reduced. Germination percentage of natural sun dried ear corn was 97 % and for solar dried samples at air velocities 0.5, 1.0 and 1.5 m/s was 79, 81, and 89%, respectively. The corresponding values for shelled corn were 93, 97 and 98 %.and 95 % for natural sun dried ones. The vigor test of dried ear corn recorded 90 for natural sun drying method and 34, 45, and 66% for solar drying at air velocities of 0.5, 1.0 and 1.5 m/s, respectively. The corresponding values for shelled corn were 86, 96 and 97% respectively, and 82 for natural sun dried samples. The recorded drying times were 26, 24 and 28 hours to reduce the moisture content from an initial level of 31.73 to final level of 14.07% (d.b.) for ear corn and for shelled corn were 20, 16 and 24 hours to reduce the moisture content from an initial level of an initial level of 31.73 to final level of 14.07% (d.b.) for ear corn and for shelled corn were 20, 16 and 24 hours to reduce the moisture content from an initial level of 27.23% to 14.12% compared with 46 and 38 hours for ear and shelled corn dried by natural sun drying method. Hourly costs of ear corn drying were 0.95, 0.88, 1.00 and 1.03 L.E/ kg for solar drying at air velocities 0.5, 1.0 , 1.5m/s and natural sun drying respectively. The corresponding values for shelled corn were 0.74, 0.58, 0.89 and 0.96 L.E/ kg. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the effect of traditional sun-drying method (TM) with four alternative dehydration methods [(a) multiple horizontal wires (MHW), (b) multiple vertical pallets (MVP), (c) low greenhouse (LGH) and (d) hot-air dryer treatment (HAD)] on phenolic composition, oenological parameters, aroma potential and browning compounds of musts obtained from dehydrated grapes ( Vitis vinifera cv. ‘Xynisteri’). Dehydrated grapes of the examined cultivar are being used to produce ‘Commandaria’ dessert wine, a protected designation of origin product in Cyprus. LGH and HAD treatments led to a significant reduction of the dehydration period. Soluble solid contents were used to monitor the progress of dehydration process; no changes among the examined dehydration methods in reducing sugar composition were found. Notably, HAD led to a dramatic rise (3.2-fold) of titratable acidity that was obviously not related only to the concentration effect. Furthermore, all dehydration methods concentrated total bound volatiles and induced the formation of brown pigments. Based on the Folin-Ciocalteu index, only HAD and LGH induced a significant increase in total phenolic content in dehydrated grape musts. Subsequently, forty phenolic compounds were identified and quantified by LC-DAD-qTOF-MS. Results showed a significant effect of dehydration methods that vary according to the different groups of phenolic compounds considered. Similarly to Folin-Ciocalteu index, HAD and LGH methods increased significantly the phenolic content in grape musts, whereas MHW and MVP methods increased it slightly higher than the concentration factor. Flavonols, flavan-3-ols and flavanonols were the most affected polyphenolic groups. A significant increment of hydroxybenzoic and hydroxycinnamic acids, the predominant groups of phenolic compounds found in ‘Xynisteri’ grapes, was monitored. Taking into consideration that HAD cannot be exploited under the existing legal framework, LGH showed the greatest potential for the production of high quality dehydrated ‘Xynisteri’ grape must. [ABSTRACT FROM AUTHOR]

In the northern coastal and jungle areas of Peru, cocoa beans are dried using artisan methods, such as direct exposure to sunlight. This traditional process is time intensive, leading to a reduction in productivity and, therefore, delays in delivery times. The present study was intended to numerically characterise the thermal behaviour of three configurations of solar air heating collectors in order to determine which demonstrated the best thermal performance under several controlled operating conditions. For this purpose, a computational fluid dynamics model was developed to describe the simultaneous convective and radiative heat transfer phenomena under several operation conditions. The constructed computational fluid dynamics model was firstly validated through comparison with the data measurements of a one-step solar air heating collector. We then simulated two further three-step solar air heating collectors in order to identify which demonstrated the best thermal performance in terms of outlet air temperature and thermal efficiency. The numerical results show that under the same solar irradiation area of exposition and operating conditions, the three-step solar air heating collector with the collector plate mounted between the second and third channels was 67% more thermally efficient compared to the one-step solar air heating collector. This is because the air exposition with the surface of the collector plate for the three-step solar air heating collector former device was twice than the one-step solar air heating collector. [ABSTRACT FROM AUTHOR]

The drying characteristics of edible seaweed Durvillaea antarctica subjected to hot-air drying at 40, 50, 60, 70, and 80°C were investigated. Desorption isotherm was performed to estimate the equilibrium moisture content. Ten mathematical models were applied on the drying kinetics. The effect of drying temperatures on the proximate composition in this seaweed was also evaluated. Drying process resulted in an apparent increase of the ash and crude protein contents as compared to fresh sample. Midilli-Kucuk model presented the best-fit quality on drying curves. An effective diffusional coefficient from 0.74 × 10−9 to 2.37 × 10−9 m2 s−1 was determined. At last, the energy consumption and efficiency value at 80°C were 13.54 kWh kg−1 and 34.57%, respectively. Furthermore, it is possible to estimate the hot-air drying conditions and obtain a dehydrated product as alternative to solar drying. Practical applications Durvillaea antarctica is a brown seaweed, which has proving to be very significant in terms of its nutritional value and bioactive compounds, which can benefit human health. For this reason, it is expected that its commercialization and consumption will increase strongly. Usually, D. antarctica requires of a drying process due to large amount of water that contain in its fresh state. Traditionally, it is dried under the sun but this operation can cause losses of material, degradation of nutritional values and poor quality on this seaweed. The use of a convective dryer with controlled conditions can be a good alternative to explore for this seaweed. Several mathematical modeling have been widely used for analysis of drying of various marine products such as seaweed to determine the best operation conditions and to understand the water transfer mechanisms from seaweed to surrounding air. [ABSTRACT FROM AUTHOR]

In this research, the effects of different drying methods on the two biomarker compounds concentrations, such as sinensetin (SEN) and rosmarinic acid (RA) of Orthosiphon staminues Benth leaves, flowers, stems and mix were investigated. SEN and RA retention among the dehydrated samples were maximum 83.07% in leaves and 92.54% in flowers, respectively by heat pump assisted solar drying method. For heat pump assisted solar dried samples, there are no significant differences ( p > .05) in the retention of SEN and RA as compared to fresh samples. However, there are significant differences ( p < 0.05) in SEN and RA retention in solar dried leaves, flowers, stems and mix as compared to fresh samples. Besides, an optimization study was performed to evaluate the optimal drying conditions for obtaining high SEN yields from Misai Kucing's leaves, flowers, stems and mixes with high RA contents within the drying parameters. Practical applications Sun drying is the standard practice adopted by most of the Malaysian Orthosiphon staminues (or also known as Misai Kucing) herbal producers due to its low capital and processing cost. However, long drying time was taken by sun drying due to unpredictable weather conditions and the active ingredients are degraded due to very high drying temperature in long processing time under sun exposure. Hence, a combining solar energy and other effective drying method such as heat pump technology are needed. Heat pump assisted solar dryer systems can overcome all the difficulties by solar drying solely and satisfy important demands in industrial drying with respect to product quality control, reduced energy consumption and reduced environmental impact. The objective of this research was to determine the relationship between the drying methods (sun drying and heat pump assisted solar drying) and bioactive metabolites compositions of different parts in Orthosiphon staminues plant. [ABSTRACT FROM AUTHOR]

This article presents a study on the performance of a forced convective multi-pass solar air heating collector (MPSAHC) system assisted with granite as a sensible energy storing matrix. Experimental drying of Roselle was carried out in August 2015 at Solar Energy Research Site of Universiti Teknologi PETRONAS, Malaysia (4.385693° N and 100.979203 S). The present investigation was conducted under the daily average relative humidity, solar irradiance, ambient temperature and wind speed of 64.5%, 635.49 Wm −2 , 32.24 °C, and 0.81 ms −1 , respectively. An average drying rate of 33.57 g (kg m 2 h) −1 was achieved while the system optical efficiency, collector efficiency, drying efficiency and moisture pickup efficiency of 70.53%, 64.08%, 36.22% and 66.95% were obtained, respectively. MPSAHC dryer was 21 h faster with fair color retention when compared to open sun drying approach (OSDA) that was conducted together under the same weather condition. Techno economic analysis reflected a payback period of 2.14 years. However, drying efficiency could be improved if the inlet air humidity can be controlled to favor drying operation. [ABSTRACT FROM AUTHOR]

Daylily flowers is an important vegetable in eastern Asia, widely used in many dishes. Daylily flowers are usually sold in dried forms in the supermarkets. There are a few method for processing fresh daylily flowers, however, no study has been conducted to analyze the effects of the processing methods in the composition of final products. In the present study, a flow-injection mass spectrometric fingerprinting (FIMS) method in combination with principal component analysis (PCA) was used to differentiate two species of daylily flowers (Mengzi and Chongli) with three different treatments (vacuum freeze drying, solar drying and hot-air drying treatments) for each. The results showed the fast and simple FIMS method could successfully differentiate between species (raw material) and treatments among each species. However, the two species could not be discriminated very well after being processed in hot-air drying treatment. The difference in chemical profiles of species and treatments were discussed. [ABSTRACT FROM AUTHOR]

Fruit and vegetable pomaces are co-products of the food processing industry; they are underutilized in part because their high water activity (aw) renders them unstable. Drum drying is one method that can dry/stabilize pomaces, but current drum drying methods utilize conventional, high-environmental-impact heating mechanisms. In this work, a small-scale double drum dryer (20 cm length x 15 cm diameter) was interfaced with a 98.3 m2 External Compound Parabolic Concentrator (XCPC) [solar thermal collector] array designed to produce up to approximately 40 kW of heating power. The conditions for drying prune and tomato pomaces were optimized on this system via a split-plot design. The design had 4 variables: added water, added maltodextrin carrier, dwell time and drum surface temperature. Moisture content, aw and color of the dried pomaces were assessed to determine the effectiveness of the drying. Both pomaces were rendered shelf-stable (aw < 0.6) for all tested conditions. However, prune pomace exhibited a narrower range of aw values than did tomato pomace. Conditions for adequate drying with minimal color change (and thus expected minimal nutrition loss) were established. This work demonstrates the potential for solar thermal energy to provide the heat for drum drying fruit and vegetable pomaces. [ABSTRACT FROM AUTHOR]