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Vacuum freeze drying (VFD) combined with thermal drying can solve the defects of vacuum freeze-dried chives, such as faint flavor, unpleasant color, and taste. However, the mechanisms for enhancing flavor, reducing lightness, and improving taste through combined drying remain to be explored. In this study, the effects of vacuum freeze drying combined with hot air drying, vacuum freeze drying combined with infrared hot air drying, and vacuum freeze drying combined with catalytic infrared drying (VFD-CIRD) on the flavor and quality characteristics of chive leaves and stems were investigated. The results demonstrated that VFD-CIRD had the richest flavor, attributed to the key aromas hydroxyacetone and 2-ethyl-6-methylpyrazine. Combined drying eliminated the wax layer on the surface of chive leaves, which reduced lightness. Furthermore, VFD-CIRD could degrade phenolic compounds in chives, thereby reducing the bitterness. VFD-CIRD has the potential to become the basis for the industrial production of high-quality dried chives. [ABSTRACT FROM AUTHOR]

Copyright of Food & Machinery is the property of Food & Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study investigates the drying characteristics of carrots under different coupling forms of airflow and high-voltage electric fields (parallel flow, PF, and cross flow, CF) using heat pump-electrohydrodynamics (EHD) combined drying. The results show that, compared to single heat pump drying, the combined drying under PF mode reduces carrot drying time by 13.33 %–31.58 %, increases effective moisture diffusivity (Deff) by 17.80 %–32.32 %, increases specific moisture extraction rate (SMER) by 12.25 %–34.26 %. While the combined drying under CF mode reduces carrot drying time by 12.5 %–18.18 %, increases Deff by 7.27 %–13.14 %, increases SMER by 4.64 %–12.58 %. The improvements in parameters under the CF mode are weaker than those under the PF mode. Additionally, the β-carotene content under PF mode is consistently higher than under CF mode. Based on the experimental results, the Modified Page model was improved, yielding an updated model MR = aexp(-(kt)^n), with an R2 value of up to 0.9999–1, which provides theoretical guidance for optimizing the heat pump-EHD combined drying process.

Traditional drying processes used to dry high-quality baijiu yeast-Sporidiobolus johnsonii A do not offer advantages such as high efficiency, high survival rate, and low energy consumption. Therefore, we investigated the damage inactivation mechanism of S. johnsonii A for the spray drying process. Subsequently, the combined drying process and equipment for spray + vacuum-microwave-vibration were designed. The results reveal selective permeability damage and collapse owing to gel and anti-hexagonal phase transitions of the cell membrane, resulting in S. johnsonii A inactivation and massive inactivation at 52 °C with a water content of 0.21 and at 71 °C with a water content of 0.07, respectively. The combined drying process developed in this study successfully dried S. johnsonii A with high efficiency (1.1 h) and excellent quality (85.4 ± 2 %). [ABSTRACT FROM AUTHOR]

[Objective] To improve the drying quality of pumpkins. [Methods] This study conducted experiments on hot air drying, vacuum drying, and combined hot air-vacuum drying, these drying characteristics were evaluated and compared based on unit energy consumption, rehydration ratio, and color difference indicators. Combining BP neural network model with genetic algorithm, combined with entropy weight and weighted scoring method, a multi-objective comprehensive optimization was carried out for the combined hot air-vacuum drying of pumpkins. [Results] Under the same conditions, the highest drying efficiency was hot air drying; And the findings revealed that at drying temperatures was 55 ℃, with a moisture content transition point of 30%, the combined drying method reduced the drying time by 52.63%, compared to vacuum drying. The lowest unit energy consumption was vacuum drying; The worst rehydration performance was hot air drying. The best color was vacuum drying. The optimal drying parameters determined by the genetic algorithm combined with a BP neural network model were a hot air drying temperature of 65 ℃, conversion point moisture content of 50%, and vacuum drying temperature of 56.050 9 ℃. Verification experiments demonstrated that the average relative errors between the genetic algorithm optimized values and the experimental values for unit energy consumption, rehydration ratio, and color difference were 2.5%, 5.53%, and 4.84%, respectively, all lower than 6%. [Conclusion] The combined hot air-vacuum drying of pumpkin integrates the advantages of both hot air drying and vacuum drying, and combined with BP neural network genetic algorithm model can optimize the process parameters for pumpkin hot air vacuum drying.

Grain drying equipment is an important equipment in Chinese agricultural production process, which can significantly improve the quality of grain processing after harvest and reduce the loss rate of mildew and germination during grain storage. At present, the mechanical drying rate of grain in China was only about 30%, and its overall penetration rate still had a great opportunity to improve. The market for grain dryers has great potential for development, and under the encouragement of national policies, the research on the technology, technology and applicability of dryers has been also constantly improved. In recent years, most research on grain drying has focused on process optimization, while there has been less research on grain drying equipment, which has made it difficult to apply excellent process technology and restricted the progress of grain drying equipment. This paper summarized the latest large and medium-sized grain drying equipment and the existing main problems, and put forward some suggestions, which could provide a reference for the research and development of grain drying technology and equipment.

Copyright of Science & Technology of Cereals, Oils & Foods is the property of Science & Technology of Cereals, Oils & Foods Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To understand the moisture transfer mechanism of walnuts during the combination of hot air (HA) and microwave–vacuum (MV) drying (HA-MVD) process, the drying characteristics and moisture diffusion characteristics of walnut during HA-MVD were investigated. The results indicated that the HA-MVD of walnuts occurred mainly in the falling-rate stage. The value of effective moisture diffusivity (Deff) dropped continuously with the decrease in moisture content (MC) during the HA drying, while switching to MV drying could truncate the decrease in Deff and still maintain a high value until the end of drying. The HA temperature, MC of the transition point, microwave power, and MV thermostatic temperature have significant effects on the moisture diffusion characteristics of walnuts. The values of Deff for walnuts ranged from 2.33 × 10−9 m2/s to 6.89 × 10−8 m2/s. The third-order polynomial prediction model of Deff related to the sample MC and drying conditions was established to describe the dynamic change in the Deff of walnuts during the HA-MVD process. The application of MVD in the final stage of drying could rapidly increase the internal vapor pressure of the walnuts, accelerate the diffusion speed of the internal moisture, and re-enhance the drying rate. The findings have practical value for the development of efficient and energy-saving drying methods in the walnut industry. [ABSTRACT FROM AUTHOR]

The combination of vacuum freeze drying (FD) and hot air drying (HAD) has been observed to markedly reduce the volumetric shrinkage of hot air dehydrated products. While the FD can be attributed to concurrently optimizing energy consumption. However, the appearance quality of combined drying materials is still unstable at present. This study aims to clarify the shrinkage mechanism of apple products during the FD-HAD. Four points of moisture transition (moisture contents of dry basis were 1.00, 0.76, 0.53, and 0.33 g/g, respectively) were selected for the combined drying of apples. Shrinkage, texture, microstructure and pore distribution were determined in the dehydration products. The water migration and distribution of the samples were analyzed at the HAD stage using low-field nuclear magnetic resonance (LF-NMR). The results showed that the shrinkage of FD-HAD samples was significantly (P<0.05) better than that of HAD ones. The moisture transition point shared a significant (P<0.05) effect on the shrinkage of the samples (6%-45%). There was no outstanding volumetric shrinkage when the moisture content at the transition point was below 0.53 g/g. The samples were more shrinkable, harder and less crisp, as the moisture content increased at the transition point. There was a great variation in the center collapse. The decrease was found in the porosity and average pore size, with the increase of moisture content at the transition point. FD-HAD treatment saved energy more substantially (23.58%-28.95%), compared with the FD. The unit energy consumption decreased gradually with the increase of water content at the conversion point. The shrinkage of the sample in the FD-HAD occurred in the HAD when the moisture content at the conversion point was greater than 0.53 g/g. The sample was divided into two phases of rising and falling in the HAD, where the volumetric shrinkage of the sample mainly occurred in the rising phase. A three-phase transition of water was found in the sample from the ice crystals to the liquid and water vapor, which was then removed from the sample. There was a rapid decrease in the free water, and little change was measured in the content of bound and immobile water. There was a larger humidity difference between the center and the surface of the sample. The water was migrated from the center to the surface. The ice crystals inside the sample were basically removed by sublimation, and then to reduce the melting of ice crystals, when the moisture content at the transition point was less than 0.53 g/g. The small amount and range of free water and its migration resulted in a small shrinkage of the sample. In summary, the controllable transition point of co-drying controls shrinkage can be expected to reduce the amount and extent of ice crystal melting, as well as the free water migration in the HAD phase of the sample. There was less damage to the microscopic pores caused by moisture migration. This finding can provide the basic data and theoretical reference for the precise regulation of the appearance quality of FD-HAD samples and energy saving. [ABSTRACT FROM AUTHOR]

The paper examines the intensification of drying apple slices to low residual moisture content. It is proposed to use an energy-efficient multi-stage mode of convective drying at 80/60 °C and a combined multi-stage mode with IR radiation and IR convective heating (100 W) + 60°C / 60°C. The paper presents the temperature and kinetic curves and changes in drying speed for the studied dehydration regimes. A formula was obtained for determining the total duration of the process of drying apple slices using a combined method, and a dependence of the Rebinder number for the studied dehydration modes was constructed. Based on the experimental data analysis and generalization of research results, a method of determining the drying intensity based on the average moisture exchange and the average temperature of material heating per minute, at the first stage of drying and during the entire drying time, was proposed for the first time. The efficacy of the proposed modes is confirmed by a reduction in drying duration 1.9 times compared to the stationary mode at a coolant temperature of 60 °C. The obtained dried product is characterized by high recoverability (78-80%) and appropriate organoleptic properties. [ABSTRACT FROM AUTHOR]

In this study, experiments were conducted to investigate the effect of moisture distribution during pre-drying on the microstructure and textural quality of hot air-vacuum freeze dried peach slices. The moisture distribution during the hot air pre-drying process at different temperatures (40, 60 and 80 ℃) and the product temperature during heating were monitored. Three levels of dry-basis moisture content (7, 6 and 5 g/g) were selected as moisture conversion points for each temperature. The color, shrinkage rate, microstructure, pore distribution, textural properties and hygroscopicity of peach crisps were measured. The results showed that drying temperature had a great impact on the moisture distribution during the pre-drying process, but the overall trends of moisture mobility were consistent among the different drying temperatures. The lower the moisture content of the pre-dried sample, the closer the color of the final dried sample to that of the fresh sample. The color of the sample dried at 40 ℃ with a moisture conversion point of 5 g/g was the closest to that of the fresh sample. Drying time had a greater effect on the shrinkage rate than temperature. It took longer to dry peach slices to the same moisture conversion point at 40 ℃ than 60 and 80 ℃. The sample shrank distinctly during both pre-drying and combined drying. There was a significant difference in the pore structure between the freeze-dried and combined dried samples. The sample with a moisture conversion point of 5 g/g had the most heterogeneous pore structure. The average hardness value of the hot air-vacuum freeze dried sample increased by 52.11% compared with that of the freeze-dried sample. The lower the moisture content of the pre-dried sample, the higher the hardness value of the hot air-vacuum freeze dried sample. This study showed that hot air pre-drying can effectively control the crunchiness and hardness of peach crisps. The decrease in the hygroscopicity of the hot air-vacuum freeze dried sample compared with the vacuum freeze dried one may be related to the structure changes during the pre-drying process. In summary, hot air-vacuum freeze drying is conducive to improving the texture quality and storage stability of peach crisps than vacuum freeze drying.

This study analyzes the drying of alfalfa using hot air, infrared and combined drying techniques at different temperatures, irradiation heights and radiant powers. Different temperatures, radiation heights, radiation power and wind speed are used as control factors, and drying time, color, crude protein and specific energy consumption are used as evaluation indicators. After assigning weights to each indicator, the comprehensive evaluation index is calculated. Test results and data analysis show that the drying performance is optimal when the hot air flow velocity is 1.5 m/s, the hot air temperature is 62.1°C, the radiation distance is 10 cm, the radiation power is 1200 w, and the material thickness is 20 mm, it has the best drying performance; its coefficient of determination R2 is 0.9995. The comprehensive evaluation index of alfalfa drying after combined drying is between 1.00 and 1.30, which is overall higher than hot air drying and infrared drying. Combined drying technology can effectively improve the efficiency and quality of the alfalfa drying process. [ABSTRACT FROM AUTHOR]

Image processing techniques are used in several fields and gained popularity in food processing. In this study the drying and shrinkage characteristics of pumpkin slices were determined by using thresholding method. A continuous measurement of the weight change and an imaging of the pumpkin slices to measure the area of the sample before and after drying were performed to define the shrinkage characteristics. The drying times of the pumpkin discs were between 8.5–9 and 55–65 minutes for 2 mm thick samples. Drying in the microwave oven resulted in 85% less time and lower values of water activity were obtained. The shrinkage rate of samples dried by microwave drying method (46–60%) was found to be statistically lower than samples prepared by convection drying method (58–73%) (p < 0.05). Non‐parametric Spearman correlation coefficient technique was used to evaluate the relationship between the moisture content and shrinkage for drying under different conditions. Practical application: With the advancement of image processing technologies, there is significant potential for food safety and preservation. This research will lead to advancements in the fields of food quality and preservation analyses for food manufacturers. Furthermore, this technology can be employed in the food business for quick quality determination for mass production. This research indicates that image processing may be used to evaluate food shrinkage characterization. It is expected that the application of this technology will serve the food sector by optimizing process parameters and energy usage, saving time, and developing sustainable systems, particularly in the large‐scale food industry where mass manufacturing is carried out. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To describe the changes of juicy peach microstructure under different drying methods, microstructure images and cell parameter distribution curves of juicy peach under different moisture ratios were obtained by using paraffin section, micro-imaging and image processing technologies, after treated by five drying methods (i.e. hot-air drying (HAD), vacuum drying (VD), freeze drying (FD), hot-air and vacuum combined drying (HA-VD), freeze and hot-air combined drying (F-HAD)). The effect of drying methods on microstructure parameters (i.e., cell area, cell perimeter, cell roundness, cell wall surface roughness and porosity) were analyzed via cell parameters distribution curves. Fitting equations were built by polynomial fitting to describe the correlation between cell parameters and moisture ratios. The results showed that microstructural parameters of juicy peach primarily changed in the first half process (moisture ratio>0.5) of hot air drying and second half process (moisture ratio

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Aeronautical Science Bulletins / Repüléstudományi Közlemények is the property of National University of Public Service and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The object of research is the process of convective and combined drying of apple raw materials treated before dehydration in an ultrasonic bath. The use of pretreatment solves the issue of intensifying the dehydration process and maintaining the quality of the product. Sonication for 5 min reduces the dehydration process by 13.7 %, and at 10 min processing – by 27.8 % compared to traditional convective drying. With increasing processing time to 20 minutes, the dehydration rate deteriorates. Sonication of raw materials for 5 minutes under combined heating does not intensify the dehydration process, and within 10 and 20 minutes it reduces the efficiency of moisture removal. When processed for 10 minutes, the time to reach the final moisture content is increased by 17.2 %, and at 20 min – by 23.4 % compared to control samples. Regardless of the processing time, there is a decrease in the maximum temperature of the samples in the combined drying process. When processed for 5 minutes, the maximum temperature of the samples decreased by 4.3 %, and with 10 and 20-minute processing – by 8.6 % and 12 % compared to the temperature of samples without sonication. The results are explained by the "sponge effect" caused by ultrasonic vibrations and the phenomenon of cavitation that occurs in the liquid during the action of the ultrasonic field. The peculiarity of the pre-sonication before drying is the possibility to intensify the convective dehydration process without increasing the heat carrier's temperature. The use of this type of processing in a combined energy supply will solve the problem of preserving the quality of the finished product by reducing the maximum temperature of the raw material. The research reported here could be a prerequisite for practial design of an energy-efficient electrical system for drying fruit and vegetable raw materials. [ABSTRACT FROM AUTHOR]

To understand the moisture transfer mechanism of walnuts during the combination of hot air (HA) and microwave–vacuum (MV) drying (HA-MVD) process, the drying characteristics and moisture diffusion characteristics of walnut during HA-MVD were investigated. The results indicated that the HA-MVD of walnuts occurred mainly in the falling-rate stage. The value of effective moisture diffusivity (Deff) dropped continuously with the decrease in moisture content (MC) during the HA drying, while switching to MV drying could truncate the decrease in Deff and still maintain a high value until the end of drying. The HA temperature, MC of the transition point, microwave power, and MV thermostatic temperature have significant effects on the moisture diffusion characteristics of walnuts. The values of Deff for walnuts ranged from 2.33 × 10−9 m2/s to 6.89 × 10−8 m2/s. The third-order polynomial prediction model of Deff related to the sample MC and drying conditions was established to describe the dynamic change in the Deff of walnuts during the HA-MVD process. The application of MVD in the final stage of drying could rapidly increase the internal vapor pressure of the walnuts, accelerate the diffusion speed of the internal moisture, and re-enhance the drying rate. The findings have practical value for the development of efficient and energy-saving drying methods in the walnut industry.

Copyright of Storage & Process is the property of Tianjin Academy of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hot air drying is the most common drying and processing technology for agricultural products. However, the shortcomings of single hot air drying technology limit its efficient and high-quality application. Coupling with the characteristics of two or more drying technologies, the combined drying technology can form complementary advantages. In this paper, the existing superheated steam-hot air, ultrasonic-hot air, freezing-hot air, microwave-hot air, radio frequency -hot air, infrared -hot air, heat pump -hot air and vacuum -hot air in total 8 kinds of combined hot air drying technology applications and related equipment were comprehensively summarized, whereas further applicable conditions and equipment operating conditions were compared. Finally, the development trend and challenges of hot air and its combined drying technology were discussed, which provided a reference for the efficient application of hot air and its combined drying technology in actual production and life. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of vacuum freeze drying combined with catalytic infrared drying (FD-CIRD) process on aromas, free amino acids, reducing sugars and free fatty acids in chive leaves and stems. Gas chromatography-mass spectrometry combined with multivariate data analysis revealed that dipropyl disulfide was the key aroma that distinguished the differences between chive leaves and stems. The key aromas benzeneacetaldehyde, decanal and 1-octen-3-ol enhanced FD-CIRD chive leaves and stems aromas. The free amino acid content was highest at FD-CIRD stage in all samples except for the control (FD), while the reducing sugar content was lowest. The content of unsaturated fatty acids gradually decreased at FD stage and increased at FD-CIRD stage. Additionally, correlation analysis revealed that phenylalanine was a potential precursor of benzacetenealdehyde, oleic and linolenic acids were potential precursors of decanal and 1-octen-3-ol. Therefore, FD-CIRD technique helps to improve the sensory profile of dried chives. [Display omitted] • First study on aroma changes in drying chive leaves and stems. • Pearson reveals the relationship between aroma precursors and key aroma compounds. • Metabolic pathways of key aroma compounds hypothesized. • Benzeneacetaldehyde, decanal, and methional are key aromas in FD-CIRD chive leaves. • (E)-2-heptenal and 1-octen-3-ol are key aromas in FD-CIRD chive stems. [ABSTRACT FROM AUTHOR]

As one of the important oil crops in the world, peanuts occupy a pivotal position in crops. Fresh harvested peanut fruit are susceptible to mildew and aflatoxins due to their high moisture content, thus affecting the safety of use and reducing the economic value of peanuts. The timely drying of peanut fruit after harvest can effectively inhibit the growth and reproduction of microorganisms and molds, reduce the effects of environmental temperature and humidity on peanut storage, and ensure the quality and safety of peanuts. This paper summarizes the research status of peanut fruit drying technology and equipment at home and abroad, introduces various drying methods of peanuts fruit and corresponding drying equipment, sum up the existing problems, proposes relevant research recommendations, providing reference for peanut fruit drying technology equipment research.

The drying characteristics of yam slices using heat pump-electrohydrodynamics (EHD) combined drying were studied under the conditions of the drying temperatures of 50–60 °C, the voltages of 80–100 kV and the wind speeds of 1∼3 m/s. The results show that compared with the single heat pump drying, the combined drying can effectively reduce the drying temperature by approximately 5 °C. This is relatively friendly to heat sensitive materials and can also improve the running performance of the heat pump system. Furthermore, the sensory score is increased by approximately 21.4% and the specific energy consumption of combined drying at the voltage of 100 kV is reduced by approximately 27.8%. Under the later stage of the combined drying, the wind speed can be reduced to save energy consumption. Through the analysis of model parameters, Page model is more consistent with the variation law of drying experimental data. This paper provides practical guidance for optimizing the process of yam slices using heat pump-EHD combined drying.

The present study aimed at investigating the use of a drying system combining the concept of low-pressure superheated steam drying and heat pump drying for fish. The effects of various drying medium pressures on the temperature field, airflow field, drying time, equipment performance as well as the power consumption of the drying process were investigated and discussed. Four comparative tests with different initial pressures were carried out according to a specified drying process by the combined drying system. The results showed that when the vacuum was high, the temperature field and airflow field in the drying chamber were more uniform. Due to the poor heat transfer performance of the drying medium at high vacuum, the drying time increased with a decrease in initial pressure. It was also found that with the decrease in drying medium pressure, the power consumption of the heat pump and the axial fans was reduced, while the power consumption of the electric heater went up. Overall, the total power consumption is directly proportional to the drying medium pressure. [ABSTRACT FROM AUTHOR]

Xinjiang quince peels (XQP) are rich in bioactive compounds and have anti-tyrosinase potential. However, due to their short shelf life, effective preservation techniques are needed to retain their nutritional and medicinal properties. While freeze drying (FD) is effective, combining FD with hot air drying (HAD) offers greater efficiency. The study aimed to evaluate the effects of freeze-hot air drying on the physicochemical properties and anti-tyrosinase activity of XQP. The results showed that peels subjected to FD for 18 h followed by HAD for 0.3 h (FD18-HAD0.3) had the highest contents of total phenolics, total flavonoids, chlorogenic acid, rutin, and ascorbic acid, while reducing drying time by 25 % compared to FD alone. FD18-HAD0.3 peels also showed the highest anti-tyrosinase activity, with the smallest IC 50 value (7.84 ± 0.03 mg/mL). The study concludes that FD18-HAD0.3 showed potential as the optimal drying process for XQP. [Display omitted] • Freeze drying for 18 h followed by hot air drying for 0.3 h (FD18-HAD0.3) reduced drying time by 25 % compared to FD alone. • FD18-HAD0.3 peels showed the highest anti-tyrosinase activity and active compound content. • Freeze-hot air drying increased the total flavonoids in quince peels. [ABSTRACT FROM AUTHOR]

Cultivation and use of Virginia 202 broadleaf skeletal variety for the production of smoking tobacco has broad prospects. Problems of post-harvest processing of large leaves with a massive midrib consist in high energy costs with an artificial drying method or the provision of facilities for long-term natural drying. The aim of the research is to apply physical method of cutting the leaf midrib to intensify drying and to determine the effect of this technique on the quality indicators of raw materials. It has been found that the technique of cutting the midrib on the Virginia 202 variety contributes to a significant optimization of the drying process without reducing the quality of raw materials. The drying time of leaves with the combined method is reduced by 2,8 times, with the natural method – by 2,3 times, and the quality indicators of raw materials improve. Commercial quality is characterized by the yield of 1 commercial grade, for combined drying the yield of 1 grade has increased in comparison with the control sample by 27% and amounted to 86,5%, with natural drying – the increase in yield is 4%. Cutting the midrib increases the fiber yield by 3–5% and contributes to an increase in the volumetric-elastic properties of the fiber, providing an economical consumption of raw materials for the production of smoking articles, the consumption is 676,8–753,8 g/1000 pcs. The gustatory quality improves, raw materials with a cut midrib have optimal values of the ratio of carbohydrate-protein balance in the range of 1,08–1,5, the strength is preserved due to the lower consumption of nicotine during the shorter drying period, in comparison with drying the leaf without cutting the midrib. Cutting the midrib in Virginia 202 is cost effective.

In this paper, a multi-heat source complementary system of combined drying was designed, which used three heat sources, solar energy, heat pump and combustion furnace, with two drying technologies, hot air drying and vacuum drying. It had the advantages of saving drying energy consumption and improving product quality. The simulation model of the multi-heat source complementary system of combined drying was established based on TRNSYS. Using the meteorological parameters of Xi'an as input, and a comparison of experiments and simulations verified the correctness of the model. The overall error is between 2.0% and 8.9%. The model predicted the system's performance parameters, operating energy consumption, and operating costs. The results show that the operating energy consumption of the system is affected by season, with solar energy and heat pumps being more significant. The average monthly COP of the heat pump system is between 2.4 and 3.62, and the COP of the system decreases after the addition of auxiliary electric heating. The annual operating cost of the multi-source complementary heating mode is reduced by the maximum of 42.6% compared with other heating modes, its carbon emission is reduced by the maximum of 33.1% compared with other heating modes, and the minimum payback period is 1.64 years compared with different heating modes, thus reducing energy consumption and cost. [ABSTRACT FROM AUTHOR]

Copyright of Science & Technology of Cereals, Oils & Foods is the property of Science & Technology of Cereals, Oils & Foods Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rice analog is a kind of ready to eat food prepared by twin-screw extruder. Few people study the drying process of wet-extruded foods and the effects of extrusion parameters on product properties based on multi-level. In this research, the experimental investigation of drying was a two-stage procedure: the evaporation of free water rapidly at first and then expansion at high temperature. The influence of the interaction of extrusion parameters on the physiochemical properties was analyzed by using response surface methodology and principal component analysis. Results showed that with regard to microwave drying in the first step, improving drying efficiency, but made the water distribution uneven. The first and second drying had opposite effects on solubility, peak viscosity, and setback of extruded products. This impact of feeding speed was most evident in hardness. Temperature was the most predominated factor for residence time, final viscosity, water-holding capacity, hardness, adhesiveness, and chewiness. The influence of interaction of extrusion parameters to the properties of rice analogs was orderly. Except for the interaction between feeding speed and screw speed, chewiness was influenced deeply by other interactions. The pasting properties were negatively correlated with elasticity, cohesion, and adhesiveness, but positively correlated with compression work. The adhesiveness had a good reference for optimizing processing parameters and control the properties of extruded foods.

Purple cabbage is one of the world's most widely consumed vegetables with high nutritional values containing the antioxidants and anti‐inflammatory activity of anthocyanins, vitamins, and minerals. But due to rapid postharvest quality decay, novel processing techniques including drying are required. In order to determine the conditions of combined microwave and hot air drying for purple cabbage, factors affecting the drying process including microwave density, hot air temperature, and the dry base water content at conversion point were investigated using the anthocyanin content, DPPH antioxidant capacity, chewiness, △E, rehydration ratio, and average drying rate as responses. The combined drying conditions were optimized considering three independent variables at three different levels by response surface methodology. The results showed that the processing parameters of purple cabbage with combined microwave and hot air drying technology were microwave density at 2.5 W/g, moisture content of conversion point at 4.0 g/g, and hot air temperature at 55°C. Under these conditions, the anthocyanin content, DPPH antioxidant capacity, chewiness, △E, rehydration ratio, average drying rate, and overall score of the dried purple cabbage were 175.87 mg/100 g, 87.59%, 4,521.468 g, 26.5, 4.3, 0.76 g/min, and 0.785, respectively. Therefore, combined microwave and hot air drying technology is an effective, suitable method for drying purple cabbage. [ABSTRACT FROM AUTHOR]

Native potato flour is one of the functional additives for dough making in food processing to meet the increasing healthy food requirements. To explore an efficient combination drying methods for native potato flour processing, different drying treatments including hot air (AD), freeze-drying (FD) and radio frequency (RFD) were introduced and investigated in this study. The associated color, thermal, pasting, crystalline, rheological, and morphological properties of the potato flour were investigated and evaluated systematically. The gelatinization temperature of potato flour increased from 63.73 to 69.47 °C with drying temperature increased, which indicated the thermal stability of the flour can be strengthened by drying temperature. The gelatinization enthalpy, viscosity, and relative crystallinity of the dried potato flours decreased as the treatment temperature increase, which indicated the extension of thermal denature as the effect of increasing drying temperature. It is worth to note that the RFD combined method has the most efficient drying rate and moderate heat damage. Therefore, combined drying methods are meaningful for native potato flour processing, which might be valuable for industrial development. [ABSTRACT FROM AUTHOR]

Hot air drying (HAD) at temperatures below the spontaneous evaporation temperature could be combined with microwave (MW) radiation as a thermal energy source in order to reduce the drying time. A photon flux in the microwave range interacts with dipolar molecules (water) through orientation and induction, producing electrical energy storage and thermal energy accumulation and generating an increase in the internal energy of food. The different mechanisms involved in water transport could change when the microwave penetration depth exceeds the sample characteristic dimension of mass transport. The aim of this paper is to determine the effect of MW in the combined HAD-MW drying of raw potato in order to obtain the real driving forces and mechanisms involved in the water transport, with the purpose of optimizing the MW power used. For this purpose, combined drying was carried out on potato samples (0, 4 and 6 W/g). The sample surface temperature was monitored by infrared thermography, and the sample mass was measured continuously through a precision balance. In parallel with continuous drying, another drying treatment was performed at different times (20, 40, 60, 90, 120, 180, 420 min) and conditions (0, 4 and 6 W/g) to analyze the dielectric properties, mass, moisture, volume and water activity. The results show that it is possible to monitor combined drying by infrared thermography, and it can be concluded that the convection heating is mostly transformed into surface water evaporation, with negligible thermal conduction from the surface, and microwave radiation is mostly transformed into an increase in the potato's internal energy. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to determine the effect of osmotic dehydration (OD) using fruit concentrates (apple, pear, pineapple, sour cherry, blackcurrant, and chokeberry), before combined drying involving convective drying and vacuum-microwave finish drying, on the drying kinetics and physiochemical parameters (dry weight, water activity, content of l-ascorbic acid, sugars, organic acids, and phenolic compounds). Moreover, biological activities, including antioxidant, antidiabetic, and anticholinergic activities, of the dried Japanese quince fruit and osmotic fluids before and after osmotic dehydration have been assessed. The chokeberry concentrate reduced the final moisture ratio by half compared with the non-OD Japanese quince fruit, and the pineapple and sour cherry concentrates hindered the dehydration process during vacuum-microwave drying. OD significantly shortened the combined drying time compared with non-OD samples. The OD Japanese quince fruit was characterized by an increased content of sugars (up to 20 times more) and a significant reduction in the content of organic acids (even 77% reduction compared with non-OD fruit). Total phenolic content and antioxidant capacity of OD fruits decreased, but increased inhibition potential of α-amylase, acetylcholinesterase, and butyrylcholinesterase was observed. Osmotic fluids were also analyzed before and after the OD, and the following changes were found: reduction of sugars and increase of organic acid content, increase in phenolic content, antioxidant and antidiabetic potential, regardless of the concentrate used. To sum up, the osmotic dehydration process has the potential to modulate the chemical composition and biological properties of the Japanese quince fruit. [ABSTRACT FROM AUTHOR]

Broccoli is considered one of the attractive raw materials for dehydrated vegetables owing to its high nutritional value. However, information about how drying methods affect the physicochemical and nutritional properties of broccoli is limited. In this study, broccoli pieces were subjected to freeze drying (FD), hot air drying (HAD), microwave vacuum drying (MVD), vacuum drying (VD), MVD combined with HAD (MVD + HAD), and MVD combined with VD (MVD + VD). Quality attributes of dehydrated broccolis were contrasted in terms of color, texture, volume shrinkage, nutritional components, antioxidant activity, and rehydration capacity. Results demonstrated that FD better preserved the nutrients while HAD displayed the worst effect. The combination of MVD + HAD and MVD + VD resulted in higher retention of nutritional compositions, better antioxidant activity, and lower energy consumption than that of HAD. Furthermore, combined drying processing exhibited similar rehydration capacity but lower hardness compared to that of HAD. [ABSTRACT FROM AUTHOR]

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The chemical components and cell structure of fruit and vegetable tissues are the main factors affecting the textural properties of fruit and vegetable crisps, while the pore structure formed inside the crisps determines their specific crispness. This study investigated the factors influencing the textural properties of different fruit and vegetable crisps by examining the differences between the chemical components, cell structures, pore-forming structures of six different fruits and vegetables. The results showed that there were large differences between the chemical components, cellular structure and pore structure among different fruits and vegetables. The chemical components in the raw materials of fruits and vegetables were the main factors affecting the textural properties of fruit and vegetable crisps, while the cellular structure was a secondary factor. The starch in starchy fruits and vegetables supported the structure of the product, which in turn increased its firmness. The chelating pectin (CSP) content of non-starchy fruits and vegetables was the main factor influencing hardness, cell wall material (CWM) content was the primary element affecting crispness. The pore structure of different fruit and vegetable crisps was mainly dominated by connected pores, with pore diameters mainly distributed between 20 and 150 μm. The isolated pores in the pore structure were the major elements impacting the textural properties of the product, followed by porosity. [Display omitted] • Chemical components and cellular structures of fruits and vegetables were analyzed. • Pore structure of fruit and vegetable crisps were investigated by using CT technology. • Chemical components were the main factors affecting the texture. • Chelating pectin could affect the hardness, cell wall could affect brittleness. • Isolated pores in the pore structure impact significantly the texture. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the influence of different drying methods on physicochemical parameters of 3 saskatoon berry cultivars: 'Honeywood', 'Smoky' and 'Martin'. Convective drying (CD), microwave-vacuum drying (MVD) and combined drying (CD/MVD) significantly affected moisture content, water activity and colour. Among polyphenolic compounds, 10 flavan-3-ols, 7 anthocyanins, 8 phenolic acids and 11 flavonols were identified by the UPLC-PDA-Q/TOF-MS system in dried saskatoon berries. The total content of identified polyphenolic compounds present in dried saskatoon berries ranged from 21.4 to 66.3 g/kg dry matter, for respectively 'Martin' and 'Smoky'. The strongest ability of extracts to scavenge ABTS radical cations was noted for 'Honeywood', followed by both 'Smoky' and 'Martin'. Antioxidant capacity of products was connected with the content of polyphenolic compounds. 'Honeywood' and 'Smoky' can be best recommended for the production of dried merchandise. The microwave vacuum drying at 480 W with reduction to 120 W give product with the quality similar to this obtained by freeze drying, especially when it comes to the retention of polymeric procyanidins and flavonols present in the fruit. In conclusion, quality of dried saskatoon berry can be successfully moderated by appropriate selection of drying techniques and parameters. • 38 polyphenolic compounds were identified in dried saskatoon berry. • Similar quantity of polyphenolics can be obtained after microwave vacuum and freeze drying. • Polyphenols of saskatoon berry can be retained by microwave-vacuum drying technique. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this research, the effect of microwave pre-treatment on qualitative characteristics and sensory properties of air-dried potato stickswas investigated. Different powers (180-900W) and times (1-5 minutes) of microwave were used before air-drying of samples. The moisture content, rehydration, shrinkage, browning, colour indices and sensory properties (taste, colour, shape, strength, and total acceptance) of potato samples were evaluated after the drying process and the response surface method (RSM) was used to determine the optimal conditions for the microwave treatment. Used for the highest levels of physicochemical and sensory properties. results showed that, with increasing the power and time of the microwave oven resulted in an increase in the moisture content, shrinkage, rehydration and total colour change of the samples. Sensory evaluation results showed that in the microwave pre-treatment, only the scores of the taste and colour of potato sampleswere influenced by the microwave power and time. According to the results of optimization by the surface response method, the power of 180Watts and the time of 3.5 minutes for the microwave pre-treatment were introduced as optimum conditions. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hot air drying (HAD) at temperatures below the spontaneous evaporation temperature could be combined with microwave (MW) radiation as a thermal energy source in order to reduce the drying time. A photon flux in the microwave range interacts with dipolar molecules (water) through orientation and induction, producing electrical energy storage and thermal energy accumulation and generating an increase in the internal energy of food. The different mechanisms involved in water transport could change when the microwave penetration depth exceeds the sample characteristic dimension of mass transport. The aim of this paper is to determine the effect of MW in the combined HAD-MW drying of raw potato in order to obtain the real driving forces and mechanisms involved in the water transport, with the purpose of optimizing the MW power used. For this purpose, combined drying was carried out on potato samples (0, 4 and 6 W/g). The sample surface temperature was monitored by infrared thermography, and the sample mass was measured continuously through a precision balance. In parallel with continuous drying, another drying treatment was performed at different times (20, 40, 60, 90, 120, 180, 420 min) and conditions (0, 4 and 6 W/g) to analyze the dielectric properties, mass, moisture, volume and water activity. The results show that it is possible to monitor combined drying by infrared thermography, and it can be concluded that the convection heating is mostly transformed into surface water evaporation, with negligible thermal conduction from the surface, and microwave radiation is mostly transformed into an increase in the potato’s internal energy.

Drying is known as the best method to preserve fruits, vegetables, and herbs, decreasing not only the raw material volume but also its weight. This results in cheaper transportation and increments the product shelf life, limiting the food waste. Drying involves the application of energy in order to vaporize and mobilize the moisture content within the porous products. During this process, the heat and mass transfer occurs simultaneously. The quality of dehydrated fruits, vegetables, and aromatic herbs is a key problem closely related to the development and optimization of novel drying techniques. This review reports the weaknesses of common drying methods applied for fruits, vegetables, and aromatic herbs and the possible options to improve the quality of dried products using different drying techniques or their combination. The quality parameters under study include color, bulk density, porosity, shrinkage, phytochemicals, antioxidant capacity, sugars, proteins, volatile compounds, and sensory attributes. In general, drying leads to reduction in all studied parameters. However, the behavior of each plant material is different. On the whole, the optimal drying technique is different for each of the materials studied and specific conditions must be recommended after a proper evaluation of the drying protocols. However, a novel or combined technique must assure a high quality of dried products. Furthermore, the term quality must englobe the energy efficiency and the environmental impact leading to production of sustainable dried products.

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study is to find a better drying method to replace conventional hot air drying (HAD) in terms of faster, energy efficient and better product quality. Two alternative drying techniques, microwave combined with hot air drying (MHD) and microwave vacuum drying (MVD), are compared in this study to dry peeled and destoned longan fruit. Both MHD and MVD reduced the drying time up to 48 % and energy consumption as compared to HAD. These techniques provided lower product redness, yellowness and shrinkage but higher lightness and porous structure as compared to HAD. MVD reduced hardness and toughness of the dried product. MHD provided the highest preference score in terms of colour and shape and was as acceptable as the commercial product dried by HAD. MHD is the most suitable method for longan drying. [ABSTRACT FROM AUTHOR]

The aim of this study was to select an appropriate drying technique from air-impingement jet drying (AIJD), hot air drying (HAD) and microwave drying (MWD) which can be combined with freeze drying (FD). Results showed that AIJD with relatively high efficiency, low energy consumption and good drying quality was suitable to be combined with FD. To further improve the drying technology of kiwifruits, the energy consumption and quality of dried kiwifruit with different conversion point during combined FD and AIJD were also tested. The energy consumption obtained for AIJD+FD and FD+AIJD was lower than that obtained for FD alone. Among the products, the kiwifruit processed by AIJD+FD not only showed better attractive green colour and higher sweetness perception, but also revealed higher rehydration ratio than FD and FD+AIJD kiwifruits, which was positively related to microstructure changes. The best AIJD+FD process, from nutrient retention and antioxidant activity considerations, was the combination of 65 min AIJD pre-drying and FD finish drying. Therefore, AIJD pre-drying and FD finish drying as a promising way with short drying time and strong nutrient retention capacity may be applied to the drying processing of agricultural products. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate and compare different drying methods (microwave, hot air + microwave, and osmotic dehydration + microwave) in raspberries (cv. Heritage). A portion of raspberries was pretreated with osmotic dehydration (60°Brix sucrose solution at 20°C for 360 min) and another with hot air drying (HAD) (1.5 m/s air speed at 60°C for 300 min). Pretreated raspberries were then dried by microwave and at three different intensities (3.5, 7.5, and 11 W/g). Physicochemical properties (moisture content, water activity, and drying rate) and quality parameters (optical properties, mechanical properties, antioxidant capacity, and rehydration capacity) of dried raspberries were evaluated. Results showed that the microwave drying (MWD) at 7.5 W/g (50 min and final temperature of 79 ± 5.1°C) allowed a high yield of dried raspberries. The combined processes were not efficient to accelerate the decrease of moisture content, due to the low drying rate of the pretreatments. In terms of quality, none of the drying processes allowed a high retention of the antioxidant capacity. However, they allowed an appropriate rehydration performance. The combination of HAD with MWD allowed obtaining a good appearance and desirable texture on the dried product. Thus, this last option seems to be the best among the drying methods tested, but additional studies are required to improve the efficiency of the process and the effect on the antioxidant capacity during drying. [ABSTRACT FROM AUTHOR]

The drying of coal slime with high moisture content is indispensable for the majority of its industrial applications. In view of the low drying rate at the falling-rate drying period during the conventional drying process, hot-air drying followed by microwave drying, a featured deep drying method, can fundamentally solve this problem and achieve fast and efficient dewatering. In this study, the combination of hot-air and microwave drying to dry coal slime was presented, the general behavior of combined drying method was investigated at a combined fixed bed reactor with hot-air in the temperature range of 120–200 °C and a microwave oven with a maximum power of 800 W. The critical point of hot-air drying, also termed transition point at which hot air drying switched into microwave drying, were experimentally determined and the results showed that the moisture contents of the critical points were about 15% for the samples used. Furthermore, the effects of different target moisture contents and microwave powers on the drying performance and energy consumption of combined dewatering were studied. The results showed that microwave drying could significantly elevate the drying rate when the coal slime reached the critical moisture contents during the hot-air drying method, which indicated that combined drying was an effective method to achieve deep drying of coal slime with a significant reduction in total drying time. [ABSTRACT FROM AUTHOR]