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Drying is a crucial unit operation within the functional foods and biopharmaceutical industries, acting as a fundamental preservation technique and a mechanism to maintain these products' bioactive components and nutritional values. The heat-sensitive bioactive components, which carry critical quality attributes, necessitate a meticulous selection of drying methods and conditions backed by robust research. In this review, we investigate challenges associated with drying these heat-sensitive materials and examine the impact of various drying methods. Our thorough research extensively covers ten notable drying methods: heat pump drying, freeze-drying, spray drying, vacuum drying, fluidized bed drying, superheated steam drying, infrared drying, microwave drying, osmotic drying, vacuum drying, and supercritical fluid drying. Each method is tailored to address the requirements of specific functional foods and biopharmaceuticals and provides a comprehensive account of each technique's inherent advantages and potential limitations. Further, the review ventures into the exploration of combined hybrid drying techniques and smart drying technologies with industry 4.0 tools such as automation, AI, machine learning, IoT, and cyber-physical systems. These innovative methods are designed to enhance product performance and elevate the quality of the final product in the drying of functional foods and biopharmaceuticals. Through a thorough survey of the drying landscape, this review illuminates the intricacies of these operations and underscores their pivotal role in functional foods and biopharmaceutical production. [ABSTRACT FROM AUTHOR]

During drying herbs, the aim is to preserve their bioactive properties and characteristic aroma, which requires choosing a drying method and parameters that minimize degradation. In this study, the effects of convection and vacuum drying methods on peppermint (Mentha piperita L.), sweet basil (Ocimum basilicum L.), and lemon balm (Melissa officinalis L.) were compared. Fresh herb leaves were dried at 35 °C (using both methods) with an airflow of 0.5 m·s−1 for convection (CONV) and with reduced pressure (300 mbar) for the vacuum method (VAC). Physical and chemical properties were measured (color measurement in the L*a*b* system, weight loss, profile of volatile compounds, total phenolic content (TFC), total flavonoid content (TFC), and total antioxidant activity (TAA)). After drying, a reduction in the brightness of the leaf color and the proportion of red color was observed in most replicates (e.g., for peppermint—control sample L* = 43.11, CONV sample L* = 40.21, VAC sample L* = 37.30). Water evaporated by varying degrees depending on the herb species and the drying method as follows:. The TPC of peppermint was 332.44 mg gallic acid equivalent (GAE)/100 g of sample for CONV and 451.38 for VAC; for sweet basil sequentially: 80.59 and 105.63 GAE/100 g; for lemon balm 248.31 and 314.41 GAE/ 100 g. TFC of peppermint was 244.12 mg quercetin/100 g of sample for CONV and 261.92 for VAC; sweet basil sequentially: 76.91 and 83.31 mg quercetin/100 g; lemon balm 186.50 and 203.87 mg quercetin/100 g. The TAA of peppermint was 84.28% for convection drying, 87.49% for vacuum drying, and sweet basil, it was 20.35% and 47.35% sequentially, and for lemon balm, it was 87.67% and 89.69%. The vacuum method was statistically more effective in preserving the polyphenols and flavonoids in the herbs. Different drying methods also affected the volatile compounds recognized in dried herbs using the Electronic Nose. [ABSTRACT FROM AUTHOR]

The effects of three drying methods, hot air (HA), microwave (MW), and radio frequency (RF), on the protein structure and texture properties of Chinese dried noodles were investigated. The results of the Raman spectra showed that the main change in the secondary structure is an increase in the number of β-sheets, and the main change in the tertiary structure was an increase in the gauche-gauche-gauche content. Microstructure analysis showed that dielectric drying (MW and RF) enables the dough to form a more ordered network structure. In addition, dielectric drying reduced the content of free sulfhydryl groups, increased the content of glutenin macropolymer, and enhances the degree of protein aggregation, as evidenced by size-exclusion high-performance liquid chromatography and fluorescence spectroscopy. The results of the thermogravimetric analysis also demonstrated that dielectric drying enhances the stability of the protein network by enhancing the cross-linking of gluten proteins. The results of the quality characteristics analysis showed a significant increase in textural and cooking properties of the dielectric dried noodles. This study showed that dielectric drying affects the functional properties and quality of the final product by changing the conformation of the protein; this change is most evident in MW drying. [ABSTRACT FROM AUTHOR]

Pectin is a natural complex carbohydrate widely used in the food, chemical, cosmetic and pharmaceutical industries. Hawthorn fruit is a new source for extracting pectin. This study investigated the effects of different drying methods on the characterisation of hot-air-dried hawthorn fruit pectin (ADHFP), microwave-vacuum-dried hawthorn fruit pectin (MVDHFP) and conventional freeze-dried hawthorn fruit pectin (CFDHFP). The apparent viscosity, monosaccharide composition, molecular weight (MW), chemical structure, esterification degree, gel properties and microstructure were compared. Monosaccharide analysis showed that hawthorn fruit pectin (HFP) is composed of glucose (Glu), rhamnose (Rha), galactose (Gal), mannose (Man) and galacturonic acid (GalA). Fourier transform infrared spectroscopy (FTIR) showed no significant structural differences in the three types of pectin. At a concentration of 3% (w/w) in water, all three types of pectin showed pseudoplastic behaviour. However, different drying conditions affected the MW, GalA content, degree of esterification (DE) and gelation capacity of pectin. CFDHP had the highest MW and DE, and the gels formed by CFDHP had the highest hardness, viscosity and chewiness and were bound more tightly to water. ADHFP had the highest GalA content and the lowest number of side chains. Compared with commercial citrus pectin, HFP has high potential in food application. [ABSTRACT FROM AUTHOR]

Grape pomace is a high potential by-product due to its content of valuable compounds, such as pectin. It is highly perishable and requires pretreatment for its conservation. Therefore, this work aims to evaluate the effect of four drying methods: convective drying, freeze-drying, infrared-radiation drying, and solar drying, on the properties of pectin fractions obtained from pisco grape pomace. Freeze-drying and convection drying reported the highest extraction yields. The drying of grape pomace by all the methods evaluated decreased the degree of esterification on the pectins. The highest reducing sugar content (19.8%) and antioxidant capacity (7238 µmol TE/100 g d.m.) were obtained from freeze-drying pretreatment. The highest galacturonic acid content (28.4%) and molecular weight (63.3 kDa) were found in the pectin obtained from the convective drying pretreatment. Thus, each drying method evaluated affects the pectin's physicochemical properties differently. Also, pectin fractions with a high degree of methoxylation and a high antioxidant capacity were obtained from pisco grape pomace. This study provides information about the effect of drying as a pretreatment of pisco grape pomace on the properties of the pectin obtained from it. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the effects of different drying methods included hot air (HD), vacuum (VD) and freezing drying (FD) on the chemical composition, structural characteristics, antioxidant activities and glucose consumption of HepG2 cells in vitro of coconut water polysaccharides (CWPs). Results showed that drying methods had significant effects on the contents of neutral sugars and total phenols, the size and distribution of molecular weight, biological activities in vitro of CWPs. All CWPs composed of six monosaccharides including rhamnose, arabinose, galactose, glucose, xylose and galacturonic acid were small molecule acidic heteropolysaccharide containing pyranoid ring structure and a-glycosidic linkages. And the CWP-HD, CWP-VD and CWP-FD would not decompose when the temperature was lower than 183.76 °C, 182.75 °C and 176.48 °C. Furthermore, CWP-HD had the best DPPH (IC50 value of 0.21 ± 0.001 mg/mL) and ABTS radical scavenging ability (IC50 value of 5.44 ± 0.05 mg/mL), while CWP-FD had the best hydroxyl radical scavenging ability (IC50 value of 20.80 ± 0.002 mg/mL) and promoting effect on glucose consumption of HepG2 cells. These could provide support for the high-value development and utilization of coconut water. [ABSTRACT FROM AUTHOR]

To extend the shelf life of food, structural, sensory or mechanical properties are analysed to provide superlative quality for the dried product. The purpose of this paper is to examine the impact of drying methods and their parameters on the properties of strawberries (their structure, mechanical parameters and sensory profiles). The drying methods influenced the internal structure of strawberries. At the same temperature (45 °C) among various drying methods, strawberries obtained by vacuum drying (VD) had higher hardness than convective-dried fruits (AD), but it was significantly lower compared to freeze-dried samples (FD). Increase in temperature in the VD method caused changes in the hardness of dried fruits. They differed in the sensory profile including: appearance, texture and taste/flavour. The lowest intensity of cooked strawberries' aroma with high intensity of fresh strawberries' flavour, higher level of sour taste and lower sweetness were obtained in FD. By lowering the temperature in VD, the sensation of crispness or crunchiness decreased, and the intensity for gumminess, the impression of aroma of cooked or fresh strawberries increased. The highest correlations between sensory and mechanical properties were noted for VD fruits dried at temperature of 55 °C and set pressure of 4 kPa. [ABSTRACT FROM AUTHOR]

Having the advantages of a higher yield, lower cost and less environmental impact, lignin-containing cellulose nanofibrils (LCNFs) obtained by mechanically fibrillating unbleached pulps have been demonstrated to be a promising alternative to high-purity nanocellulose. In this study, the structural changes after four drying methods containing freeze-drying (FD), oven-drying (OD), centrifugal followed by vacuum-drying (CVD), and evaporation followed by vacuum-drying (EVD), and efficient reuse of LCNFs were extensively explored. It was found that the structural characteristics of LCNFs after drying were maintained by freeze drying with high lignin contents where the aggregation of fibrils was alleviated by lignin. The freeze-dried LCNFs were further redispersed by homogenizer in water, which exhibited excellent dispersion characteristics. In addition, the redispersed LCNFs were further assembled into PVA films to fabricate high-strength composites. The results showed that when the addition of redispersed LCNFs was up to 16.9%, the tensile strength and elongation at break of the as-prepared composite film increased by 325.2% and 335.2%, respectively. This study demonstrated a more sustainable approach to utilize LCNFs to produce biomass-based composite films than those of CNF-based composite films. [ABSTRACT FROM AUTHOR]

Chlorella vulgaris is known for its protein, growth factor, and nutritional constituents. Chlorella vulgaris was cultivated in a 1000-L outdoor open raceway pond with a maximum volumetric productivity of 130 mg L-1 day-1. The harvested biomass was dried through different methods, viz., sun drying (30 °C), oven drying (60 °C), lyophilization (−110 °C), drum drying (120 °C), and spray drying (100–150 °C). The effect of the drying method on proximate composition, pigments (chlorophyll, carotenoids), bioactive compounds (total phenolic content, flavonoid content), vitamin B12, antioxidant properties (ferric reducing antioxidant power, DPPH, and total antioxidant activity), and the color quality of C. vulgaris biomass was evaluated. Surface characterization by scanning electron microscopy (SEM) and functional group characterization through Fourier transform infrared spectroscopy were also performed. The biomass dried through lyophilization and sun drying retained maximum bioactive compounds and antioxidant activities. In contrast, drum drying resulted in a loss of nutrients, viz., protein (up to 44%), lipid (up to 41%), vitamin B12 (up to 40%), total phenolic content (> 50%), total flavonoid content (> 50%), and antioxidant activity (> 50%). Oven drying led to a loss of 30% in total flavonoid content and 17% in ferric reducing antioxidant power. SEM showed the destruction of cell wall integrity in the drum-dried sample and porous structure in the spray-dried sample. This study suggests that drying methods affect the nutrients and bioactive compounds of C. vulgaris biomass, and therefore a drying method should be selected carefully depending on the end use of the biomass. [ABSTRACT FROM AUTHOR]

With the drying process, the water activity and moisture content of the foods are reduced, so the growth of microorganisms in the foods is largely prevented/postponed. But low-aw foods should not be considered sterile they can be contaminated by fungi and other contaminants during the drying process under unhygienic conditions. If drying is not done to a sufficient degree of moisture during food processing and storage, where dried foods are processed, sometimes the minimum value is reached for the growth of microorganisms. In dry foods, some pathogens, yeast and molds can continue to grow during storage, transport and transportation until the sale and they causing spoilage. They can even cause health problems if enough pathogen or spore cells remain viable. Considering this situation today, it is attempted to obtain high-quality dried foods with good microbiologically and chemically properties. For this purpose, various drying methods have been developed. Most studies suggest that when foods are pre-treated with the ascorbic acid or sodium metabisulfite or applied with various combined methods such as UV irradiation, supercritical carbon dioxide (SCO2), low-pressure superheated steam drying (LPSSD), and infrared (IR) drying, they can be effective on inactivation of microorganisms. We have reviewed in this study how these methods made dried products efficient of microbial inactivation and microbiologically safe. [ABSTRACT FROM AUTHOR]

In this study, different drying methodologies (convective air, oven and microwave) of Myrtus communis L. (M. communis L.) leaves were conducted to investigate their effects on the levels of phenolic compounds, antioxidant capacity of ethanolic extracts (EEs) as well as the soybean oil oxidative stability. Drying methodology significantly influenced the extractability of phenolic compounds. Microwave drying led to an increase in the amounts of total phenols, flavonoids and proanthocyanidins followed by oven drying at 70 °C. Higher temperature of drying (100 and 120 °C) led to a significant reduction of their amounts (p < 0.05). An ultra-performance liquid chromatography method combined with high resolution mass spectroscopic detection was used to analyze the phenolic fraction of extracts. Higher amounts of the identified compounds were observed when leaves were heat treated. Furthermore, the evaluation of the antioxidant activity showed that the studied extracts possess in general high antioxidant capacities, significantly dependent on the employed drying methodology. The incorporation of the different extracts at 200 ppm in soybean oil showed that its oxidative stability was significantly improved. Extracts from leaves treated with microwave (EE_MW) and at 70 °C (EE_70) have better effect than BHT. The results of the present study suggest that microwave drying could be useful to enhance the extractability of phenolic compounds and the antioxidant capacity of M. communis L. leaf extract. [ABSTRACT FROM AUTHOR]

We describe a method for the fabrication of acoustic metasurfaces, which is based on soft porous polymer materials. The materials are obtained using an emulsion templating technique, which allows for the fabrication of soft porous polymers with fully controlled porosity values between 0 and 30%. Our approach involves the polymerization of water-in-silicone emulsions with controlled water volume fractions. The obtained wet solid monolith samples are dried using three different methods. Due to the softness of the polymer matrix, and like in polyHIPE hydrogels or silica aerogels, the first method—regular air drying—leads to a collapse of the material and we present a complete experimental study of the observed kinetics as well as a model to account for the observed results. We show that this model can catch the kinetics characteristics. Then, using two alternative drying techniques, H2O2-assisted and supercritical drying, we show that it is possible to obtain materials with fully controlled porosities. The speed of sound—or equivalently the material acoustic index—inside the material being dependent on its porosity, we obtain a gradient-index acoustic material by spatially controlling the porosity distribution along the two dimensions of these metasurfaces. Their ability in terms of wavefront shaping is then demonstrated through a deflecting experiment performed in water with a sample having a thickness five times smaller than the incident acoustic wavelength at ultrasonic frequencies. [ABSTRACT FROM AUTHOR]

This work was aimed to investigate the effect of geographical regions and drying methods on phenolics, flavonoids, antioxidant properties, sugars, and acid content of Chinese jujube. The results revealed significant differences in the antioxidant properties and phenolics content of jujube as affected by geographical origin (Hebei, Shandong, Shanxi, Xinjiang, and Henan province) and drying method (puff-drying and convective hot air-drying). The highest concentrations of DPPH (90.01 ± 0.48% DW), FRAP (0.76 ± 0.05 mM TEAC/g DW), TAC (187.16 ± 2.66 mg AEAC /100 g DW), TFC (3.03 ± 0.09 g REAC /100 g DW), TA (1.15 ± 1.10 g CA /100 g DW) and TS (75.10 ± 1.35 g GE /100 g DW) were recorded in the puff dried jujube samples from Xinjiang province. However, samples from Hebei had highest concentration of TPC (2.82 ± 0.13 g GAAC /100 g DW), TANC (46.47 ± 1.64 mg anthocyanin /100 g DW) and TCC (4.27 ± 0.88 mg β-carotene /g DW), while most ABTS (54.45 ± 0.72 µM TEAC/g DW) was recorded in the jujube samples from Henan. Likewise, jujube from Shandong demonstrated highest ferrous chelating activity (89.17 ± 0.52% DW). Similarly, puff dried jujube from Xinjiang had the highest concentration of gallic acid (29.52 ± 0.15 µg/g DW), phloridzin (16.73 ± 0.45 µg/g DW) and cianidanol (60.87 ± 0.71 µg/g DW), whereas, higher concentrations of L-epicatechin (143.59 ± 0.69 µg/g DW) and rutin (10.94 ± 0.78 µg/g DW) were recorded in Hebei, and caffeic acid (66.21 ± 0.88 µg/g DW) in Shanxi province. Conclusively, the bioactive profile of Chinese jujube varies depending upon their geographical origin or drying method used, with puff-drying being a better option to retain the bioactivity. [ABSTRACT FROM AUTHOR]

Coffee is one of the most widely used beverages in the world. Postharvest techniques mainly affect the nutritional value and bioactive components of the food samples. In this study, the effect of drying methods and extraction solvents was assessed on different parts of coffee fruit. The total polyphenol content, total flavonoid content, and the antioxidant activity in terms of DPPH scavenging and reducing power of the samples were measured. Results revealed that oven drying of the coffee fruit parts led to significantly higher total polyphenol content, total flavonoid content, and antioxidant activities compared to the shade drying at room temperature. Ethyl acetate extracts of all samples exhibited significantly lower total polyphenol content, total flavonoid content, and antioxidant activities than the methanolic extracts. Coffee beans were more potent in terms of phenolic content and antioxidant activity as compared to the coffee pulp and parchment. These results suggest that oven drying method can be adopted for processing of coffee fruit. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of three different drying methods, freeze drying (FD), vacuum drying (VD) and oven drying (OD) on phenolic contents and antioxidant activities of litchi fruits. 20 polyphenols were exactly identified in the litchi fruits by UPLC-QqQ/MS. Significant losses were observed in the contents of total polyphenols and antioxidant activities in the dried litchi when compared with the fresh litchi. Principle component analysis indicated that there was significant difference of phenolic component between the use of thermal drying (VD and OD) and FD. Our results suggest that FD is the optimum drying method for litchi fruits considering the content of total polyphenols and antioxidant activities. [ABSTRACT FROM AUTHOR]

Drying treatments are an effective method for preserving original beneficial ingredients of postharvest plants. This work supplied the suitable drying conditions of three drying methods by investigating the changes of lotus leaves' quality and antioxidant activity. The results indicated that: (1) Oven drying (55–65 °C) was the most appropriate way to keep the higher contents of alkaloids and amino acids, and the higher activities in DPPH radical scavenging and hydroxyl radical scavenging in lotus leaf treated with three drying methods; (2) Steam kill-enzyme torrefaction (3–5 min) was the most appropriate method for keeping the higher contents of flavone and the higher activities of superoxide radical scavenging in lotus leaf treated with three drying methods; (3) Microwave drying (680–850 W) was the most appropriate means to keep the higher contents of vitamin C, soluble sugar and protein in lotus leaf treated with three drying methods; (4) The color of lotus leaf treated with microwave treatments was more bright green than that treated with the other two methods; Therefore, the actual conditions of each drying means have to be taken into consideration when use the drying means. [ABSTRACT FROM AUTHOR]

Beets contain the red and yellow pigments known as betalains, as well as nitrates and other phytochemicals that may affect human health, and have been studied for possible effects on lowering blood pressure and enhancing athletic performance. Betalains are heat-labile, so developing relatively low-temperature drying methods is one way to turn the perishable root vegetable into a value-added ingredient. The objective of this study was to determine if continuous vacuum belt drying (VBD) could be used to produce powdered ingredients with good color, physical properties, and retention of betalains. Drying studies showed that drying rate could be increased somewhat by increasing temperatures from 75 to 95 °C, with drying times ranging from 160 to 115 min. Drying times were substantially shorter than for powders produced by freeze drying (FD) (26 h) or hot air drying (HAD) (~ 6 h). Properties such as flowability or color did not depend on drying temperature. VBD beet powders had a red-purplish color that was slightly darker (L* = 25.74) than for freeze-dried powders (L* = 38.92). In contrast, HAD samples were much darker than VBD or FD powders, and showed signs of browning. Flowability was improved by the addition of maltodextrins, but at the expense of some increase in drying time. VBD powders were less hygroscopic than FD powders, but reached the same final moisture content. HAD powders were less hygroscopic. VBD samples had slightly lower betalain levels (261–273 mg betanin/g dry beet) than FD powders (291.2 mg betanin/g dry beet). Both had much greater levels than HAD powders (127.8 mg betanin/g dry beet). Powder dried at 95 °C without maltodextrin was optimal as it dried most quickly and had minimal betalain loss. [ABSTRACT FROM AUTHOR]

Ganoderma lucidum, a famous Chinese medicinal mushroom, is cultivated systematically, harvested seasonally and dried for preservation. In this study, the effects of sun drying, hot air drying at 50 °C and 70 °C, microwave drying at 420 W and 700 W, and freeze drying on the moisture content, rehydration capacity, the contents of total phenolics, flavonoids and triterpenoids, as well as on the antioxidant activity of G. lucidum were investigated. The results showed that the physical properties, bioactive ingredients and antioxidant activity of G. lucidum were significantly affected by the different drying techniques. Microwave drying at 700 W resulted in the lowest moisture content, whereas freeze drying resulted in the highest rehydration rate compared with the other drying methods. The content of total phenolics and flavonoids, the 2,2-diphenyl-1-picrylhydrazyl radical scavenging ability, and the ferric reducing antioxidant power were found to be the highest at the G. lucidum dried by microwave drying at 700 W. Overall, Microwave drying was of short duration and significantly retained the antioxidant activity and high content of phenolics in G. lucidum. Thus, Microwave drying could be suggested as the optimal method for preserving the fruiting body of G. lucidum. [ABSTRACT FROM AUTHOR]

The geochemical fractions of heavy metals in sediments are crucial indexes for their mobility and bioavailability evaluations. However, different drying processes of sediment pretreatment could change metal geochemical fractions, especially for Hg, which is potentially volatile. In this study, the influence of pretreatment methods including oven-drying, air-drying, freeze-drying, and fresh sediments on the analysis of Hg fractions in sediments was investigated. Results showed that remarkable differences of Hg concentration were observed between fresh sediments and dried pretreatment sediments (P < 0.05). Briefly, the concentrations of the water-soluble and human stomach acid–soluble fractions in oven-dried and air-dried sediments generally showed significant increasing trends compared with those in the fresh sediments, while the organo-chelated fraction exhibited significant decreasing trends. The cause of this phenomenon was primarily the oxidation of organic matter, aging process, and the diffusion of Hg into micropores. The significant loss was also observed at elemental Hg fraction due to its volatilization effect. The freeze-drying posed minor influence on changes of Hg fraction analysis compared with oven-drying and air-drying. Moreover, the total Hg concentrations in pretreated sediments showed a decline of varying degrees compared with those in fresh sediments ascribing to the volatilization of elemental Hg. Finally, Pearson correlation analysis further confirmed that freeze-drying could minimize the errors of the Hg fraction analysis in sediments. [ABSTRACT FROM AUTHOR]

Chilean papaya slices were dried using different technologies to evaluate the effect of the different technologies on drying kinetics, bioactive compounds and biological activities. Five techniques were used: freeze drying (FD), vacuum drying (VD), solar drying (SD), convective drying (CD) and infrared drying (IRD). Fresh and dried samples were evaluated in terms of proximate composition, phenolic profiles, total phenolic and flavonoid contents, β-carotene, vitamin C, and antioxidant and α-glucosidase activities. CD-papaya showed lower processing time, requiring 270 min to reach the dynamic equilibrium condition, while SD-papaya required 870 min. The five drying technologies were found to have variable effects on proximate composition. VD-samples showed the lowest loss of individual phenolic compounds, total phenolic content and vitamin C while IRD- and CD-samples showed lower total flavonoids (42%) and β-carotene (32%) loss after processing, respectively. With respect to biological activities, all samples possessed enzymatic activity in a dose-dependent manner (0–2.0 mg ml−1), being IRD-sample the most effective in inhibiting α-glucosidase (IC50 = 13 mg ml−1). Also, the highest antioxidant capacity measured by DPPH and ORAC was obtained for the papaya samples dried using a vacuum drier. [ABSTRACT FROM AUTHOR]

The bioaccessibility, antioxidant activity, and bioactive and volatile compounds of freeze-dried Asian pear powder (FDAPP) and hot air-dried Asian pear powder (HDAPP) were investigated. Compared to FDAPP, HDAPP exhibited significantly (p < 0.05) higher total phenolic, arbutin, and bioaccessible phenolic contents and the ferric reducing ability of plasma for the free phenolic fraction. However, all antioxidant activities for the bound phenolic fraction were lower in HDAPP, which could contribute to the release of bound antioxidant components due to cell rupture in the HDAPP. Based on the volatile profile, hot air drying provided a sweet as well as attractive flavor in the Asian pear powder (APP). Considering economic viability, higher levels of bioactive compounds, and desirable aromatic properties, hot air drying is the better option compared to freeze-drying for APP production, which could be used as a functional ingredient in food products. [ABSTRACT FROM AUTHOR]

Hawthorn fruits are rich in nutrients and antioxidant compounds. Dehydration is the major processing and preservation method for hawthorn fruits. The rates of moisture loss; polyphenol, flavonoid and triterpenoid acid contents; and antioxidant activities and their relationships were investigated in hawthorn slices that were dried by four dehydration techniques (microwave drying, solar drying, hot air drying and freeze drying) under different operation conditions. The results showed that both the drying method and the processing parameter affected the antioxidants. Microwave drying and hot air drying at high temperatures (≥ 80 °C) resulted in the degradation of the polyphenols, flavonoids and triterpenoid acids in the hawthorn slices. These antioxidant compounds were best preserved by freeze drying and hot air drying at 60 °C. Epicatechin and chlorogenic acid were the major phenolic compounds identified in this research, and these compounds were significantly affected during processing. The antioxidant activities of the hawthorn fruits were significantly related to the total polyphenol, flavonoid and triterpenoid acid contents. Hot air drying at proper temperatures could be suitable for hawthorn slice dehydration processing that conserves the antioxidant properties of the fruit. [ABSTRACT FROM AUTHOR]

Drying method is one of the most important steps in the preparation of plant materials for phytochemical analysis and biological evaluation. In this sense, this research endeavoured to evaluate the effects three drying methods (oven, freeze, and shade drying) on phytochemical component, antioxidant, and enzyme inhibitory effects of Salvia absconditiflora Greuter & Burdet. Antioxidant activities were screened by phosphomolybdenum, DPPH, ABTS, FRAP, CUPRAC, and metal chelating activity. Enzyme inhibitory effects were assessed against cholinesterases (AChE, BChE), tyrosinase, α-amylase, and α-glucosidase. Drying methods were found to affect the chemical component and biological properties. Shade drying showed the highest TPC (99.33 mgGAE/g) and TFC (46.88 mgRE/g) followed by oven (58.15 mgGAE/g for TPC, 40.65 for TFC), and freeze drying (43.73 mgGAE/g for TPC, 36.68 mgRE/g for TFC). The main phenolic compound characterized by HPLC was rosmarinic acid, which was observed to be highest following shade drying. Shade drying contained highest total bioactive compounds and exhibited the strongest antioxidant properties. The enzyme inhibitory effects of S. absconditiflora performed using different depends were dependent on the drying methods. Our results tend to suggest that shade drying was most suitable for S. absconditiflora because of possessing the highest rosmarinic acid and biological properties. [ABSTRACT FROM AUTHOR]

The demand for duck meat and eggs in Asian countries increases every year. Duck egg albumen has become an important ingredient in the food industry alongside its hen counterpart, because of its excellent nutritive and functional properties. The major proteins in duck albumen are ovalbumin, ovomucoid, ovomucin, conalbumin, and lysozyme. Comparing with hen albumen, lower contents of ovalbumin, conalbumin, lysozyme and ovoflavoprotein are found in duck albumen. Nevertheless, duck albumen shows better gelling and foaming properties than hen albumen. During storage, duck albumen gel properties are enhanced, while foam volume and foam stability are decreased. Moreover, the changes in quality indices of duck egg including the thinning of the albumen, an increase in albumen pH, loss of water and carbon dioxide occur as storage time is increased. Some processes such as alkaline treatment also cause the loss in nutritive value of egg albumen. In this review, the composition and functional properties of duck albumen and how they are affected by processing conditions are also addressed, in comparison with hen albumen. A better understanding of duck egg albumen would be beneficial so that the food processing industry can exploit the potential of this avian protein. [ABSTRACT FROM AUTHOR]

Metabolomics is often used to comprehensively elucidate the metabolites in organisms like seaweed. Amino acids hydrolysed from proteins and certain targeted metabolites in seaweed have been investigated. However, water-soluble metabolites like free amino acids, organic acids, and sugars have seldom been comprehensively analysed. Metabolomics are valuable tools for these studies, but they require optimisation of pre-treatment methodology. Here, we evaluated various pre-treatment drying and extraction methods for brown seaweed metabolomics. Three edible brown seaweeds (Cladosiphon okamuranus [Mozuku], Saccharina japonica [Kombu], and Undaria pinnatifida [Wakame]) were used. Freeze-drying and oven-drying at both 40 and 80 °C were investigated. Methanol-water extracts with and without chloroform were compared. Metabolites were evaluated and quantified using liquid chromatography-mass spectrometry and capillary electrophoresis-mass spectrometry. The results showed that metabolite profiling was determined mainly by seaweed species identity rather than pre-treatment method. Freeze-drying yielded higher metabolite concentrations than oven-drying at either 40 or 80 °C. The effects of extraction with and without chloroform on metabolite concentration varied with seaweed species. [ABSTRACT FROM AUTHOR]

To select a suitable drying process for using chestnut products in the food industry, this study investigated the effect of five drying methods, including natural drying, microwave drying (MD), hot air drying (HAD), freeze-vacuum drying (FVD) and microwave-vacuum drying (MVD) on the nutritional composition, flavor, and functional properties of dried chestnuts. The results indicated that the nutritional aspects and functional properties of chestnuts were enhanced by the freeze-drying process compared with the other four drying methods. The quality of the chestnuts dried using the MVD was second to the FVD. The hot-air dried products were quite similar to the naturally dried samples in terms of their functional component content and processability. In terms of the produce texture, the HAD was found to be the best. In total, 45 flavor components were identified in the samples, which comprised the following: 5 aldehydes, 4 alcohols, 4 esters, 8 terpenes, 16 hydrocarbons and, 8 others substances. The highest relative content of the ingredients in microwave-vacuum dried samples was pyrazine and 3-ethyl-2, 5-dimethyl. In the samples treated using the other four drying methods, benzyl alcohol was the ingredient with the highest concentration. Considering the fast drying rate, low energy consumption, and improved quality of chestnut products, MVD is the most suitable dehydration method for commercial production of Chinese chestnuts. [ABSTRACT FROM AUTHOR]

Sour cherry (Prunus cerasus L.) contains substantial quantities of phenolic compounds, specifically anthocyanins, and is mainly processed into different products including juice, whose by-product, namely sour cherry pomace (SCP), represents a potential source of high added bioactive compounds currently underutilized. Oven drying and freeze drying (FD) are simple methods, often used to stabilize food matrices, and can be also successfully employed for the stabilization of sour cherry pomace. In the present study, the influence of genotype (Bianchi d’Offagna and Montmorency cvs), drying method and their interaction on the extractability of phenolic and anthocyanin profiles of sour cherry pomace were evaluated. Both genotype and drying method significantly influenced (p ≤ 0.001) the overall phytochemical content (total monomeric anthocyanin, total flavan-3-ol, total phenolic, and vitamin C) of the analyzed pomaces. The interrelationships between the parameters analyzed, the genotype, and the different drying conditions, as well as the relationships among variables, were investigated by principal component analysis (PCA). PCA results pointed out that the phytochemical content of sour cherry pomace was firstly influenced by the cultivar (which accounted for about 70% of the total variance), followed by the drying process (about 18% of the total variance), and their interaction (about 12% of the total variance), with the exception of total flavan-3-ols, where a similar contribution (about 50%) of the two factors was observed. Besides, the antidiabetic potential of SCPs was also investigated, showing Bianchi D’Offagna FD pomace to be the most active. The obtained results point out that the SCP stabilized by means of the freeze-drying process is a valuable second-generation biorefinery for food supplements and nutraceutical and pharmaceutical markets. [ABSTRACT FROM AUTHOR]

Porous alumina ceramics with uniform total porosity (69.6-70.3%), spherical pores, and different pore size (22.9 ± 10.3, 197.7 ± 80.0 and 714.1 ± 207.2 μm) were prepared by using suspension emulsion, direct foaming, and solid template as pore forming mechanism, respectively and gelcasting technology. Different drying methods were selected according to the different pore forming agents. Pore size could significantly affect the mechanical and thermal properties. The compressive strength decreased evidently from 116.25 ± 10.96 to 22.43 ± 1.15 MPa and thermal conductivity of 1000 °C increased from 0.28 ± 0.01 to 0.58 ± 0.01 W/(m K) with the increasing pore size (from 22.9 ± 10.3 to 714.1 ± 207.2 μm). [ABSTRACT FROM AUTHOR]

The effects of different extraction solvents (water, EtOH, MeOH, acetone, DMSO, and their mixture) and various drying methods (air, oven, microwave, and freeze drying) were investigated on total polyphenol content (TPC), total flavonoid content (TFC) and antioxidant activity of peel, pulp, and seeds of yuzu fruit. Mixed solvents exhibited better results compared to the absolute solvents. 50 % acetone exhibited the highest FRAP and CUPRAC value in peel and pulp and TPC in seeds of yuzu fruits. 80 % acetone which also gave nearly similar results with 50 % acetone (p > 0.05) showed the highest TPC in peels and pulp and highest CUPRAC values in seeds. Absolute acetone was the least desirable solvent employed for extraction in most of the samples. Drying methods also significantly affected the total polyphenols content, total flavonoid content and antioxidant potential of yuzu fruits. Oven drying resulted in declines of the TPC, TFC, FRAP, DPPH, and CUPRAC from 0.2 to 33.0 % relative to fresh samples while air drying resulted a decrease in the range between 2.5 and 30.6 %. Freeze dried samples showed the highest percent retentions of polyphenols content, flavonoid content, and antioxidants (70.6-122.1 %). Drying methods caused the highest loss of TPC, TFC, FRAP, and CUPRAC in pulp samples except DPPH radical scavenging activity. In overall, the extraction of secondary metabolites and antioxidants was highly dependent on the extraction solvent, type of sample and sample processing methods. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the functional and antioxidant properties of chicken skin gelatin hydrolysate (CSGH) as affected by the drying method used in the preparation of gelatin (freeze-dried and vacuum dried). CSGH obtained from freeze-dried gelatin showed better functional properties such as emulsifying activity index (EAI), water holding and oil binding capacity at different pH compared to CSGH produced from vacuum dried gelatin. Meanwhile, the CSGH of the vacuum dried gelatin exhibited a better emulsifying stability index (ESI), foaming capacity and stability. CSGH from freeze-dried gelatin showed better antioxidant, DPPH radical scavenging and metal chelating activity. [ABSTRACT FROM AUTHOR]

Jerusalem artichoke is an economic crop widely planted in saline-alkaline soil. The use of Jerusalem artichoke is of great significance. In this study, the response surface method was employed to optimize the effects of processing variables (extraction temperature, pH, extraction time, and liquid-to-solid ratio) on the yield of Jerusalem artichoke pectin. Under the optimal extraction conditions: pH 1.52, 63.62 min, 100°C and a liquid-to-solid ratio of 44.4 mL/g, the maximum pectin yield was predicted to be 18.76%. Experiments were conducted under these optimal conditions and a pectin yield of 18.52±0.90% was obtained, which validated the model prediction. The effects of diff erent drying methods (freeze drying, spray drying and vacuum drying) on the properties of Jerusalem artichoke pectin were evaluated and they were compared with apple pectin. FTIR spectral analysis showed no major structural diff erences in Jerusalem artichoke pectin samples produced by various drying treatments. The antioxidant activities of pectin dried by diff erent methods were investigated using in vitro hydroxyl and DPPH radical scavenging systems. The results revealed that the activities of spray dried pectin (SDP) and apple pectin (AP) were stronger than those of vacuum oven dried pectin (ODP) and vacuum freeze dried pectin (FDP). Therefore compared with the other two drying methods, the spray drying method was the best. [ABSTRACT FROM AUTHOR]

The influence of four drying methods on nonvolatile taste components of White Hypsizygus marmoreus (WHM) was studied. The soluble sugar, free amino acids, organic acids, and flavor nucleotides of WHM were determined and compared by HPLC after hot air drying, vacuum drying (VD), microwave-vacuum drying (MVD), and vacuum freeze-drying (FD). Equivalent umami concentration (EUC) was used to evaluate the umami taste of WHM. The results showed that the four drying methods had different influence on the soluble sugar, free amino acids, organic acids, and flavor nucleotides. Soluble sugar retention after MVD was the highest (192.61 mg/g), but the EUC (147.6 g/100 g) was lower. The content of essential amino acids (22.83 mg/g), flavor amino acids (22.05 mg/g), and total amino acids (48.95 mg/g) after VD was the highest, but the EUC was the lowest; FD can reduce the loss of the total flavor nucleotides to the minimum, compared with the other three drying methods. FD got the highest retention rate of the total organic acids especially succinic acid, and the influence on amino acids was almost the same with VD. Considering the maximum retention of nonvolatile taste components, FD is the most optimal drying method. Different drying methods have their respective advantages, and this study provided reference for the processing of the WHM. [ABSTRACT FROM AUTHOR]

Ginger rhizomes sliced to various lengths of 5, 10, 15, 20, 30, 40, 50 mm and whole rhizomes were dried from an initial moisture content of 81.3 % to final moisture content of less than 10 % by various drying methods like sun drying, solar tunnel drying and cabinet tray drying at temperatures of 50, 55, 60 and 65 °C. Slicing of ginger rhizomes significantly reduced the drying time of ginger in all the drying methods. It was observed that drying of whole ginger rhizomes under sun took the maximum time (9 days) followed by solar tunnel drying (8 days). Significant reduction in essential oil and oleoresin content of dry ginger was found as the slice length decreased. The important constituents of ginger essential oil like zingiberene, limonene, linalool, geraniol and nerolidol as determined using a gas chromatography was also found to decrease during slicing and as the drying temperature increased. The pungency constituents in the oleoresin of ginger like total gingerols and total shogoals as determined using a reverse phase high performance liquid chromatography also showed a decreasing trend on slicing and with the increase in drying temperature. It was observed from the drying studies that whole ginger rhizomes dried under sun drying or in a solar tunnel drier retained the maximum essential oil (13.9 mg/g) and oleoresin content (45.2 mg/g) of dry ginger. In mechanical drying, the drying temperature of 60 °C was considered optimum however there was about 12.2 % loss in essential oil at this temperature. [ABSTRACT FROM AUTHOR]

Crack-free mesoporous equimolar SiO-AlO-TiO ternary aerogel beads have been synthesized and characterized. Silica sol, alumina sol, and titania sol were synthesized individually to prevent the formation of inhomogeneous structure due to the different hydrolization and polymerization rate of individual precursor. After mixing these three types of acidic sols, SiO-AlO-TiO ternary beads were prepared by the ball dropping method. The ternary aerogel beads were typically mesoporous, showing high surface area (305 m g), large pore volume (1.32 cm g), and high surface acid amount (0.884 mmol NH g). Moreover, the acid sites of the ternary aerogel beads showed higher thermal stability than those of binary aerogel beads. Gradient drying (GD), supercritical drying (SD), ambient drying (AD), extended aging (EA) and hydrophobic modifying drying (HM) have been employed to investigate the effects of drying method on the characteristics of the aerogel beads. The surface areas of the ternary aerogel beads obtained by different drying methods decrease in the sequence EA > HM > GD > SD > AD. The ternary aerogel beads have been characterized by scanning electron microscopy, nitrogen adsorption, X-ray powder diffraction, Fourier-transform infrared spectroscopy (FTIR), solid-state NMR, temperature-programmed desorption measurements, pyridine adsorption FTIR, and differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

CaAl-layered double hydroxides (CaAl-LDHs) with various carbonate ion contents are essentially formed in Bayer liquors during the causticisation step in alumina production. Under well-defined conditions hemicarbonate is formed, which is beneficial in the process of retrieving both Al(OH) and OH ions. In the current work, CaAl-LDHs with various carbonate contents were prepared by the co-precipitation procedure and the products were dried in different ways. Structural information was obtained by a variety of methods, such as X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Elemental maps were constructed through a combination of SEM images and EDX measurements. The targeted CaAl-hydrocalumites were successfully synthesised. It was found that the method used for drying did not influence the basal spacing although it significantly altered the particle sizes. [ABSTRACT FROM AUTHOR]

Garlic slices were dehydrated by convective drying (CD) and by a combined method consisting of convective pre-drying followed by vacuum-microwave finishing drying (CPD-VMFD). Drying of garlic using VMFD led to samples with high values of lightness and slightly lower values of the coordinates a* and b*. The treatment CPD-VMFD significantly decreased the drying time from 630 min for CD to 49 min and contributed to an important energy saving compared with CD (54.4-86.3 %). The total drying time was shorter when vacuum microwaves were introduced earlier and microwave power was higher. The highest temperature (114 °C) was found for samples pre-dried to a moisture content of 60 % and then dried at 360 W while showing the lowest energy consumption (98 ± 1 kJ g). In general, the total antioxidant capacity increased after drying of garlic slices; however, the content of total phenolic compounds showed the opposite trend, and thus other compounds, such as allicin, should be involved in the antioxidant capacity of dried garlic. Garlic slices were CP dried until 30 % of moisture content followed by VMFD at 240 or 360 W showed the best results in terms of energy consumption and antioxidant capacity. [ABSTRACT FROM AUTHOR]

Effect of cultivar ( Efuru and Abuja) and drying method (cabinet and foam mat) on color, pasting, and sensory properties of instant pounded yam flours was investigated. Color ( L*, a*, b*) values of fresh and dried flour samples were measured, and deltachroma (∆ C), color difference (∆ E), and hue angle were calculated. Pasting properties of flour and sensory attributes of fresh and reconstituted flour were determined. Foam density of yam pastes decreased from 0.97 g/cm to between 0.362-0.538 and 0.308-507 g/cm for cultivars Abuja and Efuru, respectively. Foam-mat dried flour showed higher L*, Δ C, Δ E, and hue angle but lower a* and b* values. Peak viscosities of cabinet and foam-mat dried Abuja and Efuru were 217, 304, 377.42, and 316.50 RVU, respectively. Sensory attributes of reconstituted foam-mat dried Abuja and fresh pounded yam were not significantly different ( p > 0.05). However, fresh pounded yam (8.5-8.9) and reconstituted foam-mat dried flour (7.4-8.5) samples were significantly different ( p > 0.05) from the cabinet-dried (6.9-7.9) and commercial samples (7.2-7.8). [ABSTRACT FROM AUTHOR]

A study has been made of the effects of sun and oven drying methods on the physicochemical characteristics and compressibility of Okra powder and the release properties of its metronidazole tablet formulation. Corn starch was used as the reference standard. The mechanical properties of the tablets were evaluated using crushing strength and friability, while the release properties were determined using the disintegration times and dissolution rates. The results obtained showed that sun-dried Okra powder had smaller particle size, exhibited good flow and possessed higher hydration and swelling capacities compared to the oven dried samples. The compressibility of Okra powders assessed by the indices of plasticity from Heckel (Py) and Kawakita plots (Pk) showed that sun dried Okra powders had higher Py but lower Pk values than the oven-dried Okra powder. Metronidazole tablets formulated with oven dried Okra powder formed stronger tablets than tablets containing sun dried Okra powder. Generally, tablets containing sun dried Okra powders had faster disintegration and dissolution than tablets formulated with oven-dried powder. The results suggest that the choice of drying method during the processing of pharmaceutical raw materials is critical to its physicochemical properties and the release properties of its tablet formulations. [ABSTRACT FROM AUTHOR]

Experiments were conducted to study the influence of sowing seasons and drying methods on the seed vigour of two spring soybean ( Glycine max (L.) Merr.) cultivars. Two cultivars, ‘Huachun18’ and ‘Huachun 14’, were sown in three seasons viz., spring, summer and autumn and the harvested seeds were dried using three different methods. The results showed that soybean sown in spring had a higher number of branches per plant, pods per branch and seed weight, and consequently resulted in higher seed yields than that of soybean sown in autumn or summer seasons. Seeds sown in the autumn season had the lowest values of electrical conductivity during seed imbibitions, higher peroxidase (POD) activity in germinated seedlings and lower contamination by the seed-borne fungi on the MS medium, which indirectly improved the seed vigour, which was followed by summer sown seeds. Seeds sown during the spring season resulted in poor seed vigour. In addition, the effect of drying methods on the seed vigour was also clarified. Seeds that hung for four days before threshing and then air-dried had the poorest seed vigour which was determined by germination, electrical conductivity, POD activity and seed borne fungal growth. There was no difference in seed vigour between other methods, i.e. seeds threshed directly at harvest and then air-dried on a bamboo sifter or concrete floor. These results indicated that autumn sowing soybean and the drying method in which seeds were threshed directly at harvest and then air-dried on a bamboo sifter resulted in higher seed vigour. [ABSTRACT FROM AUTHOR]

Drying of leaf protein concentrate (LPC) in either a cabinet dehydrator or in a steam heated drum drier adversely affected extractability of lipids and availability of essential amino acids. Extraction of heated protein with chloroform: methanol mixture or acetone improved availability of amino acids. The amount of available essential amino acids in the freeze dried LPC was also increased by solvent extraction. [ABSTRACT FROM AUTHOR]

Use of molecular techniques to study plant systematics has been restricted to either largely temperate groups or groups from which seed is readily obtained. Dried material has advantages over other methods of preservation for molecular analyses; it is cheap, easily undertaken, overcomes the difficulties associated with seed recalcitrance and the absence of seeding plants in the field, and most taxonomists are familiar with the method. Three drying techniques were assessed using material collected in the tropics. No differences in either the quantity or the quality of DNA extracted from material dried by these methods was detected. The implications of using dried material in molecular analyses are discussed. [ABSTRACT FROM AUTHOR]

A study was undertaken to prepare ginger powder using various drying methods and their nutritional evaluation was carried out. Ginger ( Zingiber officinale) was dried using shade, solar, oven and microwave drying methods. All the samples were ground in grinder to make fine powder. Sensory analysis indicated that acceptability of all types of ginger powders were in the range of 'liked very much' to 'liked moderately' by the panelists. The mean score obtained for colour was higher in shade dried ginger powder i.e., 8.20 as compared to oven dried (7.60), solar dried (7.70) and microwave dried ginger powder (7.80). Moisture content ranged from 3.55 % in solar dried ginger powder to 3.78 % in shade dried ginger powder. Slightly higher moisture content was found in shade dried ginger powder. Protein, crude fiber, fat and ash contents ranged from 5.02 to 5.82, 4.97 to 5.61, 0.76 to 0.90 and 3.38 to 3.66 %, respectively. β-carotene and ascorbic acid content was found maximum in shade dried ginger powder i.e., 0.81 mg/100 g and 3.83 mg/100 g, respectively. Polyphenol content was almost similar in all the samples whereas calcium was slightly higher in the shade dried ginger powder i.e., 69.21 mg/100 g. Results have shown that ginger powder prepared from various drying methods had good sensory and nutritional profile. [ABSTRACT FROM AUTHOR]