Search

BACKGROUND: Goji berries, renowned for their nutritional benefits, are traditionally dried to extend shelf life and preserve quality. However, conventional drying methods often result in uneven drying, color loss and reduced rehydration capacity. This study investigates an innovative hybrid strategy combining ultrasonic–ethyl oleate (US+AEEO) pretreatment with heat pump drying (HPD) to enhance the drying process of Goji berries. RESULTS: Fresh Goji berries underwent US+AEEO pretreatment, which significantly disrupted the waxy layer, enhancing drying efficiency and water infiltration during rehydration. Compared to freeze drying (FD), HPD combined with US+AEEO pretreatment resulted in higher retention of total polyphenol content (TPC) and total flavonoid content (TFC) in the Goji soaking soup. Specifically, the HPD‐US+AEEO samples exhibited the highest TPC and TFC levels, significantly outperforming FD samples. Additionally, the DPPH and ABTS antioxidant assays demonstrated higher scavenging activities in HPD‐US+AEEO samples. The rehydration kinetics revealed that HPD samples had a superior rehydration rate and final moisture content compared to FD samples. Low‐field nuclear magnetic resonance and magnetic resonance imaging analyses confirmed enhanced water distribution and higher mobility in HPD‐US+AEEO samples. Scanning electron microscopy indicated a more porous structure in US+AEEO‐treated samples, facilitating better water absorption and functional component retention. CONCLUSION: The combination of US+AEEO pretreatment with HPD significantly improves the drying process of Goji berries, enhancing nutrient retention, color preservation and rehydration properties. This innovative drying method offers a promising solution for producing high‐quality dried Goji berries, benefiting both the food industry and health‐conscious consumers. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Polysaccharides from Auricularia auricula (AAP) were extracted by hot water extraction and fractionated by sequential precipitation with 10% and 80% (final concentration) ethanol into two fractions (named AAP-10 and AAP-80, respectively). Each fraction was further separated into three subfractions: AP-10-I, AAP-10-II, AAP-10-III, AAP-80-I, AAP-80-II and AAP-80-III. Each of the six polysaccharides was vacuum infiltrated into white radish before dehydration and rehydration. The effects of these polysaccharides on the rehydration characteristics of white radish were investigated by measuring the rehydration ratio, expansibility, water-holding capacity (WHC), color and texture parameters. Polysaccharides that greatly differed in their ability to improve the rehydration characteristics of dehydrated radish were selected for structural characterization. The results showed that compared with dehydrated radish without osmotic treatment, treatment with AAP could improve the rehydration characteristics of dehydrated radish in varying degrees. The effect of AAP-80-III was most pronounced among the six polysaccharides. The rehydration ratio of radish treated with AAP-80-III was 7.32, the expansibility was 3.22 mL/g, and the water-holding capacity was 87.2%; it had better color (L* value of 62.68 ± 0.17, a* value of ?1.06 ± 0.02, and b* value of 4.23 ± 0.09), hardness (1 746.14 ± 11.9) N and chewiness (1 207.09 ± 9.39) N. AAP-10-I could also improve the rehydration characteristics of dehydrated radish, but the difference was not significant. AAP-10-I and AAP-80-III contained neither protein nor nucleic acid, and both had hydrophilic functional groups. But the molecular mass of AAP-80-III was less than that AAP-10-I, and so AAP-80-III could more easily penetrate into radish tissue. Moreover, arabinose accounted for a larger proportion in the monosaccharide composition of AAP-80-III, which increased the water-holding capacity of radish tissue. Based on the above results, AAP-80-III can effectively improve the rehydration characteristics of dehydrated radish.

The increasing demand of rehydrated foods is due to its better storage stability at ambient conditions and not requiring refrigeration. Prior to drying at 55, 60, 65, and 70°C in a hot air tray dryer, hot water blanching (HB), steam blanching (SB), and microwave blanching (MB) were employed as pretreatments. Rehydration of dried pretreated sweet corn kernel was performed in boiling water. The pretreatments and drying temperatures were independent factors that affected the dependent factors such as rehydration ratio, total sugar, ascorbic acid, geometric mean diameter, color, sensory evaluation, water absorption, mass, and geometric mean diameter. Peleg, Weibull, and newly proposed models were considered to describe the change in moisture content during rehydration. The proposed model performed better than other models and indicated the rise in equilibrium moisture content of rehydrated sweet corn with an increase in dehydration temperature of sweet corn due to higher R2 (0.994), and lower chi‐square (0.005) and RMSE (0.064). The rehydrated sweet corn obtained from samples processed with microwave blanching and dehydration at 70°C showed higher retention of total sugar, ascorbic acid, geometric mean diameter, and color. [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.)

Summary: Soy protein, one of the most commonly used raw materials for texturised vegetable protein, has an important influence on texturised soy protein (TSP) with its 7S and 11S fractions. In this study, soy 7S and 11S proteins were extracted from soybean isolate and added back to the raw material to prepare TSP and analyse the effect of both on the physical properties of TSP. The results showed that the addition of 5% soy 7s or 11s protein increased the water‐holding capacity (up to 9.04%) and rehydration rate (up to 25.71%) of TSP. Compared with adding soy 11s protein, adding soy 7s protein has a faster rehydration rate at a lower temperature (30 and 45 °C). After extrusion, the content of free sulphhydryl groups, total sulphhydryl groups, and disulphide bonds was significantly reduced (P < 0.05). The extrusion treatment caused degradation of the protein chains, and the proteins mainly formed insoluble polymers. Electrophoretic analysis revealed that the sodium dodecyl‐sulphate (SDS) reducing the extractable rate of the precipitate after SDS non‐reduction extraction of the TSP added with 5% soy 7S and 11S proteins were lower than that of the control. The proportion of different soybean protein components in TSP could change its texture, water‐holding, and rehydration characteristics of it, which provides a new method for the characteristics design of TSP. [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.)

The aim of this work was the evaluation of the geometrical, physical and nutritional properties of five commercial pear cultivars ('Williams', 'Red Williams', 'Santa Maria', 'Beurré Alexander Lucas', 'Abate'). The flesh and peel of the pear cultivars were studied for their total phenolic content, total flavonoid content and DPPH radical scavenging activity. The pears were sliced and dehydrated by hot air drying at 57oC and the effects of the drying process on the color and rehydration characteristics of dried pear slices were determined. Geometric mean diameter ranged from 66.1 to 74.65 mm, sphericity 73.43 to 87.96%, volume 135.33 to 219.21 cm3 and fruit weight ranged from 134.83 to 227.31 g. Physico-chemical characteristics of the tested cultivars revealed variable amounts of moisture (82.84-84.84%), total soluble solids (12.66-14.38%), and titratable acidity (0.10-0.32% in terms of malic acid). The total phenolic content ranged between 17.29 mg GAE/100 g fw (cv. 'Red Williams') and 20.31 mg GAE/100 g fw (cv. 'Santa Maria') in the flesh and between 83.75 mg/100 g fw (cv. 'Beurré Alexander Lucas') and 176.25 mg/100 g fw (cv. 'Red Williams') in the peel. The antioxidant activity was established in the range of 1.15-1.55 mmol Trolox/100 g in the flesh and 5.05-9.32 mmol Trolox/100 g in the peel among the investigated cultivars. Browning degree of the flesh of the five pear cultivars was in a descending order of 'Red Williams' > 'Beurré Alexander Lucas'> 'Santa Maria' > 'Abate' > 'Williams'. [ABSTRACT FROM AUTHOR]

Impact of glycerol on the physico-functional, morphological, mechanical, and rehydration properties of corn starch-based aerogel has been investigated. The aerogel was prepared from hydrogel (sol-gel method) using solvent exchange and supercritical CO 2 drying. Glycerol-infused aerogel had a more connected, denser structure (0.38–0.45 g/cm3), enhanced hygroscopic behavior, and was reusable up to eight times in terms of its capacity to absorb water after being drawn from the soaked sample. However, the inclusion of glycerol reduced the aerogel's porosity (75.89–69.91 %) and water absorption rate (WAR; 118.53–84.64 %) but enhanced its percentage shrinkage (75.03–77.99 %) and compressive strength (26.01–295.06 N). The most effective models for describing the rehydration behavior of aerogel were determined to be the Page, Weibull, and Modified Peleg models. Glycerol addition improved the internal strength of the aerogel so could be recycled without significant change in the physical characteristics of the aerogel. By effectively eliminating the condensed moisture that was developed inside the packing owing to the transpiration of fresh spinach leaves, the aerogel extended the storage life of the leaves by up to eight days. The glycerol-based aerogel has the potential to be employed as a carrier matrix for various chemicals and a moisture scavenger. [Display omitted] • Developed lightweight, highly porous, mechanically stable corn starch-based aerogel using glycerol. • Number of interconnections inside the aerogel matrix increased with addition of glycerol. • Addition of glycerol increased the reusability and recompressibility of aerogel. • The developed aerogel was successfully used to absorb condensed moisture from the package of stored fresh spinach leaves. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of far-infrared radiation (FIR) assisted heat pump drying (HPD) on moisture distribution and rehydration kinetics of squid fillets during rehydration, squid samples were dried by HPD or combining with FIR at 100, 500, and 800 W. Nuclear magnetic resonance (NMR) images showed that water penetrated from the periphery to the central region during rehydration. After 60 min of rehydration, the HPD samples had high NMR signal intensity, followed by HPD + FIR (100 W), HPD + FIR (500 W), and HPD + FIR (800 W). The Peleg model was the most suitable for describing the rehydration process at all conditions based on the experimental data evaluation. HPD samples presented the highest rehydration ratio and ability, while the lowest rehydration ratio and capacity was found for HPD + FIR (800 W) samples. This result would contribute to optimizing the balance among rehydration ability, final product texture quality, and drying processing control. [ABSTRACT FROM AUTHOR]

This study is designed to investigate drying kinetics, nutrient retention and rehydration ratio of onion slices under air-impingement jet drying (AIJD) with different drying temperatures (40, 50 and 60°C), air velocities (11, 12 and 13 m/s), and the distance between jet nozzles and material box (0, 40 and 80 mm). Additionally, the influence of AIJD and hot air drying (HAD) on drying efficiency and product quality of onion slices was comparatively investigated. It was found that the moisture effective diffusivity of onion slices under AIJD ranged from 3.51 × 10−10 to 5.51 × 10−10 m2/s, and the activation energy ( Ea) of onion determined from Arrhenius equation was 14.73 kJ/mol, and ascorbic acid content (AAC), total phenolic content (TPC) and DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activity (DSA) significantly decreased in the dried onions compared to that in fresh onion. In addition, the results suggest that the Modified Page model provides the best fit for AIJD curves. Furthermore, AIJD product is better than HAD both in decreasing drying time and enhancing drying rate, AAC, TPC, DSA and rehydration ratio. Accordingly, the AIJD method has advantages in drying time and quality of products, indicating that this technology can be widely applied to food drying process. [ABSTRACT FROM AUTHOR]

• Rehydration property for FD mushroom lies between rehydrated 40 ℃-50 ℃ HAD mushroom. • Protein denaturation and ice crystal in FD process cause more damage to cell wall. • Hydration capcity of cell wall fibrous material is increased by FD. Shiitake mushrooms are unique in their porous structure, which could be affected by various chemical/physical changes during freeze-drying process. In this work, rehydration characteristics of freeze-dried products which were pre-frozen at −20 ℃, −40 ℃, −80 ℃, and −196 ℃ (by liquid nitrogen) were explored from aspects of pores and cell wall fibrous material. Although the appearance and rehydration rate of freeze-dried samples was better than hot-air dried samples with drying temperature ranging from 30 ℃ to 90 ℃, the final rehydration ratio was still less than hot-air dried samples dried at low temperature (30 ℃ and 40 ℃) due to the more serious structural damage by freeze-drying. Hydration capacity of the cell wall fiber was increased by freeze-drying, which might be ascribed to the loosen structure of cell wall instead of composition changes. Thus, hot-air drying at low temperature is still recommend and freeze-drying should be further optimized. [ABSTRACT FROM AUTHOR]

Abstract: Drying characteristics of water chestnut were evaluated in a commercially available cabinet oven at different air temperatures (50, 60, 70, 80 and 90°C) to compare the drying rate and to analyze the effect of different drying air temperature on rehydration properties. The product dried at 70°C had better rehydration characteristics. The rate constants of the exponential and Page’s model for thin-layer drying were established by regression analysis of the experimental data which were found to be affected by drying air temperature. The rate constant (k) increased (0.254–0.940h−1) with the drying air temperature. The ΔE value decreased while increasing the temperature with the values varied from 91.17 to 89.66. Rehydration characteristics were significantly affected by the drying air temperature and found to decrease with increase in drying air temperature. [Copyright &y& Elsevier]

This work aimed to study the rehydration characteristics of vacuum freeze- (VFD) and hot air-dried (HAD) garlic slices and explain the rehydration mechanism. It was observed that VFD samples had significantly faster water absorption rates than HAD samples. However, VFD samples had lower final moisture contents than the HAD samples. Additionally, the effect slice thickness on rehydration characteristics of samples was lower than that of drying methods. The contact angle and microstructure analysis of dried samples revealed that the strong water wettability and the porous structure contributed to the faster water absorption rate of VFD samples. Moreover, we found and confirmed, for the first time, that numerous air bubbles trapped in the VFD samples hindered the absorption of water. This resulted in a lower water holding capacity in VFD samples compared with HAD samples, which had less air bubbles. • Rehydration characteristics of dried garlic slices were studied. • Vacuum freeze-dried samples showed a faster water absorption rate. • Hot air-dried samples obtained the highest moisture content after rehydration. • The strong water wettability and porous structure promote the water absorption. • Air bubbles trapped in the tissue reduce the water holding capacity of samples. [ABSTRACT FROM AUTHOR]