Effect of postharvest storage time on quality characteristics of explosion puffing dried whole shiitake mushroom (Lentinula edodes) crisps.

BACKGROUND: Non-fried shiitake mushroom (Lentinula edodes) crisps fabricated by explosion puffing drying (EPD) are receiving worldwide attention because of their crispness, convenience, nutrition and health functions. The quality of mushroom crisps varies with storage time of fresh L. edodes. Therefore, the effect of postharvest storage time (ranging from 0 to 14 days) of fresh L. edodes on quality characteristics of EPD- processed mushroom crisps was evaluated. RESULTS: The weight loss and total color difference of fresh L. edodes were increased to 2.95% and 24.66, but moisture content, firmness and lightness were reduced by 6.14%, 40.70% and 43.57%, respectively, after 14 days storage. The puffing degree of mushroom crisps was initially increased to its highest value (55.95%) on the 4th day storage and thereafter decreased. The highest rehydration ratio (2.36) and crispness (63.67), and lowest hardness (102.95 N) of mushroom crisps were fabricated with L. edodes on the 4th day of storage. Free water was predominant in fresh L. edodes, which was decreased for fresh L. edodes, whereas it increased initially to the maximum value and decreased thereafter for osmotic dehydrated and heat pump pre-dried L. edodes with increasing storage time. Principal component analysis and hierarchical cluster analysis confirmed that fresh L. edodes stored at different times had a remarkable effect on quality characteristics of mushroom crisps. CONCLUSION: Fresh L. edodes stored at 4 ± 1 °C for 4 days is recommended for fabrication of mushroom crisps with superior quality. This study provides a theoretical basis for selection of a suitable storage time for fresh L. edodes before EPD of crisps. © 2023 Society of Chemical Industry.

Effects of ultrasound pretreatment on the drying kinetics, water status and distribution in scallop adductors during heat pump drying.

BACKGROUND: A material's physical and chemical properties during drying are influenced by water status and distribution. However, merely overall water removal is reported in many investigations, which hinders clarification of the drying mechanism. Therefore, the effects of ultrasound (US) pretreatment (0 W, CK; 90 W, US-90; 180 W, US-180) on the drying kinetics and quality of heat pump drying (HPD) scallop adductors was performed based on low-field nuclear magnetic resonance (LF-NMR). RESULTS: Compared with CK, effective moisture diffusion coefficient was increased by 12.43% and 23.35% for US-90 and US-180, respectively. The Weibull model satisfactorily described the drying characteristics with a high r2 (> 0.998), low rmse (< 0.0120) and χ2 (< 0.00008). LF-NMR revealed that the immobilized water was predominant in scallop adductors. As drying proceeded, the relaxation time of free and immobilized water was decreased sharply, whereas the relaxation time of bound water scarcely changed. The time required to reduce approximately two-fifths of the original peak area of immobilized water was 720, 630 and 540 min for CK, US-90 and US-180, respectively. The amplitude of immobilized water was decreased and bound water increased significantly, although free water was kept constant (ranging 1-2%). US pretreatment reduced total color difference and hardness, but enhanced the toughness of dried scallop adductors. However, US had no significant influence on the product rehydration rate and shrinkage rate. CONCLUSION: LF-NMR was successfully employed to evaluate the drying degree of scallop adductors. US facilitated the conversion of immobilized water to free water and, consequently, promoted water removal during HPD. © 2021 Society of Chemical Industry.

Vitamin C inhibits lipid deposition through GSK-3ß/mTOR signaling in the liver of zebrafish.

In this study, the mechanism that VC inhibits lipid deposition through GSK-3ß/mTOR signaling was investigated in the liver of Danio rerio. The results indicated that 0.5- and 1.0-g/kg VC treatments activated mTOR signaling by inhibiting GSK-3ß expression. The mRNA expression of FAS, ACC, and ACL, as well as the content of TG, TC, and NEFA, was decreased by 0.5- and 1.0-g/kg VC treatments. Moreover, to confirm GSK-3ß playing a key role in regulating TSC2 and mTOR, GSK-3ß RNA was interfered and the activity of GSK-3ß was inhibited by 25- and 50-mg/L LiCl treatments, respectively. The results indicated that GSK-3ß inactivation played a significant role in inducing mTOR signaling and inhibiting lipid deposition. VC treatments could induce mTOR signaling by inhibiting GSK-3ß, and mTOR further participated in regulating lipid deposition by controlling lipid profile in the liver of zebrafish.

Effects of sodium alginate-based coating pretreatment on drying characteristics and quality of heat pump dried scallop adductors.

BACKGROUND: Drying efficiency and quality maintenance are the major concerns of both manufactures and consumers. Heat pump drying (HPD) is suitable for heat sensitive foodstuffs due to its ability to independently control the drying operation parameters. However, lower drying rate and energy efficiency in the later period of HPD are the bottlenecks that restrain its application. A novel approach using hydrocolloids as pretreatment coatings prior to drying was designed to solve these problems. The effects of sodium alginate (SA) coating, drying temperatures and air velocities on the drying characteristics and quality attributes of scallop adductors were evaluated. RESULTS: Drying took place in the falling rate period. Drying time decreased with increasing temperature, air velocity and SA coating. The Two Term model and the Wang and Singh model gained the best fit for thin-layer drying of scallop adductors and SA film, respectively. Effective moisture diffusivity increased with temperature, velocity and SA coating and were in the range 7.352-14.620 × 10-11 , 9.890-17.100 × 10-11 and 2.348-4.604 × 10-10  m2  s-1 for uncoated scallop adductors, SA coated scallop adductors and SA films, respectively. The activation energies for SA films, coated and uncoated scallop adductors were 17.07, 20.78 and 26.17 kJ mol-1 , respectively. Dried scallop adductors with SA coating pretreatment exhibited a significant lower value of shrinkage rate and hardness, and higher value of toughness than uncoated ones at 30 °C and 2.0 m s-1 (P < 0.05). CONCLUSION: Hydrocolloid coating is a promising pretreatment in improving HPD efficiency and enhancing quality attributes of dried scallop adductors. © 2019 Society of Chemical Industry.

Cross-Sectional Profile Evolution of Cu-Ti Gradient Films on C17200 Cu by Vacuum Thermal Diffusion.

To improve the wear resistance and fatigue life of Cu alloys, surface modification by combining the magnetron sputtering of Ti film followed by vacuum thermal diffusion is always applied, where the structure and composition of the fabricated film play a determinant role on the mechanical properties. In the present work, the evolution of the layered structure and the element distribution of the formed multi-phases coating on C17200 Cu alloy are investigated by mathematical calculation based on Fick's law, and the experimental verification by the thermal diffusion of the gradient Cu-Ti film was undertaken under different temperatures and durations. The results show that the layered structure of the fabricated coating is dependent on the Cu-Ti atom concentration, the increasing time and the temperature, where a single or stratified layer is formed due to the generated Cu-Ti intermetallics for the inter-diffusion between the Cu and Ti atoms. The atom distribution by the proposed simulation method based on Fick's law corresponds to the experimental results, which can be applied to designing the structure of the modification layer.

Development and characterization of active and pH-sensitive films based on psyllium seed gum incorporated with free and microencapsulated mulberry pomace extracts.

Intelligent packaging with a pH indicator has been a hot research topic due to its extra active role compared with traditional ones. Considering the possible toxicity of synthetic pH sensitive pigments, natural pigments are promising alternative indicators. This work aimed to develop and characterize active and pH sensitive films based on psyllium seed gum (PSG) incorporated with free and microencapsulated mulberry pomace extracts (MPE). Compared with PSG control film, PSG-MPE films showed an increase in total phenolic content and DPPH scavenging activity, and decrease in surface hydrophobicity, lightness, and tensile strength. The molecular interactions between PSG and MPE were confirmed by thermal and microstructure analysis. Moreover, PSG-MPE films displayed wide color differences from red to blue at pH 2.0 - 12.0. PSG-based films containing 10% free and microencapsulated MPE demonstrated better overall performance and economy in packaging applications, which could be used as promising active and pH-sensitive food packaging materials.

Physicochemical, mechanical and structural properties of composite edible films based on whey protein isolate/psyllium seed gum.

A composite film composed of whey protein isolate (WPI) and psyllium seed gum (PSG) was investigated. Its physicochemical, mechanical and structural properties were determined at different ratios of WPI/PSG (1:0, 3:1, 1:1, 1:3, 0:1). WPI/PSG composite films had higher water contact angle and water vapor permeability, as well as lower oxygen permeability and light transmittance as compared with single WPI or PSG films. With the increase in PSG concentration, higher film brightness and whiteness index, and smaller total color difference were observed. The tensile strength and elastic modulus of the composite film at WPI/PSG ratio of 1:1 was the highest. Elongation at break of composite films was higher than that of the single films. WPI/PSG composite films were more effective than single films in reducing the surface cracks and degree of cracks. XRD revealed a typical semi-crystalline amorphous structure of the composite films. With the increase of the PSG content, higher diffraction peak strength and crystallinity of the films were observed. The results indicated that the properties of the WPI/PSG composite film were superior to that of PSG or WPI film alone. The composite film at WPI/PSG ratio of 1:1 resulted in the highest comprehensive physicochemical and mechanical performance.

Thermodynamic Properties and State Diagram of Gum Ghatti-Based Edible Films: Effects of Glycerol and Nisin.

In this present study, the thermodynamic and thermal properties of glycerol and nisin-incorporated gum ghatti (GG, Anogeissus latifolia)-based films were determined. The films exhibited type III isotherm behaviors. Moisture content (MC) of films was increased with increasing water activity (aw) and decreased with higher temperature. The incorporation of glycerol and nisin increased the sorption ability of GG films. The net isosteric heat of adsorption (qst) and differential entropy (Sd) were decreased with increasing MC, showing an exponential negative correlation between them. Spreading pressure (φ) was increased with increasing aw, but decreased with higher temperature. This incorporation of glycerol and nisin increased the qst, Sd and φ of the GG films. The sorption behaviors were enthalpy-driven and non-spontaneous processes. The glass transition temperature (Tg), critical MC and aw of the films were decreased, and increased respectively with the incorporation of glycerol and nisin. This work provides a theoretical basis for the application of edible films in fresh food preservation.

Wnt10b Participates in Regulating Fatty Acid Synthesis in the Muscle of Zebrafish.

There are 19 Wnt genes in mammals that belong to 12 subfamilies. Wnt signaling pathways participate in regulating numerous homeostatic and developmental processes in animals. However, the function of Wnt10b in fatty acid synthesis remains unclear in fish species. In the present study, we uncovered the role of the Wnt10b signaling pathway in the regulation of fatty acid synthesis in the muscle of zebrafish. The gene of Wnt10b was overexpressed in the muscle of zebrafish using pEGFP-N1-Wnt10b vector injection, which significantly decreased the expression of glycogen synthase kinase 3ß (GSK-3ß), but increased the expression of ß-catenin, peroxisome proliferators-activated receptor γ (PPARγ), and CCAAT/enhancer binding protein α (C/EBPα). Moreover, the activity and mRNA expression of key lipogenic enzymes ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACC) and fatty acid synthetase (FAS), and the content of non-esterified fatty acids (NEFA), total cholesterol (TC), and triglyceride (TG) were also significantly decreased. Furthermore, interference of the Wnt10b gene significantly inhibited the expression of ß-catenin, PPARγ, and C/EBPα, but significantly induced the expression of GSK-3ß, FAS, ACC, and ACL. The content of NEFA, TC, and TG as well as the activity of FAS, ACC, and ACL significantly increased. Thus, our results showed that Wnt10b participates in regulating fatty acid synthesis via ß-catenin, C/EBPα and PPARγ in the muscle of zebrafish.

Characterization of a novel edible film based on gum ghatti: Effect of plasticizer type and concentration.

The feasibility of using gum ghatti (GG) as a novel film-forming material was investigated. Physical, barrier, mechanical and optical properties were determined as a function of GG content, plasticizer type and concentration. Sorbitol-GG films had lower moisture content, water contact angle, water vapor permeability and oxygen permeability but higher water solubility than glycerol-GG ones. Tensile strength and elastic modulus of films decreased whereas elongation at break increased with plasticizer concentration. GG films tended to be green and yellow. Film's total color difference increased and whiteness index decreased with plasticizer concentration. Glass transition temperature of films decreased with increasing plasticizer concentration. Smooth and regular surface morphology without phase separation between film's components were ascertained using scanning electron micrograph. X-ray diffraction revealed an amorphous-crystalline structure of GG films and crystallinity index decreased with increasing plasticizer concentration. GG has a promising potential in edible films production.

[High-spectral responses of Myrica rubra seedlings to UV-B radiation stress].

A simulated field experiment with three treatments, i. e., ambient light (control), reduced UV-B radiation, and enhanced UV-B radiation, was conducted to evaluate the effects of solar ultraviolet (UV-B) radiation on the seedlings of Myrica rubra, a typical woody species in subtropical region. The leaf chlorophyll content, spectral reflectance and spectral characteristic parameters were measured and analyzed. As compared with the control, enhanced UV-B radiation decreased the seedling chlorophyll content while reduced UV-B radiation significantly increased the chlorophyll content, and these effects reflected in the spectral reflectance. Under the effects of the three gradients of UV-B radiation, the differences in the reflectance at visible region mainly occurred around the green peak and red edge on the reflectance curve, and the peak wavelength of the red edge shifted to longer wavelength. Enhanced UV-B radiation had an accumulated temporal effect on M. rubra. The inverted-Gaussian model parameters R0, lambda0, lambda(p), Rs, and 6 were the useful guides to reveal the spectral responses of M. rubra seedlings under UV-B radiation stress, among which, Rs performed the best. The differences in the spectral reflectance under different UV-B radiation levels could be effectively distinguished with the vegetation indices composed of the spectral reflectance of narrow wave bands or the reflectance at specific wavelengths.