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In recent years, ultrasound has been widely used in the food industry as a promising non-thermal, green technology, but the exact effect of ultrasound on the physicochemical properties of myofibrillar proteins from Procambarus clarkii is not clear yet. This study investigated the effect of high-intensity ultrasound treatment at 300 W power and 20 kHz frequency for 0, 4, 8, 12 and 16 min during homogenization on the structure and physicochemical properties of myofibrillar proteins from Procambarus clarkii. The results showed that ultrasound treatment decreased the turbidity and mean particle size of myofibrillar proteins significantly (P < 0.05), but initially increased and then decreased the solubility and absolute value of ζ-potential, demonstrating altered degree of protein aggregation. The surface hydrophobicity and endogenous fluorescence intensity initially increased and then decreased with increasing treatment time; the total sulfhydryl group content significantly decreased (P < 0.05) while the carbonyl group content significantly increased (P < 0.05), demonstrating changes in the tertiary structure and a certain degree of protein denaturation. In addition, the relative contents of α-helix and random coil increased first and then decreased, whereas the opposite trend was observed for the proportion of β-sheet, indicating changes in the secondary structure. These results showed that high-intensity ultrasound treatment could affect the physicochemical properties, structure and aggregation degree of myofibrillar proteins from crayfish meat, which could provide a reference for the application of ultrasound as an auxiliary approach in the processing and storage of crayfish.

Functional aerogels composed of regenerated cellulose and tungsten oxide were fabricated by implanting tungsten-oxide nanodots into regenerated cellulose fiber. This superfast photochromic property benefitted from the small size and even distribution of tungsten oxide, which was caused by the confinement effect of the regenerated cellulose fiber. The composite was characterized using XRD and TEM to illustrate the successful loading of tungsten oxide. The composite turned from pale white to bright blue under ambient solar irradiation in five seconds. The evidence of solar absorption and electron paramagnetic resonance (EPR) demonstrated the fast photochromic nature of the composite and its mechanism. Furthermore, carbon fiber filled with preferential growth tungsten-oxide nanorods was obtained by annealing the photochromic composite in a N2 atmosphere. This annealed product exhibited good absorption across the whole solar spectrum and revealed an excellent photothermal conversion performance. The water evaporation rate reached 1.75 kg m−2 h−1 under one sun illumination, which is 4.4 times higher than that of pure water. The photothermal conversion efficiency was 85%, which shows its potential application prospects in seawater desalination. [ABSTRACT FROM AUTHOR]

Red sour soup is a traditional fermented product in southwest China. Currently, the existing production process mainly adopts the method of natural fermentation, with long fermentation cycles and poor stability between batches. Rapid establishment of dominant strains can accelerate the formation of lactic acid, which can inhibit the growth of miscellaneous bacteria. It is also helpful for the inhibition of nitrite accumulation, shortening of fermentation. In this study, the dominant strain H9, with lactic acid‐producing ability, was isolated from the natural fermented red sour soup, and was identified as Lactobacillus buchneri, based on the 16s rRNA sequence analysis and biochemical identification. Then, the optimization of fermentation conditions was performed using L. buchneri H9 strain as external bacteria. The optimized fermentation conditions were temperature of 22°C, starch dosage of 11.24 g/L, and initial inoculation of 3.5 × 108 cfu/L. The concentration of lactic acid reached 8.029 g/L after 8 days of inoculating fermentation, which exceeded 6.221 g/L for 20 days of natural fermentation. Compared with natural fermentation, the peak of nitrite during inoculating fermentation appeared earlier and the peak height was lower. While the nitrite content in inoculating fermentation decreased to safety threshold more quickly. The volatile flavor compounds analysis showed that 41 types of volatile compounds were detected in the inoculating fermentation product, while 45 in the natural fermentation product. Over 88% compounds were overlapped, which means similar flavor between two fermentation products. These results provide a sufficient scientific basis for the industrialized production of inoculating fermentation of red sour soup. [ABSTRACT FROM AUTHOR]

Background: Ergothioneine (EGT) is a high-value food functional factor that cannot be synthesized by humans and other vertebrates, and the low yield limits its application., Results: In this study, the optimal fermentation temperature, fermentation time, initial pH, inoculum age, and inoculation ratio on EGT biosynthesis of Rhodotorula mucilaginosa DL-X01 were optimized. In addition, the effects of three key precursor substances - histidine, methionine, and cysteine - on fungal EGT synthesis were verified. The optimal conditions were further obtained by response surface optimization. The EGT yield of R. mucilaginosa DL-X01 under optimal fermentation conditions reached 64.48 ± 2.30 mg L -1 at shake flask fermentation level. Finally, the yield was increased to 339.08 ± 3.31 mg L -1 (intracellular) by fed-batch fermentation in a 5 L bioreactor., Conclusion: To the best of our knowledge, this is the highest EGT yield ever reported in non-recombinant strains. The fermentation strategy described in this study will promote the efficient biosynthesis of EGT in red yeast and its sustainable production in the food industry. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)