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Alcalase and Neutrase showed optimum activity against Pacific whiting solid wastes (PWSW) at pH 9.5, 60 °C and pH 7.0, 55 °C, respectively. Alcalase had a higher proteolytic activity than Neutrase. Enzyme concentration, reaction time, and waste/buffer ratio significantly affected the hydrolysis and nitrogen recovery (NR) (p < 0.05). Optimum conditions for PWSW hydrolysis were 20 AU Alcalase/kg, 1 h reaction time, waste/buffer ratio of 1:1 (w/v). Correlation between the degree of hydrolysis (DH) and NR (R 2 = 0.970−0.978) was high. Freeze-dried hydrolysate was brownish yellow in color (L* = 54.59, a* = 6.70, b* = 27.89) and contained 2.77% moisture, 79.97% protein, 13.44% ash, and 3.83% lipid. Amino acid composition of freeze-dried hydrolysate was similar to that of PWSW and Pacific whiting muscle but tryptophan was reduced to 21.50% and 14.74%, respectively. Keywords: Waste; Pacific whiting; hydrolysate; Alcalase; Neutrase

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Essential oils are concentrated liquids of complex mixtures of volatile compounds and can be extracted from several plant organs. Essential oils are a good source of several bioactive compounds, which possess antioxidative and antimicrobial properties. In addition, some essential oils have been used as medicine. Furthermore, the uses of essential oils have received increasing attention as the natural additives for the shelf-life extension of food products, due to the risk in using synthetic preservatives. Essential oils can be incorporated into packaging, in which they can provide multifunctions termed "active or smart packaging." Those essential oils are able to modify the matrix of packaging materials, thereby rendering the improved properties. This review covers up-to-date literatures on essential oils including sources, chemical composition, extraction methods, bioactivities, and their applications, particularly with the emphasis on preservation and the shelf-life extension of food products.

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No changes in actomyosin Ca 2+ -, Mg 2+ -, or Mg 2+ -Ca 2+ -ATPase activities were observed during iced storage of Pacific whiting fillets, but Mg 2+ -EGTA-ATPase increased with a loss of Ca 2+ -sensitivity. Surface hydrophobicity of actomyosin increased substantially within 2 days, but not total sulfhydryl (SH) content. During longer storage, the SH content decreased gradually, but surface hydrophobicity remained constant. Autolytic degradation products increased in fish muscle with storage time. Myosin heavy chain (MHC) was degraded by 45% within 8 days, but no noticeable difference was observed in actin. Results indicated that autolysis may be the main cause of physicochemical changes in Pacific whiting muscle proteins during iced storage.

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