RESUMEN
Abstract Effect of sonication on the blueberry juice was studied by evaluating the pH, viscosity, electric conductivity, color, total sugars, soluble solids, polyphenol, anthocyanidin, and radical scavenging activities. There were not any remarkable (p > 0.05) change in pH and electric conductivity. However, viscosity and color of blueberry juice markedly (p < 0.05) enhanced with the extension of sonication time. Meanwhile, total sugars, soluble solids, polyphenol, and anthocyanidin were obviously enhanced (p < 0.05). Moreover, prominent increase (p < 0.05) was observed on DPPH, superoxide, and hydroxyl radicals scavenging activities of sonicated blueberry juice. The current results exhibited sonication effectively improved blueberry juice quality and enhanced its antioxidant activity.
RESUMEN
Abstract Growth of Enterobacter aerogenes and accumulation of histamine in chub mackerel (Scomber japonicus) were investigated through measuring bacterial count, histidine decarboxylase (HDC) activity and histamine content in fish samples stored at various temperatures from 4 to 37 °C. Results showed that bacterial count and HDC activity rapidly increased in chub mackerel inoculated with E. aerogenes at storage temperature above 20 °C and reached the highest values (8.64 log CFU/g and 31.68 U/g) at 37 °C. Meanwhile, fish samples stored at 25 and 37 °C for 18 h, formed histamine at above 50 mg/100 g of the potential hazard level. In contrast, bacterial growth and histamine formation were controlled for 36 h by cold storage at low temperature (4 °C). Therefore, strict temperature control was necessary for preservation and processing of chub mackerel in order to assure this marine fish safety.
RESUMEN
Abstract Melanin is a natural high molecular weight pigment with the huge application value and development potential in food industry. In the present study, medium composition for melanin production by fungus Auricularia auricula was investigated. Wheat bran extract, l-tyrosine, and CuSO4 were determined to optimize medium composition by response surface methodology with Box-Behnken design. Results indicated that the optimal medium composition was 26.80% (v/v) wheat bran extract, 1.59 g/L l-tyrosine, and 0.11 g/L CuSO4, and the maximum melanin yield was 519.54 mg/L. Melanin production through A. auricula fermentation avoided expensive enzymatic or complicated chemical methods for melanin extraction from tissues of plant or animal, which had the huge application value and development potential for efficient production of melanin.