Abstract In this study, we investigated the influence of alginate oligosaccharides (AOS) coating on the quality of white shrimp (P. vannamei) at 4 ± 1 °C. We measured shrimp quality by surveying changes in certain properties, such as sensory quality, the microbiota, total volatile basic nitrogen (TVB-N), pH, and sensory characteristics. Compared to control group, AOS coating effectively stopped the growth of bacteria and decreased the formation of TVB-N (from 40% down to 30%). The pH of samples treated with AOS was visibly lower than that of the control group. The sensory quality of the AOS coated shrimp resembled microbial and physicochemical properties, and the acceptability was improved. Furthermore, we found the abundance of spoilage microorganisms, such as Shewanella and Pseudoalteromonas, in AOS coated groups is reduced compared to control groups. All these results suggest that our AOS coating treatment may improve storage and preservation of frozen shrimp.
Deer antler is a precious animal-sourced traditional Chinese medicine. We aimed to rapidly assess the quality of deer antler slices by electronic nose so that we can ensure medical safety. In this study, response intensity of the electronic nose was favorably optimized, and samples were well assessed by using an electronic nose based on LDA model. The results obtained herein suggested that electronic nose could be an effective method to rapidly assess the quality of deer antler slices, and could also be an important tool for categorization of complex aroma mixtures for the control of quality of drugs or food.
Orthogonal design was employed to study the effect of extraction time, temperature and liquid-to-solid ratio on the production of antioxidant polysaccharides from leaves of Gynura bicolor (PLG). Analysis of variance was performed on the data obtained. The most relevant variable was extraction time. A liquid-solid ratio of 30:1 (v/w), a temperature of 80 °C and an extraction time of 3 h were found to be optimal for PLG. The optimal extraction yield of 4.9% was obtained through additional verification test. Hydroxyl radical-scavenging activity, reducing power and ferrous ion chelating ability of PLG were determined. PLG possess concentration-dependent antioxidant potency and IC50 of PLG was 4.67, 0.24 and 4.31 mg/mL for hydroxyl radical-scavenging and ferric ion chelating abilities as well as reducing power, respectively. The results suggest that G. bicolor polysaccharides could be potential source of natural antioxidant and be contributor to the health benefits of G. bicolor.
The antioxidant activities of ethanolic crude extract (LPCE) and its four different solvent sub-fractions (namely, diethyl ether fraction (LPDF), ethyl acetate fraction (LPEF), n-butyl alcohol fraction (LPBF) and residue fraction (LPR)) from longan pericarps were investigated employing various systems including 2,2-diphenyl-1-picrylhydrazyl (DPPH)/ 2,2'-amino-di(2-ethyl-benzothiazoline sulphonic acid-6)ammonium salt (ABTS)/hydroxyl radical scavenging activity, total phenolic content and reducing power. Each extract showed concentration-dependent antioxidant activity. LPEF showed the highest scavenging activity against DPPH, ABTS and hydroxyl radicals with EC50 values of 0.506, 0.228 and 4.489 mg/mL, respectively. LPEF showed the highest reducing power with EC50 values of 0.253 mg/mL. The next was LPDF with EC50 values of 0.260 mg/mL. LPEF possessed the highest total phenolic content (230.816 mg/g, expressed as gallic acid equivalents), followed by LPDF, LPBF, LPCE and LPR. The results suggested that longan pericarp fractions possessed significant antioxidant activities and could be a promising source of natural antioxidant.
Kombucha is a health-promoting fermented beverage worldwide. The present study compared the free-radical scavenging abilities and total reducing power (TRP) of kombucha prepared from low-cost green tea (LGTK), black tea (BTK), and tea powder (TPK). LGTK had the highest scavenging abilities against 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide anion and hydroxyl radicals, while BTK showed the highest TRP. Changes in content of probiotics in LGTK were investigated during storage as well. The number of acetic acid bacteria decreased moderately up to 10 days of storage. The number of lactic acid bacteria (LAB) decreased significantly, and their survival rate was only 0.98% at the 8th day of storage.