No abstract

A novel calcium‐binding peptide was first identified from Acetes japonicus proteolysate. First, the small shrimp was hydrolyzed using Flavourzyme and four peptide fractions of 10–30 kDa, 3–10 kDa, 1–3 kDa, and <1 kDa were recovered and examined for their calcium‐binding activity. The calcium affinity of <1‐kDa fraction was the highest with 277.96 ± 20.93 mg Ca2+/g protein, which was 1.7‐folds lower than that of casein phosphopeptide (CPP). A calcium‐binding peptide with its sequence of Tyr–Glu–Ile–Pro–Ala–Glu–Asp–Leu and its molecular weight of 948.4 Da was identified using mass spectrometer/mass spectrometer (MS/MS) method. Therefore, Acetes japonicus could be considered as a natural source of calcium‐binding peptide which could be used as a new calcium supplement. Practical applications Calcium‐binding peptide could be used as a natural supplement source of calcium. In this research, calcium affinity peptide was first recovered from proteolysate of a species of small shrimp which is quite cheap and underestimated in terms of both nutrition and economical value. Hence, the small shrimp, Acetes japonicus, could be considered as a natural source of calcium‐binding peptide. This will help the exploitation and utilization of the small shrimp more and more effectively.

Research background. By-products of food industry have been studied as high fiber and antioxidant ingredients for healthy food products, because of their economic and environmental benefits. However, the soluble dietary fiber (SDF) content of these materials is usually lower than the recommended value that is claimed to bring great health effects. Enzymatic treatment could be an efficient method for modifying insoluble and soluble dietary fiber contents of these materials. The purpose of this study was to investigate the effects of enzymatic treatment conditions on SDF, insoluble dietary fiber (IDF), total dietary fiber (TDF) proportions of spent green tea leaves (STL) and evaluate the quality of dough and cookies, when different levels of untreated and treated STL were added to the recipe. Experimental approach. The contents of SDF, IDF and TDF of STL powder was evaluated after STL was treated by cellulase preparation with enzyme loadings ranged from 0 to 25 U/g and treatment times ranged from 0 to 2 h. Wheat flour was replaced by untreated and treated STL powder at 0, 10, 20, 30 and 40 % in cookie formulation. Textural properties of dough, proximate composition, physical properties and overall acceptability of cookies were analysed. Results and conclusions. The appropriate condition of enzymatic treatment was enzyme loading of 20 U/g and biocatalytic time of 1.5 h, under which the SDF content of STL increased by 144.5 % in comparison with that of the control sample. The addition of STL led to the rise in dough hardness. Increase in STL level also enhanced fiber content, antioxidant activity and hardness of cookies but reduced their overall acceptability. Moreover, the enzymatic treatment of STL improved the SDF to TDF ratio of cookies, which relates to health benefits, and their textural property. Untreated and treated STL added cookies at 20 % received the overall acceptance. Novelty and scientific contribution. For the first time, enzymatic treatment of STL was performed to improve its SDF to TDF ratio. The treated STL is a new promising high fiber and antioxidant ingredient for cookies making.

In this study, the highest oil yield of kumquat peel essential oil extraction of 3.89±0.03% was achieved under the supercritical carbon dioxide (SC-CO2) extraction condition including 250 bars, 50°C, fluid rate of 20 g/min and 120 min of extraction. Limonene comprising 39.25% was the main component of the oil. It showed 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) cation radical (ABTS•+) scavenging activity and ferric reducing antioxidant power (FRAP) value of 25.29±0.17mM Trolox equivalent (mM TE)/g dry weight and 6.25±0.15 mM TE/g dry weight, 4565 and 4623 folds lower than those of vitamin C, respectively. Inhibition zone diameter (IZD) of pure oil equaled to that of (i) 9.2 µg/mL Ampicillin solution against Bacillus subtilis, (ii) 23.4 µg/mL Ampicillin solution against Staphylococcus aureus, (iii) 7.2 µg/mL Streptomycin solution against Klebsiella pneumoniae, (iv) 35.1 µg/mL Amikacin solution against Pseudomonas aeruginosa, and (v) 37.7 µg/mL Amikacin solution against Proteus mirabilis. Meanwhile, minimal inhibitory concentration (MIC) value of the oil was 5 mg/mL for B. subtilis and 10 mg/mL for the rest bacteria.