In vitro biodegradation of Bombyx mori silk fibroin (SF) was studied using food-grade proteolytic enzymes to replace acid hydrolysis. Based on the residual protein quantity and yield of amino acids (AAs) after enzymatic hydrolysis, we evaluated the proteolytic enzyme process of SF. FoodPro and Alcalase that are classified as alkaline proteases are selected as two of the best candidate enzymes for hydrolysis of SF. e activity of these enzymes exhibits a broad range of pH (6.5 to 9.0) and temperature (50°C to 65°C). e single enzyme treatment of SF using FoodPro exhibited a hydrolytic efficiency of 20-25%, and >2 g/L AAs were released after reaction for 3 h. A 2-stage enzymatic treatment using a combination of FoodPro and Flavourzyme in a sequence for a reaction time of 6 h was developed to enhance the efficiency of the proteolytic process. e yield of AAs and residual protein quantity in the enzymatic hydrolysates obtained from FoodPro-treated regenerated SF in the 1st step was 2,040 ± 23.7 mg/L and 70.6%, respectively. e yield of AAs was > two-fold (4,519 ± 42.1 mg/L), whereas the residual protein quantity decreased to 55.1% after the Flavourzyme treatment (2nd step) compared to those of the single FoodPro treatment. In the mixed treatment by simultaneously using FoodPro and Flavourzyme, approximately 45% of SF was degraded and 4.5 g/L of AAs were released within 3 h of reaction time. e regenerated SF and its enzymatic hydrolysates were characterized by performing UV-visible spectra, gel electrophoresis, and size-exclusion chromatography analyses. In the 2-stage treatment using FoodPro initially and subsequently Flavourzyme, the aggregates and high molecular weight proteins of SF were dissociated and degraded into the low molecular weight proteins/peptides (10-15 kDa and 27 kDa). SF hydrolysates as functional food might be enzymatically produced using the commercial food-grade proteolytic enzymes.

Maca (Lepidium meyeniiWalp.) has been used for nutritional and traditional purposes, owing to its chemical composition and the presence of bioactive compounds. This study aimed to develop and optimize a maceration-based method for the simultaneous extraction of total phenolic compounds (TPCs), total flavonoids (TFs), radical-scavenging activity (RSA), soluble proteins (SPs), total sugars (TSs), reducing sugars (RSs), and macamide B from maca using 95% ethanol and acidified ethanol. The effects of extraction parameters, including temperature, solvent-to-solid ratio, time, and acid concentration, on the extraction yield of TPCs, TFs, RSA, SPs, TSs, RSs, and macamide B were investigated. Optimal extraction was achieved at 40-60℃ for 5-7.5 h with the solvent-to-solid ratio of 100:10. The addition of hydrochloric acid (HCl) to ethanol significantly improved the extraction yield, and maximum extraction was achieved using 1 N HCl in ethanol. The RSA of the ethanolic extracts showed a significant linear correlation (p<0.001) with total extraction yield, TPCs, SPs, and TSs. These results imply that polyphenolic compounds, SPs/peptides, and polysaccharides are important determinants for the antioxidant function of maca. The optimized condition may be employed in nutraceutical industries to extract bioactive compounds from maca.

This study was performed to develop tteokgalbi suitable for young-aged individuals by using mudfish and radish greens, major ingredients of Chueo-tang. Mudfish-tteokgalbi (control), in which 15% of the meat and tallow was replaced with mudfish paste, was used while substituting 25 to 100% of the green onions with radish greens. The pHs and sugar contents of the tteokgalbi developed in this study were 6.07-6.28 and 9.94-10.9, respectively, and it was suitable for tteokgalbi sold in the market. Replacing green onions with radish greens while manufacturing tteokgalbi significantly reduced the color (a and b values) and weight loss during cooking compared to the control. Replacing green onions with increasing quantities of radish greens also significantly reduced the adhesiveness of the samples in the texture profile analysis. Although the overall acceptability of the control was the best, the ideal quantity of radish greens as a substitution for green onions appears to be 25-50%. The unique flavor of the supplemented radish greens was indistinguishable in the sensory evaluation and the principal component analysis with an electronic nose. Finally, radish greens were confirmed as a good ingredient for manufacturing tteokgalbi together with mudfish paste.