molecules Article Amino Acid Profile and Biological Properties of Silk Cocoon as Affected by Water and Enzyme Extraction Chuleeporn Bungthong 1 , Colin Wrigley 2, Thanathat Sonteera 3 and Sirithon Siriamornpun 1,* 1 Research Unit of Process and Product Development of Functional Foods, Department of Food Technology and Nutrition, Faculty of Technology, Mahasarakham University, Kantarawichai, Mahasarakham 44150, Thailand;
[email protected] 2 Queensland Alliance for Agriculture and Food Innovation (QAAFI), University of Queensland, Brisbane, QLD 4072, Australia;
[email protected] 3 Managing Director, Siam Natural Products Co., Ltd., Sutthisan Winitchai Road, Samsen Nai, Khet Phaya Thai, Bangkok 10400, Thailand;
[email protected] * Correspondence:
[email protected]; Tel.: +66-88-747-4136 Abstract: We compared the efficacy for protein extraction of water versus enzymatic extraction. The amino-acid composition, inhibitory activity against enzymes α-amylase and α-glucosidase, and anti-glycation activities of silk protein extract (SPE) were determined. We used water extraction (100 ◦C, six hours) and protease-enzymatic extraction. The microstructure of silk fibers was obviously different after extraction. The results showed that enzymatic extraction gave the greater values of protein content, amino acids, total phenolic content (TPC), and total flavonoid content (TFC), as well as all biological activities parameters tested, but it also provided a more bitter taste in the Citation: Bungthong, C.; Wrigley, C.; extract—contributing amino acids of 51% (arginine, phenylalanine, histidine, valine, tryptophan, Sonteera, T.; Siriamornpun, S. Amino isoleucine, and leucine) and less sweet and umami taste contributing amino acids than did water Acid Profile and Biological Properties extraction, which could be more suitable to be used as concentrated nutraceuticals.