Effects of Extraction Methods on the Amino Acid Profile, Bioactive Compounds, and Biological Activities of Silkworm Cocoon Extracts (Bombyx mori L., Leaungsaraburi Strain)

Silkworm cocoons contain proteins and bioactive compounds with potential food applications. This study compared boiling, Alcalase-assisted, and autoclave-assisted extraction of Bombyx mori L. cocoons (Leaungsaraburi strain) based on their microstructure, amino acid composition, bioactive compounds, and in vitro biological activities. Autoclaving caused the most pronounced disruption of cocoon fibers and yielded the highest protein and total amino acid contents, increasing 1.80- and 2.72-fold, respectively, compared with boiling. In contrast, the enzyme-assisted extract contained the highest relative proportion of essential amino acids (45.48%). Autoclaving also increased total phenolic acids and identified flavonoids by 7.43- and 3.61-fold, respectively, with rutin and myricetin reaching 39.43 and 37.47 µg/g DW. Compared with boiling, autoclaving enhanced ABTS and FRAP activities by 4.08- and 7.44-fold, respectively, while anti-AGE formation, α-amylase inhibition, and α-glucosidase inhibition increased by 3.85-, 3.28-, and 4.63-fold, respectively. Amino acid profiles further indicated differences in potential taste characteristics, with boiling favoring sweet-associated amino acids and autoclaving favoring bitter-associated amino acids. These findings demonstrate that extraction conditions substantially influence the composition and in vitro bioactivities of silk cocoon extracts, providing a basis for further investigations into their safety, nutritional properties, and potential food applications.