Enzymatic valorization process of yellow cocoon waste for production of antioxidative sericin and fibroin film

Abstract

BACKGROUND Cocoon waste, solid waste from the silk industry, is currently utilized as low‐cost spun silk yarn. In this study, the enzymatic valorization process of yellow cocoon waste to produce antioxidative sericin hydrolysate and fibroin film was demonstrated. RESULTS The enzymatic process involving thermostable alkaline protease from Bacillus halodurans SE5 (protease_SE5) was superior to the conventional high temperature and high pressure and 0.5% Na2CO3 processes. Protease_SE5 produced sericin hydrolysate with high peptide concentration (0.335 mg mL–1) and provided degummed fibroin with a complete structure. Sericin hydrolysate from protease_SE5‐assisted hydrolysis showed remarkable radical scavenging activities on ABTS, DPPH and FRAP assays with 602, 3.90 and 24.8 μmol Trolox equivalents (TE) g−1 protein, respectively. After ultrafiltration and size‐exclusion chromatography, two active fractions (F1 and F2) were obtained from sericin hydrolysate with ABTS radical scavenging activity of 2120 and 3289 μmol TE g−1 protein, respectively. Identification of bioactive peptides by de novo sequencing was conducted, and seven candidate peptides were identified with high content of key antioxidative amino acids (His, Phe, Trp, Tyr and Arg) in the sequences. Moreover, bioactivities of several of the peptides were predicted by bioinformatics databases. Besides, the mechanical properties of enzyme‐derived fibroin film were also improved, with tensile strength and elongation at break of 62.1 MPa and 3.6% in the dry state, and 8.5 MPa and 140% in the wet state. CONCLUSION This enzymatic process could be an effective way for valorizing cocoon waste. The value‐added products from agricultural waste have promising applications in food, pharmaceutical and biomedical materials. © 2020 Society of Chemical Industry (SCI)

Corn starch reactive blending with latex from natural rubber using Na+ ions augmented carboxymethyl cellulose as a crosslinking agent

“…Petroleum-based polymers generated from petroleum resources subject to depletion have detrimental effects on the environment 4 , 5 . Therefore, biodegradable polymers are being widely investigated to replace petroleum polymers, with examples including polylactic acid (PLA) 6 , 7 , polybutylene succinate (PBS) 8 , 9 , thermoplastic starch (TPS) 10 , chitosan 11 , 12 , pectin 13 – 15 , polysaccharides 16 , 17 , keratin 18 , and fibroin 19 .…”

Effect of Egg-Coating Material Properties by Blending Cassava Starch with Methyl Celluloses and Waxes on Egg Quality

“…The coating biomaterials used in the egg-production industry may be lipid-, protein-, or polysaccharide-based. Biomaterials with properties amenable to egg-coating include starch [4][5][6], carboxymethyl cellulose (CMC) [7][8][9], carboxymethyl chitosan [10], carboxymethyl bacterial cellulose [11], sericin [12,13], keratin [14], fibroin [15], and pectin [16][17][18][19].…”

Sericin cocoon bio-compatibilizer for reactive blending of thermoplastic cassava starch

“…Sericin extraction was performed using a high temperature-high pressure method. [22,56] Brie y, 45 g of the cocoon pieces (2 × 2 cm) were immersed in distilled water (1.5 L) in a 2.5 L laboratory bottle. Sericin was extracted by autoclaving at 121°C for 30 min.…”

“…The structure of serin contains many amino groups [22] with a reaction capability to several reactive groups, such as maleic anhydride groups [23] and epoxy groups. [24] Reactive blending is an effective process for improving the properties of polymer blends.…”