After hydrolyzing, silk fibroin can promote metabolism, reduce blood cholesterol, regulate metabolism and increase appetite, it is an ideal health food ingredient. The animalistic protein is decomposed into oligopeptides and amino acids by the body’s enzymes and micro-organisms, which are absorbed in the small intestine, but the digestibility of different animalistic proteins is different. Our rat experiment shows smaller molecular weight, more easily digested. silk fibroin is digested and absorbed by animals easily.

Silk fibroin contains 18 kinds of amino acids, more than 90% of the amino acids can be absorbed by the body, including 17% essential amino acids needed by the human body.Food browning reaction is peroxidation of dietary lipids during polyphenol oxidase. Norinisa, K. et experimentally found that silk fibroin could significantly inhibit polyphenol oxidase activity. Put the brain tissue of a male Wistar rat (weight 200-300 g) in a phosphate buffer, have it homogenized, then add it to bovine serum albumin (bovine serum albumin, BSA) and silk protein, after 12 minutes at 37℃, use 2 thiobarbituric-acid to detect thiobarbituric acid re-active substances. It was found that the thiobarbituric acid re-active substances level in silk fibroin sample decreased apparently, while the sample containing bovine serum albumin only decreased a little.

Similar results were found by detecting conjugated diene level in the samples. The conjugated diene level in the sample containing silk fibroin grows slowly over time, while the sample without silk fibroin in the sample grows rapidly, which indicated that silk fibroin significantly inhibited polyphenol oxidase activity, silk fibroin can be used as an antioxidant in foods.

Sasaki, M. et experimentally found that silk fibroin can promote intestinal absorption of zinc, iron, magnesium, calcium elements. Feed male Wistar rats with 20% egg proteins and 3% silk protein 12 days, it was found silk fibroin foods can significantly improve the absorption of zinc, iron, magnesium, calcium (41%, 41%, 21% and 17%). Meanwhile these elements levels don’t change in the serum, urine discharge of these elements is not affected due to silk fibroin intake, which indicates silk fibroin enhances the bio-availability of these elements.