Abstract
Sericin is a water-soluble protein and composed of hydrophilic amino acids and acidic amino acids. The key amino acids in sericin are serine, threonine, aspartic acid, and glutamic acid. Sericin has the antioxidative effect, the tyrosinase inhibitory effect, and the amelioration effect of the atopic dermatitis and the contact dermatitis as well as the moisture retention effect. It is rarely known that sericin contains the spore forming bacteria which are parasitic on the mulberry leaves. Here, sericin was extracted from the cocoon by changing of the extraction conditions and the effects of the conditions were investigated. All sericin can be extracted from the cocoon within 1 h with water when the extraction temperature is higher than l20°C. The sericin molecule was hydrolyzed randomly during the extraction but denaturation of sericin hardly occurred. The extraction temperature is the important factor to obtain high molar mass sericin. The ultrafiltration is the effective method to exterminate the spore forming bacteria and the pore size of 0.45 micro m is enough for the filtration.
