Simultaneous Extraction of Oil and Protein from Silkworm (Bombyx mori L.) Pupae (Lueng Parroj var.) and Their In Vitro Skin Moisturization

Oil and protein from silkworm (Bombyx mori var. Leung Pairoj) pupae, by-product from sericulture, were extracted and evaluated for their potential uses as skin biomoisturizer. The silkworm pupae (SWP) oil and protein were simultaneously extracted by using three-phase partitioning (TPP) method and determined for their physicochemical properties including fatty acid and amino acid content, respectively. The highest yields of oil and protein at 8.24 ± 0.21% and 8.41 ± 0.26% w/w, respectively were obtained from 18 h extraction. Fatty acid analysis of SWP oil was rich in linolenic acid (37.81 ± 0.34%), oleic acid (28.97 ± 0.13%), palmitic acid (21.27 ± 0.05%), stearic acid (6.60 ± 0.09%) and linoleic acid (4.73 ± 0.21%). The clear yellow SWP oil possessed saponification value of 191.51 mg/g, iodine value of 119.37 g I(2)/g and peroxide value of 2.00 mg equivalent O(2)/kg. The SWP protein composed of 17 amino acids which aspartic acid, glutamic acid, glycine and serine were the major residues. SDS-PAGE analysis revealed that the SWP protein consisted of distinct protein at around 51, 70, 175 and over 175 kDa. Cytotoxicity of the SWP oil and protein was evaluated by using MTT assay and they showed low cytotoxicity toward keratinocyte cell (HaCat cell line). The SWP oil provided moisturizing effect on pig skin comparable to olive oil, while 1% and 2% of SWP protein showed higher moisturizing efficacy than 3% hydrolyzed collagen. The study indicated that the SWP oil and protein could be potential biomoisturizers for cosmetic products.