Development of a Sulfide-Free Unhairing Method Using High- Concentration Alkali for Food- Grade Gelatin Production

Abstract

Research summary supplied by the authors

Lime splits, a by-product of the splitting process following unhairing and liming, are utilized not only for split leather production but also as raw materials for food and cosmetics, such as collagen and gelatin. However, conventional unhairing agents like sodium sulfide and sodium hydrosulfide are not approved as food additives in Japan. Although these agents are highly water-soluble and do not remain in the washed pelts, many companies remain concerned about using raw materials processed with these chemicals for food production. To address this, the Tokyo Metropolitan Leather Technology Center established an unhairing method using high-concentration alkali instead of sulfides, aiming to ensure food safety and expand applications. Given that certain high-concentration alkalis are approved as food additives, we prepared pelts using food-additive-grade high- concentration alkali and subsequently extracted gelatin from them. Furthermore, the extracted gelatin was processed into jellies, and their strength was measured to verify its potential for food applications.