Improvement of physicochemical and gel properties of chlorogenic acid-modified oxidized myofibrillar proteins by transglutaminase

Chlorogenic acid (CA), a natural polyphenolic antioxidant, is used in meat products to prevent spoilage due to oxidation. Transglutaminase (TGase) is an effective protein cross-linking agent applied to meat gel products to increase the elasticity of the protein gel. The present study illustrated the effect of CA at various additions (5, 20, and 100 mu mol/g protein) and/or TGase (0.2 g/100g protein) on physicochemical and gel characteristics of myofibrillar protein (MP). Texture and rheological results demonstrated that the TGase improved the gel structures of oxidized MP treated with CA (5 and 20 mu mol/g protein). Scanning electron microscope (SEM) result showed that TGase addition made the gel network orderly, and overcame the phenomenon induced by excessive aggregation of proteins by CA at a high dose (100 mu mol/g protein). In addition, water-holding capability (WHC) and low-field NMR (LF-NMR) results demonstrated that the TGase dramatically enhanced the water-holding capability of oxidized MP gel treated with CA (P < 0.05), and the moisture distribution became uniform. FTIR analysis showed that reduced a-helix structure contributed to improving gel properties. SDS-PAGE indicated that TGase enhanced cross-linking of proteins. Conclusionally, TGase improved the physicochemical and gel properties of CA-modified oxidized myofibrillar proteins.