Effect of protein thermal stability and protein secondary structure on the roasted mutton texture and colour from different cuts

摘要

The age and cut of mutton are important factors influencing the suitability of roasting. In this study, the sensory quality, texture profile and surface colour of roasted mutton cuts (back strap, silverside, square cut shoulder, breast and flap and oyster cut) from Merino sheep slaughtered at ages of six months and two years were investigated. Also the protein thermal stability and protein secondary structure of different samples were also evaluated. The results showed that the muscles of back strap, silverside and oyster cut were much more suitable for roasting, presented higher sensory scores and better corresponding instrumental colour, texture properties and shear force. Lower protein thermal stability of collagen, sarcoplasmic proteins and actin in raw muscle might be the cause of the higher values of sensory attributes, L*, texture profiles and lower a* value of roasted mutton. The lower relative percentage of protein alpha-helix in fresh mutton might contribute to the higher protein random coil of roasted mutton, and these contribute with a great texture and colour. It concludes that differential protein thermal stability and protein secondary structure of muscles partially affect the roast quality of lamb.