Studies On The Mechanism And Factors Of Tenderness Variation In Duck Meat

China is one of the biggest nations in duck meat production and consumption. Tenderness is considered as one of the most important factors of duck meat, while there is still lack of a systematic research and exists controversies on how to affect duck meat tenderness. Therefore, this study was designed to track the changes of duck meat tenderness and related characteristics with breed and cutting position, heating and curing, and calpain gene, and then to provide rationale for practical problems in duck meat production and also for scientific research. The details are as follows:1. Effect of breed and cutting position on tenderness in duck meatThis study was to explore the effect of breed and cutting position on duck meat tenderness and explain the mechanism involved. Three breeds of ducks as Muscovy, Cherry valley, and Gaoyou duck were selected in this study and 30 of each were used for the analyses of slaughter performance, chemical determination, mechanical and histological measurements. The results showed that Muscovy duck is superior quality in the 3 duck varieties from the slaughter rate, whole net thorax percentage, breast and thigh muscle rate and the meat tenderness. The weight and rate of breast muscle were respectively bigger than that of thigh muscle. WBSF correlated (P<0.01) with diameter of muscle fiber and perimysial thickness, and correlated (P<0.05) with cooking loss and collagen protein. WBSF of breast meat increased with the increase of collagen protein content (P<0.01), while WBSF of thigh meat decreased with the increase of insoluble collagen protein contents (P<0.05) The results suggested that the diameter of muscle fiber and perimysial thickness had significantly effect on tenderness. Cooking loss and collagen protein also influenced duck meat tenderness, but the mechanism was complex.2. Effect of cooking temperature and curing on tenderness in duck meatThis study was to explore the effect of cooking temperature and curing on duck meat tenderness and an explanation was given for how it changes during cooking and curing. Breast and thigh meat samples from duck were taken and divided into two groups. The samples of one group were heated in water to 50, 55, 60, 65, 70, 75, 80, 85 and 90℃respectively. The samples of the other group were first cured in 2%,4%,6% and 8% NaCl solution respectively and then heated to 72～75℃. The samples were used for mechanical and histological measurements. The results indicated that heating has an obviously damaging effect on the myofibril structure. 60 and 65℃is a critical cooking point for meat quality of duck breast and thigh meat respectively. Tenderness is influenced by the natures of both myofibril components and intramuscular connective tissue. DSC thermograms of tissue showed that the number of peaks was reduced and maximum temperatures of the peaks changed when the tissue was treated with increasing NaCl concentrations. Cured with NaCl has a clear effect on enhancing structural damage to the myofibril and preventing severe contraction while heating, especially at the concentration of 2%～4%.3. Effect ofμ/m calpain mRNA expression on tenderness in duck meatAccording to the sequence of chicken calpain andβ-actin, two primers were designed to amply duck muscle mRNA, and calpain gene andβ-actin gene were partially cloned. Then two primers were used to conduct real-time PCR analysis of calpain andβ-actin with SYBR Green method. The result showed: (1) 9～20 exon of calpain were cloned. The similarity of calpain gene between duck and chicken was only 90%; (2) The expression level between breast and thigh meat differ dramatically, which indicated that calpain may play an important role in duck meat tenderization.