Study On The Control Of Iridescence In Beef Products

This paper is consisted of four chapters. Chapter I : Investigation of iridescence in meat and meat products; Chapter II: Effects of processing and additives on the iridescence in beef ; Chapter III: Study on the control of iridescence in beef products; Chapter IV: Study on the relationship between iridescence and myofibrillars in beef products.Chapter I : The chapter has made an investigation on pork and beef in some of big slaughterhouses, meat and meat products in supermarkets of Nanjing were also investigated. The results showed that there was no iridescence on pork, the positions of beef appearing iridescence were Semitendinosus (ST, 83%), Longissimus lumborum (LD, 21%), Psoas major(PM, 7%) and Biceps femoris (BF, 5%). The iridescence on pastrami beef, roast beef and spiced beef was the most visible, it was also obviously found on westen-style sliced ham and salted pork.Chapter II: The effects of tumbling time, ulrasonication time ,cooking temperature and some additives on iridescence in beef semitendinosus(ST) were studied.The results showed that iridescence decreased with tumbling and ulrasonication, increased with the increasing cooking temperature; adding water had no effect on iridescence but adding NaCl and composite phosphates had a significantly effect on iridescence in beef ST (P<0.05) .Chapter III: Based on the results of chapter II, Choosing tumbling, ultrasonic bath treatment and cooking to get beef products with less iridescence in this chapter. It showed that the least iridescence appeared after tumbling for 14 h and ultrasonic bath treatment for 9 min and cooking to 68℃.The intensity and area of iridescence reached to 0.18 and 8%, respectively.Chapter IV: The proteolysis of myofibrillars treated with ultrasonic bath treatment and the myofibrillars structural change after being cooked and cured were studied in this chapter.It showed that peptides with molecular weight of 25 kDa appeared after ulrasonication and the Myofibrillar Fragmentation Index increased with ulrasonication,and the surface structure becomed disorder, simultaneity. The surface structure of transverse section becomed more smooth and myofibrillars arranged more regularity after being cured and cooked . Myofibrillars affected the origin and change of iridescence .