Studies On The Oxidation Of Pork Myofibrillar Proteins And The Its Gel Characteristics Changes

Pork is a kind of meat which has a largest production and consumption in the world. A gel is formed when the myofibrillar proteins in the pork are heated, is a most important function and characteristic of the producted meat products. The characteristic of gel and rheological behaviour and so on has played a decisive role when it happened. The furthest improvement of the quality of meat products gel, has become an important topic of the meat industry research.The proteins are oxidized by free radicals, it influents the meat appearance and quality seriously and reduces the shelf life, it not only wastes the raw material and no economic, but also can not meet the appearance and security of meats when consumers buy them. The quality and structure of protein gel in muscle can reflect the quality of meat to a certain degree, so study the change of its quality and structure when myofibrillar proteins are oxidized by free radicals has an important practical significance. This paper at the base of previous studies is aim to establish the system of vitro hydroxyl radical, reveal the mechanism of gel formation, the oxidation of myofibrillar proteins, the change of the quality and structure of gel when proteins are oxidized and the protection of the gel when the antioxidant supplements are used, in order to provide theoretical guidance to the safety and storage of meat and meat products.At the base of single factor experiment, the method of the response surface is used to optimize the hydroxyl radicals produce system in vitro. Then myofibrillar proteins are extracted from pork tenderloin, and myofibrillar proteins gels are prepared in different pH value, temperature and salinity, then the hardness, adhesiveness, springiness, and water holding capacity of the gels are determined with the method of TPA in Texture Analyzer. At the basis of single factor experiment, the optimum technological conditions are optimized with the method of the response surface. The quality and structure of the gels when they are produced in which myofibrillar proteins are oxidized with free radical in vitro are optimized with the method of the response surface, then the quality and structure and WHC of the gels are compared when myofibrillar proteins are oxidized. The protection of the antioxidant supplements to the gels is studied finally. The main research results are as follows:1、The system of the free radical in vitro is optimized. This paper is to produce hydroxyl radical with FeCl3, ascorbic acid and hydrogen peroxide, then capture it use salicylic acid-ethanol by determining the absorbance, this method is called Fenton reaction. At the base of single factor experiment, the optimum technological conditions which produces the most hydrogen peroxide are optimized with central composite design principle in Minitab15, then the results are revised as follows: FeCl30.18mL, ascorbic acid0.12mL, hydrogen peroxide solution0.72mL.2、This paper is to study the influence of pH, temperature, salt concentration to the texture of the gels are studies. At the basis of single factor experiment, the influence of the texture and WHC of the gels is different totally with multiple comparison significant analysis in DPS data processing system, it shows that the hardness, adhesiveness and WHC of the gels are significant difference respectively, but the springiness of the gels are not significant difference respectively.3、The conditions which influence the texture and WHC of the gels are optimized. At the basis of single factor experiment results, the mathematical model is estimated to optimize the hardness, adhesiveness and WHC of the gels with the CCD of Box-Behnken in Minitab15system. The best technological conditions are revised as follows:pH7.2, the temperature58℃, salt concentration0.36mol/L.4、The change of the texture and WHC of the gels when the myfibrillar proteins are oxidized is compared. The result shows that, the hardness19.7g, the adhesiveness-36.79, the WHC56.83%before oxidation, And the hardness10.2g, the adhesiveness-50.27, the WHC45.25%after oxidation. It shows that the hardness and WHC reduces, but the adhesiveness of the gel rises.5、The effect of hydroxyl radical scavenging agents (Vc, thiourea, mannitol) is studies. The capacity of scavenging agents is compared by determining the texture and WHC of the gels in the method of adding them before the oxidation occurs. The results show that capacity of the scavenging agents remove hydroxyl radicals. Vc> thiourea> mannitol.