| Chitosan is widely used in the food industry because of its high biocompatibility and excellent preservation ability, but its antioxidant ability is not that good. Chitosan contains amino groups which can react with hydroxyl group of reductive sugar, and their Maillard reaction products can significantly improve antioxidant capacity, quality and flavor of food. Traditional dry-cured meat products are favored by many consumers because of its color, fragrance and taste, however, the long time drying mature process leads to excessive lipid oxidation which can affect their quality safety, and there’re many reports about antioxidant method on them all around the world, especially numbers of which are about antioxidant method of chitosan coating technology, but there is still lack of an very effective one. Therefore, doing some research on modifying chitosan based on the Maillard reaction in order to improve its antioxidantive properties, and to reduce excessive fat oxidation degree of the cured meat products when filmed by chitosan’s MRPs are very important. This paper studied the antioxidation of the products of chitosan’s Maillard reaction modification, the antioxidative effect and influence on products’quality when it was coated on Chinese bacon using response surface method, in order to explore a new kind of antioxidant and its producing method, the specific contents are the following three aspects:1.Study on the vitro antioxidative properties of chitosan modified by the Maillard reactionUnder the condition of high tempreture, modified chitosan with glucose with the Maillard reaction. We measured the DPPH free radical scavenging activity,reducing power and iron ion chelating ability of modified chitosan Maillard reaction products of (MRPs) to determine the influences of different viscosity and concentration of chitosan, different glucose concentration, different pH and temperature such reaction conditions on the antioxidant properties of MRPs. The results showed that:the antioxidant properties of MRPs (products of chitosan modified by Maillard reaction) had been improved significantly (p<0.05); when compared with orginal chitosan, the DPPH free radical scavenging activity of MRPs was124%at1%concentration, and the reducing power of Low, medium viscosity modified chitosan had been improved by377%,403%apparently, however the iron ion chelating ability had been improved by34.41%,24.5%apparently. The DPPH free radical scavenging activity and reducing power of MRPs were positive correlation with the viscosity and concentration of chitosan, glucose contration and reaction temperature (p<0.05). The MRPs of Low, medium viscosity of modified chitosan only differed in reduing power (p<0.05). The3.6-5.4pH value had a complicated influence on the antioxidant properties of chitosan MRPs.2.Study on the influence of antioxidative effect of Chinese Bacon filmed with MRPs which were produced under different chitosan Maillard reaction conditionsA Box-Benhnken Design response surface experiment using chitosan concentration, glucose concentration and chitosan ratio of different viscosity as experimental factors and POV of final Chinese bacon product as responses was carried out, to study on interaction effect of MRPs coating on Chinese bacon. The results showed that:the interaction effect of chitosan concentration and glucose concentration, glucose concentration and chitosan ratio of different viscosity on POV were significant (P<0.05), in which critical value of chitosan concentration increases with glucose concentration (y=0.5188x+0.6457, R2=l), and critical value of glucose concentration has a linear increasing trend with chitosan ratio of different viscosityC y=0.014x+0.7238, R2=1. Using POV as the target function regression, the optimization of modified chitosan process parameters were glucose concentration1.37%, chitosan concentration1.32%, chitosan ratio of different viscosity53.94.3.Influence of lipid antioxidantive effect and quality of chitosan MRPs coating on Chinese Bacon during processingUsed the second chapter optimal produing method to prepare chitosan MRPs, filmed on Chinese bacon, we measured physicochemical indexes (moisture, pH value, color change), oxidation indexes (POV and TBARs) changes during processing progress, and we compared with blank control and unmodified chitosan groups, to explore the antioxidative effect and quality of chitosan MRPs filmed on Chinese bacon. The results showed that: during processing, the moisture content of different Chinese Bacon groups decreased, the pH value of them had been rising but they still ranged in5.5-6.3, POV and TBARs values of them were increased at first but then decreased; the L*value of final product filmed by chitosan MRPs group was highest, the its b*value was lowest, and its POV value was significantly lower than blank control group (p<0.05), and the POV, TBARs value were reduced by14.21%,45.61%apparently when compared with unmodified chitosan group. The oxidation index (POV、TBARs) was negatively correlated with water content (p<0.05), and they all showed a positive correlation with temperature (p<0.05), indicating that when tempreture go up, the product moisture would decrease at a high speed, and lipid oxidation rate would increase. |
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