Effects Of Different Oxidizing Oils On Protein Oxidation In Chinese Sausage

The effect of lipid oxidation on protein oxidation was studied through two methods, one was to develop a model system which combines lipid with proteins, the other was to replace pork fat in Chinese sausage with vegetable oil. The feasibility of application of vegetable oil in Chinese sausage was discussed. Details as follows:Oxidation indexes (acid value, peroxide value, TBARs), fatty acid, and volatile components in the process of storage of colza oil, soy-bean oil, and lard were tested. Results showed that there were significant differences within different oxidation indexes between lard, colza oil, and soy-bean oil(p<0.05). Soy-bean oil was oxidized more easily than colza oil and lard. There was a significant correlation within different oxidation indexes(p<0.05). Oxidation of lipid had a remarkable effect on the components of triglycerides fatty acid, phospholipid fatty acid, and free fatty acid. Polyunsaturated fatty acids had a high sensitivity on oxidation. Volatile components tested in lipid were mainly alcohol, ketone, aldehydes, acid, esters, furan, hydrocarbon, aromatic hydrocarbon. Relative contents of aldehydes and acid arise significantly during the storage of lipid. Through the analysis of correlation, lipid oxidation showed a positive effect on the accumulation of volatile aldehydes.Models were developed between lipid of different degrees of oxidation and sarcoplasmic proteins and myofibrils proteins in meat respectively. The effect of lipid oxidation on two kinds of protein oxidation was discussed. Results showed that with the increase of the degree of lipid oxidation, the carbonyl contents of sarcoplasmic proteins and myofibrils proteins arises significantly(p<0.05), while the sulfydryl groups declined significantly(p<0.05), and promoted the exposure of the lyophobic group of sarcoplasmic proteins and myofibrils proteins. There was a significant correlation between the the carbonyl contents and lipid oxidation indexes(p<0.05). Malondialdehyde which was the typical product of lipid oxidation had significant effect on the oxidation index of sarcoplasmic proteins and myofibrils proteins(p<0.05). The SDS-PAGE results showed that lipid oxidation had no effect on the degradation of sarcoplasmic proteins, but could promote the degradation of myofibrils proteins.Qualities of three groups of sausages were compared respectively, Chinese sausage whose fat was replaced by pre-emulsified soy-bean oil and colza oil respectively, and the normal Chinese sausage as the control group. Results showed that after the repining of sausage, the brightness value of the control was higher than the soy-bean oil group and colza oil group(p<0.05), however, the red value showed no significant difference(p>0.05). The results of sensory evaluation were as follows:Control> Soy-bean oil group> colza oil group. Soy-bean oil sausage had unique flavor, and was accepted more easily. Compared with control, the soy-bean oil group and colza oil group had no significant effect on texture properties and the moisture content of the product(p>0.05). There was no significant difference (p>0.05) in pH value between soy-bean oil group with control group, while colza oil group had slightly lower pH value. Therefore, Chinese sausage whose fat was replaced by pre-emulsified soy-bean oil was feasible comparatively through comprehensive analysis.Finally, the oxidation indexes of lipid and protein were tested. The results showed that compared with control, the replacement of soy-bean oil and colza oil promoted the oxidation of sarcoplasmic proteins and myofibrils proteins significantly. The result of analysis of the correlation between lipid oxidation and protein oxidation in sausage showed that, lipid oxidation in sausages could promote the increase of carbonyl content and the decrease of sulfydryl groups in sarcoplasmic proteins and myofibrils proteins. The result was almost consistent with the simulation system.