| Traditional Chinese meat products such as Jinhua ham, Hunan bacon, etc are loved by consumers and their color, smell, taste are known to the world. But after a long dry curing process of maturation, the fat oxidation seriously affects the safety of the product quality and purchase of psychological of consumers, the serious fat oxidation becomes key issue to product quality control, so anti-oxidation means are needed for traditional dry-cured meat products; At the same time, oil-solubility of common tea polyphenols is poor and the application of them to oil-rich foods is difficult. In response to these two aspects, study of modification method of tea polyphenols and improvement of their oil-solubility and anti-oxidation activity have an important significance for controlling serious lipid oxidation of dry-cured meat products. The aim of this paper is to investigate the optimization of processing conditions and degree of molecular modification of modified tea polyphenol, as well as its effect of anti-oxidation packaging for Chinese bacon, using water-soluble tea polyphenols as the base material, which was combined with the stearyl chloride, in order to explore new materials for anti-oxidation packaging of dry-cured meat products. The detailed contents comprise three aspects:1. The antioxidation of tea polyphenols(TP) for rich oil foods such as curing meat products was influenced by their numerous hydrophilic phenolic hydroxyls. In order to increase antioxidation of tea polyphenols for oil, stearyl chloride(SC) modification method was adopted. A Box-Benhnken Design response surface experiment using reactant proportion(mole proportion of TP and SC), catalyst use level and reaction temperature as experimental factors and POV of overheated oil added with modified tea polyphenols as responses was carried out, and the processing conditions were optimized. Based on the models established, the optimum levels of the three factors were determined to be:reactant proportion,1:3.83; catalyst use level,0.0748g and reaction temperature,56.7℃, their sequential decrease order was reaction temperature, catalyst use level and reactant proportion. Under these conditions the POV was5.711meq/kg, which was33.9%lower than that by the control group(overheated oil added with common tea polyphenols). Interaction effect analysis showed that the critical value of reaction temperature presented a linear increase trend with the addition of stearyl chloride.2. To explore the degree of molecular modification of modified tea polyphenols, qualitative or quantitative analysis of site, number and chemical bond of the molecular modification of stearyl chloride was adopted. The results showed that esterification cross-linking was formed between stearyl chloride and phenolic hydroxyls of catechins of tea polyphenols, furthermore, the main binding site was located in the A ring of catechins of tea polyphenols using molecular modification of stearyl chloride to prepare modified tea polyphenols. Although the total polyphenol content of the target product decreased by88.4%, the adsorption capacity of DPPH radical decreased by9.88%in8ppm, yet as a result of its oil-solubility significantly increased by845%(p<0.01), making beneficial effects of its good oil-solubility effectively offset adverse effects of its loss of phenolic hydroxyl, so the anti-oxidation activity in lard significantly increased by20.2%(p<0.05), moreover, the solubility scope of anti-oxidation of modified tea polyphenols was extended.3. This chapter was aimed at studying the inhibition of lipid oxidative changes of Chinese bacon by modified tea polyphenol(MTP) using coating method during the ferment aging processing. The results showed that MTP could effectively inhibited lipid oxidation of Chinese bacon. Compared to tea polyphenol(TP)-chitosan group, MTP-chitosan group significantly reduced POV, TBARs content, and AV (by28.82%,12.76%, and7.91%, respectively), and surface fat (by12.73%,17.11%, and14.37%, respectively) at the end of aging time. |
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