The Effect Of Natural Antioxidant And Coating Treatment On The Quality Of Xuanwei Ham

Xuanwei ham is a typical representative of Chinese traditional cured meat product, and it is also the famous meat product of yunnan province. Due to its beautiful appearance, rich nutrition and unique flavour, Xuanwei ham has become popular all over the world. However, tradional process has been still used for the production of Xuanwei ham. The process takes long time, moreover large oxidation loss happens during the lengthy maturation period. In addition, during the sale process, color of sliced Xuanwei ham is prone to become dark, loss of flavor also happens, which lead to the loss of economic benefit of Xuanwei ham enterprises. Based on this, the Rancimat method was used to determine the induction time of ham lipids, to explore the antioxidant effect of various natural antioxidants, such as Pu-erh tea extract, rosemary extract, grape seed extract, bamboo leaves extract, tea polyphenols and VC on ham lipids. Moreover by using single factor and orthogonal designs combined with indices, such as sensory, color, POV value, AV value, TBARs value and flavor, to select the optimal combination of natural antioxidants and edible film. Further study of natural antioxidants and coating treatment on quality of Xuanwei ham during shelf life were investigated by storage experiment. The aim of this study is to reduce the oxidation loss of Xuanwei ham during ripening period, and minimize the quality change of sliced Xuanwei ham during sale process, to improve the quality of Xuanwei ham, and thus to provide theoretical guidance for the steady development of Xuanwei ham industry. Results of this study are shown as follows:1. The antioxidant effect of different natural antioxidants on ham lipids varied. Within the usage limits of the national standard, the induction time of tea polyphenols on oxidation of ham lipid was 18.9 h, significantly longer than the control group(P < 0.05), and its antioxidant effect was the best among these six natural antioxidants; induction time of 400 mesh Pu-erh tea powder on ham lipid oxidation was 8.76 h, and its antioxidant effect was comparatively good(P < 0.05); Grape seed extract and vitamin C have certain antioxidant effects on ham lipid, but not significant; the antioxidant effects of rosemary extract and bamboo leaves extracts were comparatively poor.2. The synergetic effects of natural antioxidants and edible film on the shelf life of sliced Xuanwei ham were shown as follows: comparing with the control group, sensory taste and color differences were improved significantly(P < 0.05) of the sliced ham with coating treatment, and the weightlessness rate reduced significantly(P < 0.05); As the storage time prolonged, typically after 45 d storage, synergetic use of natural antioxidants and sodium alginate coating obviously reduced the fluctuation of pH(P < 0.05), inhibiting the increase of AV value, POV value and TBARs value(P < 0.05), maintaining the flavor of sliced ham. Amongst the treatments, coating with 4 g/L sodium alginate, 45 g/L Pu-erh tea extract and 0.3 g/L VC showed the best effect. Therefore, sodium alginate coating with additional antioxidant can effectively reduce the weightlessness rate of sliced ham, postpone the lipid oxidation, and prolong its shelf life.