| Catechin has strong antioxidant and antibacterial effects and is a highly effective and safe natural antioxidant.However,the water solubility and instability of catechin limits the application of it.Encapsulation by liposomes can improve the fat soluble of catechins and increase the stability of them,thereby consolidating the biological properties of catechins and expanding the application prospects.In this experiment,catechin liposomes and catechins were separately applied to Chinese bacon,and their delay oxidation and bacteriostatic effect were evaluated.It was explored whether catechins,catechin liposomes and ?-tocopherol could effectively inhibit the formation of nitrosamines during the processing of Chinese bacon.The effects of catechin liposomes on the quality of Chinese bacon were evaluated by physicochemical indicators,volatile compounds,color and texture analysis.The specific research content and experimental results are as follow:(1)Delay oxidation and bacteriostatic effect of catechins and catechin liposomes on Chinese bacon: different concentrations(400,600,800 and 1000 mg/kg)of catechins and catechin liposomes were applied to Chinese bacon,and the thiobarbituric acid value,peroxide value,total number of colonies and p H value were determinated after different storage times.The results showed that after 25 days of storage,the delay oxidation and bacteriostatic effect of the catechin liposome group were superior to the same concentration of catechin group,and it was dose-dependent,but when the amount was more than 600 mg/kg,the amplitude would be relatively reduced,and the addition of 600 mg/kg catechin liposome could maintain the p H stability of the Chinese bacon in the later stage of storage.(2)To evaluate the effect of 600 mg/kg catechin liposomes on the quality of Chinese bacon: determined the microstructure?volatile flavor content and chroma change in Chinese bacon after storage for different times,and then performed texture analysis.The results showed that the total content of flavor substances in the catechin liposome group was(2607.74±155.47)×106 area units(AU)and the control group was(2466.38±61.03)×106 AU after 49 days of storage(p>0.05).The content of aldehydes was 0.67% in catechin liposome group,which was greater than 0.14% of the control group(p<0.05).At the end of storage,the catechin liposomes could effectively increase the redness value(a*)of Chinese bacon and slowed the increase of hardness in Chinese bacon,and had little effect on the microstructure of it.(3)The effects of adding different antioxidant formulas on the physicochemical properties,microorganism,biogenic amines and nitrosamines during the processing of Chinese bacon were studied.The results showed that the p H of all antioxidant added groups was lower than that of the control group(p<0.05),and the p H of the catechin liposome group was the lowest at 5.17.In addition,before the roasting period,the difference between the total number of colonies and the number of lactic acid bacteria in each group was small;after the maturity period,the catechin liposome group could effectively reduce the total number of colonies during the processing of Chinese bacon and increase the number of lactic acid bacteria.The results of biogenic amine test showed that the content of five biogenic amines(putrescine,cadaverine,tyramine,spermine,phenethylamine)increased continuously in all groups during Chinese bacon processing,and 0.030% catechin liposome could control the total content of biogenic amines to a minimum.At the same time,N-nitrosodimethylamine,N-nitrosopyrrolidine,N-nitrosopiperidine and N-nitrosomethylethylamine could be detected in bacon samples,of which 0.030% catechin liposomes were most effective in reducing nitrosamines.In summary,the proper use of catechin liposomes could effectively alleviate the fat oxidation of Chinese bacon and play a bacteriostatic effect,while reducing the production of biogenic amines and nitrosamines during the production of Chinese bacon. |
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