| Dry-cured mutton ham is processed through a series of processes such as selecting materials,trimming leg blanks,low-temperature pickling,elution,air drying and maturity,which have high nutritional value.In this study,Zingibain and Actinidin were added to dry-cured ham,and the degradation of muscle protein was promoted by air-drying and ripening,thereby shortening the maturity of dried-cured mutton ham and improving its tenderness.The fresh mutton hind leg meat with bone were used as experimental materials,design 7 group for tests,one group was the control group(CK group),the other 6 groups were the experimental group;the CK group was not treated,and the experimental groups were added Zingibain(S)and Actinidin(M)with the concentration of 0.01%,0.03%,0.05%respectively according to the weight of the leg meat and based on 1 000 g and dried under the corresponding conditions,to detect its effects on the quality indicator of shear force,pH value,moisture content,Water holding capacity,thiobarbituric acid(TBA),total nitrogen(TN)content,non-protein nitrogen(NPN)content and proteolysis index(PI),combined with sensory evaluation to determine the best addition of enzyme.The CK group and two protease groups with the best enzyme addition were selected to analyze the effects of two proteases on the its muscle protein degradation,microbial phase changes and volatile flavor substances,and combined with sensory evaluation to select the most suitable exogenous plant protease.The main findings are as follows:1.Determine the optimal enzyme addition amount of Zingibain and Actinidin in dry-cured mutton ham by single factor test.The results showed that compared with the CK group at maturity stage(30 d),the muscle shear force of S group at 30 d decreased by 28.17%,the TN content increased by 1.3 times,the NPN content increased by 1.7 times,and the PI increased by 1.29 times,and at the late dried stage(23 d)increased 1.31 times,the TBA value increased by 1.11 times in the allowable range,and the 0.05%S group had a moisture content of 44.71%at 23 d,already reached the 30 d of the control group(46.96%).the pH value showed a gradual upward trend,and the Water holding capacity showed a downward trend.It can be seen that the addition of 0.05%Zingibain,can significantly promote the protein and fat degradation of mutton ham,and improve its tenderness and promote loss of water,thus its maturation cycle shortened to 23d.Compared with the CK group at 30 d,the shear force of 0.05%M group decreased by 16.36%,the TN content increased by 1.2 times,the NPN content increased by 1.5 times,the PI increased by 1.27 times,and at 23 d increased by 1.2 times,TBA increased by 1.1 times,moisture content(45.27%)of the 0.05%M group at 23 d has reached the moisture content(46.96%)of CK group at 30 d,the pH value showed a gradual upward trend,and the Water holding capacity showed a downward trend;therefore,when the amount of Actinidin added was 0.05%,it could significantly promote the degradation of protein and fat of mutton ham and increase the tenderness,and shorten the maturity to 23 days.2.The CK group and the S group and the M group with the addition amount of 0.05%were selected to study the effects of two proteases on the protein degradation of the dried-cured mutton ham by SDSPAGE.The results showed that compared with the CK group,the TN content of the M group and the S group increased by 1.2 times and 1.3 times,the NPN content increased by 1.5 times and 1.7 times,and the PI increased by 1.27 times and 1.29 times,respectively.SDS-PAGE analysis showed that Zingibain was more effective in degrading muscle protein than Actinidin.It was found by protein degradation index and SDS-PAGE electrophoresis that the degradation rate of muscle protein by Zingibain was greater than that of Actinidin.3.The effects of Zingibain and Actinidin on the microbial changes of dried-cured mutton ham were studied by PCR-DGGE method.The results showed that Staphylococcus saprophyticus,Macrococcus epidermidis,Hafnia paralvei,and Leuconostoc gelidum were the dominant bacteria of dry-cured mutton ham of each group,among them there are many species of Staphylococcus.Staphylococcus xylosus appeared in the two protease treatment groups for 30 d,indicating that the two proteases can enrich the microbial species of dried-cured mutton ham.During the whole air drying process,the microbial phase changes were relatively stable,and the effects of the two proteases were not significant.4.HS/SPME-GC/MS technique used for detect the Volatile flavor substances in dried-cured mutton ham with 0 d,CK group 30 d,S group 30 d and M group 30 d,and the sensory evaluation of each group of 30 d samples was performed using fuzzy mathematics.The results showed that a total of 116 volatile flavor substances were searched,including 25 kinds of alcohols,21 kinds of aldehydes and hydrocarbons,13 kinds of acides,11 kinds of esters,10 kinds of aromatic hydrocarbons,8 kinds of ketones,and 7 kinds of others;the content of aldehydes in group S and group M increased significantly,and the types of hydrocarbons increased significantly;indicating that the two proteases had significant effects on the changes of volatile flavors of dried-cured mutton ham.Sensory evaluation results showed that the synthesis of group M is higher than the other groups,and the quality is better.Therefore,combining the flavor and sensory evaluation results,it is determined that Actinidin is the optimal protease added in ham. |
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