| With the improvement of people's living standards,people's requirements for the nutritional and sensory texture of meat products are becoming higher and higher.The high-protein and low-fat nutritional characteristics of rabbit meat are in line with the dietary consumption concept of modern consumers.At present,the development of rabbit meat processing industry in China is lagging behind,and the deep processing is insufficient.Restructuring,as a method of deep processing of meat,has very limited application in rabbit meat.China,as a big country in rabbit meat production and consumption,where increasing the variety and proportion of rabbit meat processing products seems crucial for economy growth.At present,there are many types of restructured meat products in the market,and there are more and more researches on the technology and processing methods of restructured meat products.However,how to improve the texture characteristics of restructured meat products is still an urgent problem that needs to be solved.At the same time,restructured meat products often show poor recombination characteristics during sales,such as low water holding capacity,weak gel strength,and large cooking losses.It is expected to improve the quality of restructured meat products by adding cold-set binders and quality-improving additives,and to seek a solution for restructuring meat emulsions at relatively low temperature and normal pressure.In view of problems above,this thesis first studied the processing condition of cold-set binding of the restructured rabbit steak,discussed the effect of the added cold-set binders on the quality of the steak,and determined the optimal concentration of the binders.Then the changes of physicochemical properties and tissue structure of the restructured rabbit steak during cold-set binding process were discussed.By studying the influence of different thermal processing methods on the texture characteristics of steak,the reasonable heating temperature and time during processing were determined.Finally,the changes of physical and chemical indexes and microbial indexes of meat steaks during storage at-3? and-18? were compared in order to obtain suitable storage conditions.The main conclusions are reached as follows:(1)The effects of compound cold-set binders(?-glucan,sodium caseinate and glucono-?-lactone)on the quality characteristics of restructured rabbit meat steak werestudied by single factor experiments.It was determined that ?-glucan was added in a range of 0.3% to 0.9%,sodium caseinate was added in a range of 0.5% to 1.5%,and gluconic acid-?-lactone was added in a range of 0.25% to 0.75%.Then use the CCD experiment(central composite design)in the auxiliary software Design Expert(V.8.0.6)for design.According to Design-Expert,the optimal process parameters for the cold adhesive compound formulation are ?-glucan addition of 0.86%,sodium caseinate 1.5%,and glucono-?-lactone 0.25%.The predicted value of L* obtained from the model is62.45,the cooking loss is 12.41%,the shear force is 14.66 N,the water holding capacity is 90.5%,the restructuring quality is good,and the actual value is consistent with the predicted value.The acceptability verified by sensory evaluation is quite desirable.(2)During the low-temperature restructuring process at 4?,the nutritional quality,physical and chemical characteristics of the recombined steaks in the control group(without the composite binder)and the optimization group(with the composite binder)were changed as follows: The composition of the steaks was not significant during the restructuring.compared with the control group,the protein and ash content of the optimized group was significantly higher than that of the control group,with a protein content of about 24.22% and a low fat content of only about 2.31%.The pH value of the optimized group was significantly lower than that of the control group at 0 h of recombination,but there was no significant change during the recombination process,while the pH of the control group continued to decrease.The gel strength of the optimized group was significantly higher than that of the control group,which increased with time in the first 12 hours,and remained basically unchanged from 12 to 24 hours.During the reorganization process,the hardness,elasticity,chewiness,and adhesiveness of the control group increased significantly.The elasticity of the optimized group did not change significantly,but the elasticity and hardness were higher.The storage modulus(G')of the optimized group added with the adhesive was significantly higher than that of the control group,and the melting temperature was higher than that of the control group,indicating that it had better gel characteristics,more stable gel structure,and faster and more uniform gel network.(3)The effect of thermal processing temperature on the quality of the restructured rabbit steak is as follows: cooking loss increased with increasing heating temperature,and gel strength decreased with increasing heating temperature.The maximum gel strength is 4475.39 g when treated at 50?,the minimum gel strength is 709.19 g at90?.When rabbit steak was heated at a relatively lower temperature(50? and 60?),the increase of shearing force was not significant,but it increased significantly at high temperature(> 70?).When the temperature was lower than 70?,the pH increased significantly with the temperature rise.As the temperature rose,L* increases,but decreased slightly at 80?;a* decreased with increasing temperature;b* increased first and then decreased with temperature increasing.In terms of texture,hardness,adhesiveness,and chewiness increased with the temperature increasing significantly,and the elasticity did not change significantly.The cohesion decreases first and then increases with increasing temperature.When the cooking temperature was between50? and 70?,the cohesion decreased and then increased.(4)The effect of thermal processing time on the quality of the restructured rabbit steak is as follows: With the extension of the cooking time,the cooking loss increased significantly.When the core temperature was heated to 90? for 30 minutes,the cooking loss was the largest,17.34%.When the heating temperature was less than 60?,the gel strength increased as the heating time increasing,and when the heating temperature was higher than 60?,the gel strength decreased as the heating time increased.Shear force and pH increased significantly with the increase of cooking time,and increased significantly during the early heating period,but did not change significantly after 20-30 minutes(P> 0.05).With the increase of heating time,L * rises first and then decreased,a * increased with time,especially at 90?;b * increased with time.In terms of texture characteristics,with the increase of cooking time,the hardness increased significantly,and the elasticity increased first and then decreases;cohesion increased when the heating temperature was less than 70?,and increases with the heating time.When the heating temperature was greater than70?,the cohesiveness gradually decreased;the adhesiveness decreased with the increase of cooking time,and the chewiness showed the opposite trend.(5)The changes in freshness and physicochemical quality of the restructured steaks stored under frozen conditions(-18?)and slightly frozen conditions(-3?)for 40 days were compared.It can be seen that L* and a* values were significantly decreased during storage.The b* value showed an opposite trend.Color acceptability was higher at-3?,because a* and L* were higher.In terms of texture,hardness and chewiness first increased and then decreased as storage time went on,the elasticity gradually decreased.In the late storage period,the steaks stored at-18? have higher hardness and chewiness than the steaks stored at-3?,while the elasticity of steaks stored at-3? is greater.The steak's pH varied between 5.85 and 6.36,and the two temperatures had similar trends.5days before storage pH showed a downward trend,and then increased with the increase of storage time.The pH at-18? increased more slowly than that at-3?.The initial TBARS value of the recombined steak was only 0.25 mg/kg,and the TBARS value increased gradually during the first 15 days in storage,and remained unchanged afterwards.The TBARS values stored at-3? and-18? for 40 days were 0.34 mg/kg and 0.29 mg/kg,respectively,which showed that the degree of oxidation was low.During storage,the TVB-N of meat steaks increased with the increase of storage temperature and time.When the meat steaks were stored at-3? for 30 d,the TVB-N value reached 16.15 mg/100 g,which exceeded the standard of fresh meat.Meat steaks stored at-18? did not exceed the standard limit within 40 days.The total number of colonies is similar to that of TVB-N.At-3?,the total number of colonies after storage for 30 days reached 6.11 lgcfu/g,which exceeded the level of freshness.In comparison,when stored at-18?,the total number of colonies was still 5.08 lgcfu/g within 40 days and still met the standard of first-class fresh meat.Comprehensive consideration,when the reconstituted steaks produced under this process were stored at-3?,the storage period should not exceed 30 days. |
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