Study On The Process Improvement And The Synthetic Preservation Technology Of Spiced-meat

Spiced-meat is one of the traditional cooked meats in China and it is very popular due to its characteristic flavor and availability. The study of spiced-meat is often divided into two steps, cooking and sterilizing process. Products prepared by traditional brine cooking process presented better color and flavor, but this method is time-consuming and involves high energy consumption thus limits its industrial application in meat industry. Ready-to-eat foods have shorter shelf life and inconvenient to transport, hence food with longer shelf life has been preferred by the consumers. Shelf life of the products with low temperature sterilization process is short, and it is often combined with the cold chain system, which increases the cost. Product with high temperature sterilization process has a cooking flavor, and soft texture. In view of the present problems of spiced-meat, the study was divided into four parts:(1) In order to assess the evaluation of spiced-meat, the textural properties were studied by the principal component analysis(PCA);(2) Variation rule of quality of spiced-meat during the traditional brine cooking process was studied.(3) On the premise of guarantee product flavor, microwave combined with traditional cooking method were used to reduce the cooking time and improve the textural properties. The process improvement technology was used to prolong the shelf life;(4) Combined with the compound preservatives: synthetic preservation technique was used to extend the shelf life of products.Firstly, with the principal component analysis, the textural properties of commercial spiced-meat were analyzed the principal component. The results showed that two principal components extracted from six texture indexes. PCA 1 and PCA 2 explain 65.878% and 24.697% of the whole information, respectively. The cumulative variance contribution rate is 90.575%. The equations of the two main components were: F1=0.248X1+0.125X2-0.003X3+ 0.249X4+0.235X5+0.243X6; F2=-0.059X1+0.488X2+0.626X3+0.070X4-0.089X5-0.169X6. The system evaluation showed that product with high temperature sterilization process had soft texture and product with low temperature sterilization had better texture, and better correlativity between sensory evaluation and textural properties.Secondly, the changes of quality were studied when brine cooking at 80~100℃ for 50~120 min, respectively. The result showed that: when cooking at 80, 85, 90, 95 and 100℃, the shear stress, hardness, chewiness, increased first and then declined. The shear force reached the peak at 110, 100, 100, 90 and 70 min, respectively; the hardness reached the maximum at 110, 100, 90, 80 and 60 min, respectively; the chewiness reached the maximum at 110, 110, 100, 90 and 70 min, respectively. The textural properties decreased when cooking was continued. At 80~100℃, L* and a* increased and then decreased. Cooking loss increased first and then remained constant. Sensory score was highest at 95℃, 110 min. In the early cooking stage, the spiced-meat was in the hardening phase with the textural properties rising. Extended cooking time was conducive to the formation of flavor and color, but it would reduce the texture. The cooking temperature and time must be at a reasonable level to ensure the textural properties at a reasonable level.Thirdly, the process improvement technology of spiced-meat was studied. In the premise of the similar quality, the effect of brine cooking time, microwave cooking time and microwave cooking power on shear force, chewiness and sensory score were analyzed by response surface methodology. The comprehensive evaluation score of the three indicators was response value. Results showed that the brine cooking time, microwave cooking time, microwave cooking power were 80 min, 175℃ and 800 W, respectively. Under these conditions, the shear force was 959.38 g, chewiness was 1139.42 g, sensory score was 93.9, and the comprehensive evaluation score was 90.91 with a 1.43% error with the theoretical prediction. With the process improvement technology, the texture indexes were improved, and the cooking time was reduced by 27 min, with the quality unchanged. The shelf life of spiced-meat was extended to 14 days at 25℃.Finally, the single factor and orthogonal experiment was adopted to determine the optimum ratio of the compound preservatives: Nisin 0.015%, ε-poly-lysine 0.015%, trehalose 4.5%. Using the integrated technology of microwave sterilization and the compound preservatives, the shelf life of spiced-meat can be extended to 30 days at 25℃.