Studies On Quality Characteristics Of Market Beef And Processing Optimization Techniques Of Yak Steak

A survey was conducted on quality index of finished beef with eleven brands and six parts sampling from Beijing supermarket. The results showed that significant or high significant differences on the major quality index were observed among different brands and parts of beef, and a big space were pro vied for consumers to choice their favorite steak; Among the all measured index, water content were basically in line with GB, the pH were within a reasonable range for most samples, chroma, represented by values of L (lightness), a (red shade) and b (yellow shade), were basically within the range acceptable to consumers, shearing forces were higher, while protein and fat contents were a little bit low, the back of the three indicators should be improved preferentially in future. There were big differences in variation range among different indicators. The value of pH, water and protein content were relatively stable, CV<10. Big differences were observed in the index of shearing force, red shade (a), hardness and fat content, CV>40. It was necessary to formulate the quality standards for the four index. The variation extents of brightness (L), yellow shade (b) and elasticity were found at middle level with CV of10-40. The taste score of steak was highest for consumers when the shear force, moisture content and fat content reached2～3kg,77%and3%or more, respectively.Taking chroma as aim, and yak thick flank and topside as raw materials, orthogonal test was used to investigate the effect of adding different amount of white granulated sugar, dark soy sauce and salt on apparent sense of precast steak. The results showed as followed:(1) Processing technologies mentioned above significantly affected steak color, and the two kinds of steak raw materials had the similar responses.(2) When the white granulated sugar additive amount was in the range of0.5-2%, L*and b*values of yak steak increased linearly with the increase of white granulated sugar amount. And the color was optimal when white granulated sugar amount was1.5%. When salt additive amount was in the range of0.5-2%, L*and b*values of yak steak changed little. Sense score of yak steak was the highest, when salt additive amount was1.5%. In addition, L*and b*values of yak steak decreased with the decrease of dark soy sauce additive amount. Sense score of yak steak was the highest, when dark soy sauce additive amount was1%.(3) White granulated sugar had the greatest impact on sense score of yak steak, followed by dark soy sauce and salt. Sense score of yak steak was the highest, when amounts of the three additives were1%,0.5%and0.5%respectively. And the two kinds of steaks responded similarly to the three additives.This study was taken texture as aim, and yak thick flank and topside as raw materials. According to sense score, orthogonal test was used to explore the effects of additives and processing techniques on tenderness and elasticity of precast steak. The additives included moisture, water-retaining agent and TG enzyme. The processing techniques included pickle and tumble time.(1)When the moisture additive amount was in the range of5-30%, shear force of steak decreased and sense score increased with the increase of the moisture additive amount. When moisture additive amount was in the range of15-20%, elasticity of precast steak and sense score both were the highest.(2) When the water-retaining agent additive amount rose from0.15%to2%, shear force of steak decreased significantly, tenderness of steak increase and steak tasted well. When the water-retaining agent additive amount was about1.5%, steak elasticity was the best and the steak was the most popular.(3) The TG enzyme additive amount was in the ranged of0.15-1.5%o in this test. Yak thick flank was the most popular with the TG enzyme additive amount ranged of0.3-0.8%o, and yak topside was the most popular with the TG enzyme additive amount of0.15%o. Moreover, steak elasticity increased with the increase of TG enzyme additive amount.(4)Tenderness of yak thick flank and topside were the highest with the pickle time ranged of4-12h and8-20h, respectively. Elasticity of yak thick flank was the highest with the pickle time ranged of12-20h, and elasticity of yak topside was the highest with the pickle time of12h. Combined with the sense score, the optimal pickle time was about12h.(5) When the tumble time was in the range of10-60minutes, steak shear force had a negative relation with tumble time. Sense score was the highest with the tumble time of60minute. Steak elasticity increased firstly and then decreased with tumble time increase. Steak elasticity and sense score both were highest with the tumble time of30minutes.(6) The effect of different processing techniques on texture and sensory quality of two types of steak were different. Moisture content had the greatest impact on sense score of yak thick flank, followed by water-retaining agent content, tumble time, TG enzyme and pickle time. Water-retaining agent content had the greatest impact on sense score of yak topside, followed by moisture content, tumble time, TG enzyme and pickle time. The optimal combination of additives for both the two kinds of steaks were25%for moisture,1.5%for water-retaining agent,1%for TG enzyme,12h for pickle time and30minutes for tumble time. Steak taste and acceptable score both were the highest with this additive amount.