Study On The Effects Of Prepared Technology On Pork Quality

China is a big country in pork consumption,with a large demand for pork in the world.It occupies an important position in daily diet and is also an essential meat on residents’ tables.The domestic pork consumption accounts for more than half of the meat,and is the main meat product on residents’ tables.The processing technology of pork products includes pretreatment,salting,rolling,steaming,drying,smoking and barbecuing,etc.Especially the industrial processing of prefabricated dishes,which has become a hot topic in recent years,involves different preconditioning,storage and reheating of hot processing such as boiling,steaming,frying,etc.Different prefabrication processes have different influences on the characteristics of pork,thus determining the quality of the final product.However,in the processing of some pre-cooking products,the hot processing methods such as vacuum cooking at low temperature for a long time have attracted attention because of their advantages of reducing moisture and nutrient loss in food,inhibiting odor generation,retaining original flavor and reducing the growth of aerobic bacteria.The low temperature storage method mainly adopts cold storage or frozen storage,but the short shelf life of cold storage is difficult to meet the needs of large-scale production,and the effect of frozen storage is poor,especially the structure and quality of meat products will be greatly affected when thawing.At present,the micro-frozen storage between the two can not only effectively prolong the shelf life,but also stabilize the product quality and restrain the flavor attenuation.Most conditioning products should be reheated before consumption.The commonly used reheating methods include steaming,boiling,frying,microwave,etc.Different reheating methods have different effects on the quality of products.This topic takes pork as the research object to study the influence of steaming,boiling and lowtemperature vacuum cooking on pork quality characteristics,explore the differences in product quality and processing characteristics of micro-frozen storage combined with cold storage and freezing under two common low-temperature storage methods,and compare the influence of steaming,boiling,microwave and other reheating methods on pork quality.The measurement indexes included sensory indexes,physical and chemical indexes,microorganisms,microstructure,volatile flavor substances,electronic tongue,etc.The influences of different processing,storage and reheating methods on pork quality and processing characteristics were explored to provide theoretical support for the development of pork products.The main contents and results of this study are as follows:(1)Study on the influence of hot processing on pork quality characteristics: Taking pork as the research object,on the basis of single factor experiment,with heating temperature,vacuum degree and cooking time as response surface factors and sensory evaluation as response face value,the optimal process parameters were obtained as follows: The heating temperature was 67℃,the vacuum degree was 0.09 MPa,and the cooking time was 4 h.Under these conditions,the product quality and principal component analysis were compared with vacuum cooking,steaming and steaming.The results showed that the effects of low temperature vacuum cooking for long time on total sensory score,moisture content,cooking loss rate,L* value,a*,shear force and TBARS of pork were significant,and the corresponding optimal product indexes were 71.40,72.36%,14.20%,6.32,7089.87 g and 0.05 mg/kg,with little change in the microstructure.30 kinds of volatile flavor substances were detected,including alcohols,alkenes,alkanes,lipids,ketones and aldehydes.PCA analysis showed that sensory,moisture content,elasticity,a* value and other indexes were positively correlated to the long-term vacuum cooking pair at low temperature.Comprehensive indicators showed that compared with other cooking methods,low-temperature vacuum long-time steaming have reflected obvious advantages.(2)Effects of low temperature storage on pork quality characteristics: Volatile flavor components were determined by headspace solid phase microextraction-gas chromatographymass spectrometry at 0,7,14,21 and 28 days of storage,and sensory evaluation,cooking loss rate,p H value,chroma value,texture,shear force,TBARS and total number of colonies were also determined.The results showed that the storage life of prepared pork could be prolonged by low temperature vacuum cooking for a long time.On the 14 th day of storage,the odor of micro-frozen storage was significantly higher than that of the other two methods,and on the21 st day of storage,the tissue morphology of micro-frozen storage was significantly higher than that of the other two methods.It had significant effects on cooking loss rate,p H value,texture and total number of colonies(P<0.05).The shear force value of micro-frozen storage was significantly lower than that of other groups at 7,14 and 28 days.The volatile flavor substances are mainly alcohols,lipids and alkanes.The results showed that long vacuum cooking at low temperature could prolong the storage period of pork products,and micro freezing storage had obvious advantages in the same storage period.(3)Study on the effect of reheating on pork quality characteristics: The sensory,color value,yield,moisture content,water loss,tethering,shear force,texture and TBARS of pork cooked in low temperature vacuum for long time were significantly affected by the reheating process.Sourness and bitterness were constituted as the main taste of pork,and the taste was more prominent after reheating in a low temperature and longtime water bath.Aldehydes and ketones were the main volatile flavor substances after reheating.In conclusion,low temperature and long time water bath reheating and frying reheating were with obvious advantages.(4)It was concluded that under the present experimental conditions,the heating temperature of 67 °C,vacuum degree of 0.09 MPa and cooking time of 4 h were the best process parameters for low-temperature vacuum long-time cooking based on the results of sensory and physicochemical characteristics analysis.LTLT was superior to temperature cooking,vacuum cooking and steaming in yield,p H,chroma,microstructure,texture,shear force and TBARS.Storage life of pork products could be extended by vacuum low temperature long time steaming.Micro-frozen storage was significantly superior to cold storage and frozen storage in terms of cooking loss rate,p H value,texture and total number of colonies.The sensory,color value,yield,moisture content,water loss,tethering rate,shear force,texture and TBARS of lowtemperature vacuum long-time slow-cooked pork were significantly affected by the reheating method,and low-temperature long-time water bath reheating and deep-frying reheating were more suitable for the reheating of precooked pork.