Study On Bubbling Vacuum Cooling Of Cooked Meat

Meat products are defined as processed products,resulting from the processing of meat or from the further processing of such processed products,so that the cut surface shows that the product no longer has the characteristics of fresh meat.The improvement of people’s living standards has led to the development of cooked meat.The traditional cooling methods cannot meet the requirements of passing the dangerous temperature range（usually 55℃-10℃）as soon as possible,especially bulk meats.Cooked meats can be rapidly cooled by vacuum cooling,however,one major disadvantage of this approach is the high weight loss（about 10%）.Although the immersion vacuum cooling reduced the cooling loss,the cooling time was greatly prolonged.Therefore,a new rapid cooling method needs to be found on the basis of the former researches.In this paper,the lean pork was used as experimental material to study the feasibility of bubbling vacuum cooling in the rapid cooling of cooked meat.The results showed that bubbling vacuum cooling（BVC）can accelerate the cooling of cooked meat compared with immersion vacuum cooling（IVC）,especially at low temperature average（under 25℃）,and meanwhile the efficiency of average cooling time can be improved about 10%to 15%.The average weight loss of BVC was 2.75%and had no significant difference with IVC（P>0.05）.Meat cooled by BVC and IVC showed no significant difference in moisture content,color and TPA（P>0.05）.The effects of initial water temperature,condensing temperature,bubbling intensity,and volumetric displacement were optimized using response surface methodology.The cooling time was estimated.The result indicated that the optimum conditions were 10℃,-8℃,2960 Pa,0.0016 m³s^-1 for the initial water temperature,the condensing temperature,the bubbling pressure difference and the volumetric displacement,respectively.Under this condition,the cooling time was 9.91 min and the error from the predicted value（9.91 min）was 2.27%.The initial water temperature and bubbling intensity had significant effect on the cooling time（P<0.05）,and the volumetric displacement had no significant effect on the cooling time（P>0.05）.The cooked meat was cooled by the optimal conditions and preserved at 4℃after vacuum packaging while the cold room cooling was used as control.The results showed that the shelf life of meats was about 15 days cooled by bubbling vacuum cooling.The L value of the meat tended to decrease slowly during the storage.There was no significant difference in a value between vacuum cooling and cold room cooling（P>0.05）and it was decreasing firstly and then increasing.The b value was increasing of both methods.The moisture content and hardness of bubbling vacuum cooling cooked meat was decreasing and its higher than that of cold room cooling.There was no significant change in springiness of both cooling methods.The chewiness was slowly decreased cooled by BVC,however,there was no significant change of meat cooled by cold room cooling.The pH showed a downward trend.The TVB-N showed a tendency to rise slowly.It was 37.66 mg/100 g on the 16th day of BVC and 37.02 mg/100 g on the 20th day of cold room cooling meaning that the meat can’t be eaten.The TBARS value cooled by bubbling vacuum cooling and cold room cooling was similar and both showed a rising trend.In general,bubbling vacuum cooling is an ideal method for rapid cooling of cooked meat,which has the advantages of high cooling rate and good food quality.The key control points were initial water temperature and bubbling intensity,however,this method requires strict control of sanitary conditions of cooling equipment and environment.