Effects Of Chelating Agent And Ultra High Pressure Treatment On Camel Milk Quality

Camel milk has high nutritional value and health care effect,but the camel milk after ultra high pressure treatment will appear curdling phenomenon.In this thesis,the best compound chelating agent which can improve the quality of camel milk was selected based on sensory score,and the best technological conditions of ultra-high pressure camel milk were determined by single factor and orthogonal test with microorganism as detection index.Taking untreated camel milk as the control,the antioxidant,sensory and rheological properties of camel milk before and after UHP treatment were detected and analyzed,and the changes of various indexes of UHP camel milk during storage were discussed.The main results are as follows:(1)According to sensory scores,the screening results of a chelating agent that prevents solidification for ultra-high pressure treated camel milk showed that the optimal supplemental concentration of sodium pyrophosphate,hexametaphosphate and sodium tripolyphosphate was 0.14%,0.2%and 0.14%,respectively.The best chelating agent was sodium pyrophosphate and sodium hexametaphosphate with 0.17%and 7:10 mass ratio.(2)Under the condition of constant treatment time,the total number of bacteria in UHP camel milk decreased gradually with the increase of treatment pressure.When the treatment pressure was 600 MPa,the bactericidal effect was the best,the total bacterial colony of camel milk was less than 100CFU/m L,and the microbial mortality reached 99.98%.When the pressure was450 MPa,the total number of bacteria in UHP camel milk decreased gradually with the extension of pressure holding time.Through the two-factor orthogonal test,the optimal ultra-high pressure treatment condition of camel milk was 550 MPa,22 min,and the microbial death rate of camel milk after this condition was 99.99%.(3)After the compound chelating agent was added into the camel milk and treated with ultra-high pressure,the p H value increased,the acidity value decreased,the acidity,bitterness and astringency value decreased,and the camel milk was sensitive to nitrogen oxides,aldehydes and ketones and aromatic compounds,and the apparent viscosity was similar to that of untreated camel milk.Ultrahigh pressure treatment increased the content of free amino acids in camel milk by 1.26 mg/g,especially the content of aspartic acid by 4.9 times.The antioxidant activity of camel milk after ultrahigh pressure treatment was slightly increased.(4)During storage,L~*value a~*value and b~*value of HHP camel milk increased.The umami,abundance and sweetness of UHP camel milk did not change during storage.After 21 days of storage,sour value of UHP camel milk increased,but it was still lower than the sour value of pasteurized camel milk stored for 0 days.During storage,the long-chain alkanes in UHP camel milk increased and the sulfide content decreased.