Research On Fat Composition And Stability Property Of Goat Milk

In this paper,Laoshan dairy goat milk was used as experimental material to investigate fat composition and stability property.Using gas chromatography-mass spectrometry(GC-MS)to analyze the effect of lactation,ultra high pressure and heat treatment on fatty acid composition and content of Laoshan dairy goat milk.The ratio of absorbance before and after centrifugation(sedimentation rate)was determined to investigate the influence of lactation,temperature,ultra high pressure,pasteurization and the concentration of emulsifier,sucrose and citric acid on fat stability of goat milk.Developing milk beer incorporated with fermented goat milk with added red date juice,and conducting sensory evaluation and stability analysis.Through detecting acid value for seven consecutive days to analyze the effect of temperature and ultra high pressure on antioxidant value of goat milk fat.The results were as follows:(1)20 fatty acids were detected in Laoshan goat milk,including short chain fatty acid(SCFA),saturated fatty acids(SFA),unsaturated fatty acid(UFA),were 7.43%,54.47% and 38.1% respectively.The main component in the chromatogram were C14:0(8.15%),C16:0(25.70%),C18:0(14.67%)and C18:1(34.04%).After pasteurization,the content of short chain fatty acid(10.92%)and saturated fatty acid(61.00%)were increased,while unsaturated fatty acid(28.08%)was decreased.(2)During the whole lactation period,SFA and UFA levels were all very significantly different(P<0.001),while the SCFA was slightly different(P<0.05).Moreover,SCFA and UFA were up to the highest of 11.32% and 71.51% in the colostrum period.In contrast,USF was found to be the lowest of 20.45% in the mature period.(3)There were no significant differences under ultra-high pressure processing for the content of SCFA,SFA and USFA(P>0.05).The contents of C6:0,C8:0,C10:0,C16:0,C18:1 and C20:4 were no significant difference(P>0.05),however,C12:0 and C14:0 were increased significantly(P<0.01),C18:0,C18:2 and C18:3 were decreased significantly(P<0.05,P<0.01,P<0.05).(4)Significant differences were observed for SCFA,SFA and USFA under the treatment of heating(P<0.01,P<0.01 and P<0.001).C10:0,C12:0,C14:0 and C16:0 were significantly increase(P< 0.01,P<0.05,P<0.05,P<0.05).No significant difference was observed for C18:0(P > 0.05);C18:1,C18:2,C18:3 weresignificantly decreased(P < 0.001,P < 0.05,P < 0.01).What's more,C120:4 was not detected.(5)When the temperature was 75 ?,the stability of goat milk fat increased obviously;with the treatment of ultra high pressure,the stability of milk fat reduced,what's more,when the content of sucrose ester was more than 0.16%,the stability of fat tend to be consistent;when the amount of sucrose was added to 1%,the addition of sucrose ester arrived to 0.12%,the stability of milk fat was best;after adding citric acid,the stability of milk fat decreased obviously;a certain amount of calcium ion had little effect on the stability,When the concentration of sucrose ester was more than 0.12%,the stability of milk fat decreased obviously under different concentrations of Ca2+.(6)The optimum technological conditions of red dates goat milk beer was that the volume ratio of red dates goat milk yogurt and beer puree was 1:1,the adding amount of jujube juice was 12%,white granulated sugar was 4%;when CMC-Na was 0.2%,pectin was 0.15%,sucrose ester was 0.1%,the stability of red dates goat milk beer was best.(7)Placing goat milk fat at room temperature for seven days,the acid value changed from 1.036 to 10.897;the acid value increased from 1.968,1.594,1.842 to 8.458,9.024,9.278 on the treatment of 65 ?/30 min,90 ?/1min and boiling respectively;the acid value increased from 1.811,1.575,2.042,2.1976 to 10.987,11.620,13.562,13.701 on the ultra pressure treatment of 100,200,300 and 400 MPa respectively.