In order to estimate the shelf-life of cow milk sterilized by instant treated with Ultra Heat Temperature(UHT) in a relatively short time,the accelerated shelf-life testing (ASLT) was designed and conducted,selecting ...In order to estimate the shelf-life of cow milk sterilized by instant treated with Ultra Heat Temperature(UHT) in a relatively short time,the accelerated shelf-life testing (ASLT) was designed and conducted,selecting the histological change of the sterilized milk caused by fat droplets creaming as its criteria.The stability index (SI) and the viscosity variation of the sterilized milk were determined at preservation conditions of 20,25,30,35,40 and 45℃,using Turbiscan technology.The result showed that the SI was slightly higher for 25℃ than for 20℃,elevating linearly for temperature from 25℃ to 40℃,and decreased for 40℃ to 45℃.The SI data for 25℃ to 40℃ were fitted well with equation SIt=0.062t-1.382 (R2=0.990).If a ratio SIt/SI25℃ called as accelerated ratio (AR) was defined,the AR values calculated from the equation were 3.6,4.3 and 5.0 for 35,37.5 and 40℃,respectively,which were agreement with the data from ASLT.So,the model could be used for the prediction of the shelf-life of sterilized milk by UHT process.展开更多
目的建立气相色谱-质谱法(gaschromatography-massspectrometry,GC-MS)分析比较超高温灭菌乳(ultra-high temperature milk,UHT)和巴氏杀菌乳中10种内酯类风味物质的分析方法。方法液体乳样品用乙腈提取、无水硫酸镁干燥、正己烷除脂后,...目的建立气相色谱-质谱法(gaschromatography-massspectrometry,GC-MS)分析比较超高温灭菌乳(ultra-high temperature milk,UHT)和巴氏杀菌乳中10种内酯类风味物质的分析方法。方法液体乳样品用乙腈提取、无水硫酸镁干燥、正己烷除脂后,经Stabile-WAX色谱柱分离,在单离子监测(singleionmonitoring,SIM)模式下进行测定,采用基质匹配外标法进行定量。结果 10种风味物质在1~20μg/L浓度范围内线性关系良好,相关系数均大于0.99,方法的检出限为0.2~4.0μg/kg,定量限为0.7~13.0μg/kg。各目标化合物在3个基质加标浓度(1、5、10μg/L)下的平均回收率为85.94%~116.44%,相对标准偏差为1.06%~6.36%(n=6)。超高温灭菌乳样品中检出δ-癸内酯、γ-十二内酯、δ-十二内酯,巴氏杀菌乳样品中检出δ-癸内酯和δ-十二内酯,前者内酯类风味物质的种类和含量略高于后者。结论建立的方法操作简单,适用于液体乳中内酯类风味物质的检测。展开更多
文摘In order to estimate the shelf-life of cow milk sterilized by instant treated with Ultra Heat Temperature(UHT) in a relatively short time,the accelerated shelf-life testing (ASLT) was designed and conducted,selecting the histological change of the sterilized milk caused by fat droplets creaming as its criteria.The stability index (SI) and the viscosity variation of the sterilized milk were determined at preservation conditions of 20,25,30,35,40 and 45℃,using Turbiscan technology.The result showed that the SI was slightly higher for 25℃ than for 20℃,elevating linearly for temperature from 25℃ to 40℃,and decreased for 40℃ to 45℃.The SI data for 25℃ to 40℃ were fitted well with equation SIt=0.062t-1.382 (R2=0.990).If a ratio SIt/SI25℃ called as accelerated ratio (AR) was defined,the AR values calculated from the equation were 3.6,4.3 and 5.0 for 35,37.5 and 40℃,respectively,which were agreement with the data from ASLT.So,the model could be used for the prediction of the shelf-life of sterilized milk by UHT process.
文摘目的建立气相色谱-质谱法(gaschromatography-massspectrometry,GC-MS)分析比较超高温灭菌乳(ultra-high temperature milk,UHT)和巴氏杀菌乳中10种内酯类风味物质的分析方法。方法液体乳样品用乙腈提取、无水硫酸镁干燥、正己烷除脂后,经Stabile-WAX色谱柱分离,在单离子监测(singleionmonitoring,SIM)模式下进行测定,采用基质匹配外标法进行定量。结果 10种风味物质在1~20μg/L浓度范围内线性关系良好,相关系数均大于0.99,方法的检出限为0.2~4.0μg/kg,定量限为0.7~13.0μg/kg。各目标化合物在3个基质加标浓度(1、5、10μg/L)下的平均回收率为85.94%~116.44%,相对标准偏差为1.06%~6.36%(n=6)。超高温灭菌乳样品中检出δ-癸内酯、γ-十二内酯、δ-十二内酯,巴氏杀菌乳样品中检出δ-癸内酯和δ-十二内酯,前者内酯类风味物质的种类和含量略高于后者。结论建立的方法操作简单,适用于液体乳中内酯类风味物质的检测。
