利用对β-谷甾醇含量的检测鉴别生鲜乳中掺假植物脂肪的研究  

The Research on the Plant Fat Adulteration in Raw Milk by Determination of β-sitosterol

作　　者：魏雪冬[1] 姜毓君[1] 石馨[1] 刘波[1] 于力涛[1] 王象欣[1] 单艺[1] 

机构地区：[1]东北农业大学,国家乳制品质量监督检验中心,黑龙江哈尔滨150028

出　　处：《中国畜牧兽医》2013年第S1期71-74,共4页China Animal Husbandry & Veterinary Medicine

摘　　要：本试验建立了气相色谱―质谱法测定生鲜乳中β-谷甾醇的检测方法,由于理论研究表明生鲜乳中的乳脂肪是动物油脂,不应含有或很少含有植物油脂中特有的甾醇β-谷甾醇,因此对多个地区生鲜乳中β-谷甾醇的本底含量进行分析,给出生鲜乳中掺假植物油脂的鉴定方法。用质量比1.25的氢氧化钾水溶液25mL皂化样品,100mL维生素C的乙醇溶液作为稳定剂和抗氧化剂,皂化液用石油醚和乙醚萃取,转溶剂至甲苯,离心进样质谱。选用高柱效的60m DB-5毛细管柱,进样量1μL,程序升温在35min内实现β-谷甾醇与其他醇类及杂质的良好分离。选择离子414定量,检出限为0.10mg/L,线性相关系数r=0.9991。运用该方法对6个地区生鲜乳中β-谷甾醇含量进行检测,结果得到最高值为0.86mg/L,常见植物油中β-谷甾醇的含量为1~3g/L。表明生鲜乳中利用植物脂肪代替乳脂肪时,每提高1%植物脂肪将多产生最少相当于本底量12倍的β-谷甾醇,从而判定生鲜乳中是否掺假植物脂肪。A gas chromatography-mass spectrometric(GC-MS)method was established for the determination ofβ-sitosterol in raw milk.Theoretical studies had shown that the fat in raw milk belonged to animal fat,fresh milk should not contain plant oils or rarely contain phytosterols,especiallyβ-sitosterol.Based on the analysis of the content ofβ-sitosterol in raw milk from different area,the identical method of mixing plant oil in raw milk had been given.Using the mass ratio of KOH aqueous solution of 1.25of the 25mL saponificate sample,100mL vitamin C ethanol solution as stabilizer,liquid saponification with petroleum ether and diethyl ether,turn solvent to toluene,centrifugal inlet mass spectrometry.Selecting 60mDB-5capillary column with high column efficiency,the injection volume was 1μL,programmed raising temperature to achieve a good separation ofβ-sitosterol and other alcohols and impurities within 35minutes.Selected ion 414quantitative,the detection limit was 0.10mg/L.The linear correlation coefficient r was 0.9991.Using this method to detectβ-sitosterol content in fresh milk from 6different regions,the highest content was 0.86mg/L,the content ofβ-sitosterol common plant oil were 1to 3g/L.In conclusion,using plant fat replace dairy fat,and each one percent of plant fat would produceβ-sitosterol as 12times as the milk without plant fat at least.Thus,mixing plant fat could be identified in raw milk.

关 键 词：乳脂肪掺假 Β-谷甾醇 气相色谱―质谱法 

分 类 号：TS252.7[轻工技术与工程—农产品加工及贮藏工程]