牦牛乳制品加工过程中稳定碳、氮同位素分馏效应  

Fractionation Effect of Stable Carbon and Nitrogen Isotope Ratios in Yak Dairy Products Processing

作　　者：李继荣 刘鑫 王君 曹晓钢 次顿 LI JiRong;LIU Xin;WANG Jun;CAO XiaoGang;CI Dun(Institute of Agricultural Product Quality Standard and Testing Research,Tibet Academy of Agricultural and Animal Husbandry Sciences/Supervision and Testing Center for Farm Products Quality,Ministry of Agriculture and Rural Affairs,Lhasa 850032;Food Science College,Tibet Agriculture and Animal Husbandry University,Nyingchi 860000,Tibet;Lhasa Customs Technology Center,Lhasa 850002)

机构地区：[1]西藏自治区农牧科学院农业质量标准与检测研究所/农业农村部农产品质量监督检验测试中心(拉萨),拉萨850032 [2]西藏农牧学院食品科学学院,西藏林芝860000 [3]拉萨海关技术中心,拉萨850002

出　　处：《中国农业科学》2023年第10期1982-1993,共12页Scientia Agricultura Sinica

基　　金：西藏自治区自然科学基金(XZ202101ZR0098G);区域科技协同创新专项(QYXTZX-NQ2021-03,QYXTZX-NQ2022-01)。

摘　　要：【背景】稳定同位素指纹图谱技术已广泛应用于乳制品产地溯源研究中,但多集中于产品与原料乳稳定同位素间差异比较。乳制品加工过程中稳定同位素是否存在分馏效应,稳定碳、氮同位素能否用于牦牛乳制品的产地溯源尚不清楚。【目的】以牦牛酸奶、牦牛奶渣为研究对象,明确牦牛乳制品加工过程中各关键点样品稳定碳、氮同位素变化,分馏系数及相关性,探究不同产地牦牛乳制品稳定碳、氮同位素特征,为牦牛乳制品产地溯源提供理论与技术支撑。【方法】从西藏自治区那曲市聂荣县、嘉黎县采集酸奶加工过程(牦牛乳、煮沸5 min牦牛乳、加菌种后、40℃发酵6 h、酸奶成品)5个关键取样点对应样品和奶渣加工过程(牦牛乳、脱脂牦牛乳、煮沸10 h脱脂牦牛乳和奶渣成品)4个关键取样点对应样品共计196份。利用元素分析—同位素比率质谱仪(EA-IRMS)测定稳定碳、氮同位素比率。结合单因素方差分析,比较稳定碳、氮同位素在酸奶、奶渣加工关键采样点间的差异;酸奶、奶渣加工过程中关键采样点样品稳定碳、氮同位素的相关性进行皮尔逊相关分析;两因素方差分析比较不同产地酸奶与牦牛乳、奶渣与牦牛乳稳定碳、氮同位素差异。【结果】酸奶加工过程中存在δ^(13)C、δ~(15)N分馏,δ^(13)C_(牦牛乳)>δ^(13)C_(40℃发酵6 h、牦牛酸奶)>δ^(13)C_(添加菌种后样品),分馏系数介于0.9996—1.0009,Δ_(牦牛乳-牦牛酸奶)为0.48‰;δ^(15)N_(煮沸5 min牦牛乳、40℃发酵6 h、牦牛酸奶)>δ^(15)N_(牦牛乳),分馏系数介于0.9993—1,Δ_(牦牛乳-牦牛酸奶)为-0.61‰;部分关键取样点间稳定碳、氮同位素存在显著相关性。奶渣加工过程中,δ~(13)C_(牦牛乳、煮沸10 h脱脂牦牛乳、奶渣)>δ^(13)C_(脱脂牦牛乳),分馏系数介于0.9995—1.0005,Δ_(牦牛乳-牦牛奶渣)为0,部分关键点样品间δ^(13)C存在显著负相关;各【Background】Stable isotope fingerprinting technology has been widely adopted in the origin traceability study of products.However,most of them are focused on comparing the differences between the stable isotopes of raw milk and milk products.Nevertheless,the fractionation effect of stable isotopes on dairy products processing and the application of stable carbon and nitrogen isotopes for origin tracing of yak dairy products are still unclear.【Objective】In this study,yak yogurt and yak milk dregs were used as the study subjects to determine the changes in stable carbon and nitrogen isotope and the fractionation coefficients and correlations of yak dairy products at key points during processing,to investigate the stable carbon and nitrogen isotope characteristics of yak dairy products from different origins,so as to provide the theoretical and technical supports for origin traceability of yak dairy products.【Method】A total of 196 samples were collected from the Nerong and Jiali counties of Nagqu City,Tibet Autonomous Region,obtain five key sampling points for yogurt processing(yak milk,yak milk boiled for 5 min,sample after strain addition,fermentation at 40℃for 6 h,and yogurt)and four key sampling points for milk dregs processing(yak milk,skimmed yak milk,skimmed yak milk boiled for 10 h,and milk dregs).The stable carbon and nitrogen isotope ratios were determined using an elemental analysis isotope ratio mass spectrometer(EA-IRMS).The differences and correlations between the stable carbon and nitrogen isotopes at the key sampling points for yogurt and milk dregs processing were determined using one-way ANOVA comparative analysis and Pearson correlation analysis,respectively.Furthermore,the differences in stable carbon and nitrogen isotopes between yogurt and yak milk and milk dregs and yak milk with different origins were determined using a two-factor ANOVA.【Result】The fractionation of stable carbon and nitrogen isotope during yogurt processing was as follows:δ^(13)Cyak milk>δ^(13)C40℃fermen

关 键 词：牦牛乳 酸奶 奶渣 牦牛乳制品 稳定碳同位素 稳定氮同位素 

分 类 号：TS252.7[轻工技术与工程—农产品加工及贮藏工程]