导　　师： 肖冬光;熊正河

学科专业： 081703

授予学位： 硕士

作　　者： ;

机构地区： 天津科技大学

摘　　要： 稳定同位素技术在食品真实性和溯源控制中具有重要的作用。食品的稳定同位素组成与环境之间具有密切的联系。生命元素的同位素比率测量为食品控制提供了一个十分灵敏的工具。本研究的目的是为了揭示牛奶中同位素的组成与奶牛生活环境的关系。 研究通过等电点沉淀与离心分离牛乳中的酪蛋白和脂肪,采用元素分析仪串联稳定同位素比值质谱仪/(EA-IRMS/)测定了牛乳组分的δ13C值,经验证方法具有良好的准确性和重复性,牛乳及其各组分δ13C值测定精度标准偏差/(SD/)均小于0.1‰/(n=5/)。对不同牛乳中δ13C值进行比较表明,饲料组成直接影响了牛乳中的碳稳定同位素组成。以玉米为主要饲料的奶源地牛乳中δ13C值均高于-17.6‰,若饲料中含有羊草和苜蓿会使牛乳的δ13C值相对偏负。购买自不同地区的市售乳样品δ13C值均具有不同特点,中国市售乳样品的δ13C值与一些发达国家样品的δ13C值相比具有显著差异。 研究采用Gasbench-IRMS及TCEA-IRMS测定了牛乳水中及饮用水δ18O值,对不同地区生牛乳δ18O值的研究表明,生牛乳中的δ18O值略偏于饮用水的δ18O值,并具有线性关系/(δ18O牛乳=1.1886×δ18O饮用水+3.8729,R2=0.9138/),反映了饮用水的氧同位素组成信息。由于蒸发源效应、温度效应、大陆效应、纬度效应、高度效应对降水影响,各地自来水的δ18O值具有明显的地域特征,以此可以推断出生牛乳的大致产地。 研究结论验证了稳定同位素比值在牛乳溯源中的作用,为稳定同位素分析技术在牛乳真实性溯源的应用积累了数据与理论基础。 Isotope ratio mass spectrometry /(IRMS/) methods play a very important role in food authenticity and origin control. The stable isotope composition of food is strictly connected with environmental conditions. The measurements of bioelements /(hydrogen, nitrogen, carbon, oxygen, and sulfur/) composition provide a very sensitive tool to food control. The aim of this study is to explore the relationship between isotopic composition of milk and its origin. The stable carbon isotope /(813C/) ratios of whole milk and its isolated components /(casein, skim milk, and fat/) were determined by elemental analysis-isotope-ratio mass spectrometry /(EA-IRMS/). This technique was found to be repeatable and possess good accuracy with a standard deviation of less than0.1‰/(n=5/). A comparison of the δ13C values of different milk samples indicates that the813C composition is impacted by the type of forage consumed by the cows. The δ13C values of milk from farms in which maize is the main roughage are higher than-17.6‰, are relatively lower when the diet contains Leymus chinensis and alfalfa. The δ13C values of commercially available milk purchased from different regions demonstrate distinct characteristics, milk samples from China and countries using advanced animal husbandry practices are significant differences. δ18O values of milk water and drinking water were determined by Gasbench-IRMS and TC//EA-IRMS, results shown that δ18O values of raw milk were higher than δ18O values of drinking water, shown good linearity /(δ18ORaW milk=1.1886×δ18Odrinkingwater+3.8729, R2=0.9138/).δ18O values of milk water reflects the oxygen isotope composition information of drinking water. Due to the impact of precipitation evaporation source effects, temperature effects, continent effects, latitude effects, and height effects,δ18O value of water has obvious geographical features to generally infer origin of milk. The conclusion of this research verified values of in terms of tracing the types of milk and producing areas. The accumulated data was used to lay a theoretical foundation for the application of stable isotope analysis techniques in milk traceability.

关 键 词： 牛乳 稳定同位素 溯源技术 饲料

分 类 号： [TS252.1]

领　　域： [轻工技术与工程] [轻工技术与工程]