中文摘要：

【目的】比较加工和未加工牛肉之间稳定碳同位素组成差异，分析不同加工方式对牛肉稳定碳同位素组成变化的影响，探讨稳定碳同位素对牛肉加工制品产地溯源的可行性。【方法】分别从吉林省榆树市、河北省张家口市、宁夏自治区吴忠市采集牛肉样品，其碳同位素平均组成呈高、中、低梯度分布。牛肉样品经剔除表面脂肪、筋和膜处理后，分成四份，一份作为对照样品，其余三份分别作为煮制、煎制和烤制处理样品。煮制处理工艺为将牛肉切分为1.5 cm3，在超纯水中回流煮沸30 min；煎制处理工艺为将牛肉切分为5 cm×5 cm×1—1.5 cm，在195℃下煎制13 min；烤制处理工艺为将牛肉样品切成5 cm×5 cm×1—1.5 cm，在180℃烘烤30 min。对未加工及加工牛肉样品进行冷冻干燥、磨粉及脱脂处理。利用元素分析-同位素比率质谱仪（EA-IRMS）检测未加工和煮制、煎制、烤制加工牛肉样品，以及加工副产物汤渣、烤渣和煎渣中的δ13C值。对加工前后的牛肉样品中δ13C值进行单因素方差分析、配对样本t检验分析和Duncan’s多重比较分析，比较未加工牛肉、不同加工处理牛肉及加工副产物之间碳同位素组成差异，并利用碳同位素为指标对未加工和加工牛肉产地来源进行系统聚类分析。【结果】煮制、煎制和烤制处理与未加工脱脂牛肉之间的碳同位素组成无显著差异，加工前后碳同位素差值范围在0.006‰—0.489‰；煮制和烤制加工处理前后牛肉粗脂肪中碳同位素无显著差异，但煎制处理前后牛肉粗脂肪中δ13C值显著降低（P＜0.05），3组煎制牛肉样品粗脂肪中δ13C平均值分别降低7.790‰、7.288‰和4.104‰，说明煎炸油影响牛肉粗脂肪中碳同位素组成；碳同位素比率高、中、低的牛肉样品经煮制和烤制后，其副产物汤渣、烤渣与加工后脱脂牛肉中碳同位素组成无显著?

英文摘要：

【Objective】The purpose of this paper was to analyze the effects of processing on the stable carbon isotope composition in beef, to illuminate the characteristic differences of stable carbon isotope composition in raw and different processed beef and to probe the feasibility of identifying the geographical origin of processed beef products using stable carbon isotope composition.【Method】The high, medium and low carbon isotope value groups of raw beef samples were collected from Yushu of Jilin, Zhangjiakou of Hebei and Wuzhong of Ningxia, respectively. Each sample was divided into four halves after removing the surface fat, large ribs and the thick tissue membrane. One was used as fresh samples, and the other three to be boiled, fried and roasted, respectively. The samples used for boiling were cut into 1.5 cm cubes and boiled for 30 min with a reflux device in ultrapure water. The samples used for frying were cut into pieces of 5 cm ×5 cm×1-1.5 cm and baked at 195℃ for 13 min, and the samples used for roasting were also cut into 5 cm ×5 cm×1-1.5 cm pieces and then placed on a grill into a baking oven for 30 min at 180℃. Then all of the beef samples were freeze-dried for 48h before being pulverized in a ball mill, after that the crude fat of muscle powder was extracted. The δ13C values in de-fatted raw and processed beef, and by-products of boiled, fried and roasted were determined using an element analysis-isotope ratio mass spectrometry （EA-IRMS）. The differences of δ13C values in raw and processed beef, and by-products were compared using an one-way analysis of variance （ANOVA） and Duncan＇s multiple range test followed by a paired sample T test, the cluster analysis using δ13C values in raw and processed beef was also performed.【Result】The δ13C values in de-fatted beef of boiled, fried and roasted showed no significant difference compared with raw samples, and the difference ranged from 0.006‰-0.489‰. The δ13C values in crude fat of boiled and roasted beef showed no signifi