Abstract: 【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 significant differences with that in untreated samples, but the δ13C values in fried beef were significantly lower than that of raw beef, and the mean δ13C values in three groups reduced by 7.790‰, 7.288‰, and 4.104‰, respectively, which indicated that the fried oil had an important effect on the carbon composition of the crude fat. The δ13C values in processed by-products of boiled and roasted had no significant difference with raw and processed beef, but the remarkable difference was observed in fried by-products which was closely resembles it in crude fat. In addition, the cluster analysis results showed that the geographical origin classification was consistent using δ13C values of raw and processed beef. 【Conclusion】 The processing of boiling, frying and roasting had no significant effect on δ13C values in beef, and δ13C values is an effective indicator for tracing the geographical origin of beef processed products.

Key words: beef , processing , boiled , fried , roasted , stable carbon isotope