Japanese Black cattle (Japanese Wagyu) beef is attracting attention for its aroma and marbling, and its handling is increasing worldwide. Here, we focused on the origin discrimination of Wagyu beef and analyzed the nutritional components of Japanese Wagyu (produced in multiple prefectures of Japan), Hybrid Wagyu (a cross between Angus and Wagyu cattle born in Australia and transported to Japan), and Australian Wagyu beef using mass spectrometry (MS). Triple-quadrupole liquid chromatography–MS was used to clarify the molecular species of lipids in Wagyu beef. Fourteen classes of lipids were separated, and 128 different triacylglycerides (TGs) were detected. A simple comparative analysis of these TGs using high-performance liquid chromatography revealed significantly higher levels of triolein (C18:1/C18:1/C18:1; abbreviated OOO) and C18:1/C18:1/C16:1 (OOPo) in Japanese Wagyu. Wagyu elements beef were comprehensively analyzed using inductively coupled plasma (ICP)–MS and ICP–optical emission spectrometry. We found significant differences in the rubidium, cesium, and lithium levels of Japanese and Australian Wagyu beef. On comparing metabolites using gas chromatography–MS, we identified significant differences in the levels of amino acids and other components of the Japanese and Australian Wagyu beef. These results suggest the possibility of determining the origin of Wagyu cattle breeds using MS and genetic discrimination.

This study focused on proteins derived from beef to minimize the influence of seasonings when developing a method for determining the geographical origin of seasoned beef samples. The seasoning used was sweetened soy sauce containing sugar, soy sauce, mirin and sake. The water-soluble fraction was extracted as a cleaning step for the sample, followed by extraction of the myofibrillar protein fraction. No significant differences were observed in the carbon, nitrogen and oxygen isotope ratios of the proteins extracted from the defatted raw and cooked beef samples. The carbon, nitrogen and oxygen isotope ratios of the protein fraction extracted from defatted beef were positively correlated with the corresponding ratios in the defatted whole beef samples. These results suggest that the protein fractions were mainly composed of beef proteins, and that the addition of auxiliary materials did not affect this. To verify the possibility of determining the geographic origin of beef, the carbon, nitrogen and oxygen isotope ratios of proteins extracted from beef from the United States (U.S.), Australia and Japan were analyzed. The carbon isotope ratios of proteins extracted from U.S. beef were higher than those of Australian and Japanese beef. Additionally, the oxygen isotope ratios of proteins extracted from Australian beef were higher than those of beef from the U.S. and Japan. These results suggest that it may be possible to trace the geographical origin of beef products cooked with seasonings by extracting proteins.