# Effects of Seasonings on the Stable Isotope Analysis of Protein Fractions in Cooked Beef: A Preliminary Study for Geographical Origin Purposes

## TL;DR

This study explores how seasoning affects isotope analysis of beef proteins to determine geographical origin.

## Contribution

It shows that seasoning does not significantly alter isotope ratios in beef proteins, allowing for geographical origin tracing.

## Key findings

- No significant differences in isotope ratios between raw and cooked beef proteins.
- Carbon isotope ratios of U.S. beef proteins were higher than those of Australian and Japanese beef.
- Oxygen isotope ratios of Australian beef proteins were higher than those of U.S. and Japanese beef.

## Abstract

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.