Static headspace analysis of odorants in commercial rice proteins

- The primary rice protein odorants were identified using static headspace analysis.
- Three sulfur-containing compounds were identified among the primary odorants.
- Acetaldehyde contributed significantly to the odor of RP-O but not other samples.
- The major lipid-derived odorants included hexanal, pentanal, and 2-pentayl furan.
- Metals, sulfite, and hydroperoxides were detected in rice protein samples.

Accurate identification of the odor-contributing compounds in aqueous slurries of rice proteins is necessary to improve their overall flavor characteristics. The objective of this study was to identify the primary odorants in rice protein slurries using static headspace analysis. Five commercial rice protein (RP) products, RP-G, RP-O, RP-RM, RP-RS1, and RP-RS2, were analyzed. RP-G contained the lowest levels of most of the odorants. Acetaldehyde was present in the highest amount in RP-O (0.434 mg/m3). RP-RM had the highest levels of hexanal (5.907 mg/m3), methanethiol (0.138 mg/m3), pentanal (1.575 mg/m3), and 2-pentylfuran (5.702 mg/m3). Corresponding odor values were, 111, 86, 22 and 21, respectively. In RP-RS1 and RP-RS2, the predominant odorants were dimethyl disulfide, dimethyl trisulfide, and hexanal. The results showed the importance of the volatile compounds produced from amino acids, including the sulfur-containing compounds and acetaldehyde, as well as lipid oxidation derived odorants to the overall odor of rice proteins.