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Flavor Volatiles of Rice During Cooking Analyzed by Modified Headspace SPME/GC-MS

¹Faculty of Bioresource Sciences, Akita Prefectural University, Kaidobata-Nishi 241-438, Shimoshinjo-Nakano, Akita-shi, Akita 010-0195, Japan. ²School of Chemistry and Environment, South China Normal University, Guangzhou 510631, P.R. China. E-mail: zhizeng@scnu.edu.cn ³Corresponding author. Phone: +81-18-872-1500. Fax: +81-18-872-1676. E-mail: zhangh@akita-pu.ac.jp ⁴Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631, P.R. China.

The flavor volatiles in three Japanese rice cultivars, Nihonbare, Koshihikari, and Akitakomachi, during cooking were directly extracted by using a modified headspace solid-phase microextraction (SPME) method and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 46 components were identified, including aldehydes, ketones, alcohols, and heterocyclic compounds, as well as fatty acids and esters, phenolic compounds, hydrocarbons, etc. The amount of key odorant compounds increased with cooking, while the amount of low-boiling volatiles decreased. The similarities and differences of the three rice cultivars were determined through a comparison of their volatile components. Nihonbare was characterized by a higher amount of indole but an absence of the chemical class of fatty acid esters. In contrast, both Koshihikari and Akitakomachi had a higher amount of 4-vinylphenol and an abundance of those esters. Koshihikari and Akitakomachi were quite similar in regard to those flavor volatiles. Furthermore, the observations in the research may suggest that the volatile components at cooking stage (I) were the representatives of the flavor volatiles of uncooked rice, while the volatile constituents at cooking stage (IV) were the representatives of the flavor volatiles of cooked rice.