Understanding the Jasmine phenotype of rice through metabolite profiling and sensory evaluation

Introduction: Aromatic rices are culturally and economically important for many countries in Asia. Investigation of the volatile compounds emitted by rice during cooking is the key to understanding the flavour of elite aromatic rice varieties. Objectives: The objectives of this study were to compare Jasmine-type aromatic rices from the Greater Mekong Subregion and Australia in terms of their metabolomics and sensory profiles and to draw out associations between the volatile organic compounds and human sensory perception of rice aroma. Methods: A set of aromatic rice varieties from South East Asia and Australia, along with non-aromatic controls, was grown in tropical and temperate areas of Australia. Untargeted metabolite profiling of volatile compounds, from the heated rice flour, by static headspace extraction and separation by two dimensional gas chromatography time-of-flight mass spectrometry was performed. Volatile compounds were also assayed in the standard references used in the sensory evaluation and compared to the compounds detected in the headspace of rice. Results: While 2-acetyl-1-pyrroline (2-AP) was a discriminating compound, we identified several of its structural homologues, and a number of other metabolites that were consistently detected in fragrant Jasmine rice. 2-AP producing rice varieties have different sensory properties and these variations were defined by the discriminating compounds identified in each rice type. Conclusions: The results of this study are valuable in understanding the aspects of aromatic rice that are important to consumers, and in the identification of compounds that breeding programs can use to select for pleasant aromas, enabling breeding programs to target markets with greater accuracy