Study on taste release and perception mechanism of japonica rice during oral processing

The sensorial experience of japonica rice is a critical factor that profoundly influences consumer choice. Despite this, the mechanisms underlying the release and perception of flavors during the oral processing of japonica rice are still not clearly understood. To address this gap, we conducted an in-depth investigation into the flavor release and gustatory perception dynamics of japonica rice during mastication using high-performance liquid chromatography (HPLC) and molecular docking simulations. Our findings revealed that umami taste was predominant during the initial stages of oral processing, whereas sweetness emerged as the dominant flavor in the subsequent phases. Moreover, we identified 16 key taste-active compounds that are released during the oral processing of japonica rice. Utilizing partial least squares regression (PLSR) analysis, we observed that glucose, sucrose, proline, maltose, and fructose were positively and significantly associated with the perception of sweetness in japonica rice. Concurrently, aspartic acid and glutamic acid contributed to the enhancement of umami perception, while concurrently diminishing the perception of sweetness and sourness. Further molecular docking studies demonstrated that glucose and sucrose interact with the amino acid residues of the sweet taste receptors T1R2/T1R3, engaging in hydrogen bonding and hydrophobic interactions. These interactions potentiate the activity of T1R2/T1R3, thereby facilitating the detection of sweetness. Similarly, aspartic acid and glutamic acid bind to the amino acid residues of the umami receptors T1R1/T1R3, establishing hydrogen bonds and hydrophobic interactions. This binding enhances the activity of T1R1/T1R3, leading to an augmented perception of umami.