电饭煲中预浸泡对陈米饭气味特性影响及机制解析

Mechanisms Underlying the Influence of Pre-Soaking in Electric Cooker on Odor Characteristics of Aged Rice

摘要:

电饭煲热处理可通过物理方式提升米饭的风味，但其在改善陈米风味方面还缺少相应模式。采用气-质联用结合风味阈值鉴定得到对米饭陈味具有重要贡献的挥发性风味物质为己醛、辛醛、壬醛和癸醛。以感官评定和电子鼻分析作为评价指标，通过调控浸泡参数发现50 ℃处理10 min对籼陈米饭气味具有明显的改善作用，并与新米饭整体风味轮廓较为接近。与未浸泡的陈米相比，经50 ℃处理10 min后，米粒中脂肪酶活力降低了78.2%，过氧化值下降至1.52×10^-2 mmol/kg，丙二醛质量摩尔浓度仅升高7.5%。预浸泡有效地延缓了米粒中脂质的水解和氧化，减少籼陈米饭烹饪过程中不良风味物质的生成。本研究结果可为电饭煲烹饪籼陈米饭风味复鲜曲线的设计与改良提供借鉴。

Abstract:

The heat treatment of electric cooker can enhance the flavor of rice by physical means, however, there is still a lack of corresponding mode in improving the flavor of aged rice. The crucial flavor compounds contributing to the stale odor of rice were identified as hexanal, octanal, nonanal and decanal analyzed by gas chromatography-mass spectrometry combined with flavor threshold analysis. Using sensory evaluation and electronic nose analysis as the evaluation indexes in adjusting the immersion parameters, it was found that soaking at 50 ℃ for 10 minutes had a significant effect on improving the odor of aged indica rice, which was similar to the overall flavor profile of the fresh rice. Compared with the untreated aged rice, the lipase activity of aged rice decreased by 78.2%, the peroxide value dropped to 1.52×10^-2 mmol/kg, and the molality of malondialdehyde only increased by 7.5% after soaked at 50 ℃ for 10 minutes. Pre-soaking effectively delayed the hydrolysis and oxidation of lipids in rice grains and reduced the formation of off-flavor compounds during the cooking process of aged indica rice. The results of this study provided a reference for the design and improvement of flavor refreshness curve of aged indica rice cooked in electric cooker.