电饭煲吸水阶段浸泡参数对陈粳米饭气味改良作用的影响

Effect of soaking parameters in water absorption stage of electric cooker on odor improvement of aged japonica rice

该文借助感官评定、电子鼻和气-质联用等手段对陈粳米饭的气味特性进行了分析,结合脂肪酶活力和游离脂肪酸含量的变化探索了吸水阶段参数调整导致陈米饭挥发性风味物质差异的原因。结果表明,当吸水阶段浸泡参数为50℃处理10 min时,电饭煲蒸煮的陈米饭风味轮廓具有明显的改善,且与新米饭整体风味相似性最高。与常温浸泡相比,陈米粒中脂肪酶活力降低了86%,总游离脂肪酸和游离不饱和脂肪酸的积累量分别减少了21.6%和28.2%。中温短时浸泡处理有效地控制了米粒中内源脂肪酶的活力,延缓了米粒中脂质的水解,而且使蒸煮后米饭中来源于脂肪氧化的不良风味物质——己醛和壬醛含量明显下降。该研究为电饭煲蒸煮米饭风味改良曲线的设计奠定了理论依据。

The cooking method of an electric cooker based on thermal processing can endow japonica rice with rich flavor,however,there is no corresponding cooking mode to improve the flavor quality of aged japonica rice.The odor characteristics of aged japonica rice were analyzed by sensory evaluation,electronic nose,and gas chromatography-mass spectrometry.Combined with the changes of lipase activity and free fatty acids content,the reasons for the differences of volatile flavor substances in aged rice caused by the adjustment of parameters in the water absorption stage were explored.The results showed that soaking at 50℃for 10 min could improve the flavor profile of the aged rice,which was similar to the overall flavor of the fresh rice.Moreover,compared with soaking at room temperature,the lipase activity in aged rice decreased by 86%,and the accumulation of total free fatty acids and free unsaturated fatty acids reduced by 21.6%and 28.2%,respectively.The activity of endogenous lipase in rice grains was effectively controlled and the hydrolysis of lipids was delayed by soaking at medium temperature for a short time.In addition,the content of off-flavor compounds such as hexanal and nonanal from fat oxidation decreased significantly.This study established a theoretical foundation for the design of the flavor improvement curve of rice cooked in an electric cooker.