预糊化条件对萌芽糙米蒸煮质构特性及品质的影响

为了解决萌芽糙米不易蒸煮且蒸煮后米饭口感较硬、黏弹性不足、粗糙感明显等问题,该文应用预糊化技术对萌芽糙米进行品质改良,评价了预糊化条件(米粒含水率43.21%±2.15%、34.64%±1.49%、29.83%±1.67%,蒸汽处理时间2、5、10、15、20、25 min)对萌芽糙米蒸煮特性、米饭质构特性及感官品质的影响。研究结果表明,随着米粒含水率的降低,预糊化萌芽糙米的蒸煮时间、蒸煮吸水率、体积膨胀率显著增大(P0.05),固形物损失率显著降低(P0.05);预糊化萌芽糙米的米饭硬度、黏附性、黏聚性、胶黏性、弹性、咀嚼性随米粒含水率降低的变化较为复杂。随着蒸汽处理时间的延长,预糊化萌芽糙米的蒸煮时间显著缩短(P0.05),蒸煮吸水率、体积膨胀率、固形物损失率变化较小且无明显规律;预糊化萌芽糙米的米饭硬度先减小后增大,黏附性、黏聚性先增大后减小,胶黏性、弹性、咀嚼性变化较为复杂。感官评定结果表明,预糊化萌芽糙米的米饭感官评分随米粒含水率降低的变化较为复杂,随蒸汽处理时间的延长先增大后降低。总体而言,米粒含水率29.83%±1.67%、蒸汽处理15 min的预糊化条件可以显著改善萌芽糙米的蒸煮特性、质构特性及感官品质,使其接近白米的品质指标。研究结果可为预糊化萌芽糙米的产业化开发提供依据。

Effects of parboiling conditions on cooking properties, textural properties and quality characters of germinated brown rice

Abstract: Germinated brown rice (GBR) is difficult to cook and usually gives unfavorable harder and less sticky texture after cooking than white rice (WR). Parboiling, under the GBR moisture levels of 42.13%±2.15%, 34.64%±1.49% and 29.83%±1.67% and the atmospheric steam treatment for 2, 5, 10, 15, 20 and 25 min, respectively, was used to improve the quality characteristics of GBR. The comparative study of cooking properties, textural properties and sensory qualities among PGBR (parboiling germinated brown rice), GBR, brown rice (BR) and WR was also conducted in this study. Firstly, the cooking time, water uptake ratio and volumetric expansion of PGBR during cooking increased while the solid loss ratio of PGBR decreased with the decrease of moisture content of GBR. With the steaming time increasing, the cooking time of PGBR decreased significantly while the water uptake ratio, the volumetric expansion and solid loss of PGBR during cooking changed slightly with no obvious rule. Thus, the combination of GBR moisture content of 29.83%±1.67% and 15-25 min steaming time was recommended as the appropriate parboiling condition to improve the cooking properties of GBR, due to the significantly improved water uptake ratio and volumetric expansion, the significantly decreased solid loss ratio, and the slightly decreased cooking time of PGBR. Secondly, the variations of texture properties of PGBR with different parboiling conditions were complicated. With the moisture content of GBR decreasing, hardness of cooked PGBR decreased at first and then leveled off when the steaming time was 2-10 min or continuously decreased when the steaming time was 15-25 min; cohesiveness of cooked PGBR increased at first and then leveled off when the steaming time was 2-10 min or continuously increased when the steaming time was 15-25 min; gumminess of cooked PGBR showed no obvious rule when the steaming time was 2-5 min and continuously increased when the steaming time was 10-25 min. Whereas, the change of adhesiveness, springiness and chewiness of cooked PGBR was complicated with no obvious rules. With the steaming time increasing, the hardness of cooked PGBR decreased at first and then increased. The minimum hardness of cooked PGBR achieved to be 35.35±1.27, 27.95±1.49 and 24.4±2.4 N respectively under the conditions of the GBR moisture content of 42.13%±2.15%, 34.64%±1.49% and 29.83%±1.67% respectively with the steam time of 10, 10 and 15 min, respectively. The adhesiveness and cohesiveness increased at first and then decreased with the increase of steaming time while the changes of gumminess, springiness and chewiness were complex with no obvious rules. Thus, the combination of GBR moisture content of 29.83%±1.67% and 15-25 min steam treatment was recommended as the appropriate parboiling condition to improve the textural properties of GBR, due to the significantly reduced hardness and the significantly increased adhensiveness, springiness, cohesiveness, gumminess and chewiness. Thirdly, the sensory score of cooked PGBR increased at first and then decreased with the decreasing of moisture content of GBR when the steaming time was 2-5 min, increased with the decreasing of moisture content of GBR when the steaming time was 10-25 min, and increased at first and then decreased with the increase of steaming time. The highest sensory score of cooked PGBR achieved to be 45.94±1.35, 48.88±0.55 and 51.87±0.88 respectively under the conditions of the GBR moisture content of 42.13%±2.15%, 34.64%±1.49% and 29.83%±1.67% respectively with the steam time of 10, 10 and 15 min, respectively. Finally, the combination of GBR moisture content of 29.83%±1.67% and 15 min steaming time was recommended as the appropriate parboiling condition, due to the significantly improved flavor, taste and textural characteristics of cooked rice. These results demonstrated that all the cooking properties, textural properties and sensory qualities of PGBR were significantly improved after properly parboiled, indicating that parboiling has a certain application value in the GBR processing and a broad industrial application prospect.