干制过程中甘薯粉条老化规律研究

Study on the retrogradation of starch during the drying of sweet potato starch noodles

目的 保持干燥温度恒定为60℃,探究干燥过程粉条中水分对淀粉老化的影响规律。方法 将新鲜制备的甘薯粉条在相同温度不同相对湿度条件下干燥至相同水分含量,以及在相同干燥条件下干燥至相同水分含量后恒定在该水分含量及温度条件下保持不同时间,对上述样品的结晶特性、短程有序度、热特性等进行测定和分析,研究水分变化对甘薯粉条老化特性的影响。结果 干燥温度恒定,淀粉老化受热风相对湿度影响,这主要在于影响了粉条中水分蒸发速度;随着粉条水分含量减小,粉条中淀粉相对结晶度及短程有序度增加。当保持干燥条件不变时,粉条具有较高的老化速度的水分含量区间在25%~40%,对应的水分活度值为0.7~0.9。结论 粉条干燥过程中淀粉老化具有水分依赖性,通过控制水分含量可对淀粉老化进行调控。

Objective To explore the influence of moisture content on starch retrogradation during drying, the drying temperature is kept at 60℃. Methods The freshly prepared sweet potato starch noodles were dried to the same moisture content under conditions with the same temperature but different relative humidity, and sealed after being dried to the same moisture content under the same drying conditions, then incubated at a constant temperature over time. The crystallization characteristics, short-range order and thermal characteristics of the above samples were measured and analyzed to investigate the effects of moisture content on the retrogradation characteristics of sweet potato noodles. Results As the drying temperature kept constant, the starch retrogradation was affected by the relative humidity of hot air which mainly determined the evaporation rate of water in the starch noodles. The relative crystallinity and short-range order of starch in the noodles increased with the decrease of the moisture content in the starch noodles. While keep that drying condition constant, the moisture content of the vermicelli with higher aging rate ranged from 25% to 40%, and the corresponding water activity value was 0.7–0.9. Conclusion During the drying process of starch noodles, starch retrogradation is moisture dependent and can be regulated by controlling the content of moisture.