School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, China.
School of Food and Bioengineering, Xihua University, Chengdu, China.
J Sci Food Agric. 2020 Jun;100(8):3498-3506. doi: 10.1002/jsfa.10390. Epub 2020 Apr 6.
The general enzymatic method for producing reducing sugar is liquefaction followed by saccharification of starch. This method results in lower yields, consuming high energy and time. Therefore, the present study evaluated a new approach for producing reducing sugar from sweet potato starch (SPS), including simultaneous liquefaction (by α-amylase) and saccharification (by glucoamylase) of SPS pretreated with high power ultrasound. The effects of ultrasound parameters on the conversion rate of SPS and mechanism were investigated.
The optimum ultrasound pretreatment conditions were a frequency of 20 kHz, SPS concentration of 125 g L , temperature of 30 °C, pulsed on-time of 3 s, pulsed off-time of 5 s, power density of 8 W mL and sonication time of 15 min. The ultrasound assisted enzymolysis resulted in a SPS conversion rate of 59.10%, which was improved by 56.35% compared to the control. The results of pasting properties and thermal analysis showed that ultrasound pretreatment decreased the peak viscosity, breakdown temperature, setback viscosity, gelatinization range (T - T ) and enthalpy of gelatinization (ΔH) of SPS significantly (P < 0.05) by 12.1%, 7.6%, 6.6%, 18.8% and 44.4%, respectively. Fourier-transform infrared spectroscopy indicated that ultrasound damaged the ordered structures and crystallization zone. This was confirmed by X-ray diffraction analysis, which showed that the relative crystallinity was reduced by 15.0%. Scanning electron microscopy showed that ultrasound destroyed the surfaces and the linkages between starch granules.
Prior to simultaneous liquefaction and saccharification of SPS, high power ultrasound pretreatment is a promising method for improving the conversion rate of starch. © 2020 Society of Chemical Industry.
生产还原糖的常用酶法是液化淀粉后再糖化。该方法产率较低，需要消耗大量的能量和时间。因此，本研究评估了一种从甘薯淀粉（SPS）生产还原糖的新方法，包括用高功率超声预处理 SPS 同时进行液化（用α-淀粉酶）和糖化（用糖化酶）。考察了超声参数对 SPS 转化率的影响及机制。
超声预处理的最佳条件为频率 20 kHz、SPS 浓度 125 g/L、温度 30°C、脉冲时间 3 s、脉冲间隔 5 s、功率密度 8 W/mL 和超声时间 15 min。超声辅助酶解使 SPS 的转化率达到 59.10%，比对照提高了 56.35%。糊化性能和热分析结果表明，超声预处理使 SPS 的峰值黏度、下降温度、回生黏度、糊化范围（T - T ）和糊化焓（ΔH）分别显著降低了 12.1%、7.6%、6.6%、18.8%和 44.4%（P<0.05）。傅里叶变换红外光谱表明，超声破坏了淀粉的有序结构和结晶区。X 射线衍射分析证实了这一点，表明相对结晶度降低了 15.0%。扫描电子显微镜显示，超声破坏了淀粉颗粒的表面和连接。
在 SPS 同时液化糖化之前，高功率超声预处理是提高淀粉转化率的一种很有前途的方法。 © 2020 英国化学学会。
