超声预处理对玉米蛋白可酶解性的影响

旨在采用超声预处理改善玉米蛋白的酶解性,研究了超声频率模式(单频、双频、定频和扫频)及频率参数对玉米蛋白酶解水解度及溶解率的影响,采用高效尺寸排阻色谱法对酶解液的分子质量分布进行了表征。研究发现,(68±2)kHz/(28±2)kHz双频扫频为最佳超声频率模式,优化试验获得超声预处理的最佳工作参数为:超声温度30℃、料液比1:20(g/mL)、超声处理时间40 min、扫频周期500 ms、超声功率密度80 W/L、脉冲超声的工作时间10 s和间歇时间3 s。在最佳超声频率模式及工作参数预处理的条件下,水解度和蛋白溶解率分别为23.6%和75.2%,较对照组(未经超声处理)分别提高了39.4%和54.7%,且酶解液具有更窄的分子质量分布范围。这表明超声预处理能促进玉米蛋白向多肽转化,尤其有利于分子质量为200~1 000 u的玉米蛋白肽的形成。

Effects of Ultrasound Pretreatment on Enzymatic Hydrolysis of Corn Gluten Meal

The objective of this paper was to study the effects of ultrasound pretreatment on the degree of hydrolysis (DH) and dissolution ratio (DR) of corn gluten meal (CGM). The frequency mode (single frequency, dual-frequency, fixed frequency, and sweep frequency), and the operating parameters of ultrasound on the enzymatic hydrolysis of CGM were optimized, and the high performance size exclusion chromatography (HPSEC) was employed to characterize the molecular weight (MW) distribution of hydrolysate. The results showed that the optimal frequency mode of ultrasound was (68±2) kHz/ (28±2) kHz and the optimum operating pretreatment parameters were temperature of ultrasonic condition 30 °C, ultrasonic treatment time 40 min, pulsed on-time 10 s and off-time 3 s, cycle time of the sweep frequency 500 ms, ultrasonic power density 80 W/L. The pretreated CGM was subsequently hydrolyzed by Alcalase 2.4L with the ratio of enzyme to substance 4 740 U/g, temperature 50 °C, pH 9.0 and 60 min. Under the condition of optimum ultrasonic frequency mode and operating parameters, the DH and DR of CGM were found as 23.6% and 75.2%, which were 39.4% and 54.7% higher than that of control, respectively. The results indicated that the ultrasonic pretreatment has a facilitative effect on the enzymatic hydrolysis of CGM, promoting the conversion of protein to peptides, especially the peptides with a MW of 200 - 1 000 u.