School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China; Institute of Applied Chemistry and Biological Engineering, Weifang Engineering Vocational College, 8979 Yunmenshan South Road, Qingzhou, Shandong 262500, China.
School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China; Institute of Food Physical Processing, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
Ultrason Sonochem. 2020 Oct;67:105124. doi: 10.1016/j.ultsonch.2020.105124. Epub 2020 Apr 9.
The effect of dual-frequency ultrasound treatment with different working modes on the lysinoalanine (LAL) formation and structural characterization of rice dreg protein isolates (RDPI) was studied during alkaline exaction processing. Ultrasonic notably decreased the LAL amount of RDPI and enhanced the protein dissolution rate. The LAL content of RDPI, especially sequential dual frequency 20/40 kHz, decreased by 12.02% (P < 0.05), compared to non-sonicated samples. Herein, the protein dissolution rate was higher. The changes in sulfhydryl groups was positively correlated with the LAL formation. The amino acids (AA) such as threonine (Thr), lysine (Lys), and arginine (Arg) were reduced, resulting in a decrease in LAL content following sonication. Besides, ultrasonication altered protein secondary structure by reducing random coil and β-sheet contents, while α-helix and β-turn contents increased. Alterations in the surface hydrophobicity, particle size, particle size distribution, and microstructure indicated more irregular fragment with microparticles of RDPI by sonochemical treatment. Thus, ultrasound treatment may be a new and efficacious process for controlling the LAL generation in prepared-protein food(s) during alkali extraction.
研究了不同工作模式的双频超声处理对碱性提取过程中米渣蛋白分离物（RDPI）赖氨酰-丙氨酸（LAL）形成和结构特性的影响。超声显著降低了 RDPI 的 LAL 含量，并提高了蛋白质溶解率。与未经超声处理的样品相比，RDPI 的 LAL 含量（特别是连续双频 20/40 kHz）降低了 12.02%（P < 0.05），同时蛋白质溶解率更高。巯基变化与 LAL 形成呈正相关。经超声处理后，苏氨酸（Thr）、赖氨酸（Lys）和精氨酸（Arg）等氨基酸减少，导致 LAL 含量降低。此外，超声处理通过降低无规卷曲和β-折叠含量，同时增加α-螺旋和β-转角含量，改变蛋白质二级结构。表面疏水性、粒径、粒径分布和微观结构的变化表明，超声化学处理后 RDPI 具有更多不规则碎片和微粒子。因此，超声处理可能是一种新的、有效的控制碱提取制备蛋白食品中 LAL 生成的方法。
