Technology Integration Base for Vegetable Dehydration Processing Ministry of Agriculture PR China, School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
Technology Integration Base for Vegetable Dehydration Processing Ministry of Agriculture PR China, School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
Ultrason Sonochem. 2017 Sep;38:19-28. doi: 10.1016/j.ultsonch.2017.02.026. Epub 2017 Feb 21.
The effects of ultrasound pretreatment with different frequencies and working modes, including mono-frequency ultrasound (MFU), dual-frequency ultrasound (DFU) and tri-frequency ultrasound (TFU), on the degree of hydrolysis (DH) of rice protein (RP) and angiotensin-I-converting enzyme (ACE) inhibitory activity of RP hydrolysate were investigated. Ultraviolet-visible (UV) spectroscopy, fourier transform infrared (FTIR) spectroscopy, surface hydrophobicity and scanning electron microscopy (SEM) of RP pretreated with ultrasound were measured. The results showed that ultrasound pretreatment did not increase DH of RP significantly (p>0.05). However, all the ultrasound pretreatment increased the ACE inhibitory activity of RP hydrolysate significantly (p<0.05). The MFU of 20kHz showed higher ACE inhibitory activity compared to that of other MFU. The ACE inhibitory activity of sequential DFU was higher than that of simultaneous with the same frequency combination. Sequential TFU of 20/35/50kHz produced the highest increase in ACE inhibitory activity in contrast with other ultrasound frequencies and working modes. All the results under ultrasound pretreatment showed that ultrasound frequencies and working modes were of great effect on the ACE inhibitory activity of RP. The changes in UV-Vis spectra and surface hydrophobicity indicated the unfolding of protein and exposure of hydrophobic groups by ultrasound. The FTIR analysis showed that all the ultrasound pretreatment with different frequencies and working modes decreased α-helix, β-turn content and increased β-sheet, random coil content of RP. The SEM results indicated that ultrasound pretreatment resulted in the deformation of RP. In conclusion, the frequency selection of ultrasound pretreatment of RP is essential for the preparation of ACE inhibitory peptide.
研究了不同频率和工作模式的超声预处理（包括单频超声（MFU）、双频超声（DFU）和三频超声（TFU））对大米蛋白（RP）水解度（DH）和 RP 水解物血管紧张素转化酶（ACE）抑制活性的影响。测量了经超声预处理的 RP 的紫外可见（UV）光谱、傅里叶变换红外（FTIR）光谱、表面疏水性和扫描电子显微镜（SEM）。结果表明，超声预处理对 RP 的 DH 没有显著影响（p＞0.05）。然而，所有超声预处理均显著提高了 RP 水解物的 ACE 抑制活性（p＜0.05）。20kHz 的 MFU 比其他 MFU 具有更高的 ACE 抑制活性。相同频率组合的顺序 DFU 的 ACE 抑制活性高于同时 DFU。与其他超声频率和工作模式相比，20/35/50kHz 的顺序 TFU 产生了最高的 ACE 抑制活性增加。所有超声预处理下的结果均表明，超声频率和工作模式对 RP 的 ACE 抑制活性有很大影响。UV-Vis 光谱和表面疏水性的变化表明超声使蛋白质展开并暴露出疏水区。FTIR 分析表明，所有不同频率和工作模式的超声预处理均降低了 RP 的α-螺旋、β-转角含量，增加了β-折叠、无规卷曲含量。SEM 结果表明，超声预处理导致 RP 变形。总之，RP 的超声预处理频率选择对于制备 ACE 抑制肽至关重要。
