Department of Food Science and Technology, Punjab Agricultural University, Ludhiana 141004, Punjab, India.
Department of Food Science and Technology, Punjab Agricultural University, Ludhiana 141004, Punjab, India.
Ultrason Sonochem. 2018 Dec;49:333-342. doi: 10.1016/j.ultsonch.2018.08.026. Epub 2018 Aug 27.
Ultrasound, an emerging non-thermal technique, has potential to modify the functionality of bio-molecules like protein. In the present study, the impact of ultrasound on whey protein (WP) was assessed with functional, rheological, heat coagulation and transition temperature, SDS-PAGE, FTIR spectra, scanning electron microscopy and transmission electron microscopy. The results of this study showed that the raw WP had broad bimodal particle size distribution while after ultrasonication, modified WP exhibited narrower distribution along with smaller particle size (0.683 ± 0.225 μm) compared to untreated WP (2.453 ± 0.717 μm). The solubility of WP also increased after ultrasonication (72.22 ± 0.68% to 79.21 ± 1.08%). During the rheological evaluation, both the samples exhibited Newtonian behaviour but, the modified WP exhibited dramatically higher storage modulus (G') throughout the temperature profile compared to raw WP mainly due to enhanced proteins aggregation during heating which revealed more elastic and stronger gel. The modified WP exhibited significantly higher (about 6-times) heat stability compared to raw WP which signified that after ultrasonication the WP can withstand higher temperature during processing for longer time. The results were also confirmed by higher transition temperature (T) of modified WP (93.32°) compared to untreated WP (81.93 °C). The SDS-PAGE profile of raw and modified WP showed that the ultrasound significantly decreased the bands density of low molecular weight molecules (β-lactoglobulin and α-lactalbumin). FTIR spectra also showed noticeable difference between the secondary structure component of raw and modified WP. Finally, the structural micrographs of raw and modified WP from SEM and TEM analysis also confirmed the adequacy of modification of WP employing non-thermal techniques. The modified WP revealed smaller, regular and more homogenous and ordered structures compared to untreated sample.
超声是一种新兴的非热技术，具有改变生物分子（如蛋白质）功能的潜力。本研究采用功能、流变、热凝固和转变温度、SDS-PAGE、FTIR 光谱、扫描电子显微镜和透射电子显微镜评估了超声对乳清蛋白（WP）的影响。研究结果表明，原始 WP 具有广泛的双峰粒径分布，而超声处理后，改性 WP 的粒径分布更窄，粒径更小（0.683±0.225μm），与未处理的 WP（2.453±0.717μm）相比。WP 的溶解度也在超声处理后增加（72.22±0.68%到 79.21±1.08%）。在流变评估中，两种样品均表现出牛顿行为，但改性 WP 在整个温度范围内表现出明显更高的储能模量（G'），主要是由于加热过程中蛋白质聚集增强，导致形成更具弹性和更强的凝胶。改性 WP 的热稳定性明显高于原始 WP（约 6 倍），这表明超声处理后 WP 在加工过程中可以承受更高的温度并持续更长时间。改性 WP 的转变温度（T）也更高（93.32°C），与未处理的 WP（81.93°C）相比，这也证实了这一结果。原始和改性 WP 的 SDS-PAGE 图谱表明，超声显著降低了低分子量分子（β-乳球蛋白和α-乳白蛋白）的带密度。FTIR 光谱也显示了原始和改性 WP 二级结构成分之间的明显差异。最后，SEM 和 TEM 分析的原始和改性 WP 的结构微观照片也证实了非热技术对 WP 改性的充分性。与未处理的样品相比，改性 WP 显示出更小、更规则、更均匀和有序的结构。
