Bordignon Juliany Cristiny Sonda, Badaró Amanda Teixeira, Barbin Douglas Fernandes, Mariutti Lilian Regina Barros, Netto Flavia Maria
School of Food Engineering, State University of Campinas, Street Monteiro Lobato, 80, 13082-862, Campinas, SP, Brazil.
Heliyon. 2023 Jul 6;9(7):e17981. doi: 10.1016/j.heliyon.2023.e17981. eCollection 2023 Jul.
This study investigated the oxidative susceptibility of whey protein isolate (WPI) dispersions treated by microwave or thermal convection before freeze-drying. WPI (20 mg protein/mL) in distilled water (DW) was heated at 63 ± 2 °C for 30 min by microwave (WPI-MW) or convection heating (WPI-CH) and freeze-dried. Untreated WPI (WPI-C), WPI solubilized in DW and freeze-dried (WPI-FD), and WPI solubilized in DW, heated at 98 ± 2 °C for 2 min and freeze-dried (WPI-B) were also evaluated. Structural changes (turbidity, ζ potential, SDS-PAGE, and near-infrared spectroscopy (NIR)) and protein oxidation (dityrosine, protein carbonylation, and SH groups) were investigated. WPI-FD showed alterations compared to WPI-C, mainly concerning carbonyl groups. Microwave heating increased carbonyl groups and dityrosine formation compared to conventional heating. NIR spectrum indicated changes related to the formation of carbonyl groups and PCA analysis allowed us to distinguish the samples according to carbonyl group content. The results suggest that NIR may contribute to monitoring oxidative changes in proteins resulting from processing.
本研究调查了乳清分离蛋白（WPI）分散液在冷冻干燥前经微波或热对流处理后的氧化敏感性。将蒸馏水中的WPI（20 mg蛋白质/mL）通过微波（WPI-MW）或对流加热（WPI-CH）在63±2°C下加热30分钟，然后冷冻干燥。还对未处理的WPI（WPI-C）、溶解于蒸馏水中并冷冻干燥的WPI（WPI-FD）以及溶解于蒸馏水中、在98±2°C下加热2分钟并冷冻干燥的WPI（WPI-B）进行了评估。研究了结构变化（浊度、ζ电位、SDS-PAGE和近红外光谱（NIR））和蛋白质氧化（二酪氨酸、蛋白质羰基化和SH基团）情况。与WPI-C相比，WPI-FD出现了变化，主要涉及羰基。与传统加热相比，微波加热增加了羰基和二酪氨酸的形成。近红外光谱表明了与羰基形成相关的变化，主成分分析使我们能够根据羰基含量区分样品。结果表明，近红外光谱可能有助于监测加工过程中蛋白质的氧化变化。
