Georgiev Radoslav, Kalaydzhiev Hristo, Ivanova Petya, Silva Cristina L M, Chalova Vesela I
Department of Biochemistry and Molecular Biology, University of Food Technologies, 26 Maritsa Blvd, 4002 Plovdiv, Bulgaria.
Department of Analytical Chemistry and Physicochemistry, University of Food Technologies, 26 Maritsa Blvd, 4002 Plovdiv, Bulgaria.
Foods. 2022 Feb 14;11(4):541. doi: 10.3390/foods11040541.
Rapeseed meal is a by-product of the oil-producing industry with a currently underestimated application. Two protein isolates, PI or PI, were obtained from industrial rapeseed meal after treatment with an aqueous ethanol solution. The alkaline-extracted proteins were sequentially precipitated by two different modes, from pH 10.5 to 2.5, and vice versa, from 2.5 to 8.5, with a step of 1 pH unit. The preparation approach influenced both the functional and antioxidant properties of the isolates. The PI exhibited higher water and oil absorption capacities than PI, reaching 2.68 g HO/g sample and 2.36 g oil/g sample, respectively. The emulsion stability of the PI, evaluated after heating at 80 °C, was either 100% or close to 100% for all pH values studied (from 2 to 10), except for pH 6 where it reached 93.87%. For the PI, decreases in the emulsion stability were observed at pH 8 (85.71%) and pH 10 (53.15%). In the entire concentration range, the PI exhibited a higher scavenging ability on 2,2-diphenyl-1-picryl hydrazyl (DPPH) and hydroxyl radicals than PI as evaluated by DPPH and 2-deoxyribose assays, respectively. At the highest concentration studied, 1.0%, the neutralization of DPPH radicals by PI reached half of that exhibited by synthetic antioxidant butylhydroxytoluene (82.65%). At the same concentration, the inhibition of hydroxyl radicals by PI (71.25%) was close to that achieved by mannitol (75.62%), which was used as a positive control. Established antioxidant capacities add value to the protein isolates that can thus be used as both emulsifiers and antioxidants.
菜籽粕是油脂生产行业的一种副产品，目前其应用价值被低估。通过用乙醇水溶液处理工业菜籽粕，获得了两种蛋白质分离物，PI或PI。碱性提取的蛋白质通过两种不同模式依次沉淀，一种是从pH 10.5到2.5，另一种是相反，从2.5到8.5，步长为1个pH单位。制备方法影响了分离物的功能和抗氧化性能。PI的吸水和吸油能力高于PI，分别达到2.68 g水/g样品和2.36 g油/g样品。在80℃加热后评估，PI在所有研究的pH值（从2到10）下的乳液稳定性要么为100%，要么接近100%，pH 6时除外，此时乳液稳定性达到93.87%。对于PI，在pH 8（85.71%）和pH 10（53.15%）时观察到乳液稳定性下降。在整个浓度范围内，通过DPPH和2-脱氧核糖测定分别评估，PI对2,2-二苯基-1-苦基肼（DPPH）和羟基自由基的清除能力高于PI。在研究的最高浓度1.0%时，PI对DPPH自由基的中和能力达到合成抗氧化剂丁基羟基甲苯的一半（82.65%）。在相同浓度下，PI对羟基自由基的抑制率（71.25%）接近用作阳性对照的甘露醇（75.62%）。已确定的抗氧化能力为蛋白质分离物增添了价值，因此这些分离物可用作乳化剂和抗氧化剂。
