Diedericks Claudine F, Shek Carol, Jideani Victoria A, Venema Paul, van der Linden Erik
Laboratory of Physics and Physical Chemistry of Foods, Wageningen University and Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands.
Department of Food Science and Technology, Cape Peninsula University of Technology, P.O. Box 1906, Bellville 7535, South Africa.
Food Res Int. 2020 Dec;138(Pt B):109773. doi: 10.1016/j.foodres.2020.109773. Epub 2020 Oct 6.
Plant proteins, and specifically those from legume crops, are increasingly recognised as sustainable and functional food ingredients. In this study, we expand on the knowledge of Bambara groundnut (Vigna subterranea (L.) Verdc.) [BGN] proteins, by characterising the composition, microstructure and rheological properties of BGN protein isolates obtained via wet extraction and protein-enriched fractions obtained via dry fractionation. The BGN protein isolates were compared in the context of the major storage protein, vicilin, as previously identified. Molecular weight analysis performed with gel electrophoresis and size-exclusion chromatography coupled to light-scattering, revealed some major bands (190 kDa) and elution patterns with molecular weights (205.6-274.1 kDa) corresponding to that of BGN vicilin, whilst the thermal denaturation temperature (T 91.1 °C, pH 7) of BGN protein isolates also coincided to that of the vicilin fraction. Furthermore, the concentration dependence of the elastic modulus G' of the BGN protein isolates, closely resembled that of BGN vicilin (both upon NaCl addition); suggesting that vicilin is the main component responsible for gelation. Confocal laser scanning and scanning electron micrographs revealed inhomogeneous aggregate structures, which implies that fractal scaling were better suited for description of the BGN protein isolate gel networks. Concerning the BGN protein-enriched fractions, both rotor and impact milling with air jet sieving and air classification, respectively, were successfully applied to separate these fractions from those high in starch; as evident from compositional analysis, particle size distributions and microscopic imaging. When considering sustainability aspects, dry fractionation could thus be a viable alternative for producing BGN protein-enriched fractions.
植物蛋白，特别是豆类作物中的蛋白，越来越被认为是可持续且具有功能性的食品成分。在本研究中，我们通过表征经湿法提取获得的班巴拉花生（Vigna subterranea (L.) Verdc.）[BGN] 蛋白分离物以及经干法分级获得的富含蛋白级分的组成、微观结构和流变学特性，拓展了对BGN蛋白的认识。在先前鉴定出的主要贮藏蛋白豌豆球蛋白的背景下，对BGN蛋白分离物进行了比较。通过凝胶电泳和与光散射联用的尺寸排阻色谱进行的分子量分析，揭示了一些主要条带（190 kDa）以及分子量（205.6 - 274.1 kDa）与BGN豌豆球蛋白相对应的洗脱模式，而BGN蛋白分离物的热变性温度（T 91.1 °C，pH 7）也与豌豆球蛋白级分的热变性温度一致。此外，BGN蛋白分离物的弹性模量G'对浓度的依赖性，与BGN豌豆球蛋白的依赖性非常相似（两者在添加NaCl时）；这表明豌豆球蛋白是负责凝胶化的主要成分。共聚焦激光扫描和扫描电子显微镜图像显示出不均匀的聚集体结构，这意味着分形标度更适合描述BGN蛋白分离物凝胶网络。关于富含BGN蛋白的级分，分别采用转子磨以及气流筛分和空气分级的冲击磨，成功地将这些级分与高淀粉级分分离；从成分分析、粒度分布和微观成像中可以明显看出。在考虑可持续性方面时，干法分级因此可能是生产富含BGN蛋白级分的可行替代方法。
