Effect of Extraction Methods on the Structural and Functional Properties of Okra Proteins

IF 3.9 4区农林科学 Q2 FOOD SCIENCE & TECHNOLOGY

Food Biophysics Pub Date : 2026-05-26 DOI:10.1007/s11483-026-10159-z

Theodoros Karakasidis, Christos Ritzoulis, Vassilis Kontogiorgos, Maria Papageorgiou, Eleni P. Kalogianni

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Abstract

The present study investigates the impact of extraction techniques on the quality and functionality of protein products derived from okra (Abelmoschus esculentus), with the overarching goal of developing natural surface-active ingredients for food applications. Protein mixtures were prepared using five extraction methods, including salt extraction (OPC-SE), ethanol/phosphate (OPC-PE), and ultrasound-assisted extraction (OPC-UAE), the latter affording a protein content of72% and a yield of 2.23%. A conventional aqueous extraction at pH 6.6 (OPC-CE), performed without buffering agents, resulted in the highest protein content (79%) but a lower recovery (186%). In contrast, alkaline extraction at four pH levels (OPC-pH 8, 8.5, 9, 9.5) produced concentrates with lower protein content (44–70%) but higher yields (up to 4.0%) and limited functionality. Each protein extract was subjected to a comprehensive physicochemical characterisation (extraction yield, protein concentration, solubility, ζ-potential and dynamic-light scattering, critical aggregation concentration (CAC), size-exclusion chromatography, and electrophoresis. Technological functionality was evaluated through foaming and emulsification performance. Of the methods employed, OPC-CE and OPC-UAE stood out, displaying high protein content, high solubility (up to 73.2%), strong electrostatic stability (ζ-potential down to − 18.7 mV) and low CAC vales (~ 0.8% w/w), traits that correlated directly with superior foam (FC up to 73%, FS up to 50%) and emulsion stability (d₄,₃ ~11.2 μm; CI ~ 20%). By contrast, extracts obtained under alkaline conditions (pH ≥ 8) suffered from protein denaturation and the co-extraction of non-protein macromolecules, leading to diminished functionality. Overall, conventional extraction (OPC-CE) and ultrasound assistance (OPC-UAE) emerged as the most suitable approaches for producing okra protein concentrates with enhanced functional performance, making them promising ingredients for food systems requiring stable foaming or emulsifying properties.

Graphical Abstract

The alternative text for this image may have been generated using AI.

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提取方法对秋葵蛋白结构和功能特性的影响

本研究探讨了提取技术对秋葵蛋白质产品质量和功能的影响，以开发用于食品应用的天然表面活性成分为总体目标。采用盐提法（OPC-SE）、乙醇/磷酸盐法（OPC-PE）和超声辅助提取法（OPC-UAE）制备蛋白混合物，超声辅助提取法的蛋白含量为72%，得率为2.23%。在pH 6.6 （OPC-CE）条件下，不使用缓冲剂进行常规水萃取，蛋白质含量最高（79%），但回收率较低（186%）。相比之下，在4个pH水平（OPC-pH 8、8.5、9、9.5）下碱性提取得到的浓缩物蛋白质含量较低（44-70%），但产率较高（高达4.0%），功能有限。每个蛋白提取物都进行了全面的物理化学表征（萃取率，蛋白质浓度，溶解度，ζ-电位和动态光散射，临界聚集浓度（CAC），尺寸排除层析和电泳）。通过发泡和乳化性能来评价工艺功能。在所采用的方法中，OPC-CE和OPC-UAE表现出高蛋白质含量、高溶解度（高达73.2%）、强静电稳定性（ζ-电位低至- 18.7 mV）和低CAC值（~ 0.8% w/w），这些特性与优异的泡沫（FC高达73%，FS高达50%）和乳液稳定性（d₄，₃~11.2 μm, CI ~ 20%）直接相关。相反，在碱性条件下（pH≥8）得到的提取物遭受蛋白质变性和非蛋白质大分子的共同萃取，导致功能下降。总的来说，传统提取（OPC-CE）和超声辅助（OPC-UAE）是生产秋葵浓缩蛋白的最合适方法，具有增强的功能性能，使它们成为需要稳定发泡或乳化性能的食品系统的有前途的成分。此图像的替代文本可能是使用AI生成的。

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来源期刊

Food Biophysics 工程技术-食品科技

CiteScore

5.80

自引率

3.30%

发文量

审稿时长

1 months

期刊介绍： Biophysical studies of foods and agricultural products involve research at the interface of chemistry, biology, and engineering, as well as the new interdisciplinary areas of materials science and nanotechnology. Such studies include but are certainly not limited to research in the following areas: the structure of food molecules, biopolymers, and biomaterials on the molecular, microscopic, and mesoscopic scales; the molecular basis of structure generation and maintenance in specific foods, feeds, food processing operations, and agricultural products; the mechanisms of microbial growth, death and antimicrobial action; structure/function relationships in food and agricultural biopolymers; novel biophysical techniques (spectroscopic, microscopic, thermal, rheological, etc.) for structural and dynamical characterization of food and agricultural materials and products; the properties of amorphous biomaterials and their influence on chemical reaction rate, microbial growth, or sensory properties; and molecular mechanisms of taste and smell. A hallmark of such research is a dependence on various methods of instrumental analysis that provide information on the molecular level, on various physical and chemical theories used to understand the interrelations among biological molecules, and an attempt to relate macroscopic chemical and physical properties and biological functions to the molecular structure and microscopic organization of the biological material.