Optimization of sunflower albumin extraction from oleaginous meal and characterization of their structure and properties

Abstract

This article proposes an alternative extraction strategy for the valorization of the sunflower meal leading to the production of an albumin isolate for human nutrition and a valuable residual meal for feed application. For this purpose, a response surface methodology was employed to study the effect of pH (3–6) and NaCl (0–0.5 mol.L−1) on albumin extraction (yield, content, and phenolic contamination). Total phytate and nitrogen content in residual meal were also considered. As a result, the significant influence (p-value<0.05) of both pH and NaCl concentration on investigated responses was demonstrated. The analysis of regression and variance confirmed a high accuracy of developed models for process prediction. Based on generated equations, a multi-objective optimization was applied for simultaneous maximization of albumin extraction performances and the residual meal value. The best trade-off for sunflower albumin extraction was found at pH 4.1 and 0.25 mol.L−1 of NaCl concentration. Under this condition, good albumin recovery was achieved (>70%), whereas extract was enriched in sunflower albumin fraction (>90% of total proteins) and phenolic contamination of albumins was considerably reduced (<1.6 mg of covalently bound chlorogenic acid per gram of proteins). The selected condition produced value-added residual meal with low phytate level (<4% on dry matter basis) and high protein content (>40% on dry matter basis). Further purification of sunflower albumins yielded a white color product characterized by excellent solubility (approximately 100% at pH 2–11), stable conformation of structure against pH and temperature, and beneficial functional properties (foaming and emulsifying).