Sunflower meal valorization through enzyme-aided fractionation and production of emerging prebiotics

Abstract

Abstract Sunflower meal, a plentiful and underutilized oil industry by-product, is currently discarded as waste or used as cheap component of animal feed with poor protein content and high content of complex carbohydrates. To harness its great potential for valorization, we propose an efficient method through enzyme-aided fractionation yielding 47.8% of hemicellulosic fraction, with simultaneous generation of various other potentially valuable fractions (including polyphenol-rich fraction, protein isolate, pectin, and lignin). According to the monomeric composition the main type of extracted hemicellulose was xylan with the common feature of a backbone of β-(1→4)-linked xylose residues, with a common substitution with arabinose moieties and some glucuronic acid residues. Subsequently, the xylan fraction underwent enzymatic treatment using commercial xylanase (ROHALASE® SEP-VISCO) to produce highly valuable compounds - emerging prebiotics xylo-oligosaccharides (XOS). Under optimized reaction conditions (70°C, pH 6 and enzyme concentration of 0.005% v/v using 5% w/v xylan solution) a yield of XOS with a polymerization degree DP<50 reached approximately 52.3% after 2 hours (majority of obtained product had DP<6 with predominance of XOS2 and XOS3 and without significant xylose generation).