Enzymatic generation of cocoa bean shells oligosaccharides and feruloylated oligo/polysaccharides

Abstract

Cell wall polysaccharides isolated from two varieties (NAC, CCN) of cocoa bean shell (CBS) consisted mainly of pectic polysaccharides, primarily rhamnogalacturonan, and hemicelluloses. Enzymatic hydrolysis of CBS polysaccharides was performed using bi-enzymatic (arabinase/galactanase) and multi-enzymatic systems. Viscozyme® L led to the highest yield (76.64%) of NAC-based oligosaccharides of DP 3–5 (42.04%, mol) and 6–10 (36.78%, mol). The hydrolysis of CCN-based polysaccharides by Depol™ 670L led to 20.72% yield, while generating a diverse complex of oligosaccharides of DP up to 10. When tested for the promotion of the growth of selected probiotic strains, Lactobacillus rhamnosus GG and Bifidobacterium longum, oligosaccharides performed similarly or more than inulin and rhamnogalacturonan based on the prebiotic activity scores. In addition, the production of lactic, acetic, butyric and traces of propionic were prominent. Free feruloyl esterases from rumen microorganism provided best feruloylation efficiencies with CBS polysaccharides (56.9–60.1%), while that from Humicola insolens provided best feruloylation efficiencies with the oligosaccharides (30.8–50.5%). The antioxidant activity of feruloylated polysaccharides were expressed using three assays, DPPH, ORAC, and ABTS. Feruloylated CBS polysaccharides prompted significantly notable increases in the scavenging and antioxidant activity compared to their native forms as well as ferulic and ascorbic acid. Overall, CBS oligo- and feruloylated polysaccharides show great potential for use as optimal functional food ingredients.