Corn cob agro-waste as valuable material for XOS production by fungal enzymes

Abstract

Since each region of the world has different agricultural sectors, specific residues are generating and at the same time a wide range of alternative novel sources of nutrients emerge, such as carbohydrates, proteins and minerals. Usage of biomass residues as start material for prebiotics production is preferable from the standpoint of ecology and as cheap production process. Corn cob can be considered as the main source for xylooligosaccharides (XOS) production. XOS are prebiotic, functional food ingredients, with biological benefits such as immunomodulatory and anti-inflammatory properties, anticancer and antioxidant activity. The European Commission has approved XOS produced from corn cob as a safe for human consumption. The corn cob mainly consists of lignocellulose. Chemical treatment is used to extract the hemicelullose from corn cob which is then hydrolyzed to XOS by fungal xylanases. Xylanase produced by fungi genera Aspergillus and Trichoderma are considered key enzymes for XOS production. Fermentation enzyme extract of strain Aspergillus tubingensis FAT35, obtained after SSF on corn cob as substrate, was used for hydrolysis of corn cob xylan to XOS. A. tubigensis FAT35 produced high level of xylanase (350 U/mL). Obtained XOS (2-10 units) were characterized by TLC and by antioxidant activity (ORAC, DPPH, FRAP, and ABTS). Significant antioxidant potential was shown by all used antioxidant tests. The obtained XOS are suitable to be a functional food additive and are obtained from agro-waste material by environmentally and economically suitable way.