CHEMICAL VALORIZATION OF AGRICULTURAL BY-PRODUCTS: ISOLATION AND CHARACTERIZATION OF XYLAN-BASED ANTIOXIDANTS FROM ALMOND SHELL BIOMASS

Abstract

The isolation of non-cellulosic polysaccharides from both almond shells and their solid residue after autohydrolysis using a two-step alkaline extraction without and in combination with short ultrasonic treatment was investigated. The obtained polysaccharide preparations were characterized by yield, chemical composition and structural features, and the antioxidant activity of the water-soluble preparations was discussed in relation to the content of phenolics. The results suggested that, depending on the extraction conditions used, xylan associated to various extent with pectic polysaccharides and phenolics can be prepared, and the reaction time significantly shortened by application of ultrasound. The xylan polymers might serve as biopolymer sources in native form or after targeted modification for production of value-added substances and polysaccharide-based antioxidants, applicable in food, cosmetics and other areas.

Keywords

• Almond shells
• Extraction
• Ultrasound
• Xylan
• Pectic polysaccharides
• Phenolics content
• Antioxidant activity