MICROWAVE AND ULTRASONIC TREATMENT AS A PRELIMINARY STAGE OF OBTAINING WATER-SOLUBLE MANNAN FROM COFFEE SLUDGE

Abstract

In recent years, interest in immunocorrectors of natural origin has increased significantly. Among them is a group of polysaccharides such as mannans. Mannans are polysaccharides composed of D-mannose residues as the main chain. They possess a number of properties: immunomodulatory, cancer-protective, antimicrobial, and normalize blood cholesterol levels. Mannans are present in a number of plants, algae and microorganisms. One of the promising sources of mannans can be coffee sludge, which is accumulated on an industrial scale at instant coffee companies. This article describes a biotechnological method for the production of water-soluble mannan from coffee sludge and investigates the possibility of increasing the yield of water-soluble low-molecular-weight mannan with the maximum content of physiologically active fractions by pretreating the raw material with ultrasound and ultrahigh-frequency radiation. The sludge was pretreated in an aqueous medium using ultrasound at 25, 35 and 40 kHz for 15 minutes and treatment in a 2.45 GHz ultra-high-frequency electric field with a power of 300 W, 600 W and 800 W for 5 minutes. Next, the physical disintegrate was treated with an enzyme preparation with beta-mannanase activity and centrifuged. The resulting water-soluble products were characterized by gel chromatography to determine the molecular weight distribution of the fractions of each sample. It was found that the pretreatment with ultrasound is expedient, since the total amount of fractions with a molecular weight of less than 20 kDa is almost 80%. The treatment of raw materials with microwave rays is inefficient and leads to an increase in fractions of molecular weight less than 1 kDa. Thus, varying the conditions of the preliminary physical treatment of coffee sludge allows to regulate the molecular weight distribution of water-soluble enzymolysis products and obtain products with the required range of molecular weight values.