Enzymatic Liquefaction of Cell-Walls from Kent and Tommy Atkins Mango Fruits

Abstract

Tab le mango varieties discarded by the export market are generally not considered suitable for processing mainly because they yield too viscous fruit purees. The objective of this study was determining if appropriate enzy mat ic treatment can overcome this barrier. Cell-wall polysaccharides fro m mesocarp and pericarp of fu lly ripe table mangoes were characterized analy zing the alcohol-insoluble residues (AIR). Content of celluloses, hemicellu loses, lignin and soluble and insoluble pectin were assessed after selective ext raction. After hydrolysis of main fractions, neutral sugars were determined by gas chromatography showing that xylose prevails (12-14 %) in the non-cellu losic fract ion of ins oluble cell walls fro m mesocarp, indicating predo minance with cellulose, of xilan-type polysaccharides in mango flesh. Water insoluble AIR (WAIR) was incubated with co mmercial preparat ions, characterized for their main enzy mat ic activit ies and comprising balanced proportion of pectinases and cellulases with other different secondary activities. At equivalent 500 µl per kilogram of puree and at 45°C, solubilisation rates of uronids and neutral sugars reach respectively 100 and 90% only when xy lanase activities were present. Then, a commercial enzy me preparation containing pectinases, cellulases and high xylanase activities was applied to native mango puree varying enzyme concentration and incubation time according to a central composite rotatable design. It was shown that percent of final suspended insoluble solids and Bostwick consistency could be considerably reduced in minutes, using a relatively lo w amount of enzyme preparation (150 µl.L -1 ). Rheological properties of mango purees can be modulated easily according to incubation time and concentration of enzymatic solution to fit the needs of food industries.