Effects of heat treatment and dehydration on bioactive polysaccharide acemannan and cell wall polymers from Aloe barbadensis Miller

• Published in: Carbohydrate polymers Vol. 51; no. 4; pp. 397 - 405
• Main Authors: Femenia, Antoni, Garcı́a-Pascual, Pablo, Simal, Susana, Rosselló, Carmen
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2003; Elsevier Science
• Subjects: Acemannan; Aloe barbadensis Miller; Applied sciences; Dehydration; Exact sciences and technology; Natural polymers; Physicochemistry of polymers; Starch and polysaccharides; Structural modifications; Acemannan; Aloe barbadensis Miller; Dehydration; Structural modifications; Convection drying; Air drying; Adsorption capacity; Chemical degradation; Experimental study; Property processing relationship; Pectic substance; Cell wall; Medicinal plant; Warm air; Plant origin; Fat; Oside polymer; Water holding capacity
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/S0144-8617(02)00209-6

Physico-chemical modifications promoted by heat treatment and dehydration at different temperatures (30–80 °C) on acemannan, a bioactive polysacharide from aloe vera ( Aloe barbadensis Miller) parenchyma, were evaluated. Modification of acemannan, a storage polysaccharide, was particularly significant when dehydration was performed above 60 °C. Heating promoted marked changes in the average molecular weight (MW) of the bioactive polysaccharide, increasing from 45 kDa, in fresh aloe, to 75 and 81 kDa, for samples dehydrated at 70 and 80 °C, respectively. This could be attributed to structural modifications, such as deacetylation and losses of galactose-rich side-chains from the mannose backbone. These structural modifications were reflected by the significant changes occurring in the related functional properties, such as swelling, water retention capacity, and fat adsorption capacity, which exhibited a significant decrease as the temperature of dehydration increased. Further, dehydration also promoted significant modification of the main type of cell wall polysaccharides present within the aloe parenchyma tissues. Pectic polysaccharides from the cell wall matrix were affected by heating, probably due to either β-elimination processes or enzyme-catalysed degradation. The influence that these physico-chemical modifications might have on the bioactivity and properties of processed products from A. barbadensis Miller needs to be considered.