Blanching of red beet (Beta vulgaris L. var. conditiva) root. Effect of hot water or microwave radiation on cell wall characteristics

Abstract

The effect of enzymes inactivation through traditional (water, 90 C) and microwave blanching (constant power of 350Wand changing power with values higher than 900W) on cell wall polysaccharides as well as on microstructure of beet root tissue was studied with the goal of attaining a better understanding of the changes produced by treatment and its consequences on the functional properties of cell wall polymers. Powers higher than 900 W produced greater tissue microstructural damage due to alteration of the cell wall network. The contact between neighboring cells persisted after microwave treatment at 350 W while traditional blanching or blanching at higher microwave powers (90MW) produced separation of the middle lamella at different points and also cell separation was observed for the last mentioned treatment. The formation of entanglements of pectin-in-extensin in 350 W-treated beet root and the higher content of calcium and diferulated cross linked pectins in the case of traditional treatment may account for the better mechanical performance observed for these tissues. The microwaving at 350 W modified the cell wall polymers in such a manner that produced an increase in their hydrophilicity.