Changes in rapid visco-analysis (RVA) viscosity reveal starch digestion behaviours

Changes in the rapid visco‐analysis (RVA) viscosity of potato and waxy maize starches during digestion were studied using amyloglucosidase and α‐amylase (60–1700 U/mL), and three solids contents (3–20%) of the starch dispersions in a replicated randomised experiment. The starches were gelatinised in...

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Bibliographic Details
Published in:	Die Stärke Vol. 65; no. 5-6; pp. 437 - 442
Main Authors:	Sorba, Anaelle, Sopade, Peter A.
Format:	Journal Article
Language:	English
Published:	Weinheim WILEY-VCH Verlag 01-05-2013 WILEY‐VCH Verlag Wiley Wiley Subscription Services, Inc
Subjects:	Amyloglucosidase Applied sciences Biological and medical sciences Exact sciences and technology First-order kinetic model Food industries Fundamental and applied biological sciences. Psychology Natural polymers Physicochemistry of polymers Starch and polysaccharides Starch and starchy product industries Visco-digestogram α-Amylase Viscosity Glucan 1,4-α-glucosidase Enzyme Visco-digestogram Amyloglucosidase Experimental study Corn starch Modeling Glycosylases Kinetic model Glycosidases First-order kinetic model Potato starch Enzymatic digestion Hydrolases Oside polymer Time curve Kinetics Hydrogel α-Amylase Comparative study
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Summary:	Changes in the rapid visco‐analysis (RVA) viscosity of potato and waxy maize starches during digestion were studied using amyloglucosidase and α‐amylase (60–1700 U/mL), and three solids contents (3–20%) of the starch dispersions in a replicated randomised experiment. The starches were gelatinised in the RVA before digestion at 50°C at a shear rate of 17 s−1 for 5 min. Control dispersions effectively did not change (<10%) in viscosity with time. With the enzyme‐treated gels, irrespective of the starch, enzyme or concentration, the RVA viscosity reduced with time as low molecular weight (MW) products were produced. A modified first‐order kinetic model suitably described (r2>0.9) the starch viscosity‐digestograms. The rate of change in starch viscosity, KVIS (an index of the rate of starch digestion), was significantly (p<0.05) inversely related to the solids content, and directly related to the enzyme concentration. KVIS of the waxy maize starch was higher than that of the potato starch, and a higher KVIS was measured with the α‐amylase than with the amyloglucosidase. Differences in potato and waxy maize starch structures, specificity of enzymes and enzyme:substrate ratios can explain the results, and rheology is proposed as valuable in starch digestion.
Bibliography:	Colour online: See the article online to view Figs. 1 and 2 in colour. References to companies and commercial products do not constitute endorsement by the authors or their organisation. istex:E3484681F29BB8BF84A98283D810BE9870924771 ArticleID:STAR201200176 Part of this paper was presented at the sixth International Symposium on Food Rheology and Structure, Zurich Switzerland, 10-13 April 2012. ark:/67375/WNG-63NXFLTD-S Colour online See the article online to view Figs. 1 and 2 in colour. Part of this paper was presented at the sixth International Symposium on Food Rheology and Structure, Zurich Switzerland, 10–13 April 2012.
ISSN:	0038-9056 1521-379X
DOI:	10.1002/star.201200176