Effect of the Extent of Conversion and Retrogradation on the Digestibility of Potato Starch

• Published in: Starch - Stärke Vol. 53; no. 9; pp. 431 - 436
• Main Authors: Farhat, Imad A., Protzmann, Juliane, Becker, Antje, Vallès-Pàmies, Baltasar, Neale, Roger, Hill, Sandra E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 01.09.2001; WILEY‐VCH Verlag GmbH; Wiley-VCH
• Subjects: Amylase; Biological and medical sciences; Carbohydrates; Food industries; Fundamental and applied biological sciences. Psychology; Metabolisms and neurohumoral controls; Resistant starch; Retrogradation; Starch and starchy product industries; Starch conversion; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Swelling; Enzyme; Amylopectin; Conversion; Physical properties; Retrogradation; Glycosidases; Potato starch; Water content; Hydrolases; α-Amylase; O-Glycosidases; Polysaccharide; Digestibility; Sodium Chlorides
• ISSN: 0038-9056; 1521-379X
• DOI: 10.1002/1521-379X(200109)53:9<431::AID-STAR431>3.0.CO;2-R

The effect of starch conversion on the susceptibility of potato granules to α‐amylase was studied by direct sampling at different pasting times corresponding to different points on the RVA profile of a 6.4% (w/w) suspension of starch in distilled water. Native granules showed high resistance to α‐amylase with 8.6 ± 0.4% digestibility for a 6 h incubation period with the enzyme. When the suspension was heated to 60 °C, the digestibility increased to 53.5 ± 0.7% although, at this temperature, there was still no noticeable increase in the measured viscosity (≤0.040 Pa · s). The material sampled after a pasting time corresponding to the RVA peak viscosity showed a digestibility of 88.4 ± 0.5%. This suggested, owing to the expected retrogradation of amylose on cooling, the quasi‐total susceptibility of amylopectin to enzymatic digestion at this pasting stage. The effect of ions on the swelling of potato starch was used to assess whether the decrease of the swelling of the granules in the presence of NaCl was paralleled by an increase in resistance to α‐amylase. A small (∼6.1%) but significant decrease in the digestibility of pasted starch was observed in the presence of salt. Finally, the effect of the retrogradation of the amylopectin fraction on its digestibility was assessed in extruded potato starch ribbons containing 35% (w/w) water and stored at different temperatures. After 14 days of storage, the digestibility decreased from 77.0 ± 0.9% in the freshly extruded samples to between 28.0 ± 1.7% and 42.1 ± 0.3%, depending on the storage temperature. This suggested a measurable difference in the α‐amylase susceptibility between the A and B polymorphs of retrograded amylopectin.