Analysis of starch amylolysis using plots for first-order kinetics |
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Authors: | Peter J Butterworth Frederick J WarrenTerri Grassby Hamung PatelPeter R Ellis |
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Institution: | King's College London, School of Medicine, Diabetes and Nutritional Sciences Division, Biopolymers Group, Franklin-Wilkins Building, 150, Stamford Street, London SE1 9NH, United Kingdom |
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Abstract: | Investigators often study product release from starches during prolonged incubations with α-amylase in vitro. The reaction time courses usually fit to a linear form of a first order rate equation, i.e., ln(C∞ − Ct)/C∞] = −kt. This equation calls for an accurate estimate of C∞, i.e., the concentration of product at the end of the reaction. Estimates of C∞ from digestibility curves can be unreliable. The Guggenheim method does not require prior knowledge of C∞ but seems not to have been applied to starch hydrolysis data. An alternative method is also available in which the logarithm of the slope (LOS) of a digestibility curve at various time points is plotted against time. This allows estimations of both k and C∞ and can also reveal whether changes occur in digestion rate from rapid to slow as digestion proceeds. We describe the Guggenheim and LOS methods and provide examples of their application to starch digestibility data. |
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Keywords: | Starch Digestion α-Amylase First order kinetics Guggenheim Log of slope plot |
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