Digestion kinetics of native and modified cardaba banana starch: A biphasic approach

To understand the mechanism through which cardaba banana starch is hydrolysed, the starch digestion kinetics of native and modified cardaba banana starch samples of Nigeria origin were investigated using an in vitro procedure. The digestion kinetics of the starch samples revealed the samples exhibited a biphasic digestogram. A second-order polynomial with an average coefficient of determinant (r²) of 0.7732 (p < 0.005) was used to segment the biphasic digestogram into two monophasic digestograms. The digestion kinetics parameters (average) obtained using a modified first-order model suggested the accuracy of the model in describing the digestogram. The values obtained for the initial and final digestion rate constant (initial, k_i = 3-4 × 10^-2 min^-1; final k_f = 6-8.3 × 10^-2 min^-1) revealed that the final monophasic segment had a faster rate of digestion after the initial resistant to digestion had been overcome. The logistic model approach in which the digestogram was carried out in a single process also accurately predicted the biphasic behaviours of the cardaba banana (average r² = 0.9736, p < 0.05; root mean square of error, RMSE = 1.588). Weibull model was used for the first time to describe the biphasic approach of cardaba banana starch and according to the digestogram parameters obtained (average r² = 0.9954, p < 0.05; root mean square of error, RMSE = 0.578), the model accurately predicts the biphasic digestogram. In comparison among the models, the Weibull model best described the biphasic digestogram of the cardaba banana starch. The maximum starch digestion obtained in each of the digestion approaches was less than 100% which is an indication of the presence of resistant starch.