The effect of thermal processing and storage on the physicochemical properties and in vitro digestibility of potatoes

Summary Shepody potatoes were cooked using three common cooking methods – microwaving, boiling and pressure cooking. Microwaving for 2.5 min retained the highest amounts of slowly digestible starch ( SDS , 19.6%) and resistant starch ( RS , 48.8%) as compared to the other cooking treatments. Similarly, enthalpy and FTIR results (ratio of 1047/1022 cm −1 ) were also higher for microwaved samples, again indicating incomplete gelatinisation. Potatoes were also boiled for 15, 30 or 45 min, followed by 1, 3 or 7 days retrogradation at 23 or 4 °C. Retrogradation enthalpy increased significantly ( P  ≤ 0.05) with increased storage time and decreased storage temperature; FTIR results displayed temperature dependency; at 4 °C, ordered structure increased with increasing storage time, whereas the opposite trend was seen at 23 °C. Lastly, formation of SDS and RS was favoured for longer boiling times (30 – 45 min), extended storage times (3–7 days) and 4 °C.