Studies on effect of multiple heating/cooling cycles on the resistant starch formation in cereals, legumes and tubers

Abstract

‘Resistant starch’ (RS) is defined as starch and starch degradation products that resist the action of amylolytic enzymes. The effect of multiple heating/cooling treatments on the RS content of legumes, cereals and tubers was studied. The mean RS contents of the freshly cooked legumes, cereals and tubers (4.18%, 1.86% and 1.51% dry matter basis, respectively) increased to 8.16%, 3.25% and 2.51%, respectively, after three heating/cooling cycles (P≤0.05) with a maximum increase of 114.8% in pea and a minimum of 62.1% in sweet potato (P≤0.05). Significant positive correlations were observed between the RS content and amylose (y=0.443x−5.993, r=0.829, P≤0.05, n=9) as well as between the percentage increase in RS and insoluble dietary fiber content (y=2.149x–24.787, r=0.962, P≤0.05, n=9). A differential scanning calorimeter study showed an increase in the T₀, T_p, T_c and ΔH values of the repeatedly autoclaved/cooled starches. The intact granular structure was also observed disappear, as studied using scanning electron microscopy.

• Resistant starch
• amylose
• gelatinization
• retrogradation
• insoluble dietary fiber