Effects of amylose and resistant starch on starch digestibility of rice flours and starches
Amylose and resistant starch (RS) content in rice flours and starches were manipulated by adding high amylose and high RS maize starch. The maize starches were added to rice flours and rice starches at the levels of 10-50% w/w, resulting in the increase of amylose from approximately 30-56 and RS from 8 – 33 g/100 g dry sample. Physicochemical properties and starch digestibility of the mixtures, both flour and starch mixtures, were investigated. Differential scanning calorimetry (DSC) results showed that the addition of high amylose high RS maize starch at the levels in this study did not significantly (p > 0.05) alter gelatinization temperatures. Texture analysis as exhibited by hardness and adhesiveness of the mixture gels found inconsistent results. The key benefit of adding high amylose and high RS maize starch was that it can alter starch digestion rates and consequently lower estimated glycaemic indices (GIs) in both rice flour and starch mixtures.