In Vitro Digestibility of Native and Resistant Starches: Correlation to the Change of its Rheological Properties

The broadly investigated and applied resistant starches have several health benefits: they can help, for instance, in the treatment of obesity and prevention of colon cancer; therefore, the accurate knowledge of the properties of these starches is elementary. In our study, the digestibility properties of two native starches (maize and wheat) and two resistant starches (RS2, Hi-maize™260; RS4, Fibersym™70), as well as their stoichiometric mixtures before and after cooking (at 100 °C), were investigated. Moreover, correlations were investigated between two different enzymatic methods and the rapid visco analyzer (RVA) method. Our aim was to prove strong relationship between rheological and enzymatic digestibility characteristics. To conclude the results of our measurements regarding resistant starches, it can be stated that the two resistant starches show different digestibility in raw and cooked form. After cooking, RS2 caused a linear decrease in the initially and the totally liberated glucose concentration in cooked mixtures; thus, these parameters can be predicted in the function of resistant starch addition. Additionally, we did not find any synergistic effects in the mixtures after heat treatment. Significant (p < 0.05) and strong correlations were found between enzymatic digestion and RVA methods in both cases of untreated and gelatinized starches. These results provide promising information for the prediction of in vitro digestibility from RVA results. Our results may confirm the theory that there is a relationship between the physicochemical and enzymatic digestibility properties of starches.