Title : Functional and nutritional behavior of starch blends with different granule sizes and amylose content
Abstract:
The combination of starches with different structural and compositional characteristics at different ratios has emerged as a relevant clean-label alternative with potential for the food industry. In the present study, cassava (CS) and yam (YS) starches with amylose contents of 28.39 and 40.32 % and granule sizes of 11.30 and 19.51 μm, respectively, were blended. The ratios for the blends were: 75:25, 50:50, 25:75 (CS:YS, respectively). The viscosity profile of the blends was below the individual starches, following the order from highest to lowest viscosity based on the CS ratio (CS 75-YS25 > CS50-YS50 > CS25-YS75). The DSC results showed the presence of two gelatinization peaks in the blends and the thermal parameters were dependent on the ratio of the starches, suggesting an additive effect. The deconvolution of the thermograms of the blends revealed that YS contributed to the total area significantly at each ratio, even though its gelatinization temperature was higher than that of CS. YS showed lower values of rapidly digested starch (RDS) and slowly digested starch (SDS) and higher resistant starch (RS) content than CS, associated with its amylose content and granule size. In mixtures of CS and YS, the fractions of RDS and SDS decreased, and RS increased with increasing proportion of YS. According to these results, CS, YS and their blends present an interesting nutritional profile. CS and CS75-YS25 CS cause a lower increase in blood glucose levels due to their higher SDS content. Meanwhile, the high RS content in YS, CS50-YS50, and CS25-YS75 could have a positive influence on gut health. Overall, these results indicate an effective CS to diversify the functional properties of native starches by blending individual materials with different structural and physicochemical properties.
Key words: cassava, yam, starch blending, digestibility, gelatinization, viscosity.
