Synthesis of Pyrodextrins and Enzymatically Resistant Maltodextrins from Makal (Xanthosomayucatenensis) Starch

Research background. Enzymatically resistant maltodextrins (ERM) are a resistant starch type 4, synthesized from native starch. They are obtained by the sequential application of two processes: pyrodextrinization, which produces pyrodextrins, and enzymatic hydrolysis, which produces ERM. In these processes atypical bonds are formed that confer pyrodextrins and ERM similar properties to dietary fiber, such as resistance to digestion. The aim of this work is to determine and evaluate some physicochemical properties of pyrodextrins and ERM obtained from native starch isolated from makal (Xanthosoma yucatanense) tubers. Experimental approach. Pyrodextrinization and complementary hydrolysis were conducted using factorial designs. For pyrodextrinization, factors and their levels were (m(starch):V(HCl))=80:1 and 160:1 (c(HCl)=2.2 M), temperature 90 and 110 degrees C and reaction time 1 and 3 h, and for enzymatic hydrolysis, alpha-amylase per pyrodextrin volume fractions 0.5 and 1 mu L/mL and reaction time 10 and 30 min. The physicochemical profile included determination of resistant starch content, estimation of color change (Delta E), microscopy and determination of dextrose equivalents (DE). Results and conclusions. According to the factorial design, the best treatment conditions for pyrodextrinization were: (m(starch):V(HCl))=160:1, 90 degrees C and 3 h, since they resulted in the highest resistant starch content (84.73 %) and the lowest Delta E (3.742). Due to the low DE (13.89 %), increased amount of resistant starch (90.73 %) and low Delta E (4.24) in the resulting ERM, complementary hydrolysis with alpha-amylase per pyrodextrin volume fraction 0.5 mu L/mL and hydrolysis time 10 min was selected as the best treatment. Novelty and scientific contribution. The results show that the pyrodextrins and ERM obtained from makal can be used as ingredients for the development of functional foods, due to their high content of indigestible material and low degree of browning.