Digestibilidade do amido in vitro e valor calórico dos grupos de farinhas de mandioca brasileiras/In vitro starch digestibility and caloric value of Brazilian cassava flour groups

Brazilian cultural preferences gave rise to groups and sub-classifications of cassava flour according to the processes used. Differences in the processing of cassava flours may affect starch digestibility, so the caloric value was investigated. Five samples from the three cassava flour groups: Seca, Bijusada and D'água were selected. The starch digestibility test was carried out in vitro by incubating the flour suspensions with amylase (1,4-alpha-glucan-4-glucanohydrolase) under temperature and pH conditions that simulated human digestion. Aliquots were collected every 15 min for 1 hour and the glucose content released expressed in readily available calories. The results showed that the caloric value of all the cassava flour samples remained at around 300 kcal. 100 g-1. Considering the release kinetics as a function of time and group, the cassava flour samples showed differences. The samples with smaller particle sizes, Biju Fina and Furnas (Bijusada and Seca Group), showed rapid sugar release after 15 minutes, ranging from 110 to 215 kcal. 100 g-1, respectively. The fine granulation flour (Seca Group) released glucose uniformly throughout the evaluation. The sugar released by the cassava flours with greater granulometry, Biju Grossa and D'água (Bijusada and D'água Group) presented two peaks: the first after 15 minutes of incubation (liberating 84.2 and 120.48 kcal. 100 g-1, respectively); and the second after 45 minutes (112 kcal. 100 g-1) for the Biju Grossa flour, and after 60 minutes (67.88 kcal. 100 g-1) for the D'água flour. The microscopic evaluation showed the presence of residual, non-hydrolyzed starch granules, ranging from 2.42 to 17.85%. The results showed that the caloric value of cassava flour varied according to the processing which affected the flour particle size, which, in turn, influenced starch gelatinization, factors that determine the intensity of the enzyme action in releasing glucose.