Identification of carbohydrate parameters in commercial unripe banana flour

Unripe banana flour (UBF), which is rich in resistant starch (RS), has shown several positive physiological effects in clinical trials. Although such observations encourage the emergence of UBF in the food market, specific identity or quality standards for the product are still lacking. This work aimed to assess and propose characterization parameters for commercially available UBF. The results showed that three of the brands examined presented a RS content higher than 40%, whereas nine showed a lower content, with two having less than 10% RS and over 80% total starch, which was fully identified as cereal starch by light microscopy (LM). The presence of banana peel in the flour was correlated with the lipid (r = 0.870), ash (r = 0.812), protein (r = 0.704) and total starch (r = -. 0.761) contents. According to principal components analysis (PCA) and LM identification, the main parameters for the characterization of commercial UBFs are the contents of RS, dietary fiber, lipid and ash. The large variability in RS content (4 to 62%) found in commercial UBFs is one reason why consumers would benefit from additional labeling information, such as the inclusion of the RS and soluble sugar (SS) contents, the unripe banana cultivar used, and indications about use of the peel. Moreover, adulterations could be verified by food inspection agencies via LM, which can be used as a tool to identify the type and state of the starch present.