Starch digestibility and predicted glycemic indices of raw and processed forms of hausa potato (Solenostemon rotundifoliuspoir)

Abstract

This study reported for the first time, the starch digestibility and predicted glycemic indices (pGIs) of the flours from raw and processed (boiled and fried) S. rotundifolius tubers following standard techniques. The flours contained considerable amounts of proteins and starch. The fried tubers had higher fat contents compared with the raw or boiled while the ash contents of the processed tubers did not differ significantly from the raw. The boiled tubers had lower digestible starch (DS) and rapidly digestible starch (RDS) but statistically same amounts of amylose compared with the raw or fried tubers; higher amounts of resistant starch (RS) compared with the raw, fried and white bread, respectively. While RDS and DS were positively correlated with the pGIs of the tubers, RS was negatively correlated and RS formation during processing was evident only in the boiled tubers. The study showed that the raw and processed tubers possessed intermediate glycemic indices. Practical applications There has been an upsurge in recent times on the interest in nutraceuticals, one of which reasons is attributed to their roles in arresting some metabolic disorders, one of which is type 2 diabetes. People with type 2 diabetes are often restrained to particular types of diets which results in their complaints of monotony of staying on a particular diet. S. rotundifolius tuber is one of such plants that have been found to possess nutraceutical potentials due to its nutritional and pharmacological properties as reported in several studies. However, the tuber is eaten after being processed and there is paucity of information in literature on the effect of processing on the digestibility of its starch. Therefore, the findings of this study which revealed that both the raw and processed S. rotundifolius tubers possessed intermediate glycemic indices indicate their usefulness as potential meals for people with type 2 diabetes mellitus.