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.

Dietary intake of boiled breadfruit (Treculia africana) seeds did not improve hyperglycemia in streptozotocin induced diabetic rats: Effect on the oral glucose tolerance of normoglycemic rats

“…On the other hand, Ajiboye et al (2016) reported the hypoglycemic action of this plant in experimentally induced diabetic rats, and the findings of this study suggest that the processing of this plant by boiling (which is the form in which it is eaten in typical diets) affects its reported hypoglycemic action. This variation between our results and those of Ajiboye and colleagues could be attributed to the fact that, while Ajiboye and colleagues worked on raw seeds, we worked on cooked seeds, and cooking has been reported to affect the nutrient constituents and the digestibility of starches in foods, which could also affect their glycemic indices (Capriles et al, 2008;Eleazu et al, 2016;Eleazu et al, 2017).…”

Starch Hydrolysis, Polyphenol Contents, and In Vitro Alpha Amylase Inhibitory Properties of Some Nigerian Foods As Affected by Cooking

“…The higher percentage of SD in raw R. virescens, A. auricula-judae , and boiled sweet potatoes compared with other FS investigated could be attributed to the non-detectable levels of RS in them. Furthermore, the higher percentage of SD in boiled unpeeled potato compared with the raw form could be attributed to its loss of RS during the boiling process as cooking of foods has been shown to affect the digestibility of starches in foods (4, 15). On the contrary, the lower percentages of SD in boiled R. virescens, A. auricula-judae , and peeled potato compared with their raw could be attributed to the increased amount of RS in them when they were boiled.…”

“…Several factors influence the digestibility of starches in foods such as: carbohydrate contents of foods, nutritional composition of starch [rapidly digestible starch, slowly digestible starch, and resistant starch (RS)], method of cooking foods, and others. These factors tend to affect the change in blood glucose after eating a meal (4). …”

The Effect of Processing and Cooling Methods on Coleus tuberosus in vitro Starch Digestibility

“…Based on temperature and water activity, thermal processes enhance starch hydrolysis rate by gelatinization (Alsaffar, 2011). Contrarily, Eleazu et al (2017) and Capriles et al (2008) said differences in cooking methods did not significantly affect total starch in food ingredients. The highest total starch was obtained by boiling C. tuberosus followed by cooling to room temperature (86.59%), and this is possibly due to the complete gelatinization process in boiling with adequate temperature and water availability.…”