Colonic Fermentation of Unavailable Carbohydrates from Unripe Banana and its Influence over Glycemic Control.

The aim of this study was to evaluate the effect of the colonic fermentation of unavailable carbohydrates from unripe banana (mass - UBM - and starch - UBS) over parameters related to glucose and insulin response in rats. Wistar male rats were fed either a control diet, a UBM diet (5 % resistant starch - RS) or a UBS diet (10 % RS) for 28 days. In vivo (oral glucose tolerance test) and in vitro (cecum fecal fermentation, pancreatic islet insulin secretion) analyses were performed. The consumption of UBM and UBS diets by Wistar rats for 28 days improved insulin/glucose ratio. Also, pancreatic islets isolated from the test groups presented significant lower insulin secretion compared to the control group, when the same in vitro glucose stimulation was done. Total short chain fatty acids produced were higher in both experimental groups in relation to the control group. These findings suggest that UBM and UBS diets promote colonic fermentation and can influence glycemic control, improving insulin sensitivity in rats.

Positive impact of a functional ingredient on hunger and satiety after ingestion of two meals with different characteristics.

The ingestion of unavailable carbohydrates - functional ingredients - has presented an inverse relationship with the risk for chronic non-communicable diseases. The objective of this work was to evaluate the effects of addition of inulin to two ready-to-eat frozen meals on the release of gastrointestinal hormones and other parameters related to hunger and satiety. Prototypes of two different kinds of frozen meals were elaborated by the food industry: control meal (C1 and C2); and test meals, added inulin (T1 and T2). Three sequential clinical assays were performed with healthy volunteers: 1) evaluation of glycemic response (n=16); 2) evaluation of gastrointestinal hormones related to satiety (n=15); and 3) evaluation of satiety (by Visual Analogue Scale - VAS and energy intake) (n=52). The meals showed low glycemic index and glycemic load, and T1 showed a decreased glycemic response peak compared to C1. The addition of inulin (~8g) to the test meals (lunch) provided significant satiety, resulting in an decrease in energy intake of 419 (group 1) and 586kJ (group 2) in the two subsequent meals (after 180min and 360min) and a decrease in hunger and increase in satiety at 120 and 180min when comparing with control meals. A positive post-prandial variation was observed in the plasmatic levels of ghrelin and insulin in relation to the control meal (hormones related to hunger in high levels), after the intake of both two test meals. Inulin is an ingredient that presents several positive characteristics for the elaboration of products that stimulate healthy eating habits. These effects are currently being evaluated in medium-term trials.

In vitro colonic fermentation and glycemic response of different kinds of unripe banana flour.

This work aimed to study the in vitro colonic fermentation profile of unavailable carbohydrates of two different kinds of unripe banana flour and to evaluate their postprandial glycemic responses. The unripe banana mass (UBM), obtained from the cooked pulp of unripe bananas (Musa acuminata, Nanicão variety), and the unripe banana starch (UBS), obtained from isolated starch of unripe banana, plantain type (Musa paradisiaca) in natura, were studied. The fermentability of the flours was evaluated by different parameters, using rat inoculum, as well as the glycemic response produced after the ingestion by healthy volunteers. The flours presented high concentration of unavailable carbohydrates, which varied in the content of resistant starch, dietary fiber and indigestible fraction (IF). The in vitro colonic fermentation of the flours was high, 98% for the UBS and 75% for the UBM when expressed by the total amount of SCFA such as acetate, butyrate and propionate in relation to lactulose. The increase in the area under the glycemic curve after ingestion of the flours was 90% lower for the UBS and 40% lower for the UBM than the increase produced after bread intake. These characteristics highlight the potential of UBM and UBS as functional ingredients. However, in vivo studies are necessary in order to evaluate the possible benefit effects of the fermentation on intestinal health.