Vem crescendo a cada dia o interesse pelo aproveitamento biológico dos carboidratos não-disponíveis no que se refere ao amido resistente (AR) e à fibra alimentar (FA) e seus efeitos sobre a fisiologia do intestino grosso. O objetivo do presente trabalho foi avaliar o efeito trófico, decorrente da fermentação de carboidratos não-disponíveis da banana verde, no intestino grosso de ratos adultos. As amostras estudadas foram: ABV (amido isolado de plátano verde - Musa paradisíaca L.) e MBV (banana nanicão - Musa acuminata, variedade Nanicão - verde cozida com casca, descascada e seca). Foi realizado estudo de média duração (28 dias) com ratos Wistar adultos, divididos em três grupos: grupo Controle (G-C), que recebeu ração padrão (R-C), e dois grupos experimentais, que receberam rações com concentrações crescentes de AR, ou seja, G-MBV recebeu ração R-MBV, com 5% de AR, e G-ABV recebeu ração R-ABV, com 10% de AR. Foram avaliados consumo e fermentabilidade in vitro das rações; peso corpóreo; peso e umidade das fezes; pH e histologia cecais. Não foi observada diferença no consumo médio diário de ração entre os grupos. O consumo de R-ABV proporcionou menor crescimento dos animais. No G-ABV, além da queda do pH cecal, houve aumento do peso seco das fezes e do conteúdo cecal, possivelmente devido ao aumento da microbiota intestinal. Ainda nesse grupo, houve aumento do peso total do ceco, evidenciando não somente ganho de umidade (aumento do peso do conteúdo cecal) como também possível proliferação celular (aumento do peso da parede do ceco). No G-MBV, houve queda do pH cecal, devido à produção de ácidos graxos de cadeia curta pela fermentação, e ganho de umidade no conteúdo cecal, resultado coerente com a maior presença de FA solúvel nesta ração. Porém, não houve aumento do peso seco das fezes nesse grupo. Pela análise histológica do tecido cecal, foi possível evidenciar que tanto a fermentação da R-ABV como a da R-MBV exerceram efeito trófico no intestino grosso desses animais (p<0,01). Os resultados obtidos indicam que os carboidratos não-disponíveis presentes na banana verde exercem efeitos positivos sobre a fisiologia dos animais, apontando a possibilidade de utilização dessa matéria-prima na elaboração de alimentos voltados para a prevenção de determinadas doenças crônicas não-transmissíveis. / The interest in unavailable carbohydrates, mainly in the possible effects of resistant starch (RS) and dietary fiber (DF) on the physiology of the large bowel, has recently increased. The present work aimed to evaluate the trophic effect, caused by the fermentation of unavailable carbohydrates from banana, on the large bowel of adult rats. Two samples were studied: ABV (starch isolated from unripe plantain - Musa paradisíaca L.) and MBV (unripe banana -Musa acuminata, variety Nanicão - cooked with peel, peeled and dried). An assay was carried during 28 days, with adult Wistar rats, divided into three groups: Control group (G-C), fed standard diet (R-C), and two experimental groups fed crescent RS concentrations (G-MBV, fed R-MBV with 5% RS, and G-ABV, fed R-ABV with 10% RS). Consumption and in vitro fermentation of the diets; body weight; feces weight and moisture; cecum pH and histology were evaluated. No difference was observed in the average daily consumption among the groups. Rats fed R-ABV presented decreased growth. On G-ABV, besides cecum pH decrease, there was an increase in feces and cecum content dry weight, possibly due to the increase in intestinal microbiota. There was an increase in cecum total weight, evidencing not only moisture gain (increase in cecum content weight) but also possible cellular proliferation (increase in the cecum wall weight). On G-MBV, there was a decrease in the cecum pH, due to the production of short-chain fatty acids by the fermentation, and moisture gain in the cecum content, which is coherent with the greater concentration of soluble DF in this diet. However, an increase in feces dry weight was not observed in this group. Considering the histology of the cecum tissue, it was possible to evidence that the fermentation of both R-ABV and R-MBV exerted trophic effect in the large bowel of the animais (p<0,01). The results obtained indicate that unavailable carbohydrates from unripe banana exert positive effects on the physiology of the animais, pointing to the possibility of using this product on the elaboration of foods aimed to preventing certain non-transmissible chronic diseases.

Background: African-Americans are a vulnerable population group with disproportionately elevated rates of type 2 Diabetes Mellitus (DM). Resistant starch is a promising food ingredient that has the potential to reduce the risk factors involved in the development of type 2 DM. To date, there is a dearth of published research studies on the effect of resistant starch on African-Americans who are at increased risk for type 2 DM. Objective: The major objective of this study was to determine if daily consumption of approximately twelve grams of high-maize™ 260 resistant starch (RS) added to bread improved glucose homeostasis by monitoring changes in fasting plasma glucose, fructosamine, hemoglobin A1c, insulin, glucagon-like peptide-1, C-reactive protein, homeostasis model assessment insulin resistant (HOMA- IR) and beta-cell function (HOMA-Beta), serum acetate, propionate, and butyrate levels. Design: A fourteen-week, randomized, double-blind, within-subject crossover design feeding study was carried out in African-American males (n=8) and females (n=7) at increased risk for type 2 DM who resided in Southwest Virginia. All participants consumed bread containing added RS or control bread (no added RS) for six-weeks. RS and control bread feedings were separated by a two-week washout period. Results: Fasting Plasma Glucose (FPG) levels were significantly lower (P = 0.0179) after six-week control bread feedings compared to baseline. FPG levels were also significantly lower (P < 0.0001) after two-week washout period than at baseline. FPG levels were significantly higher (P < 0.0001) after six-week resistant starch bread feeding than at washout. FPG levels due to consumption of resistant starch versus control bread approached significance (P = 0.0574). Fructosamine levels were significantly lower (P = 0.0054) after control bread and resistant starch bread (P < 0.0012) consumption compared to baseline. No significant differences were found in fructosamine levels due to resistant bread intake versus control (P = 0.9692). Mean baseline HbA1c levels were 6.9% (n=15). This value was slightly lowered to 6.79% (n=14) at the end of the fourteen-week study, although statistical significance was not found. Mean ± standard errors for HbA1c values were 6.9% ± 0.18% and 6.9% ± 0.14% at baseline for the sequence groups, resistant starch first (n=7) and control treatment first (n=8) groups, respectively. Mean± standard error HbA1c values were 6.7%± 0.27% and 6.9% ± 0.27% at the conclusion of fourteen-week study for sequence groups, resistant starch first group (n=7) and control treatment first group, respectively. Baseline mean and standard errors C-reactive Protein (CRP) levels for male and female combined results were 0.62 ± 0.16 mg/dL (n=15). Mean CRP levels were 0.53 ± 0.12 mg/dL for resistant starch bread and 0.64 ± 0.21 mg/dL for control bread feeding periods. No significant differences were found for treatment, gender, or sequence effects for C-reactive protein levels during the fourteen-week study (P > 0.05). Mean HOMA-IR levels following six-week resistant starch and control bread consumption decreased to normal values (> 2.5), although no significant differences were found for treatment (P = 0.5923). Conclusions: Eighty-seven grams of Hi- maize™ 260 Resistant Starch added to baked loaves of bread consumed by a free-living African-American population at increased risk for type 2 diabetes did not consistently show significance in all clinical indicators and biochemical markers assessed. On the basis of the evidence in this study we do not have evidence that this amount of resistant starch in this population's diet will prevent the onset of diabetes. However, results are suggestive that higher levels of resistant starch in a more controlled experiment could reduce clinical risk factors for type 2 diabetes. / Ph. D.

Tortilla sales are projected to exceed 9.5 billion by 2014. However, currently no wheat cultivars have been identified that possess the intrinsic quality attributes needed for the production of optimum quality tortillas. Tortillas made with refined wheat flour low in dietary fiber (DF) are popular in the United States due to their sensory properties. This study explored the use of wheat lines (WL) possessing variations in high molecular weight glutenin allele sub-units (HMW-GS) for production of tortillas and also investigated the use of corn based resistant starches (RS), type II (RS2) and wheat based RS type IV (RS4) to increase DF in tortillas. Tortillas were made with 0-15 percent RS and 100 percent whole white wheat (WW). Flour protein profiles, dough, and tortilla properties were evaluated to determine the effects of the allelic variations and RS substitution on tortilla quality. Sensory properties of tortillas with RS were determined. Variations in HMW-GS composition significantly affected the protein quality and tortilla properties. Flour from WL possessing allelic combinations (2*, 17+18, 7, 2+12), (1, 17+18, 5+10), (2*, 17, 2+12) and (1, 2*, 17+18, 2+12) had 12.8-13.3 percent protein. These WL had extensible doughs and produced large diameter tortillas with superior (greater than or equal to 3.0) flexibility after 16 days compared to control. However, WL with (17+18 and 5+10) and (2*, 17+7, 5) produced extensible doughs, large, but less flexible, tortillas compared to control. WL with (2*,17+18,5+10) and (1,2*,7+9,5+10) produced smaller diameter tortillas, but with superior flexibility compared to control. RS2, WW, and cross-linked-pre-gelatinized RS4 (FiberRite) produced hard, less-extensible doughs and thinner tortillas compared to control, due to high water absorption. Cross-linked RS4 (Fibersym) dough and tortillas were comparable to control. 15 percent of RS2 and RS4 increase DF in control to 6 and 14 percent respectively, compare to control (2.8 percent DF). WW tortillas were less acceptable than control in appearance, flavor and texture, while tortillas with 15 percent Fibersym had higher overall acceptability than control. RS2 negatively affected dough machinability and tortilla shelf stability. However, 15 percent RS4 improved the DF in refined flour tortillas to meet FDA's "good source of fiber claim," without negatively affecting dough/tortilla quality.