Amount Of Resistant Starch Research Articles

Resistant starch formation in bread as influenced by choice of ingredients or baking conditions

The formation of resistant starch (RS) in bread products was evaluated in vitro in relation to the processing conditions. The impact of the particular baking conditions applied to pumpernickel bread was investigated as well as the presence of malt and sourdough acids, commonly present in such bread. Also studied was the potential effect of including wholemeal barley from a high-amylose genotype. In some bread, the rate of hydrolysis of the potentially available starch fraction was evaluated by an in vitro procedure. A low-temperature, long-time baked product (20 h at 120 °C) contained significantly higher amounts of RS (5.4%, starch basis) than a corresponding ordinary baked bread (40min at 200 °C) (3.0%, starch basis). Addition of lactic acid increased RS recovery further (6.6% starch basis), whereas malt had no impact on RS yield. The highest level of RS was noted in a long-time baked bread based on high-amylose barley flour (7.7%, starch basis). In contrast to all other products, this bread also displayed a lowered rate of amylolysis of the non-RS fraction (hydrolysis rate index = 68). It is concluded that exchanging ordinary baking conditions for pumpernickel baking, particularly in the presence of certain organic acids, may substantially increase the RS content.

Effect of resistant starch on fecal bulk and fermentation-dependent events in humans

This study investigated the effect of two diets, which differed in resistant starch (RS) concentration, on fecal bulk and fermentation-dependent events in 11 humans. Amounts of RS consumed were 5.0 +/- 0.4 and 39.0 +/- 3.0 g/d (mean +/- SEM) for the low- and high-RS diets, respectively. The two diets were fed for 3 wk each in a randomized crossover design. Fecal collections were made in the third week of each study period. The high-RS diet produced an increase (P < 0.01) in total fecal output (from 138 +/- 22 to 197 +/- 37 g/d) and lowered fecal pH (6.9 +/- 0.1 to 6.3 +/- 0.1). There were significant increases (P < 0.05) in the fecal concentrations and daily excretion of butyrate (+38% and +100%, respectively) and acetate (+26% and +72%, respectively) during the high-RS period. The fecal excretion (g/d) of nonstarch polysaccharides (NSP) also rose by 50% during the high-RS diet, suggesting that the presence of starch in the colon may affect the fermentation of NSP. Subjects reported an increase in flatulence and easier defecation. These results demonstrate that RS has a significant impact on putative markers of colonic health in humans.

Resistant starch in the diet increases breath hydrogen and serum acetate in human subjects

The colonic fermentation of two diets differing in amounts of resistant starch (RS) was studied. High- and low-RS diets were fed to eight healthy subjects in three meals for 1 d. Breath hydrogen and two blood samples were collected over a 28-h period. The high-RS diet provided 59.1 +/- 4.7 g (mean +/- SE) RS and the low-RS diet provided 5.2 +/- 0.4 g RS. Breath hydrogen and the average total serum acetate were significantly higher during the high-RS diet than during the low-RS diet: 34.1 +/- 4.7 and 23.9 +/- 3.9 ppm (P < 0.001) and 169.1 +/- 12.8 and 118 +/- 6.6 mumol/L (P < 0.01), respectively. Butyrate and propionate were also detected in serum samples. Although not statistically significant, there was a trend (P = 0.087) for butyrate to increase with the high-RS diet. Subjects reported greater gastrointestinal symptoms during the high-RS diet. These results suggest that RS may have effects comparable with those of some fermentable dietary fibers.

Both raw and retrograded starch decrease serum triacylglycerol concentration and fat accretion in the rat

Male Wistar rats were meal-fed on diets containing various amounts of resistant starch in the form of raw starch (either amylomaize starch, potato starch or modified high-amylose starch) or retrograded starch (prepared from each of the starches) for 6 weeks. Two diets containing normal maize starch were fed as diets poor in resistant starch. Energy absorption (energy consumption minus faecal energy loss), growth, weight of the epididymal fat pads, serum total cholesterol and triacylglycerol concentrations and a number of intestinal and faecal variables were determined. The resistant starches affected all the variables determined except the serum total cholesterol concentration. Relationships were found between energy absorption and both growth and the weight of the fat pads, and between the weight of the fat pads and both the serum triacylglycerol concentration and the serum total cholesterol concentration. No clear differences between the effects of the two types of resistant starch (raw starch v. retrograded starch) were found except that raw potato starch hardly stimulated H2 excretion and led to lower amounts of propionic and butyric acids in the caecal contents than the other starches. The results suggest that dietary resistant starch reduces energy absorption leading to less abdominal depot fat and lower serum triacylglycerol concentrations.

Validation of an in vitro assay for predicting the amount of starch that escapes digestion in the small intestine of humans

The aim of the present study was to validate an in vitro assay for quantifying resistant starch (RS) in foods against an in vivo model. The amount of starch escaping digestion in the small intestine of ileostomates was compared with that observed by using the in vitro assay. Subjects with ileostomies were fed five foods containing different types and amounts of RS (baked beans, pearl barley, cornflakes, and whole and ground rice). The total amount of starch escaping digestion and recovered in the effluent (ranging from 5.7% in baked beans to 0.7% in ground rice) was compared with results obtained by using the in vitro assay with an incubation time of 6 h. The assay was found to be a good qualitative predictor (r = 0.90, P < 0.05), but a poor quantitative predictor of RS amounts. Increasing the duration of incubation with alpha-amylase and amyloglucosidase to 15 h resulted in a very close agreement between results from the in vitro technique and the in vivo model. These data indicate that for a variety of foods the in vitro assay produced an excellent estimate of starch escaping digestion in the small intestine of humans.

Measurement of resistant starch: factors affecting the amount of starch escaping digestion in vitro

We developed an in vitro assay system that mimics the physiological conditions for starch digestion. In this system all undigested starch was termed resistant starch (RS). The richest sources of RS were firm bananas and roasted chickpeas. Different food-processing techniques produced different amounts of RS. RS in uncooked oats (0.161 g/g dry wt) and firm bananas (0.247 g/g dry wt) was reduced by cooking to 0.028 and 0.032 g/g dry wt, respectively. Cooling boiled potato overnight at 4 degrees C produced a 2.8-fold increase in the amounts of RS. Whole rice contained more RS than did ground rice whereas grinding did not affect amounts of RS in roasted chickpeas. Amounts of RS in food decreased with increased chewing, indicating that chewing can also affect the amount of starch escaping digestion. This assay may be useful in predicting which foods and processing techniques result in high amounts of starch escaping digestion in the small intestine.

Carbohydrate Composition and Nutritional Quality for Rats of Sorghum Tô Prepared from Decorticated White and Whole Grain Red Flour

The carbohydrate composition and nutritional quality of acid, neutral and alkali tô, prepared from a decorticated white (DW) flour containing no polyphenols or whole grain red (WGR) flour high in polyphenols, were studied. The diets were characterized with regard to non-starch polysaccharides, Klason lignin, resistant starch (RS) and amino acid content. The nutritional properties were studied in balance trials with rats. Digestible energy of DW flour was higher than that of WGR flour because of a lower dietary fiber (DF) content and a higher digestibility of DF. Recovery of cellulose in feces of rats fed diets containing DW flour was 45-59% and recovery of noncellulosic polysaccharides (NCP) was 17-31%. In rats fed diets derived from WGR flour, recoveries were 76-83 and 54-67% for cellulose and NCP, respectively. Cooking resulted in formation of appreciable amounts of RS. Twenty-three to fifty-six percent of the RS in DW tô and 59-74% of RS from WGR tô were recovered in feces. Endosperm protein kafirins formed complexes during cooking. The result was a lower true protein digestibility and higher biological value in tô than in flour. Amino acid data revealed that the unavailable kafirins serve as a nitrogen source for the hindgut microflora. A high affinity of dietary polyphenols for proline and glycine residues can be postulated from digestible amino acid data. The net effect was a change in the excretory route of nitrogen from urine to feces.

Seeing at a distance by electricity

To understand the susceptibility of glutinous rice starch to digestive enzymes and its potential impact on glycemic response, enzyme kinetics and in vitro digestibility of the native and gelatinized starches were investigated. The results showed that the Km values of the native and gelatinized starch were 10.35 mg/mL and 9.92 mg/mL, respectively. The digestion rate coefficients k values of the native and gelatinized starches were 2.0 × 10−3 min−1 and 1.1 × 10−2 min−1, respectively. The contents of rapid digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) in native glutinous rice starch were 8.92%, 21.52% and 69.56%, respectively. After gelatinization, the amounts of RDS, SDS and RS were 18.47%, 29.75% and 51.78%, respectively. The native and gelatinized glutinous rice starches were 10.34% and 14.07% for hydrolysis index (HI), as well as 43.14% and 45.92% for glycemic index (GI), respectively. During the in vitro digestion, the crystallinity of native glutinous rice starch was increased from 34.7% to 35.8% and 38.4% after 20 and 120 min, respectively.