Ingestion of resistant starch by mice markedly increases microbiome-derived metabolites.

Recent research has shown significant health benefits deriving from high-dietary fiber or microbiome-accessible carbohydrate consumption. Compared with native starch (NS), dietary resistant starch (RS) is a high microbiome-accessible carbohydrate that significantly alters the gut microbiome. The aim of this study was to determine the systemic metabolic effects of high microbiome-accessible carbohydrate. Male C57BL/6 mice were divided into 2 groups and fed either NS or RS for 18 wk (n = 20/group). Metabolomic analyses revealed that plasma levels of numerous metabolites were significantly different between the RS-fed and NS-fed mice, many of which are microbiome-derived. Most strikingly, we observed a 22-fold increase in gut microbiome-derived tryptophan metabolite indole-3-propionate (IPA), which was positively correlated with several gut microbiota, including Allobaculum, Bifidobacterium, and Lachnospiraceae, with Allobaculum having the most consistently increased abundance of all the IPA-associated taxa across all RS-fed mice. In addition, major changes were observed for metabolites solely or primarily metabolized in the gut (e.g., trimethylamine-N-oxide), metabolites that have a significant entero-hepatic circulation (i.e., bile acids), lipid metabolites (e.g., cholesterol sulfate), metabolites indicating increased energy turnover (e.g., tricarboxylic acid cycle intermediates and ketone bodies), and increased antioxidants such as reduced glutathione. Our findings reveal potentially novel mediators of high microbiome-accessible carbohydrate-derived health benefits.-Koay,Y. C., Wali. J. A., Luk, A. W. S., Macia, L., Cogger, V. C., Pulpitel, T. J., Wahl, D., Solon-Biet, S. M., Holmes, A., Simpson, S. J., O'Sullivan, J. F. Ingestion of resistant starch by mice markedly increases microbiome-derived metabolites.

Starch digestion kinetics and mechanisms of hydrolysing enzymes in growing pigs fed processed and native cereal-based diets.

This study aimed to examine in vivo starch digestion kinetics and to unravel the mechanisms of starch hydrolysing enzymes. Ninety pigs (23 (sd 2·1) kg body weight) were assigned to one of nine treatments in a 3×3 factorial arrangement, with starch source (barley, maize, high-amylose (HA) maize) and form (isolated, within cereal matrix, extruded) as factors. We determined starch digestion coefficients (DC), starch breakdown products and digesta retention times in four small-intestinal segments (SI1-4). Starch digestion in SI2 of pigs fed barley and maize, exceeded starch digestion of pigs fed HA maize by 0·20-0·33 DC units (P<0·01). In SI3-4, barley starch were completely digested, whereas the cereal matrix of maize hampered digestion and generated 16 % resistant starch in the small intestine (P<0·001). Extrusion increased the DC of maize and HA maize starch throughout the small intestine but not that of barley (P<0·05). Up to 25 % of starch residuals in the proximal small intestine of pigs was present as glucose and soluble α(1-4) maltodextrins. The high abundance of glucose, maltose and maltotriose in the proximal small intestine indicates activity of brush-border enzymes in the intestinal lumen, which is exceeded by α-amylase activity. Furthermore, we found that in vivo starch digestion exceeded our in vitro predictions for rapidly digested starch, which indicates that the role of the stomach on starch digestion is currently underestimated. Consequently, in vivo glucose release of slowly digestible starch is less gradual than expected, which challenges the prediction quality of the in vitro assay.

Durum wheat particle size affects starch and protein digestion in vitro.

PURPOSE: The term bioaccessibility refers to the proportion of a nutrient released from a complex food matrix during digestion and, therefore, becoming potentially available for absorption in the gastrointestinal tract. In the present study, we assessed the starch and protein bioaccessibility from a range of wheat endosperm products differing in particle size. METHODS: Five porridge meals (size A, flour, mean particle size 0.11 mm, size B, small, mean particle size 0.38 mm, size C, semolina, mean particle size 1.01 mm, size D, medium, mean particle size 1.44 mm, size E, large, mean particle size 1.95 mm) with theoretically different postprandial glycaemic responses were subjected to oral processing in vitro, followed by simulated gastric and duodenal digestion. RESULTS: A significant increase (P < 0.001) in starch degradation was observed in size A (52%) compared with size E (25%). Both sizes C and D gave less, although not significantly, digestible starch (32 and 28%, respectively). The glucose release significantly decreased as the particle size of the meal increased (92.16% detected for size A vs 47.39% for size E). In agreement with starch degradation and glucose release, size A gave the most digestible protein. CONCLUSIONS: This data provide further evidence that, by decreasing the size of wheat endosperm, starch release and glycaemic response are enhanced. We also showed that protein bioaccessibility followed a similar trend as for starch digestion. Finally, these results support the hypothesis that different degrees of starch encapsulation elicit different blood glucose responses.

The nutritional property of endosperm starch and its contribution to the health benefits of whole grain foods.

Purported health benefits of whole grain foods in lowering risk of obesity, type 2 diabetes, cardiovascular disease, and cancer are supported by epidemiological studies and scientific researches. Bioactive components including dietary fibers, phytochemicals, and various micronutrients present in the bran and germ are commonly considered as the basis for such benefits. Endosperm starch, as the major constituent of whole grains providing glucose to the body, has been less investigated regarding its nutritional property and contribution to the value of whole grain foods. Nutritional quality of starch is associated with its rate of digestion and glucose absorption. In whole grain foods, starch digestion and glucose delivery may vary depending on the form in which the food is delivered, some with starch being rapidly and others slowly digested. Furthermore, there are other inherent factors in whole grain products, such as phenolic compounds and dietary fibers, that may moderate glycemic profiles. A good understanding of the nutritional properties of whole grain starch is important to the development of food processing technologies to maximize their health benefits.

Digestion of starch in a dynamic small intestinal model.

PURPOSE: The rate and extent of starch digestion have been linked with important health aspects, such as control of obesity and type-2 diabetes. In vitro techniques are often used to study digestion and simulated nutrient absorption; however, the effect of gut motility is often disregarded. The present work aims at studying fundamentals of starch digestion, e.g. the effect of viscosity on digestibility, taking into account both biochemical and engineering (gut motility) parameters. METHODS: New small intestinal model (SIM) that realistically mimics gut motility (segmentation) was used to study digestibility and simulated oligosaccharide bio accessibility of (a) model starch solutions; (b) bread formulations. First, the model was compared with the rigorously mixed stirred tank reactor (STR). Then the effects of enzyme concentration/flow rate, starch concentration, and digesta viscosity (addition of guar gum) were evaluated. RESULTS: Compared to the STR, the SIM showed presence of lag phase when no digestive processes could be detected. The effects of enzyme concentration and flow rate appeared to be marginal in the region of mass transfer limited reactions. Addition of guar gum reduced simulated glucose absorption by up to 45 % in model starch solutions and by 35 % in bread formulations, indicating the importance of chyme rheology on nutrient bioaccessibility. CONCLUSIONS: Overall, the work highlights the significance of gut motility in digestive processes and offers a powerful tool in nutritional studies that, additionally to biochemical, considers engineering aspects of digestion. The potential to modulate food digestibility and nutrient bioaccessibility by altering food formulation is indicated.

Spray-dried high-amylose sodium carboxymethyl starch: impact of α-amylase on drug-release profile.

Spray-dried high-amylose sodium carboxymethyl starch (SD HASCA) is a promising pharmaceutical excipient for sustained-release (SR) matrix tablets produced by direct compression. The presence of α-amylase in the gastrointestinal tract and the variations of the gastric residence time of non-disintegrating dosage forms may affect the presystemic metabolism of this excipient and, consequently, the drug-release profile from formulations produced with SD HASCA. In this study, the influence of α-amylase and the residence time in acidic conditions on the drug-release profile was evaluated for a once-daily acetaminophen formulation (Acetaminophen SR) and a once-daily tramadol hydrochloride formulation (Tramadol SR). Both formulations were based on SD HASCA. α-Amylase concentrations ranging from 0 IU/L to 20000 IU/L did not significantly affect the drug-release profiles of acetaminophen and tramadol hydrochloride from SD HASCA tablets (f2 > 50) for all but only one of the studied conditions (f2 = 47). Moreover, the drug-release properties from both SD HASCA formulations were not significantly different when the residence time in acidic medium was 1 h or 3 h. An increase in α-amylase concentration led to an increase in the importance of polymer erosion as the main mechanism of drug-release instead of drug diffusion, for both formulations and both residence times, even if release profiles remained comparable. As such, it is expected that α-amylase concentration and residence time in the stomach will not clinically affect the performance of both SD HASCA SR formulations, even if the mechanism of release itself may be affected.

Preparation of starch macrocellular foam for increasing the dissolution rate of poorly water-soluble drugs.

Starch macrocellular foam (SMF), a novel natural bio-matrix material, was prepared by the hard template method in order to improve the dissolution rate and oral bioavailability of poorly water-soluble drugs. Nitrendipine (NDP) was chosen as a model drug and was loaded into SMF by the solvent evaporation method. SMF and the loaded SMF samples (NDP-SMF) were characterized by scanning electron microscopy, differential scanning calorimetry, X-ray powder diffraction and Fourier transform infrared spectroscopy. In vitro drug release studies showed that SMF significantly increased the dissolution rate of NDP. In vivo studies showed that the NDP-SMF tablets clearly increased the oral bioavailability of NDP in comparison with the reference commercial tablets. All the results obtained demonstrated that SMF was a promising carrier for the oral delivery of poor water-soluble drugs.

Assam Bora rice starch based biocompatible mucoadhesive microsphere for targeted delivery of 5-fluorouracil in colorectal cancer.

The aim of this study was to develop novel colon targeted mucoadhesive microspheres (MAMs) for site specific delivery of 5-fluorouracil (5-FU) to colon without the drug being released in the stomach or small intestine. MAMs were prepared using Assam Bora rice starch, a natural mucoadhesive polymer, by a double emulsion solvent evaporation method. The microspheres were characterized for their shape, size, surface morphology, size distribution, incorporation efficiency, and in vitro and in vivo drug release studies. The release study confirmed the insignificant release of 5-FU in physiological condition of stomach and small intestine and major drug release in the cecal content. In vivo release study of the optimized MAMs was compared with immediate release (IR) 5-FU. 5-FU was distributed predominantly in the upper GI tract from the IR, whereas 5-FU was distributed primarily to the lower part of the GI tract from the MAM formulation. Enhanced levels of liver enzymes were found in animals given IR 5-FU as well as augmented levels of serum albumin, creatinine, leucocytopenia and thrombocytopenia was also observed. Thus to sum up, it can be appropriately established that the 5-FU release pattern from MAMs exhibits slow and extended release over longer periods of time with reduced systemic side effects.

[Scutellarin starch microspheres' permeability through nasal mucosa of different animals in vitro].

OBJECTIVE: To study scutellarin starch microspheres' permeability through nasal mucosa of different animals in vitro. METHOD: The Franz diffusion cell method was used to experiment the permeability test (n = 4), taking fresh nasal mucosa of dog, swine and domestica in vitro as permeation barrier separately, with scutellarin starch microspheres (scutellarin 0.25 mg) above them, and blank pH 6.8 PBS as absorption liquid to detemine the scutellarin by HPLC. RESULT: The permeability coefficient of scutellarin starch microspheres through nasal mucosa of dog, swine and domestica in vitro were (5.295 +/- 0.637) x 10(-3) (4.065 +/- 1.140) x 10(-3), (1.855 +/- 0.150) x 10(-3) cm x mL(-1) separately. The permeability coefficient order of scutellarin starch microspheres through nasal mucosa of different animals in vitro is dog > swine > domestica, and there are significant differences between the permeability coefficient of scutellarin starch microspheres through nasal mucosa of dog, swine in vitro, and that through nasal mucosa of swine and domestica in vitro. CONCLUSION: Drugs in scutellarin starch microspheres could permeate through the above-mentioned nasal mucosa in vitro. There might be different permeability coefficient among different species.

Starch with high amylose content and low in vitro digestibility increases intestinal nutrient flow and microbial fermentation and selectively promotes bifidobacteria in pigs.

Diets containing different starch types can affect enzymatic digestion of starch and thereby starch availability for microbial fermentation in the gut. However, the role of starch chemistry in nutrient digestion and flow and microbial profile has been poorly explained. Eight ileal-cannulated pigs (29.4 ± 0.9 kg body weight) were fed 4 diets containing 70% purified starch (amylose content, <5, 20, 28, and 63%; reflected by in vitro maximal digestion rate; 1.06, 0.73, 0.38, and 0.22%/min, respectively) in a replicated 4 × 4 Latin square. Ileal and fecal starch output, postileal crude protein yield, fecal total SCFA and total butyrate content, and gene copies of Bifidobacterium spp. in feces were higher (P < 0.05) when pigs consumed the slowly digestible starch diet than the remaining 3 starch diets. The in vitro starch digestion rate had a negative, nonlinear relationship with ileal starch flow (R(2) = 0.98; P < 0.001). Ileal starch flow was positively related to Bifidobacterium spp. (R(2) = 0.27; P < 0.01), Lactobacillus group (R(2) = 0.22; P < 0.01), and total butyrate content (R(2) = 0.46; P < 0.01) but was not related to Enterobacteriaceae (R(2) < 0.00; P = 0.92). In conclusion, starch with high amylose content and low in vitro digestibility increased postileal nutrient flow and microbial fermentation and selectively promoted Bifidobacterium spp. in the distal gut.

Starch-lipid interaction alters the molecular structure and ultimate starch bioavailability: A comprehensive review.

Starch bioavailability which results in eliciting postprandial glycaemic response, is a trait of great significance and is majorly influenced by the physical interaction among the matrix components governed by their molecular structure as well as dynamics. Among physical interactions limiting starch bioavailability, starch and any guest molecules like lipid interact together to alter the molecular structure into a compact V-type arrangement endorsing the processed crystallinity, thus limiting carbolytic enzymatic digestion and further bioavailability. Considering the importance of starch-lipid dynamics affecting bioavailability, intensive research based on endogenous (internal lipids which are embedded into the food matrix) as well as exogenous (those are added from outside into the food matrix during processing like cooking) lipids have been carried out, endorsing physical interactions at colloidal and microstructural levels. The shared insights on such binary (starch-lipid) interactions revealed the evolution of characterization techniques as well as their role on altering the functional and nutritional value. It is very much vital to have a thorough understanding about the mechanisms on the molecular level to make use of these matrix interactions in the most efficient way, while certain basic questions are still remaining unaddressed. Do starch - lipid complexation affects the ultimate starch bioavailability? If so, then whether such complexation ability depends on amylose - fatty acid/lipid content? Whether the complexation is influenced further by fatty acid type/concentration/chain length or saturation? Further comprehending this, whether the altered bioavailability by binary (starch-lipid) could further be affected by ternary (starch-lipid-protein) and quaternary (starch-lipid-protein-phenolics) interactions are also discussed in this comprehensive review.

Structural changes of A-, B- and C-type starches of corn, potato and pea as influenced by sonication temperature and their relationships with digestibility.

The effect of sonication temperature on the structures and digestion behaviour of corn starch (CS, A-type), potato starch (PtS, B-type), and pea starch (PS, C-type) was investigated. For CS, sonication temperature resulted in a rough surface, decreased apparent amylose content, gelatinization enthalpy and gelatinization degree, increased short-range orders, long-range orders, retrogradation degree and resistant starch content. For PtS, sonication temperature led to a coarser surface with scratches, increased apparent amylose content and gelatinization degree, decreased short-range orders, long-range orders, gelatinization enthalpy, retrogradation degree, and resistant starch content. For PS, sonication temperature showed partial disintegration on surface, increased gelatinization degree, decreased apparent amylose content, short-range orders, long-range orders, gelatinization enthalpy, retrogradation degree and resistant starch content. This study suggested that starch digestion features could be controlled by the crystalline pattern of starch used and the extent of sonication temperature, and thus were of value for rational control of starch digestion features.

Insights into the multi-scale structural properties and digestibility of lotus seed starch-chlorogenic acid complexes prepared by microwave irradiation.

By inspecting starch hierarchical structural evolution, this work explored how microwave irradiation tailored the digestion characteristics of lotus seed starch-chlorogenic acid mixtures. The results showed that after microwave treatment, the granular structure, short-range ordered structure, helical conformation, and lamellar structure of starch exhibited different degrees of disorganization. In this procedure, chlorogenic acid interacted with starch molecules to form lotus seed starch-chlorogenic acid complexes and participated in the reorganization of the matrixes of the starch substrate in three forms: V-type inclusion complex, non-inclusion complex, and simply physically entrapped. These structural changes, coupled with the inhibition of chlorogenic acid on carbohydrate hydrolyzing enzymes, contributed to the slowly digestible features of lotus seed starch-chlorogenic acid complexes. This study provided a basis for understanding the multi-scale structure-digestibility relationship of starchy foods rich in phenolic acids under microwave treatment.

In vitro digestion rate of fully gelatinized rice starches is driven by molecular size and amylopectin medium-long chains.

In current study, the effects of starch fine molecular structures on its in vitro digestibility at fully gelatinized stage were investigated. The digestion kinetics of 15 fully gelatinized rice starches were obtained and correlated with starch chain-length distributions and molecular size distributions. Both logarithm of slopes and parallel first-order kinetic model were applied to fit the digestion curves to a few kinetics-based parameters. Result showed there were two simultaneous digestion fractions (fast versus slow) for fully gelatinized rice starches. The rate constants of slowly-digestible fraction significantly correlated with starch molecular sizes, especially with that of amylopectin molecules. Hydrodynamically larger amylopectin molecules tend to contain more shorter branches but less long chains. This slows down the starch hydrolysis by α-amylase while the action of AMG is less antagonistically hindered, increasing overall digestion rate. This study provides important information for rice breeders and manufacturers to develop rice products with reduced starch digestibility.

Evaluation of the effect of carrier material on modification of release characteristics of poor water soluble drug from liquisolid compacts.

Liquisolid compact is a novel dosage form in which a liquid medication (liquid drug, drug solution/dispersion in non-volatile solvent/solvent system) is converted to a dry, free flowing powder and compressed. Objective of the study was to elucidate the effect of carrier material on release characteristics of clopidogrel from liquisolid compacts. Different formulations of liquisolid compacts were developed using microcrystalline cellulose, starch maize, polyvinyl pyrollidone and hydroxypropyl methylcellulose as carrier material in three concentrations (40, 30 and 20%, w/w). Liquid vehicle was selected on the basis of solubility of clopidogrel. Colloidal silicondioxide was used as coating material and ratio of carrier to coating material was kept 10. A control formulation comprised of microcrystalline cellulose (diluents), tabletose-80 (diluents), primojel (disintegrant) and magnesium stearate (lubricant) was prepared by direct compression technique and was used for comparison. All the formulations were evaluated at pre and post compression level. Acid solubility profile showed higher solubility in HCl buffer pH2 (296.89±3.49 µg/mL). Mixture of propylene glycol and water (2:1, v/v) was selected as liquid vehicle. Drug content was in the range of 99-101% of the claimed quantity. All the formulations showed better mechanical strength and their friability was within the official limits (<1%). Microcrystalline cellulose and starch maize resulted in faster drug release while polyvinyl pyrollidone and HPMC resulted in sustaining drug release by gel formation. It is concluded from results that both fast release and sustained release of clopidogrel can be achieved by proper selection of carrier material.

Molecular-structure evolution during in vitro fermentation of granular high-amylose wheat starch is different to in vitro digestion.

This study investigates the evolution of the distributions of whole molecular size and of chain length of granular wheat starches (37 ~ 93% amylose content), subjected to in vitro fermentation with a porcine faecal inoculum or digestion with pancreatic enzymes. The results showed that the molecular structures of high-amylose starch (HAS) unfermented residues largely remained unchanged during the fermentation process, while wild-type starch (37% amylose content) showed a preferential degradation of the amylopectin fraction. In contrast, under simulated digestion conditions, the undigested residues of HAS showed structural changes, including a decrease in amylose content, a shift of amylose peak position towards lower degrees of polymerisation, and an enzyme-resistant fraction. These changes of starch structure are likely to be dependent on the different starch-degrading enzyme activities present in pancreatic vs. microbial systems. Molecular changes in response to fermentation metabolism revealed by size-exclusion chromatography can help understand the microbial utilization of resistant starch.

Investigation of starch functionality and digestibility in white wheat bread produced from a recipe containing added maltogenic amylase or amylomaltase.

In the crumb of fresh white wheat bread, starch is fully gelatinized. Its molecular and three-dimensional structure are major factors limiting the rate of its digestion. The aim of this study was to in situ modify starch during bread making with starch-modifying enzymes (maltogenic amylase and amylomaltase) and to investigate the impact thereof on bread characteristics, starch retrogradation and digestibility. Maltogenic amylase treatment increased the relative content of short amylopectin chains (degree of polymerization ≤ 8). This resulted in lower starch retrogradation and crumb firmness upon storage, and reduced extent (up to 18%) of in vitro starch digestion for fresh and stored breads. Amylomaltase only modestly shortened amylose chains and had no measurable impact on amylopectin structure. Modification with this enzyme led to slower bread crumb firming but did not influence starch digestibility.

Effect of four viscous soluble dietary fibers on the physicochemical, structural properties, and in vitro digestibility of rice starch: A comparison study.

The effect of carboxymethyl cellulose (CMC), high-methoxyl pectin (HMP), konjac glucomannan (KGM), and xanthan gum (XG) on the physicochemical, structural properties, and digestibility of rice starch were investigated and compared. The four viscous soluble dietary fibers (VSDFs) increased the viscosity, storage modulus and loss modulus while decreased the pasting temperature and gelatinization enthalpy. Moreover, XG produced the lowest peak viscosity and dynamic modulus compared with the other VSDFs. Furthermore, the degree of short-range ordered structure of starch with KGM increased from 0.8448 to 0.8716; and the relative crystallinity of starch with XG increased by 12%. An ordered and reunited network structure was observed in SEM. In addition, VSDF inhibited the digestibility of rice starch and significantly increased the resistant starch content. This study compared the effect of four VSDFs on the physicochemical, structural and digestion properties of rice starch to fully understand and develop their application to starchy foods.

Effects of soluble dietary fibers on the viscosity property and digestion kinetics of corn starch digesta.

Four soluble dietary fibers (SDFs) were fortified with corn starch (CS) at different concentrations to match the same viscosity equivalents. The mixtures were subjected to a simulated digestion procedure to study the effects of SDFs on viscosity properties and digestion kinetics of CS. Results showed that SDFs increased the hydration property and decreased the water mobility of digesta. During digestion process, SDFs increased the apparent viscosity of digesta to some extent, and showed significant difference to delay the decay of digesta viscosity (kv). The amylolysis inhibitory ability was similar when each SDF was present at the same viscosity equivalent, however, significant differences were found on the digestion rate constant of k2. Linear correlations between kv and k2 were established for 1 and 2 equivalent groups. These results demonstrated that SDFs could delay the digestion process as chemistry differences, which related to their ability on delaying the change of digesta viscosity.

Functionality and starch digestibility of wrinkled and round pea flours of two different particle sizes.

Wrinkled and round peas (two varieties each type) cultivated in two locations were milled to obtain fine and coarse wrinkled (WPF) and round pea flour (RPF). WPF exhibited markedly increased pasting viscosities at 120 and 140 °C compared with 95 °C. Overall, the pasting properties of WPF were considerably lower than those of RPF. Resistant starch (RS) contents of cooked WPF (17.2-22.2%, dsb) were significantly larger than those of RPF (7.9-11.4%), resulting from higher starch gelatinization temperatures, greater amylose contents, and presence of more protein and fiber in WPF. The two particle sizes affected the water-holding capacity (WHC) of WPF, gelatinization enthalpy changes (ΔH) of WPF and RPF, and pasting properties and starch digestibility of RPF. Pearson correlation and principal component analysis (PCA) were conducted to reveal the relationships among the techno-functional parameters of pea flours. Wrinkled pea showed promise to generate new pea flours with distinct functionality and enhanced nutritional value.