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Controlled interaction among amylose, protein and free fatty acids was performed using a pasting cell installed in a rheometer resulting in the formation of a soluble high molecular weight complex. Rheological characterization of solutions of the formed complex as well as during its formation in a range of temperatures of 25–95 °C and shear conditions ranging from 2.5 to 16.7 rad/s were performed. Different fatty acids (oleic acid, linoleic, palmitic, and conjugated linoleic acids), corn starch and whey protein, in a range of protein concentrations from 3.75% to 10% were used to produce the complex. By using rheological techniques and size exclusion chromatography was found that concentration of protein, type of free fatty acid, temperature, time and shear rates, all, had a significant effect on the formation of the complex and its rheological properties. Rheological results proved that the formation of the complex starts at 75 °C but its structure set during cooling at 55 °C. Increases in the shear rates applied during the complex formation significantly reduced its viscosity. Increases in the amount of protein increased the order of the complex. Conjugated linoleic acid, a bioactive compound, was able to be incorporated in the complex but using a slower heating rate than that used for the other fatty acids.

Citation Mirmonsef P, Gilbert D, Zariffard MR, Hamaker BR, Kaur A, Landay AL, Spear GT. The effects of commensal bacteria on innate immune responses in the female genital tract. Am J Reprod Immunol 2011; 65: 190–195 The innate and adaptive immune systems are important mechanisms for resistance to pathogens in the female lower genital tract. Lactobacilli at this site help maintain a healthy vagina by producing several factors including lactic acid. Indeed, bacterial vaginosis, a condition in which the genital microbiota is altered, is strongly associated with increased rates of a number of infections including HIV. However, the precise factors that contribute to increased rates of microbial and viral infections in bacterial vaginosis remain to be elucidated. We have studied the effects of bacterial microbiota in the lower genital tract on innate immunity and have found that Toll-like receptor ligands and short chain fatty acids, produced by bacterial microbiota, have dramatic effects on immune function. In this review, we will discuss these results, in addition to some recent articles that we believe will enhance our understanding of how microbes might interact with the immune system.

Fiber incorporation in foods has, to date, been approached largely in an empirical manner, with emphasis on modifying process conditions and formulation and fiber characteristics to obtain an acceptable product. There is a lack of fundamental studies relating fiber functionality during processing with its structural characteristics. In this study, we have investigated the rheological properties; such as solution shear viscosity and extensional viscosity, and some structural features of four corn bran arabinoxylan preparations. The solution shear viscosity of the fibers was influenced by the molecular weight and size of the molecules. The extensional viscosity of doughs containing the fibers was affected by the degree of branching, and differences in extensional viscosity have been explained on the basis of differences in branching as observed using multi-angle laser light scattering. Clear relationships between solution viscosity and molecular weight, and extensional viscosity and degree of branching were established for the fibers. Fundamental studies such as this one will aid in building a strong science-based approach to fiber incorporation in food by improving understanding of how structure of fiber molecules affects their functionality in food systems and how the structure can be modified to improve functionality.

The prevalence of obesity has reached epidemic proportions, making finding effective solutions to reduce obesity a public health priority. One part of the solution could be for individuals to increase consumption of nonoilseed pulses (dry beans, peas, chickpeas, and lentils), because they have nutritional attributes thought to benefit weight control, including slowly digestible carbohydrates, high fiber and protein contents, and moderate energy density. Observational studies consistently show an inverse relationship between pulse consumption and BMI or risk for obesity, but many do not control for potentially confounding dietary and other lifestyle factors. Short-term (≤1 d) experimental studies using meals controlled for energy, but not those controlled for available carbohydrate, show that pulse consumption increases satiety over 2–4 h, suggesting that at least part of the effect of pulses on satiety is mediated by available carbohydrate amount or composition. Randomized controlled trials generally support a beneficial effect of pulses on weight loss when pulse consumption is coupled with energy restriction, but not without energy restriction. However, few randomized trials have been conducted and most were short term (3–8 wk for whole pulses and 4–12 wk for pulse extracts). Overall, there is some indication of a beneficial effect of pulses on short-term satiety and weight loss during intentional energy restriction, but more studies are needed in this area, particularly those that are longer term (≥1 y), investigate the optimal amount of pulses to consume for weight control, and include behavioral elements to help overcome barriers to pulse consumption.

Low moistures foods containing starches exhibit a sub- T g endotherm (55–60 °C) when they are stored at constant temperatures. Although the origin of the endotherm is still debatable, it has been attributed to the water–hydroxyl group interactions and/or enthalpic associations between water and carbohydrates. In the present study, physical aging of the starch components of corn flakes prepared with two different levels of starch fragmentation was studied using thermal and rheological methods. A sub- T g endotherm was observed at temperatures around 50–60 °C by both DSC and Oscillatory Squeezing Flow measurements. An increase of 1.5% of moisture content was observed for both fragmented flakes during aging. The temperatures at which the sub- T g endotherms occurred were independent of aging and moisture content increase during storage, whilst enthalpy increased with both aging time and moisture content. Although the moisture content of the two types of flakes were different the aging time at which the first endotherm appeared and the rate at which the enthalpy increased were dependent only on the level of starch fragmentation. Corn flakes with a high level of starch fragmentation required a longer period of aging time before the presence of the endotherm could be detected and had a greater rate of increase in enthalpy. Overall, flakes having higher starch fragmentation absorbed more water, and the percent of water uptake decreased with aging time. Flakes with low starch fragmentation exhibited little to no change in water uptake during aging.

Previously, starch granules of maize (Zea mays), sorghum (Sorghum bicolor), and millet (Pennisetum americanum) were found to contain channels connecting the interior cavity with the outside surface, and the channels of maize starch channels were found to contain, presumably to be lined with, proteins. One objective of this study was to identify and characterize channel proteins of maize starch granules. A putative starch granule channel protein extract was subjected to 2D-PAGE. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to identify the proteins. Data analysis indicated the presence of actin-like and tubulin-like (FtsZ) proteins, ADP-glucose pyrophosphorylase large and small subunits (Shrunken2 [Sh2] and Brittle2 [Bt2], respectively), granule-bound starch synthase (GBSS), and Brittle1 (Bt1, an adenylate translocator). A combination of Western blot analysis and immunolocalization confirmed the presence of an actin-like protein within the starch granule structure. Another objective was to determine the origin of maize starch granule channels. TEM examination of maize endosperm amyloplasts that did not contain a formed starch granule revealed structures that were connected to the amyloplast membrane and extended inward to the center of the plastid.

Providing balanced energy and nutrients for microbiota growth is essential for the maintenance of the colon ecosystem, and dietary fiber (DF) fermentation, particularly butyrogenic fermentation, augments colon health. Cereal DF, which are the complex carbohydrates of cereal grains that escape small intestine digestion and function either as substrate for colonic fermentation or as bulking material, are a dietary measure to mitigate the occurrence of certain colonic diseases, and perhaps to some degree act as therapeutic agents. In developed Western countries, as well as in many developing countries, colon cancer is one of the major causes for premature death and disability, and inflammatory bowel disease and other colonic disorders have become serious health issues. The function of DF in colon health is mediated through its physicochemical properties (e.g., water-holding for laxative effect) or effect on colon microbiota (e.g., leading to immune regulation), as well as through colonic fermentatio...

Carcass and blood components of broiler chickens fed sorghum or millet as replacement for maize in the semi arid zone of Nigeria 1Clement Ijaduwa Medugu, 2Ibrahim Dankasa Kwari, 2Joseph Igwebuike, 3Iro Nkama, 3Ibrahim Dukku Mohammed and 4Bruce Hamaker Borno State Agricultural Development Programme (BOSADP) Maiduguri Department of Animal Science, University of Maiduguri, P.M.B. 1069, Maiduguri – Nigeria Department of Food Science and Technology, University of Maiduguri, P.M.B. 1069, Maiduguri – Nigeria Department of Food Science, Purdue University, 1160 Food Science building West Lafayette, IN 47907-1160 ABSTRACT

Performance and economics of production of broiler chickens fed sorghum or millet as replacement for maize in the semi-arid zone of Nigeria 1Clement Ijaduwa Medugu, 2Ibrahim Dankasa Kwari, 2Joseph Igwebuike, 3Iro Nkama, 3Ibrahim Dukku Mohammed and 4Bruce Hamaker Borno State Agricultural Development Programme (BOSADP) Maiduguri Department of Animal Science, University of Maiduguri, PMB 1069, Maiduguri – Nigeria Department of Food Science and Technology, University of Maiduguri, PMB 1069, Maiduguri–Nigeria Department of Food Science, Purdue University, 1160 Food Science building West Lafayette, IN 47907-1160 ABSTRACT

Scope Slowly digestible starch (SDS), as a functional carbohydrate providing a slow and sustained glucose release, may be able to modulate food intake through activation of the gut-brain axis. Methods and results Diet-induced obese rats were used to test the effect on feeding behavior of high-fat (HF) diets containing an SDS, fabricated to digest into the ileum, as compared to rapidly digestible starch (RDS). Ingestion of the HF-SDS diet over an 11-week period reduced daily food intake, through smaller meal size, to the same level as a lean body control group, while the group consuming the HF-RDS diet remained at a high food intake. Expression levels (mRNA) of the hypothalamic orexigenic neuropeptide Y (NPY) and Agouti-related peptide (AgRP) were significantly reduced, and the anorexigenic corticotropin-releasing hormone (CRH) was increased, in the HF-SDS fed group compared to the HF-RDS group, and to the level of the lean control group. Conclusion SDS with digestion into the ileum reduced daily food intake and paralleled suppressed expression of appetite-stimulating neuropeptide genes associated with the gut-brain axis. This novel finding suggests further exploration involving a clinical study and potential development of SDS-based functional foods as an approach to obesity control.

The purpose of this research was to test the hypothesis that starch-entrapped microspheres would produce favourable fermentation profiles and microbial shifts duringin vitrofermentation with the faecal microbiota from patients with inflammatory bowel disease (IBD).In vitrofermentation was carried out using a validated, dynamic, computer-controlled model of the human colon (Toegepast Natuurwetenschappelijk Onderzoek gastro-intestinal model-2) after inoculation with pooled faeces from healthy individuals, patients with inactive IBD (Crohn's disease (CD)) or patients with active IBD (ulcerative colitis (UC)). Starch-entrapped microspheres fermented more slowly and produced more butyrate than fructo-oligosaccharides (FOS) when fermented with the faecal microbiota from patients with active UC. When fermented with the microbiota from patients with inactive CD, starch-entrapped microspheres also fermented more slowly but produced similar amounts of butyrate compared with FOS. Starch-entrapped microspheres showed a greater ability to maintain a low pH during simulated-distal colon conditions compared with FOS. After fermentation with the microbiota from inactive CD patients, starch-entrapped microspheres resulted in lower concentrations of some potentially harmful gut bacteria, included inBacteroides,Enterococcus,FusobacteriumandVeillonella, compared with FOS. These findings suggest that slow fermenting starch-entrapped microspheres may induce a favourable colonic environment in patients with IBD through high butyrate production, maintenance of low pH in the distal colon and inhibition of the growth of potentially harmful bacteria.

With emerging knowledge of the impact of the metabolic quality of glycemic carbohydrates on human health, there is a need for novel carbohydrate ingredients that can be custom-made to deliver controlled amounts of glucose to the body and to test hypotheses on the postprandial metabolic consequences of carbohydrates.The goal of the present study was to demonstrate the applicability and action of starch-entrapped biopolymer microspheres as customized, novel, slowly digestible carbohydrates to obtain desired glycemic responses.Starch-entrapped microspheres were developed; and starch digestion and glucose release, subsequent to their cooking (100 degrees C, 20 min) in water, were initially monitored by measuring the rapidly digestible, slowly digestible, and resistant starch fractions using the in vitro Englyst assay. Glycemic and insulinemic responses after consumption of glucose and two different slowly digestible starch microsphere diets were compared using a crossover study in 10 healthy individuals. The mechanism of starch digestion in the microspheres was elucidated from scanning electron microscopic images of the in vitro digested microspheres.Factors such as biopolymer type and concentration, microsphere size, and starch type were manipulated to obtain starch materials with defined amounts of slowly digestible starch based on in vitro studies. Scanning electron microscopy showed that cooked starch entrapped in the dense biopolymer matrix is digested layer by layer from the outside to the inside of the microsphere. Glycemic and insulinemic responses to microsphere test diets were moderate as compared to a glucose diet, but more important, they showed extended glucose release.Starch-entrapped microspheres provide a useful tool to study the postprandial metabolic consequences of slowly digestible carbohydrates.

Incorporation of insoluble fibers into extruded cereals severely limits their expansion and reduces crispness. The specific objective of this work was to investigate how corn bran and its fractions mixed with cornmeal affect rheology and extrudate expansion. Alkali-treated bran (ATB) and alkaline-soluble bran (ASB) were prepared from unmodified corn bran (UMB). Mixtures of the different corn bran fractions and degermed cornmeal having a 26% (w/w) of total dietary fibers were extruded in a twin screw extruder and expansion of the extrudates was determined. Melt shear rheology of mixtures of cornmeal and different corn bran fractions having a 20% total dietary fiber was determined using a capillary rheometer at 120 °C while the extensional rheology was determined using lubricated squeezing flow. The expansion of extrudates containing ATB was larger than those containing UMB, while extrudates containing ASB showed a greater expansion that was close to that of the control. Addition of UMB to cornmeal increased shear and extensional viscosity significantly as compared to the control. ATB addition increased the shear viscosity of the mixture to a small extent but showed the highest extensional viscosity amongst the samples. Addition of ASB resulted in mixtures having lower shear and extensional viscosities than the control.

Storage retrogradation behavior and properties of sorghum, maize, and rice starches were compared to better understand the relationship of amylopectin fine structure to quality issues. Long-term changes in texture of starch gels were attributed to amylopectin retrogradation. In starch pastes aged 7 days at 4 °C, change in the storage modulus (ΔG′ΔG′) during heating (representing intermolecular associations) was highly and positively correlated (r = 0.93, p

Limited research in humans suggests that slowly digestible starch may blunt the postprandial increase and subsequent decline of plasma glucose and insulin concentrations, leading to prolonged energy availability and satiety, compared to more rapidly digestible starch. This study examined the postprandial metabolic and appetitive responses of waxy maize starch (WM), a slow-digestible starch. It was hypothesized that the waxy maize treatment would result in a blunted and more sustained glucose and insulin response, as well as energy expenditure and appetitive responses. Twelve subjects (6 men and 6 women) (age, 23 +/- 1 years; body mass index, 22.2 +/- 0.7 kg/m(2); insulin sensitivity [homeostatic model assessment], 16% +/- 2%; physical activity, 556 +/- 120 min/wk) consumed, on separate days, 50 g of available carbohydrate as WM, a maltodextrin-sucrose mixture (MS), or white bread (control). Postprandial plasma glucose and insulin, energy expenditure, and appetite (hunger, fullness, desire to eat) were measured over 4 hours. Compared to control, the 4-hour glucose response was not different for MS and WM, and the 4-hour insulin response was higher for MS (P.005) and lower for WM (P.05). Compared to MS, WM led to lower 4-hour glucose and insulin responses (P.001). These differences were driven by blunted glucose and insulin responses during the first hour for WM. Postprandial energy expenditure and appetite were not different among treatments. These results support that WM provides sustained glucose availability in young, insulin-sensitive adults.

A ternary complex consisting of amylose, whey protein, and free fatty acids (FFA) has been identified in our previous investigations, and its iodine binding properties were investigated. After reaction with iodine solution, an absorption peak ( λ max ) at 620 nm was shown for pure amylose whereas the λ max decreased to 510 nm when amylose was first complexed with FFA. Interestingly, a λ max of 550 nm with an intermediate absorbance was observed for the ternary complex indicating its intermediate spectrophotometric property. Consistently, the amount of iodine bound by the ternary complex was between free amylose and typical amylose–FFA complex from potentiometric titration indicating the amylose–FFA complex within the ternary complex is less compact and more space is left for iodine binding. This in-between property of the ternary complex suggests it can be used as a molecular carrier to accommodate a forth component in addition to its functional lipids carrying capability in food product development.

Protein digestibility in grain sorghum (Sorghum bicolor (L.) Moench) is affected by the structure of endosperm protein bodies that limits access of digestive enzymes to storage protein. In this experiment, we studied the effect of endosperm dosage of high digestible alleles (hd + ) on protein digestibility in sorghum hybrids carefully constituted for such a study. We also examined the effect that these alleles may have on endosperm protein body structure and agronomic performance of the hybrids. The results showed that protein digestibility, endosperm texture and protein body morphology were highly influenced by dosage of mutant alleles. Genotypes carrying two or more hd + alleles had significantly higher protein digestibility than those with one or no mutant allele. Similarly, higher doses of these alleles resulted in opaque endosperm phenotype while the wild type alleles produced normal vitreous texture. Moreover, hybrids carrying variable proportions of mutant alleles had uniquely irregular but variable protein body structure that was distinct from spherical protein bodies found in normal genotypes. Agronomic performance was not affected by dosage of digestibility alleles.

Previous research has revealed that waxy corn starch which has been entrapped in a matrix of electrostatically cross-linked alginate, shows a slow digestion rate such that much of the starch may reach the colon; thus making this a new type of resistant starch. The purpose of this research was to test the fermentative properties of starch-entrapped microspheres using a batch fecal fermentation method. Fermentation of starch-entrapped microspheres showed significantly lower rates of gas production compared to waxy corn starch, and showed significant increases in total SCFAs during the latter stages of fermentation (24-48 h), whereas waxy corn starch did not. Cooking the starch-entrapped microspheres increased the amount of SCFAs and the molar fraction of butyrate produced during fermentation. Bacterial fingerprinting revealed that uncooked starch-entrapped microspheres have a unique effect on the microbiota that is different from waxy corn starch alone, but cooking causes a shift toward a pattern more closely resembling that of the starch. Starch-entrapped microspheres may deliver slowly fermentable carbohydrate to the colon, with the ability to influence the microbiota. Further human studies are required to determine whether these characteristics occur in vivo.

The benefits of dietary fiber on inflammatory bowel disease may be related to the fermentative production of butyrate in the colon, which appears to decrease the inflammatory response. The benefits of dietary fiber against colon cancer may be related to both fermentative and non-fermentative processes, although poorly fermentable fibers appear more influential. Dietary fiber fermentation profiles are important in determining optimal fibers for colonic health, and may be a function of structure, processing conditions, and other food components. A greater understanding of the relationships between fermentation rate and dietary fiber structure would allow for development of dietary fibers for optimum colonic health.

Carbohydrate research increasingly is focused on changing the biochemical nature of starch to create more efficient substrates for biofuel production; parallel work is aimed at healthier foods for human consumption. A key factor in both of these efforts is the rate at which starch is digested by amylases. Starch digestibility is influenced heavily by genetically controlled factors including starch granular and molecular structure and composition. Maize mutant varieties with increased starch digestibility would help to make more cost-efficient biofuels. To identify such mutants among segregating families of ethyl methane sulfonate-mutagenized maize, we developed a miniaturized, high-throughput single kernel preparation and starch digestion assay that can process over 500 samples per week. In a preliminary screen of 480 families, we have identified 62 mutants with faster rates of digestion as compared to wild type and, in the same screen, an additional 53 lines with slower rates of digestion, thus tremendous potential health benefits. These mutants can be used for detailed structural analysis of starch and flour physical and chemical properties, factors that interact with starch in the cell and analysis of an apparently large number of genes that can impact rates of starch digestion.

The relationship between the slow digestion property of cooked maize starch and its molecular fine structure was investigated. Results of the in vitro Englyst assay showed a range of rapidly digestible starch (RDS) (70.1-98.9%), slowly digestible starch (SDS) (0.2-20.3%), and resistant starch (RS) (0.0-13.7%) among the tested maize mutant flour samples. Further analysis showed that amylose content was significantly correlated ( R = 0.763, P0.001) with RS amount but not with that of SDS, indicating that amylopectin is the starch molecule associated with SDS. Total starch debranching analysis revealed a parabolic relationship between SDS content and the weight ratio of amylopectin short chains (DP13, named SF) to long chains (DP/= 13, named LF), which means amylopectin with a higher amount of either short chains or long chains can produce relatively high amounts of SDS. Furthermore, debranching analysis of the SDS materials from samples with the highest and lowest weight ratios of SF/LF (both had a high amount SDS) showed significantly different profiles, indicating there is not a uniform molecular structure for SDS. Thus, genetic mutants of maize samples have a good potential to provide raw starch materials of high nutritional quality. An additional finding showed that a simple and comparably high-throughput technique of Rapid Visco-Analyzer (RVA) can be used to screen genetic mutants on the basis of their RVA profiles.

The mechanism underlying the previously reported parabolic relationship between amylopectin fine structure, represented by the weight ratio of linear short chains [degree of polymerization (DP13) to long chains (DP/= 13], and slowly digestible starch (SDS) content was investigated from the viewpoint of starch retrogradation and substrate susceptibility to enzyme hydrolysis. A maize mutant sample, termed "highest long-chain starch" (HLCS) representing group I samples with a higher proportion of long chains, showed a bell-shaped SDS pattern with retrogradation time, whereas insignificant changes in SDS were found for the sample termed "highest short-chain starch" (HSCS) representing group II samples with a higher proportion of short chains. This corresponded to results from X-ray powder diffraction and differential scanning calorimetry that showed a rapid increase of crystallinity and enthalpy for HLCS during retrogradation, but negligible changes for sample HSCS. Therefore, retrogradation was associated with SDS content for group I samples, but not for group II samples. Analysis of amylopectin fine structure, SDS content, retrogradation enthalpy, SDS material debranching profile, and hydrolysis pattern demonstrated, for group I samples, that linear branched chains of DP 9-30 of amylopectin may act as anchor points to slow the digestion of branced-chain fractions of DP30, which constitute the major slowly digestible portion, whereas for group II samples, it is the inherent molecular structure of amylopectin with a higher amount of branches and shorter chains that is not favorable for rapid enzyme digestion. The concept of a slowly digestible starch state (SDS state) that could be a chemical or physical entity is proposed to better describe the mechanistic underpinning of the slow digestion property of starches.

The detailed mechanistic aspects for the final starch digestion process leading to effective alpha-glucogenesis by the 2 mucosal alpha-glucosidases, human sucrase-isomaltase complex (SI) and human maltase-glucoamylase (MGAM), are poorly understood. This is due to the structural complexity and vast variety of starches and their intermediate digestion products, the poorly understood enzyme-substrate interactions occurring during the digestive process, and the limited knowledge of the structure-function properties of SI and MGAM. Here we analyzed the basic catalytic properties of the N-terminal subunit of MGAM (ntMGAM) on the hydrolysis of glucan substrates and compared it with those of human native MGAM isolated by immunochemical methods. In relation to native MGAM, ntMGAM displayed slower activity against maltose to maltopentose (G5) series glucose oligomers, as well as maltodextrins and alpha-limit dextrins, and failed to show the strong substrate inhibitory "brake" effect caused by maltotriose, maltotetrose, and G5 on the native enzyme. In addition, the inhibitory constant for acarbose was 2 orders of magnitude higher for ntMGAM than for native MGAM, suggesting lower affinity and/or fewer binding configurations of the active site in the recombinant enzyme. The results strongly suggested that the C-terminal subunit of MGAM has a greater catalytic efficiency due to a higher affinity for glucan substrates and larger number of binding configurations to its active site. Our results show for the first time, to our knowledge, that the C-terminal subunit of MGAM is responsible for the MGAM peptide's "glucoamylase" activity and is the location of the substrate inhibitory brake. In contrast, the membrane-bound ntMGAM subunit contains the poorly inhibitable "maltase" activity of the internally duplicated enzyme.

The molecular features of five tef starches along with those of commercial normal maize starch were investigated by size-exclusion chromatography with multi-angle laser light scattering-differential refractive index detection (SEC/MALLS-DRI) after solubilization in water by cooking in a household pressure cooker. The weight-average molar mass () and weight-average root-mean square radius of gyration ( w) of the amylopectin (AP) of tef starches ranged from 10.1×107 g/mol (156 nm) to 16.5×107 g/mol (205 nm) with a mean of 13.9×107 g/mol (186 nm). The AP of the tef starches was considerably smaller than that of maize starch ( = 19.6×107 g/mol, w = 207 nm). These considerably smaller AP molecules in tef starches were most probably responsible for the low paste viscosity of tef starches as compared to maize starch. In most tef starches, the polydispersity index (PI) of the AP was broader than that of the AP of maize starch. The intermediate fraction (IN) 1.0−1.6, mean = 1.1) of most tef starches were similar to those of the IN of maize starch. The amylose (AM) (range 1.5×106−3.0×106 g/mol, mean = 2.2×106 g/mol) and size (range 176−214 nm, mean = 191 nm) of most tef starches was also apparently similar to that of the maize starch ( = 2.3×106 g/mol, w = 193 nm), but the polymer distribution was narrower. The AM−iodine complex of the tef starches had a λmax range of 611−679 nm and the absorption shifted toward longer wavelengths by 8−14 nm as compared to the maize starch AM−iodine complex. The blue value (absorption at λmax) for 1 mg/mL of tef AM had a range of 2.3−2.8 (mean = 2.5), whereas for the maize starch, the mean was 2.2. The branched nature of tef starches was also investigated by debranching with isoamylase and determination of chain lengths (DPn) of the branches by size exclusion chromatography with refractive index detector (SEC-RI). The AP in tef starches had a polymodal distribution with a periodicity similar to that of cereal starches. The branches had DPn values of A = 11, B1 = 16, B2 = 46 (range 46−47), B3 = 70 (range 69−72) and B4 = 118 (range 113−123). The outer (A + B1) chains were shorter than those of maize starch AP with abundance (74%, w/w) only slightly less than that of the maize starch (75%, w/w). The slow rate of retrogradation, the slightly lower percent crystallinity, the lower gelatinization temperatures and the lower gelatinization enthalpy observed for tef starches (as compared to maize starch) are probably related to the shorter outer (A + B1) chain lengths of their amylopectin molecules, and may be the foundation of the comparably good keeping quality of tef injera, the main staple in the Ethiopian diet.

BACKGROUND: Starches are the major source of dietary glucose in weaned children and adults. However, small intestine alpha-glucogenesis by starch digestion is poorly understood due to substrate structural and chemical complexity, as well as the multiplicity of participating enzymes. Our objective was dissection of luminal and mucosal alpha-glucosidase activities participating in digestion of the soluble starch product maltodextrin (MDx). PATIENTS AND METHODS: Immunoprecipitated assays were performed on biopsy specimens and isolated enterocytes with MDx substrate. RESULTS: Mucosal sucrase-isomaltase (SI) and maltase-glucoamylase (MGAM) contributed 85% of total in vitro alpha-glucogenesis. Recombinant human pancreatic alpha-amylase alone contributed

Digestion of starch requires activities provided by 6 interactive small intestinal enzymes. Two of these are luminal endo-glucosidases named alpha-amylases. Four are exo-glucosidases bound to the luminal surface of enterocytes. These mucosal activities were identified as 4 different maltases. Two maltase activities were associated with sucrase-isomaltase. Two remaining maltases, lacking other identifying activities, were named maltase-glucoamylase. These 4 activities are better described as alpha-glucosidases because they digest all linear starch oligosaccharides to glucose. Because confusion persists about the relative roles of these 6 enzymes, we ablated maltase-glucoamylase gene expression by homologous recombination in Sv/129 mice. We assayed the alpha-glucogenic activities of the jejunal mucosa with and without added recombinant pancreatic alpha-amylase, using a range of food starch substrates. Compared with wild-type mucosa, null mucosa or alpha-amylase alone had little alpha-glucogenic activity. alpha-Amylase amplified wild-type and null mucosal alpha-glucogenesis. alpha-Amylase amplification was most potent against amylose and model resistant starches but was inactive against its final product limit-dextrin and its constituent glucosides. Both sucrase-isomaltase and maltase-glucoamylase were active with limit-dextrin substrate. These mucosal assays were corroborated by a 13C-limit-dextrin breath test. In conclusion, the global effect of maltase-glucoamylase ablation was a slowing of rates of mucosal alpha-glucogenesis. Maltase-glucoamylase determined rates of digestion of starch in normal mice and alpha-amylase served as an amplifier for mucosal starch digestion. Acarbose inhibition was most potent against maltase-glucoamylase activities of the wild-type mouse. The consortium of 6 interactive enzymes appears to be a mechanism for adaptation of alpha-glucogenesis to a wide range of food starches.

The secondary structure of a dough-like zein polymer was compared to the structure present in a wheat viscoelastic system using FT-IR spectroscopy. When zein was mixed at 35 °C, which is above its glass transition temperature (Tg), changes in its secondary structure suggested that the protein loses its native structure, mainly composed of α-helices (∼68%), and a viscoelastic system is formed by a structural rearrangement that favors β-sheet structures. This rearrangement is very similar to the structural changes observed in gluten viscoelastic polymers. Upon removal of shear stress, the zein polymer showed a rapid decrease in the proportion of β-sheet structures (from ∼48% to ∼28% after the first 3 min) in favor of unordered structures. At the same time, the viscoelasticity of the polymer decreased rapidly. In contrast, gluten, in a similar viscoelastic system and held at the same temperature, showed a fairly constant high content of β-sheet structures (∼49%) coinciding with the slow relaxation time typical of gluten networks after the removal of shear. We speculate that the addition of a protein capable of causing extensive and stable β-sheet formation in the zein–starch viscoelastic polymer could increase the stability and relaxation time of the zein system and, thereby, create the possibility of a zein dough with similar functionality to a wheat viscoelastic system.

Sorghum is a critical source of food in the semiarid regions of sub-Saharan Africa and India and a potential source of dietary phytochemicals including carotenoids. The objective of this study was to determine the carotenoid profiles of sorghum cultivars, selected on the basis of their yellow-endosperm kernels, at various developmental stages. Following extraction from sorghum flours, carotenoids were separated by high-performance liquid chromatography (HPLC) with diode array detection. Total carotenoid content in fully matured yellow-endosperm sorghum kernels (0.112-0.315 mg/kg) was significantly lower (p0.05) than that in yellow maize (1.152 mg/kg) at physiological maturity. Variation in total carotenoids and within individual carotenoid species was observed in fully mature sorghum cultivars. For developing kernels, large increases in carotenoid content occurred between 10 and 30 days after half bloom (DAHB), resulting in a peak accumulation between 6.06 and 28.53 microg of total carotenoids per thousand kernels (TK). A significant (p0.05) decline was noted from 30 to 50 DAHB, resulting in a final carotenoid content of 2.62-15.02 microg/TK total carotenoids. (all-E)-Zeaxanthin was the most abundant carotenoid, ranging from 2.22 to 13.29 microg/TK at 30 DAHB. (all-E)-Beta-carotene was present in modest amounts (0.15-3.83 microg/TK). These data suggest the presence of genetic variation among sorghum cultivars for carotenoid accumulation in developing and mature kernels.

Two experiments were conducted to evaluate the nutritional quality of 2 varieties of Purdue high-digestible sorghum (PHD1 and PHD2) and a normal sorghum, compared with corn, in diets of pigs and broiler chicks. In Exp. 1, 12 pigs (average BW, 55 kg) fitted with ileal T-cannula were fed 4 diets containing 946 g of corn or sorghum (PHD1, PHD2, and normal) per kg in a 2-period crossover design (i.e., each pig received 2 diets over a 2-wk period with 6 pigs per dietary treatment) to determine apparent ileal or total tract digestibility of nutrients and energy. There was no difference in the ileal or total tract digestibility of DM, energy, P, Ca, or N among dietary treatments. In Exp. 2, a total of 192 broiler chicks were grouped by weight into 8 blocks of 4 cages each with 6 chicks per cage, and cages were assigned randomly to 1 of the 4 dietary treatments within each block. Chicks were fed corn-soybean meal (SBM) or sorghum-SBM diets for 21 d to determine apparent total tract retention and then switched to diets containing 935 g of the corresponding corn or 1 of the 3 sorghum varieties per kg for 7 d to determine apparent ileal digestibility and total tract retention. Apparent ileal digestibilities of DM and P, as well as energy, were not different in chicks fed diets containing 935 g of corn or 1 of the 3 sorghum varieties per kg. However, apparent total tract retention of DM, energy, and N in chicks fed corn was greater (P < 0.05) than those fed 1 of the 3 sorghum varieties. Although the apparent ME content of corn was greater than PHD1 and normal sorghum (P < 0.01), it was not different from PHD2 sorghum. There was no difference in apparent total tract retention of DM between chicks fed the corn-SBM and PHD-SBM diets, but it was greater (P < 0.05) in chicks fed the corn-SBM diet than those fed the normal sorghum-SBM diet. Apparent total tract retention of N in chicks fed the PHD1-SBM diet was lower (P < 0.05) than in those fed the corn-SBM diet but greater (P < 0.05) than in chicks fed the normal sorghum-SBM meal diet. No difference in the apparent ME content between the corn-SBM and PHD2-SBM diets was observed, but it was greater (P < 0.05) for the corn-SBM diet than the PHD1- or normal sorghum-SBM diet. Weight gain, feed intake, and feed efficiency were not different in chicks fed the corn-SBM or sorghum-SBM diets. Sorghum could serve as a substitute for corn in cereal grain-SBM diets for pigs and broiler chicks.

Four amylose-free waxy rice starches were found to give rise to gels with clearly different morphology after storage for seven days at 4°C. The thermal and rheological properties of these gels were also different. This was remarkable in light of the subtle differences in the molecular structure of the amylopectin in the samples. Addition of iodine to the amylopectin samples suggested that not only external chains, but also the internal chains of amylopectin, could form helical inclusion complexes. It is suggested that these internal helical segments participate in the retrogradation of amylopectin, thereby stabilising the gels through double helical structures with external chains of adjacent molecules. Albeit few in number, such interactions appear to have important influences on starch functional properties.

A high protein digestibility/high-lysine mutant P721Q (hdhl) with a multi-folded protein body morphology has been developed, with a 22kDa α-kafirin single point mutation having also been recently identified. Relatively little is known regarding the resulting cellular response in hdhl endosperm. The aim is to elucidate these biochemical changes. Two-dimentional gel electrophoresis showed an apparent increase of non-kafirin and a decrease in kafirins content in hdhl endosperm. Mass spectrometry data yielded the identity of differentially expressed non-kafirin proteins in hdhl, wild-type lines such as cytoskeleton and chaperones proteins, and also others involved in amino acids and carbohydrates biochemical synthesis pathways. Western blot analysis showed that chaperone proteins were more highly expressed in the hdhl than the wild-type sorghum and confirmed the non-kafirin proteins proteomic results. Two-dimentional gel electrophoresis showed that the γ-kafirin subunits content had decreased, and the 22kDa α-kafirin subunit was increased in hdhl without any apparent molecular mass change. The observed differential expression most likely led to proteins interactions between γ- and α-kafirin subunits in particular, which resulted in a kafirins packing differently to form the protein body's multi-folded morphology, while also improving its digestibility.

Gastric emptying rates of Malian traditional foods (couscous, thick and thin porridges made from sorghum and millet) were studied versus imported staple foods that are mostly consumed in the urban ...

White rice is considered to have lower nutritional quality compared to brown rice due to the loss of its bran fiber during processing. However, components besides bran fiber that may improve the ph...

Dietary carbohydrates are important in providing energy to humans, but carbohydrates are increasingly thought of as “bad” foods associated with obesity, diabetics and associated diseases. The objec...

Maltose and maltooligosaccharides are the primary products from starch digestion by pancreatic α- amylase and are major substrates for enterocyte intestinal α-glucosidases. We have recently shown t...

Glycogen expressed by the lower genital tract epithelium is believed to support Lactobacillus growth in vivo, although most genital isolates of Lactobacillus are not able to use glycogen as an energy source in vitro. We recently reported that α-amylase is present in the genital fluid of women and that it breaks down glycogen into small carbohydrates that support growth of lactobacilli. Since the pH of the lower genital tract can be very low, we determined how low pH affects glycogen processing by α-amylase. α-amylase in saliva degraded glycogen similarly at pH 6 and 7, but activity was reduced by 52% at pH 4. The glycogen degrading activity in nine genital samples from seven women showed a similar profile with an average reduction of more than 50% at pH 4. However, two samples collected from one woman at different times had a strikingly different pH profile with increased glycogen degradation at pH 4, 5 and 6 compared to pH 7. This second pH profile did not correlate with levels of human α-acid glucosidase or human intestinal maltase glucoamylase. High-performance anion-exchange chromatography showed that mostly maltose was produced from glycogen by samples with the second pH profile in contrast to genital α-amylase that yielded maltose, maltotriose and maltotetraose. These studies show that at low pH, α-amylase activity is reduced to low but detectable levels, which we speculate helps maintain Lactobacillus growth at a limited but sustained rate. Additionally, some women have a genital enzyme distinct from α-amylase with higher activity at low pH. Further studies are needed to determine the identity and distribution of this second enzyme, and whether its presence influences the makeup of genital microbiota.

International audience; Gut microbiota has been implicated as a pivotal contributing factor in diet-related obesity; however, its role in development of disease phenotypes in human genetic obesity such as Prader-Willi syndrome (PWS) remains elusive. In this hospitalized intervention trial with PWS (n = 17) and simple obesity (n = 21) children, a diet rich in non-digestible carbohydrates induced significant weight loss and concomitant structural changes of the gut microbiota together with reduction of serum antigen load and alleviation of inflammation. Co-abundance network analysis of 161 prevalent bacterial draft genomes assembled directly from metagenomic datasets showed relative increase of functional genome groups for acetate production from carbohydrates fermentation. NMR-based metabolomic profiling of urine showed diet-induced overall changes of host metabotypes and identified significantly reduced trimethylamine N-oxide and indoxyl sulfate, host-bacteria co-metabolites known to induce metabolic deteriorations. Specific bacterial genomes that were correlated with urine levels of these detrimental co-metabolites were found to encode enzyme genes for production of their precursors by fermentation of choline or tryptophan in the gut. When transplanted into germ-free mice, the pre-intervention gut microbiota induced higher inflammation and larger adipocytes compared with the post-intervention microbiota from the same volunteer. Ourmulti-omics-based systems analysis indicates a significant etiological contribution of dysbiotic gut microbiota to both genetic and simple obesity in children, implicating a potentially effective target for alleviation. Research in context: Poorly managed diet and genetic mutations are the two primary driving forces behind the devastating epidemic of obesity-related diseases. Lack of understanding of the molecular chain of causation between the driving forces and the disease endpoints retards progress in prevention and treatment of the diseases. We found that children genetically obese with Prader-Willi syndrome shared a similar dysbiosis in their gut microbiota with those having diet-related obesity. A diet rich in non-digestible but fermentable carbohydrates significantly promoted beneficial groups of bacteria and reduced toxin-producers, which contributes to the alleviation of metabolic deteriorations in obesity regardless of the primary driving forces.

Protein body-free maize zein, when mixed at 35 degrees C (above its glass transition temperature range), significantly (p < 0.01) improved the rheological and leavening properties of sorghum-wheat composite flour dough, resulting in improved loaf volume. Confocal laser scanning microscopy was used to observe the structure of zein fibrils and the interaction between zein and gluten proteins in the composite dough and bread systems. Autofluorescence and immunolocalization techniques were used to locate gluten and zein, respectively. Optical sections were collected every 0.4 microm through the samples and digitally processed to produce reconstructed three-dimensional images. Results showed that zein fibrils form an outer layer that intermittently coats the gluten networks, thereby strengthening them. This type of microstructure is able to withstand the pressure exerted by gas cell expansion during yeast fermentation to increase loaf volume.

Changes in proteins during extrusion may influence the texture of ready-to-eat (RTE) corn-based extruded foods. This study focused on microstructural changes and dispersal patterns of corn storage proteins, zeins, that occur during extrusion processing. Model systems were used that consisted of two types of corn protein: commercial zein and corn gluten meal (CGM), combined with corn starch. Commercial zein is not encased in protein bodies, whereas CGM is comprised of zeins encapsulated in protein bodies. Mixtures were extruded under conditions that resulted in different specific mechanical energy (SME). The microstructure of the resulting extrudates was analyzed using transmission electron microscopy (TEM) with immunogold labeling of the α-zein storage protein. The micrographs showed that the greatest zein dispersal occurred in CGM/starch extrudates, especially under high SME conditions. The micrographs also showed that, at both mild and harsh extrusion conditions, commercial zein/starch extrudates contained large protein aggregates. Under mild extrusion conditions, protein bodies in the CGM/starch extrudates partially retained their spherical shapes, but during harsher processing, protein bodies were disrupted and dispersed zein appeared to form fibrils. Such protein fibrils may influence texture and/or quality of extruded corn-based snacks and breakfast foods.

Twenty-seven kilodalton gamma-zein is a subclass of the maize zein storage proteins and, due to its localization at the protein body periphery, is critical to digestibility characteristics of all zeins. This protein had low in vitro digestibility, presumably due to its high Cys content (7.35 mol%) that is similar to the hard-to-digest analogous sorghum protein, gamma-kafirin. Therefore, each of the conserved disulfide-bonded Cys' was mutated to create C144A, C148A, C155A, and C156A maize gamma-zein mutants. The C155A showed a remarkable increase in digestibility to proteases - pepsin, chymotrypsin, and trypsin. A high conservation of this Cys among cereal gamma-prolamins indicates the utility of this finding.

Summary Sorghum grain was decorticated to remove 10%, 20%, 30% and 40% of the kernel for the purpose of improving flour colour, couscous colour and yield, and porridge texture. Flour lightness increased while yellow colour decreased with increased extent of decortication. Processing of the flours into couscous caused a considerable drop in lightness and increased yellow colour in couscous at all levels of decortication. As decortication level increased, couscous colour became lighter. Yellow colour progressively increased up to 30% kernel removal and dropped at 40%. Couscous yield, as measured by the proportion of particles of 1–2 mm size, also increased up to 30% kernel removal. This improvement in yield was attributed to decreased proportion of bran as indicated by ash content. However, the yield dropped at 40% kernel removal due to formation of large chunks of agglomerated flour particles. Thick porridge became harder as decortication level increased and this was strongly associated with the concomitant increase in starch concentration. Overall, this study defined the decortication levels necessary to improve the couscous colour and yield, and texture of porridge made from different sorghum cultivars.

Development of high-protein digestibility (HPD)/high-lysine (hl) sorghum mutant germplasm with good grain quality (i.e., hard endosperm texture) has been a major research objective at Purdue University. Progress toward achieving this objective, however, has been slow due to challenges posed by a combination of genetic and environmental factors. In this article, we report on the identification of a sorghum grain phenotype with a unique modified endosperm texture that has near-normal hardness and possesses superior nutritional quality traits of high digestibility and enhanced lysine content. These modified endosperm lines were identified among F6 families developed from crosses between hard endosperm, normal nutritional quality sorghum lines, and improved HPD/hl sorghum mutant P721Q-derived lines. A novel vitreous endosperm formation originated in the central portion of the kernel endosperm with opaque portions appearing both centrally and peripherally surrounding the vitreous portion. Kernels exhi...

Various factors, including starch granule channels, have been suggested to contribute to the control of sorghum starch digestibility for animal feed. Isolated starch from two normal sorghum lines (P721N, IS6986) and one high protein digestibility (HPD) mutant line (111) that differed in starch granule morphology were selected to study the influence of these factors on starch digestibility. Scanning electron micrographs were taken of raw and digested starches. Microscopy results confirmed that in all three sorghum lines channels in starch granules are the main route of enzyme penetration and the central cavity area is the starting point of enzyme digestion. Channel density was more pronounced in the HPD sorghum mutant line than in normal lines, which may have been responsible for its relatively high digestibility. Micrographs of IS6986 showed unique starch granule morphology with a collapsed ”doughnut-shaped” structure in a portion of the granules. These unusual granules were rapidly digested and, unlike normal spherical granules, totally disappeared after 30 min of digestion. Amylases appeared to have fast access to the collapsed-appearing starch granules. Digestion profiles, following incubation with pepsin and α-amylase, showed that IS6986 and the HPD mutant (111) had the highest initial rate of starch digestion, followed by P721N. These findings provide insight as to how new sorghum cultivars might be developed with high starch digestibility for animal feed use.

Starch was isolated from kernels of 27 rice samples consisting of nine U.S. long grain rice cultivars grown in three different locations (Missouri, Arkansas, Texas). Amylose (AM) content of the starches and the fine structure of the respective amylopectin (AP) were determined and used to explain differences observed in gelatinization properties. The AM content of rice cultivars grown at the lower temperature Missouri location increased 0.4–3% and 0.5–4% when compared with the same rices grown in Arkansas and Texas, respectively. AP values of the rice samples were isolated, debranched, and separated by low-pressure size-exclusion chromatography. The eluted AP linear chains were divided into three fractions to represent extra long (FrI), long (FrII), and short chains (FrIII). The corresponding average degree of polymerization (DPn) at the peaks of fractions FrI, FrII, and FrIII were 100, 39, and 16, respectively. Total carbohydrate analysis of the fractions indicated that cultivars grown in Missour...