Study of the effect of technological processes on starch hydrolysis, non-starch polysaccharides solubilization and physicochemical properties of different ingredients using a two-step in vitro system

Fermentation Characteristics of Rye and Sorghum Depending on Water:Feed Ratio

This study was conducted to determine the fermentation characteristics of rye or sorghum mixed with different ratios of water (25%, 37.5%, 50%, 62.5%, and 75% in dry matter (DM)), incubated up to 48 h. The pH of the fermented rye at a DM content of 25% after 24 h had the lowest values (3.57) compared to that at a DM content of 75% (6.42). In fermented sorghum, pH values were lower than 4 already after incubation at 25% DM for 12 h (3.93) in comparison to that at DM content 75% (6.51). The L-lactic acid concentration in the fermented rye with 25% DM content after 24 h was significantly the highest (18.7 g/kg DM), as was that of sorghum with 25% DM content after 24 h (22.2 g/kg DM). Moreover, the acetic acid level in the fermented rye with 25% DM content after 24 h was significantly the highest (3.02 g/kg DM) compared to the other DM contents of fermented rye. Also, in fermented sorghum (25% DM), the acetic acid content was significantly the greatest (1.49 g/kg DM) in comparison to the other DM contents of fermented sorghum. Overall, fermented rye and sorghum containing 25 or 37.5% DM for 24 h and 12 h for rye and sorghum, respectively are sufficient for fermentation to be optimized based on the values of pH and lactic acid content, except for acetic acid content, which may negatively affect the palatability in animals.

Growth performance and total tract digestibility in broiler chickens fed different corn hybrids

The aim of the present study was to investigate the variability in nutrient digestibility associated with corn genetic background and its influence on the feeding value for broiler chickens. A total of 960 1-day-old male broiler chicks (Ross 308) were distributed in eight treatments, with 12 pens per treatment and 10 birds per pen in a 42-day study. Eight corn samples (Variety 1 to Variety 8) were selected based on their nutrient composition. A fixed amount of each corn (577 g/kg in the starter diets and 662 g/kg in the finisher diets) was used to formulate feeds. Diets were offered ad libitum in pellet form. Performance parameters were determined at d 21 and d 42, and excreta samples collected at d 21 to determine energy, organic matter and dry matter (DM) whole-tract digestibility. The results revealed a decrease (P < 0.05) in body weight (BW) and feed intake in birds fed variety 8 compared to other varieties at d 21. The lowest whole tract DM and energy apparent digestibility were also observed for the variety 8 diet (P < 0.05), together with varieties 3 and 5. Energy digestibility was higher in varieties 2, 4 and 7 (P < 0.05). Multivariate analysis revealed that corn protein concentration was positively correlated with vitreousness (r = 0.60, P = 0.054) and the arabinose:xylose ratio (r = 0.67, P < 0.05) and negatively correlated with starch (r = -0.62, P < 0.05). Soluble non-starch polysaccharide content was negatively correlated with the protein solubility index (r = -0.88, P < 0.05). In addition, corn protein concentration was negatively correlated (P < 0.05) with 21-d BW (r = -0.71) and weight gain (r = -0.62). In conclusion, the corn genetic background influenced the nutrient digestibility and growth performance of broiler chickens. The content and nature of the non-starch polysaccharides were found to be two of the main factors affecting the solubility and availability of nutrients in corn, and could be the reason for the negative effects on the performance of broiler chickens as shown in the present study.

Optimum inclusion levels of Leucaena leucocephala pasture leaf-meal on growth, haematology and physiological performance of growing pigs

This study was conducted to evaluate the optimum inclusion levels of Leucaena leucocephala leaf meal on growth, haematology, and physiological performance of pigs. A total of 16 grower pigs comprising of 12 females and 4 castrated males weighing an average of 13.5 kg were assigned into a completely randomized experimental layout, subjected to 4 inclusion levels of leaf meal (0, 50, 100, and 150 g/kg DM). Regression model and one-way ANOVA model were used to analyse the data. The total feed intake (TFI) and average weekly feed intake (AWFI) were significantly affected quadratically (P < 0.05) by increased inclusion levels, while tubular diameter (TD) and epithelial cell thickness (ECT) of the thyroid gland were not significantly (P > 0.05) affected quadratically. However, a significant difference due to inclusion levels on TD and ECT was established due to one-way ANOVA. Optimal inclusion levels of 70.5 g/kg for TFI and 70.0 g/kg for AWFI were significantly established with 99% regression coefficient. This implies that the quantity of Leucaena leaf meal intake continued increasing up to 70.50 g/kg inclusion levels before it started reducing; hence, the optimal inclusion levels of Leucaena for best feed intake is at 70.5 g/kg at which point all other parameters of growth, haematology, and physiological parameters were not significantly affected.

Influence of Particle Size and Xylanase in Corn-Soybean Pelleted Diets on Performance, Nutrient Utilization, Microbiota and Short-Chain Fatty Acid Production in Young Broilers

The objective of this study was to investigate the effects of particle size and xylanase supplementation in corn-based pellet diets on the performance and digestive traits in young broilers. A total of 512 male Ross 308 broilers were used in a 21-day study. The treatments were designed in a 4 × 2 factorial arrangement with four levels of geometric mean diameter (Dgw) of corn (540, 660, 1390, and 1700 µm), and two levels of xylanase (0 or 16,000 BXU/kg diet). Feeding coarse corn diets (1390 and 1700 µm Dgw) and xylanase supplementation showed an inferior coefficient of variation of body weight. Higher gizzard weight, microbiome alpha-diversity, and clustered separately beta-diversity (p < 0.05) were observed in birds fed coarse diets. The addition of xylanase promoted changes in relative bacteria abundance, increasing Lachnospiraceae, Defluviitaleaceae, Bacteroidaceae, Bacillaceae, Eggerthellaceae, and Streptococcaceae families in the 1700 µm group, and Christensenellaceae and Lachnospiraceae families in the 540 µm Dgw group. In conclusion, xylanase supplementation and particle size of corn interact in the intestinal environment, showing changes in microbial composition. Coarse diets and xylanase supplementation showed improved body weight homogeneity, which might be related to a better gut development and microbiota modulation.

Feeding Complete Concentrate Pellets Containing Ground Grains or Blend of Steam-Flaked Grains and Other Concentrate Ingredients in Ruminant Nutrition – A Review

The feed industry has attempted to encourage the animal husbandry sector to feed complete concentrate pellets containing ground grains in ruminant nutrition and thus prevent farmers from making concentrate in their farms. Reducing particle size using pre-pelleting grinding and pressing materials during pellet formation, plus starch gelatinization by heat treatment in the conditioner are key factors determining the extent and rate of starch digestion in ingested pellets. If prepelleting grinding of corn and barley grain for using in the pelleted concentrate results in ground materials of less than 1.8 mm mean particle size (especially in the case of barley grain which is highly fermentable), then it increases the rate of fermentability in the rumen which in turn increases the acidosis risk. Such situation and dissatisfaction from pellets feeding to ruminant have directed farmers to produce homemade mash concentrate which may include steam-flaked form of grains in the concentrate mixture. Pelleting process increases the time needed to collapse the pellet in the rumen so delays the access of microbes to fermentable organic matter. This counterbalance property highly depends on pellet size with highest effect obtained using 10 mm diameter pellets for cattle. Feeding separately steam-flaked grains (plus other pelleted/mash non-grain ingredients of concentrate) may give results similar to the complete concentrate pellets having ground grains prepared according to optimized recommendations (pellet diameter and grain mean particle size). Nonetheless cost benefit studies are necessary to adopt one of the above two optimized technologies that has higher starch utilization and lower fecal starch excretion by animal. In the situation where consuming steam-flaked grains has priority of application in the diet, it is strongly recommended to pellet non-grain portions of concentrate for obtaining numerous pellet advantages such as reducing transportation cost, dust, sorting and bird removal.

The effect of structure and texture on the breakdown pattern during mastication and impacts on in vitro starch digestibility of high fibre rye extrudates

The snack product category is lacking palatable, high dietary fiber containing products. This study explored how the addition of native or fermented rye bran influences the texture and sensory properties of endosperm rye flour based extrudates. In addition, mastication and bolus properties (n = 26), and in vitro starch digestibility were assessed. Three high fiber extrudates based on endosperm rye flour (EF) were produced with addition of either 40% native rye bran (NBE) or 40% fermented rye bran (FBE), and with no added bran (EFE) to achieve two pairs of extrudates to compare. EFE and FBE had different composition but resembled each other regarding macrostructure and the second pair (NBE vs. FBE) had similar core composition but different structure due to bran fermentation. The fermentation of bran was performed using exopolysaccharide (EPS)-producing strain Weissella confusa, which led to 3% (3 g per 100 g bran; dry weight) in situ dextran production. The compositionally similar extrudates (NBE vs. FBE) varied in both structure and instrumental texture: FBE were less dense, less hard and crispier than NBE. The extrudates with different composition (EFE vs. FBE) varied regarding instrumental texture: FBE were less hard and crispier than EFE. There were also subtle structural differences FBE being somewhat denser than EFE. NBE and FBE differed regarding sensory texture while textures of EFE and FBE were perceived similar. Mastication properties of the different products did not exhibit remarkable differences. There was a large number of smaller particles in both NBE and FBE bolus samples. The fragile structure of FBE, and its lower bolus viscosity, led to high in vitro starch digestibility. The results demonstrate that the structural attributes of the extrudates, rather than the core composition, dictate the breakdown pattern during mastication and in vitro starch digestibility. The extrudates with similar composition may be digested at different rates depending on their structural attributes. Although FBE had higher in vitro starch digestibility, its high DF content, palatable texture and improved sensory properties were important determinants underlying eating quality and therefore it could be a promising product to snack food category.

Effects of particle size on physicochemical and functional properties of superfine black kidney bean (Phaseolus vulgaris L.) powder

Black kidney bean (Phaseolus vulgaris L.) powder (BKBP) with particle sizes of 250–180, 180–125, 125–75, 75–38, and <38 μm was prepared by using coarse and eccentric vibratory milling, respectively. Physicochemical properties, cholesterol adsorption, and antioxidant activities of powders were investigated. Size and scanning electron microscopy analyses showed that particle size of BKBP could be effectively decreased after the superfine grinding treatment, and the specific surface area was increased. Flow properties, hydration properties, thermal stability, and cholesterol adsorption efficiency significantly improved with the reducing of particle size. The superfine powder with sizes of 75–38 or <38 μm exhibited higher antioxidant activity via 2,2-diphenyl-1-picryhydrazyl, hydroxyl radical-scavenging, and ferrous ion-chelating assays. The results indicated that the BKBP with a size of <38 μm could serve as a better potential biological resource for food additives, and could be applied for the development of low-cholesterol products.

Increasing intake of dietary soluble nutrients affects digesta passage rate in the stomach of growing pigs

The passage rate of solids and liquids through the gastrointestinal tract differs. Increased dietary nutrient solubility causes nutrients to shift from the solid to the liquid digesta fraction and potentially affect digesta passage kinetics. We quantified: (1) the effect of three levels of dietary nutrient solubility (8, 19 and 31 % of soluble protein and sucrose in the diet) at high feed intake level (S) and (2) the effect of lowv.high feed intake level (F), on digesta passage kinetics in forty male growing pigs. The mean retention time (MRT) of solids and liquids in the stomach and small intestine was assessed using TiO2and Cr-EDTA, respectively. In addition, physicochemical properties of digesta were evaluated. Overall, solids were retained longer than liquids in the stomach (2·0 h,P<0·0001) and stomach+small intestine (1·6 h,P<0·001). When S increased, MRT in stomach decreased by 1·3 h for solids (P=0·01) and 0·7 h for liquids (P=0·002) but only at the highest level of S. When F increased using low-soluble nutrients, MRT in stomach increased by 0·8 h for solids (P=0·041) and 0·7 h for liquids (P=0·0001). Dietary treatments did not affect water-binding capacity and viscosity of digesta. In the stomach of growing pigs, dietary nutrient solubility affects digesta MRT in a non-linear manner, while feed intake level increases digesta MRT depending on dietary nutrient solubility. Results can be used to improve predictions on the kinetics of nutrient passage and thereby of nutrient digestion and absorption in the gastrointestinal tract.

Effects of structural and textural properties of brittle cereal foams on mechanisms of oral breakdown and in vitro starch digestibility

Structural and textural properties as well as the dietary fibre content of solid cereal foams influence the oral breakdown of structure, bolus formation and digestibility. The aim of this study was to investigate how structural differences of solid cereal foams (puffs vs. flakes) affect in vivo chewing and in vitro starch digestion. Four extruded puffs and flakes were produced from endosperm rye flour by extrusion processing without or with 10% rye bran (RB) addition. Extruded puffs and flakes were masticated by fifteen healthy females and the process was monitored using electromyography. Extruded puffs were more porous than flakes (97% vs 35%). The two products were also significantly different (p<0.05) in their structural and textural properties such as expansion, hardness, density and crispiness. A negative correlation was observed between hardness and crispiness index (p<0.05, r=-0.950) and density and porosity (p<0.05, r=-0.964). Addition of 10% RB had a significant effect on structural, textural and mastication properties both for puffs and flakes. Mastication of puffs required less total work than flakes (204 vs. 456%) and they were degraded to smaller particles than flakes during mastication. Irrespectively of the considerable differences in structure, texture and oral disintegration process, no significant (p<0.05) differences were observed between puffs and flakes (86.4 vs. 85.1) in terms of starch hydrolysis index. RB addition increased the hydrolysis index of puffs and flakes to 89.7 and 94.5, respectively, which was probably attributable to the increased number of particles in the bolus.

Starch Characteristics Linked to Gluten-Free Products

The increasing prevalence of coeliac disease (CD) and gluten-related disorders has led to increasing consumer demand for gluten-free products with quality characteristics similar to wheat bread. The replacement of gluten in cereal-based products remains a challenge for scientists, due to its unique role in network formation, which entraps air bubbles. When gluten is removed from a flour, starch is the main component left. Starch is used as gelling, thickening, adhesion, moisture-retention, stabilizing, film forming, texturizing and anti-staling ingredient. The extent of these properties varies depending on the starch source. The starches can additionally be modified increasing or decreasing certain properties of the starch, depending on the application. Starch plays an important role in the formulation of bakery products and has an even more important role in gluten-free products. In gluten-free products, starch is incorporated into the food formulation to improve baking characteristics such as the specific volume, colour and crumb structure and texture. This review covers a number of topics relating to starch; including; an overview of common and lesser researched starches; chemical composition; morphology; digestibility; functionality and methods of modification. The emphasis of this review is on starch and its properties with respect to the quality of gluten-free products.

Processing technologies and cell wall degrading enzymes to improve nutritional value of dried distillers grain with solubles for animal feed: an in vitro digestion study

Currently, the use of maize dried distillers grain with solubles (DDGS) as protein source in animal feed is limited by the inferior protein quality and high levels of non-starch polysaccharides (NSP). Processing technologies and enzymes that increase NSP degradability might improve digestive utilization of DDGS, enhancing its potential as a source of nutrients for animals. The effects of various combinations of processing technologies and commercial enzyme mixtures on in vitro digestion and subsequent fermentation of DDGS were tested. Wet-milling, extrusion, and mild hydrothermal acid treatment increased in vitro protein digestion but had no effect on NSP. Severe hydrothermal acid treatments, however, effectively solubilized NSP (48-78%). Addition of enzymes did not affect NSP solubilization in unprocessed or processed DDGS. Although the cell wall structure of DDGS seems to be resistant to most milder processing technologies, in vitro digestion of DDGS can be effectively increased by severe hydrothermal acid treatments.

Isoenergetic replacement of fat by starch in diets for African catfish (Clarias gariepinus): effect on water fluxes in the gastro intestinal tract

The effect of an isoenergetic replacement of dietary fat by starch, on chyme characteristics and water fluxes in the gastro intestinal tract (GIT) was assessed. Adult African catfish (Clarias gariepinus) were fed a starch (SD) or fat (FD) diet and groups of fish were dissected at 2, 5 and 8 h after the consumption of a single meal. Chyme was collected quantitatively and was analysed for osmolality and dry matter (DM) content. Postprandial water fluxes were calculated, while using yttrium oxide (Y(2)O(3)) as an inert marker to account for the absorption of DM along the GIT. The largest differences in chyme characteristics between diets were observed in the stomach and decreased towards subsequent compartments. A high initial osmotic pressure was measured in the stomach for both diets (up to 498 ± 2 mOsm kg(-1)) and was likely the driver for the endogeneous water influx to this compartment. Large additions of water were recorded to the stomach and proximal intestine for both diets and absorption of water took place in the mid- and distal intestine. Interestingly, the dietary treatment had an impact on water balance in the stomach and proximal intestine of the fish, but not in the mid- and distal intestine. A strong complementary relationship suggested that 59% of the water fluxes in the proximal intestine could be explained by previous additions to the stomach. Therefore, a higher dietary inclusion of starch led to a shift in water additions from the proximal intestine to the stomach. However, the sum of water additions to the GIT was not different between diets and was on average 6.52 ± 0.85 ml water g(-1) DM. The interactions between osmoregulation and digestion, in the GIT of fed freshwater fish, deserve further attention in future research.

Plasma glucose response and glycemic indices in pigs fed diets differing in in vitro hydrolysis indices

Different dietary starch sources can have a great impact in determining starch digestion potential, thus influencing the postprandial blood glucose response. Our objectives were to define: (i) the incremental plasma glucose response in pigs fed diets containing various sources of starch differing in in vitro digestion patterns, (ii) the in vivo glycemic index (GI) values for the same diets, (iii) the possible relationship between in vitro and in vivo data. Diets, formulated with 70% of starch from five heterogeneous sources, were characterized in depth by using two distinct in vitro evaluations. The first one was based on the Englyst-assay for nutritional classification of starch fractions, whereas the second one was based on a time-course multi-enzymatic assay up to 180 min from which the hydrolysis indices (HIs) were calculated and used as a link between the physicochemical properties of starch from diets and the in vivo responses. For the in vivo study, five jugular-catheterized pigs (35.3 ± 1.1 kg body weight) were fed one of the five diets for 6-day periods in a 5 × 5 Latin square design. On day 5, blood was collected for 8 h postprandially for evaluating glucose appearance. On day 6, blood was collected for 3 h postprandially for the estimation of the GI. Starchy diets differed for rapidly digestible starch (from 8.6% to 79.8% of total starch (TS)) and resistant starch contents (from 72.5% to 4.5% of TS). Wide between-diets variations were recorded for all the kinetic parameters and for the HI calculated from the in vitro digestion curves (P < 0.05). On the basis of the obtained HI, diets contained starch with a very low to a very high in vitro digestion potential (ranging from 26.7% to 100.0%; P < 0.05). The glucose response differed among diets (P < 0.05), with marked differences between 15 and 120 min postprandial. Overall, the ranking of incremental glucose appearance among diets agreed with their in vitro HI classification: high HI diets increased plasma glucose response more (P < 0.05) than low HI diets. Lastly, different in vivo GIs were measured (ranging from 30.9% to 100.0%; P < 0.05). The relationship between HI and GI showed a high coefficient of determination (R2 = 0.95; root mean square error (RMSE) = 15.8; P < 0.05). In conclusion, diets formulated with starches with a wide range in HI potential can strongly affect the postprandial glucose response in pigs.

Food microstructure and starch digestion

Microstructural characteristics of starch-based natural foods such as parenchyma or cotyledon cell shape, cell size and composition, and cell wall composition play a key role in influencing the starch digestibility during gastrointestinal digestion. The stability of cell wall components and the arrangement of starch granules in the cells may affect the free access of amylolytic enzymes during digestion. Commonly used food processing techniques such as thermal processing, extrusion cooking, and post-cooking refrigerated storage alter the physical state of starch (gelatinization, retrogradation, etc.) and its digestibility. Rheological characteristics (viscosity) of food affect the water availability during starch hydrolysis and, consequently, the absorption of digested carbohydrates in the gastrointestinal tract. The nonstarch ingredients and other constituents present in food matrix, such as proteins and lipids interact with starch during processing, which leads to an alteration in the overall starch digestibility and physicochemical characteristics of digesta. Starch digestibility can be controlled by critically manipulating the food microstructure, processing techniques, and food composition.

New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.