Academic literature on the topic 'Plant fibre digestion'

AbstractThe positive effects of dietary fibre on health are now widely recognised; however, our understanding of the mechanisms involved in producing such benefits remains unclear. There are even uncertainties about how dietary fibre in plant foods should be defined and analysed. This review attempts to clarify the confusion regarding the mechanisms of action of dietary fibre and deals with current knowledge on the wide variety of dietary fibre materials, comprising mainly of NSP that are not digested by enzymes of the gastrointestinal (GI) tract. These non-digestible materials range from intact cell walls of plant tissues to individual polysaccharide solutions often used in mechanistic studies. We discuss how the structure and properties of fibre are affected during food processing and how this can impact on nutrient digestibility. Dietary fibre can have multiple effects on GI function, including GI transit time and increased digesta viscosity, thereby affecting flow and mixing behaviour. Moreover, cell wall encapsulation influences macronutrient digestibility through limited access to digestive enzymes and/or substrate and product release. Moreover, encapsulation of starch can limit the extent of gelatinisation during hydrothermal processing of plant foods. Emphasis is placed on the effects of diverse forms of fibre on rates and extents of starch and lipid digestion, and how it is important that a better understanding of such interactions with respect to the physiology and biochemistry of digestion is needed. In conclusion, we point to areas of further investigation that are expected to contribute to realisation of the full potential of dietary fibre on health and well-being of humans.

Plant biomass is the most abundant renewable resource on the planet, and the biopolymers of lignocellulose are the foundation of ruminant production systems. Optimizing the saccharification of lignocellulosic feeds is a crucial step in their bioconversion to ruminant protein. Plant cell walls are chemically heterogeneous structures that have evolved to provide structural support and protection to the plant. Ruminants are the most efficient digesters of lignocellulose due to a rich array of bacteria, archaea, fungi, and protozoa within the rumen and lower digestive tract. Metagenomic and metatranscriptomic studies have enhanced the current understanding of the composition, diversity, and function of the rumen microbiome. There is particular interest in identifying the carbohydrate-active enzymes responsible for the ruminal degradation of plant biomass. Understanding the roles of cellulosomes- and polysaccharide-utilising loci in ruminal fibre degradation could provide insight into strategies to enhance forage utilisation by ruminants. Despite advancements in “omics” technology, the majority of rumen microorganisms are still uncharacterised, and their ability to act synergistically is still not understood. By advancing our current knowledge of rumen fibre digestion, there may be opportunity to further improve the productive performance of ruminants fed forage diets.

The plant material in the diet that is resistant to enzymatic digestion is defined as “dietary fibre”. The primary ingredients that are classified as dietary fibres are cellulose, hemicellulose, pectic substances, gums, mucilages and lignin etc. Dietary fibre naturally exist in foods that are consumed daily viz.,cereals, fruits, vegetables and nuts. The diets with high content of fibre have shown benefits in multiple areas and systems in maintaining a mileu’-interior. Processing of foods leads to various changes in physical, chemical, enzymatic and thermal treatments, which may affect the composition of total fiber present in the diet.Fibres included in the diet leads to various changes in the qualitative aspects of the food that is processed. Favourable outcomes have been reported in various commodities such as cereals,bread,yoghurt and beverages. The importance and the uses of fibres in diet is an area of constant interest which needs to be explored further and our paper reviews and explains the relation between dietary fibres and their benefits, primarily in children [1]

SUMMARYSimulation modelling was used to investigate interactions between forage degradation characteristics, rumen processes and body weight, and to predict the voluntary food intake and digestion of a range of forages. Predicted voluntary intake and digestion agreed well with empirical data, explaining 61 and 70%, respectively, of variance in observed values. Since the data covered a wide range of animal weights and forage qualities, these results suggest that the model is a useful means of integrating the effects of animal and forage variables. Interactions were examined between animal weight and diet quality, as defined by the proportion of potentially digestible cell contents and cell walls and their rates of digestion. Retention time of food in the digestive tract was shown by regression to scale with W0·27. The time taken to comminute large fibre particles also scaled with W0·27. Longer retention of digesta by large ruminants increases digestive efficiency compared with small animals and would permit them to survive on lower-quality foods. The model showed that maximum intake of metabolizable energy scales with c. W0·87, greater than the scaling of maintenance with W0·73.

Dietary fibre is a non-digestable part of plant material in the diet which is resistant to enzymatic digestion in humans which includes cellulose, non-cellulosic polysaccharides such as hemicellulose, pectic substances, gums, mucilages and a non-carbohydrate component lignin. The diet rich in fibre such as cereals, nuts, fruits and vegetables have a positive effect on health since their consumption has been related to decreased incidence of several diseases. Higher intakes of dietary fiber are linked to less cardiovascular disease, diabetes, obesity, intestinal cancer, constipation, and other disorders that have serious adverse effects on the health of human beings and also higher intakes of fiber are linked to lower body weights. So improvement of diet with high fiber will help in maintaining good health when consumed in the required amount.

Findings that Zn and fibre source affected the nutrient apparent total tract digestibility (ATTD), made us hypothesize that interactions could occur affecting the apparent digestibility of Zn and trace elements (TEs) interacting with Zn in the digestive tract. Therefore, the study investigated the effects of Zn and fibre sources on the apparent digestibility and solubility of TEs (Zn, Cu, Fe, Mn) and pH in the small intestinal segments of 40-days-old piglets. In vitro solubility of TEs was estimated using a simulated digestion assay. Feed supplementation with potato fibre (PF) affected the ATTD of all TEs and dry matter as well as mineral solubility in the ileum and/or jejunum without any effect on pH in the small intestine. Intake of PF enhanced Zn and Cu absorption (p < 0.01), but significantly decreased ATTD of Fe and Mn (p < 0.001). Diet supplementation with Zn glycinate decreased Zn absorption in the gut (p < 0.01) and affected the solubility of other TEs in the different digestion phases. Although in vitro solubility of TEs does not provide a good prediction of mineral bioaccessibility, using a combination of in vitro and in vivo methods can enable prediction of the trace mineral absorption.

Identification of recalcitrant factors that limit digestion of forages and the development of enzymatic approaches that improve hydrolysis could play a key role in improving the efficiency of meat and milk production in ruminants. Enzyme fingerprinting of barley silage fed to heifers and total tract indigestible fibre residue (TIFR) collected from feces was used to identify cell wall components resistant to total tract digestion. Enzyme fingerprinting results identified acetyl xylan esterases as key to the enhanced ruminal digestion. FTIR analysis also suggested cross-link cell wall polymers as principal components of indigested fiber residues in feces. Based on structural information from enzymatic fingerprinting and FTIR, enzyme pretreatment to enhance glucose yield from barley straw and alfalfa hay upon exposure to mixed rumen-enzymes was developed. Prehydrolysis effects of recombinant fungal fibrolytic hydrolases were analyzed using microassay in combination with statistical experimental design. Recombinant hemicellulases and auxiliary enzymes initiated degradation of plant structural polysaccharides upon application and improved thein vitrosaccharification of alfalfa and barley straw by mixed rumen enzymes. The validation results showed that microassay in combination with statistical experimental design can be successfully used to predict effective enzyme pretreatments that can enhance plant cell wall digestion by mixed rumen enzymes.

Three ruminally and duodenally cannulated non-lactating Finnish Ayrshire cows were used to investigate ruminal and intestinal digestion of cell-wall carbohydrates by a combinedin situmethod. Five grasses cut at 10 d intervals were incubated in the rumen for 0, 6, 12, 24, 48, 72 and 96 h, and the undegraded residues were exposed to intestinal digestion. With advancing maturity of grass both the rate and extent of cell-wall digestion decreased. At early stages of growth the decreases were faster for the rate of digestion and at late stages of growth for the extent of digestion. Applying a passage rate of 0.02/h in one compartmental rumen model resulted in digestibility values markedly lower than typically observedin vivo.However, applying a rumen model incorporating a selective retention of particles and time-dependent release of particles from the non-escapable pool resulted in much higher digestibility values. Recovery of lignin after 96 h ruminal incubation with a subsequent mobile-bag incubation was very low (from 244 to 460 mg/g). Intestinal disappearance of neutral-detergent fibre (NDF) and hemicellulose decreased with advancing maturity of grass and with increasing length of preceding ruminal incubation period, i.e. with decreasing potential digestibility of the material. Disappearance of hemicellulose was much greater than that of cellulose for intact grasses but the difference diminished with increasing length of preceding rumen incubation period. On average, 195 mg/g of potentially digestible NDF disappeared from the mobile bags in the intestines. The post-ruminal digestion as a proportion of the total NDF digestibility varied between 0.034 and 0.058. Despite methodological problems both in ruminalin situand intestinal mobile bag techniques, these methods can be used to investigate ruminal and intestinal cell-wall digestion and to partition cell-wall digestibility between ruminal and post-ruminal digestion providing that appropriate rumen models are used.

Dietary fibre consists of remnants of edible plant cell polysaccharides and associated substances resistant to hydrolysis by human alimentary enzymes, which may benefit health through a wide range of physiological effects. Inulin and oligofructose are storage carbohydrates found in a number of vegetables, fruits and whole grains. They resist digestion and absorption in the stomach and small intestine of humans, as shown by their almost full recovery at the end of the ileum of healthy or ileostomised volunteers. Inulin and oligofructose thus enter into the large intestine where they are available to fermentation, as demonstrated by increased breath hydrogen. Fermentation of both substrates is complete and no residue is found in human stools. Inulin and oligofructose improve laxation. Their bulking capacity comprised between 1·2 and 2·1 g of stool per g of ingested substrate, results mainly from increases in microbial biomass in the colon. As water content of bacterial cells is high, stools are softer and easier to expulse. Stool frequency is thus increased, particularly in slightly constipated individuals. In addition, likely due to their fermentation properties, inulin and oligofructose also affect the intestinal epithelium (trophicity, mucin expression, etc.), that may strengthen mucosal protection and reduce the risk of gastrointestinal diseases. In summary, inulin and oligofructose are plant carbohydrates, resistant to digestion in the human small intestine and fermented by colonic bacteria. They exert several intestinal physiological effects contributing to maintenance of health. Therefore, inulin and oligofructose fit well within the current concept of dietary fibre.

The agro-food industry generates a large volume of by-products, whose revaluation is essential for the circular economy. From these by-products, dietary fibre concentrates (DFCs) can be obtained. Therefore, the objective of this study was to characterise (a) the proximal composition by analysing soluble, insoluble and total Dietary Fibre (DF), (b) the physicochemical properties, and (c) the phenolic profile of artichoke, red pepper, carrot, and cucumber DFCs. In addition, the bioaccessibility of phenolic compounds was also evaluated after in vitro gastrointestinal and colonic digestions. The results showed that the DFCs had more than 30 g/100 g dw. The water holding and retention capacity of the DFCs ranges from 9.4 to 18.7 g of water/g. Artichoke DFC presented high concentration of phenolic compounds (8340.7 mg/kg) compared to the red pepper (304.4 mg/kg), carrot (217.4 mg/kg) and cucumber DFCs (195.7 mg/kg). During in vitro gastrointestinal digestion, soluble phenolic compounds were released from the food matrix, chlorogenic acid, the principal compound in artichoke and carrot DFCs, and hesperetin-7-rutinoside in red pepper cucumber DFCs. Total phenolic content decreased after in vitro colonic digestion hence the chemical transformation of the phenolic compounds by gut microbiota. Based on the results, DFCs could be good functional ingredients to develop DF-enriched food, reducing food waste.

The attachment of Butyrivibrio fibrisolvens to surfaces was studied. B. fibrisolvens strain E14, sticky (S) and loose (L) that had been reported previously (Nili and Brooker 1995) were used as models. In preliminary studies, the two cell types were compared; studies included physical and growth characteristics in defined, solid or liquid medium containing various carbon sources, the presence of compounds that may induce or inhibit attachment, and their phenotypic stability. Extracellular protein, chromosomal DNA, plasmid and 16S rDNA profiles of the two variants were examined. Compared to the non-adhering L cells, the adhering S cells were shinier, spherical, more intensely pigmented (yellow), more firmly attached to the agar surface and could only be removed with scraping. After longer incubation, the cells were released from the agar but the colonies tended to stick together, and only became separable when further incubated. In contrast, the L cells were non spherical, loosely attached to the agar and separable at all stages of growth. In liquid medium, the S cells tended to clump during the early stages of growth, and be dispersed at later stages. The L cells were dispersed throughout the medium at all stages of growth. The phenotypes of the 2 variants were stable; both variants maintained their characteristics through multiple passages on solid and in liquid medium. The presence of molecules that induced attachment of S or inhibited attachment of L cells were not detected, but it was noted that S cells produced more extensive extracellular polymer than did L cells. The extracellular proteins, chromosomal DNA, endogenous plasmid, and 16S rDNA profiles of the two variants were identical, indicating that they were of the same species. The effect of attachment on nutrient utilisation was studied by comparing the growth of the two variants in various carbon or nitrogen sources, as well as their xylanase, CMCase and proteolytic activities. Although not significant, the attachment of S cells seemed to have a slight effect on nutrient utilisation, compared to L cells. The morphology of the variants were compared and examined by scanning electron microscopy (SEM). Extracellular polymer (EP) biosynthesis and attachment was studied using S and L samples prepared at various stages of growth. The effect of carbon source on morphology was studied using S and L samples prepared from cells grown in the presence of various carbon sources. The L cells seemed unable to spread EP to surfaces or to neighbouring cells, forming globular EP. Compared to other soluble carbon sources, cellobiose seemed to induce more globular (condensed) EP and less polymer spreading. It was also observed that EP might be secreted to the medium at stationary phase. The level of EP production as well as its monosaccharide and fatty acid composition between S and L cells was compared. The cell associated, secreted or total EP was isolated using gradient centrifugation, cell free medium (Stack 1988) or plate (Berri and Rollings 1995) methods, respectively. The effect of carbon source on the level of EP as well as the monosaccharide and fatty acid composition was also studied. The S cells tended to produce more EP than the L cells; the maximum ratio of EP production between S and L cells was approximately 2:1. There were no differences in the monosaccharide and fatty acid compositions between S and L EP, but the proportions of components did differ. This was most pronounced in lipid, especially C16:0 content, which was much higher in S than in L EP. Compared to other soluble carbon sources, less EP and reduced C16:0 was produced in cells grown on cellobiose. It was observed that the S and L EP behaved differently during phenol or water/methanolchloroform extraction, which suggested property differences between their EP. The C16:0 may reflect the presence of lipoteichoic acid (LTA), and there were indications that there may be an association between LTA and extracellular polysaccharide (EPS) in S but not in L EP. An attempt was made to isolate attachment gene(s). S chromosomal DNA was electroporated into competent E. coli or B. fibrisolvens E14 L cells using pBHerm plasmid as a vector. No sticky E. coli transformants were observed, but sticky-like transformants were observed from L cells that were transformed with S DNA. These transformants were stable through 5 passages under selection pressure (10 g/ml of erythromycin), although some revertants were observed after the 3rd passage when the passage was carried out without selection. Total chromosomal DNA and 16 S rDNA profiles of the transformants were identical to the original variants, and together with hybridisation analysis suggested that the transformants and the variants were related. There were indications that chromosomal integration occurred within the sticky-like transformants, probably due to homology between the donor and the host DNA. These studies have shown that B. fibrisolvens strain E14 S and L cells are closely related and that attachment of S cells is associated with characteristics and lipid content of their EP. Genetic complementation studies suggest that a change in attachment phenotype can be brought about by chromosomal integration.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2010

This chapter discusses the machinery of digestion in giraffes. The shape of the mouth of giraffes, the shape and number of their teeth, the shape and size of their tongue and the arrangement of the muscles of eating are unique and have evolved to be perfectly suited to the task of browsing. Comminution of browse is eased by large volumes of saliva secreted from salivary glands that relative to body mass are small. The digestive tract of giraffes consists of a rumen, reticulum, and omasum in addition to the usual stomach and intestines found in any mammal. The forestomachs are smaller and the small and large intestines are longer than those of grazer-ruminants. The quality, succulence and consistency of browse reduces the need for prolonged rumination. Movement of browse through the rumen-reticulum is fast, and it is likely that a mixture of plant cell contents and saliva, can bypass the rumen via an esophageal groove, and be deposited directly into the stomach. 40% of daily energy (mainly in the form of volatile fatty acids) is provided by microbial fermentation of browse in the rumen, and 60% derives from intestinal digestion mainly of glucose), rather than the reverse as found in grazer-ruminants. Significant fermentation of undigested fiber (mainly hemicellulose) occurs in the large intestine. The combination of digestive processes results in very efficient use of the nutrients and an apparent digestibility of ~85%, which is high. To provide the browse needed to meet daily energy demand giraffes need a home range of ~60 km².

Fenugreek is one of the familiar spices found in human food and has been used extensively for curing numerous disorders. It provides natural food fibers and other nutrients required in the human body. It is used in functional foods, traditional foods, and nutraceuticals as well as in physiological uses such as antidiabetic agent, antibacterial, hypocholesterolemic, hypoglycemic, antioxidant, enzymatic pathway, and modifier gastric stimulant. It has a valuable influence on digestion and also has the capability to modify food texture. In modern food technology, it is used as a food stabilizer, adhesive, and emulsifying agent due its fiber, protein, and gum content. Recent pharmocological exploration of the seed extract of this plant discovered anticancer properties. Although it has many potential effects, there are some side effects as well; therefore, there is a greater need to study the pharmacological and toxicological effects of fenugreek to examine its clinical efficacy and safety.

Fenugreek is one of the familiar spices found in human food and has been used extensively for curing numerous disorders. It provides natural food fibers and other nutrients required in the human body. It is used in functional foods, traditional foods, and nutraceuticals as well as in physiological uses such as antidiabetic agent, antibacterial, hypocholesterolemic, hypoglycemic, antioxidant, enzymatic pathway, and modifier gastric stimulant. It has a valuable influence on digestion and also has the capability to modify food texture. In modern food technology, it is used as a food stabilizer, adhesive, and emulsifying agent due its fiber, protein, and gum content. Recent pharmocological exploration of the seed extract of this plant discovered anticancer properties. Although it has many potential effects, there are some side effects as well; therefore, there is a greater need to study the pharmacological and toxicological effects of fenugreek to examine its clinical efficacy and safety.

Environmental effects from traditional energy sources and government regulations, necessitate the use of alternative energies like biogas for many uses including drying and refrigeration. Biowaste produced in educational institutions will not be uniform over the year. The non-uniform supply of biowastes, the absence of studies on bio digestion of likelihood biomass, the unreliability of energy from such conversion and the profitability of its usage in most applications are some of the factors to be considered while implementing this technology. In this regard, theoretical and experimental evaluations were carried out to accurately forecast biogas generation capabilities in educational campuses for obtaining biofuels with quantity and efficiency. It is observed that biogas generation with 52 to 58% methane content can be possible during an academic year. The quality of biogas shows that it is appropriate for almost any application. A broader analysis on different types of biogas digesters was conducted for their suitability in academic institutions. The economic benefits are analyzed for incorporating three biogas digesters namely KVIC, Fiber Reinforced Plastic (FRP) type and JANATA. There are some encouraging results to confirm the economic feasibility of biogas plants including positive net present value. Biogas generation with digesters of capacities varying between 25 and 450 cubic meter shows payback periods varies from 3.18 to 7.59 years, which confirms that it is profitable to use digesters in this range of capacities.

The current demand for plant-based food indicates that the food market is providing alternatives for products that are currently commercially available. This chapter discusses the possible use of germinated bean seeds as a raw material in the production of substitutes for dairy products, including fermented ones. Beans are a valuable source of easily digestible protein, carbohydrates, minerals, and various vitamins (e.g., B vitamin group). They also contain significant amounts of fiber which affects the proper functioning of the digestive system and antioxidant compounds. The fat content is low and is estimated to be around only 1–2%. However, it is mainly (about 70%) constituted by unsaturated fatty acids, including the polyunsaturated ones such as linoleic acid or linolenic acid, which are desirable in the human diet for the prevention of cardiovascular diseases or cancer. Biological processes such as germination or fermentation may improve the nutritional value of bean seeds (by increasing the content, digestibility, and bioavailability of some nutrients and by eliminating undesirable components) and deliver live cells of prohealth bacteria (lactic acid bacteria, propionic acid bacteria, or bifidobacteria).

Methane gas has a very significant contribution to the increase in greenhouse gases (GHG) globally. The livestock sector, especially ruminants, causes the issue of increasing GHG concentrations. The chapter presents the issue of reducing methane gas production from cattle. Various experiments to reduce methane gas production from ruminants have been carried out and have shown varying results. This series of results of the author\'s research on reducing methane gas production in livestock in beef cattle based on agriculture by-product to animal feed is addressed with this background. Agriculture by-products such as oil palm fronds and rice straw can be used to feed beef cattle in Indonesia. However, agriculture by-product as animal feed can reduce feed efficiency and increase methane gas production due to the high lignin content. Therefore, various alternatives are carried out to optimize the utilization of this plantation waste. One of them is the use of feed additives and methanogenesis inhibitors. The author\'s series of research using feed additives (direct-fed microbial) and various methanogenesis inhibitors (plant bioactive compounds and dietary lipids) were tested to determine their effect on nutrient digestibility and methane gas production in feed based on plantation waste. Experiments were carried out in vitro and in vivo on various types of ruminants. Plant bioactive compounds such as tannins are proven to reduce methane production through their ability to defaunate in the rumen. Tannins may also have direct effect on methanogens and indirectly by reducing fiber digestion. In addition, direct-fed microbial (DFM) feed additives such as Saccharomyces cerevisiae, Bacillus amyloliquifaciens, and Aspergillus oryzae can be used in ruminants to increase livestock productivity. Furthermore, virgin coconut oil as a dietary lipid contains medium-chain fatty acids, mainly lauric acid, which can inhibit the development of ciliates of protozoa and methanogenic bacteria that produce methane in the rumen.

Wastewater treatment is the method by which sewage of both residential and industrial sources is processed to promote public health and reduce environmental impacts on receiving waters. This physical and biological process generates sludge, which after being treated to reduce pathogens, is referred to as biosolids. In the US there are over 16,000 wastewater treatment plants (WWTP), and every year they produce approximately 7 million tons of biosolids according to the EPA.1 These biosolids are handled differently depending upon local conditions, but most are either buried in landfills, land applied for agriculture or incinerated. Reducing the volume of biosolids produced by each facility is desirable for improving operational efficiency since lower volumes are easier to manage and cheaper to handle and dispose. Most facilities utilize either aerobic digestion to process sludge into biosolids, but larger facilities use anaerobic digestion because this process reduces the overall volume of solids left for management. Anaerobic digestion is more complex and capital intensive, so typically only those facilities treating flows higher than 5 million gallons per day (MGD) use anaerobic digestion. Given current economic conditions and rising energy costs, however, anaerobic digestion is becoming more attractive to utility managers as they attempt to offset energy costs. The anaerobic process produces methane gas. Also called biogas, methane can be utilized not only to fire boilers for heating digesters and nearby buildings, but also to fuel internal combustion engines, microturbines or fuel cells to generate power for plant processes such as blowers in the aeration system. There is also the potential for WWTPs to obtain carbon credits for utilizing renewable energy, especially in those states with renewable portfolio standards. Because anaerobic digestion has limited application in the US, this study evaluated economic viability at plants with design flows less than 5 MGD by incorporating codigestion of food waste to improve the production of biogas for use as energy to reduce operational costs and recover capital costs.