Prebiotics: Present and future in food science and technology

Because of its resident microbiota, the human colon is one of the body’s most metabolically active organs. The use of diet to fortify certain gut flora components is a popular current aspect of functional food sciences and prebiotics have a significant role. Prebiotics are selectively fermented ingredients that allow specific changes, both in the composition and/or activity in the gastrointestinal microbiota that confers benefits upon host well-being and health. Improved techniques for analysis of the gut microflora, new food manufacturing biotechnologies, and increased understanding of the metabolism of prebiotic inulin and oligosaccharides by probiotics are facilitating development. Such developments are leading us to the time when we will be able to rationally develop prebiotics for specific functional properties and health outcomes. Thus, this review will focus on the progress of prebiotics in food science and technology in understanding the important role of prebiotics in health, beginning at the rationale of gut microflora and interactions with prebiotics. Furthermore, the classification criteria, food applications and safety assessment of prebiotics as food ingredient is also discussed.     

Intestinal fermentation of lactose and prebiotic lactose derivatives, including human milk oligosaccharides

This review describes the recent advances in technology to study fermentation of lactose and its prebiotic derivatives, including human milk oligosaccharides. Novel molecular tools to identify members of the microbiota that ferment these substrates are highlighted, as well as the use of stable isotope-labelled substrates to be able to trace exactly what happens with the prebiotics. The combined use of these novel technologies allows for the detailed pipeline from prebiotic substrate to microorganism(s) involved in fermentation of that substrate and the microbial metabolites that are produced by these microorganisms.     

Influence of functional food components on gut health

Intestinal epithelial cells (IECs) lining the gastrointestinal tract establish a barrier between external environments and the internal milieu. An intact intestinal barrier maintains gut health and overall good health of the body by preventing from tissue injury, pathogen infection and disease development. When the intestinal barrier function is compromised, bacterial translocation can occur. Our gut microbiota also plays a fundamentally important role in health, for example, by maintaining intestinal barrier integrity, metabolism and modulating the immune system, etc. Any disruption of gut microbiota composition (also termed dysbiosis) can lead to various pathological conditions. In short, intestinal barrier and gut microbiota are two crucial factors affecting gut health. The gastrointestinal tract is a complex environment exposed to many dietary components and commensal bacteria. Dietary components are increasingly recognized to play various beneficial roles beyond basic nutrition, resulting in the development of the functional food concepts. Various dietary modifiers, including the consumption of live bacteria (probiotics) and ingestible food constituents such as prebiotics, as well as polyphenols or synbiotics (combinations of probiotics and prebiotics) are the most well characterized dietary bioactive compounds and have been demonstrated to beneficially impact the gut health and the overall well-being of the host. In this review we depict the roles of intestinal epithelium and gut microbiota in mucosal defence responses and the influence of certain functional food components on the modulation of gut health, with a particular focus on probiotics, prebiotics and polyphenols.     

Prebiotics: Application in Bakery and Pasta Products

The concept of functional foods has markedly moved toward gastrointestinal health. The prebiotic approach aims at achieving favorable milieu in the human gut by stimulating beneficial bacteria. Several food products act as substrates for the application of prebiotic substances and bakery products are one such category. The trend of increasing consumption of bakery products justifies the choice of using them as vehicles for delivering the prebiotic compounds. Apart from the health benefits, the prebiotic compounds also have nutritional and technological effects in the food matrix. In addition to increasing the fiber content, the candidate prebiotics also affect the rheology and final quality of bakery products. The prebiotic compounds are selected accordingly to confer desirable properties in the final product. The health advantages of prebiotics being well established, the technological advantages in bakery products such as bread and biscuits and extruded product such as pasta are discussed elaborately.     

Dietary fibres as "prebiotics": implications for colorectal cancer

A "prebiotic" is a nondigestible food ingredient whose beneficial effects on the host result from the selective stimulation of growth and/or activity of members of the bacterial community that inhabits the human bowel (the gut microbiota). Although much of the prebiotic literature focuses on nondigestible oligosaccharides, such as oligofructose, most dietary fibres that are fermentable carbohydrates could be considered as prebiotics. Early studies suggested that colonic bacteria were risk factors for colon cancer. However, altering the composition or metabolic activity of the bowel microbiota through the use of dietary fibre might be important in reducing the prevalence of colorectal cancer. Mechanisms for beneficial effects of prebiotics might include changing the activity of exogenous carcinogens through modulating metabolic activation and/or detoxification, or stimulating the production of the short-chain fatty acid, butyrate. However, modern analytical techniques suggest that an important consequence of a modified bacterial community could be a change in the expression not only of a range of different bacterial genes in bowel contents, but also in the bowel mucosa of the host. Analogous with observations with probiotics, the stimulation of cytokines and modification of immune responses could be important in producing beneficial effects. Compared with transitory effects of probiotics, the prebiotic action of fermentable carbohydrates potentially provide the opportunity for sustainable modulation of activity of the gut microbiota. However, their mechanisms of action in humans are speculative, and research aimed at providing an integrated view of the gut microbiota and dietary fibre nutrition of humans needs to be developed.     

Effectiveness of probiotics,prebiotics, and prebiotic‐like components in common functional foods

The bioactive ingredients in commonly consumed foods include, but are not limited to, prebiotics, prebiotic‐like components, probiotics, and postbiotics. The bioactive ingredients in functional foods have also been associated with beneficial effects on human health. For example, they aid in shaping of gut microflora and promotion of immunity. These functional components also contribute in preventing serious diseases such as cardiovascular malfunction and tumorigenesis. However, the specific mechanisms of these positive influences on human health are still under investigation. In this review, we aim to emphasize the major contents of probiotics, prebiotics, and prebiotic‐like components commonly found in consumable functional foods, and we present an overview of direct and indirect benefits they provide on human health. The major contributors are certain families of metabolites, specifically short‐chain fatty acids and polyunsaturated fatty acids produced by probiotics, and prebiotics, or prebiotic‐like components such as flavonoids, polyphenols, and vitamins that are found in functional foods. These functional ingredients in foods influence the gut microbiota by stimulating the growth of beneficial microbes and the production of beneficial metabolites that, in turn, have direct benefits to the host, while also providing protection from pathogens and maintaining a balanced gut ecosystem. The complex interactions that arise among functional food ingredients, human physiology, the gut microbiota, and their respective metabolic pathways have been found to minimize several factors that contribute to the incidence of chronic disease, such as inflammation oxidative stress.     

益生元对早产儿、肥胖及老年群体肠道菌群调节机制的研究现状

肠道微生物是人体不可或缺的一部分,微生物多样性和群落结构的稳定性与机体健康息息相关。临床研究 表明,肠道微生物数量在特殊人群的疾病发展中扮演着重要角色。益生元作为人体膳食重要的组成部分,主要为植 物源的非消化性低聚糖和膳食纤维,其具有选择性促进肠道内特定菌群增殖与活力的效果。本文以肠道微生物在人 体中的变化过程为研究对象,主要对比3 类特殊人群（早产儿、肥胖人群及老年人）的肠道微生物定植差异以及益 生元对此类人群肠道菌群的调节作用。为益生元的肠道菌群调节机理和益生元功能性食品开发提供理论依据。     

Gluco-oligosaccharides as potential prebiotics: Synthesis,purification, structural characterization,and evaluation of prebiotic effect

Prebiotics have long been used to modulate the gut microbiota and improve host health. Most established prebiotics are nondigestible carbohydrates, especially short-chain oligosaccharides. Recently, gluco-oligosaccharides (GlcOS) with 2–10 glucose residues and one or more O-glycosidic linkage(s) have been found to exert prebiotic potentials (not fully established prebiotics) because of their selective fermentation by beneficial gut bacteria. However, the prebiotic effects (non-digestibility, selective fermentability, and potential health effects) of GlcOS are highly variable due to their complex structure originating from different synthesis processes. The relationship between GlcOS structure and their potential prebiotic effects has not been fully understood. To date, a comprehensive summary of the knowledge of GlcOS is still missing. Therefore, this review provides an overview of GlcOS as potential prebiotics, covering their synthesis, purification, structural characterization, and prebiotic effect evaluation. First, GlcOS with different structures are introduced. Then, the enzymatic and chemical processes for GlcOS synthesis are critically reviewed, including reaction mechanisms, substrates, catalysts, the structures of resultant GlcOS, and the synthetic performance (yield and selectivity). Industrial separation techniques for GlcOS purification and structural characterization methods are discussed in detail. Finally, in vitro and in vivo studies to evaluate the non-digestibility, selective fermentability, and associated health effects of different GlcOS are extensively reviewed with a special focus on the GlcOS structure–function relationship.     

Dietary Polyphenols and Human Gut Microbiota: a Review

Dietary polyphenols are substrates for colonic microbiota. They and their metabolites contribute to the maintenance of gastrointestinal health by interacting with epithelial cells, and largely by modulating the gut microbial composition. Polyphenols may act as promoting factors of growth, proliferation, or survival for beneficial gut bacteria—mainly Lactobacillus strains—and thus, exerting prebiotic actions and inhibiting the proliferation of some pathogenic bacteria such as Salmonella and Helicobacter pylori species. To date the interactions affecting metabolic pathways and numerous metabolites of dietary polyphenols have been widely documented. However, the effects of dietary polyphenols on the modulation of the intestinal ecology and on the growth of gut microbial species are still poorly understood. This paper summarizes data on the influence of dietary polyphenols on gut microbiota and the main interactions between dietary polyphenols and beneficial and pathogenic intestinal bacteria.     

Evaluation of potential prebiotics: a review

Prebiotics are any undigested food ingredients that are selectively fermented and allow for specific changes in the gut microbiota, thus improving the hosts’ health. In order to assess the potential of a food component to be considered as a prebiotic ingredient, several in vitro and in vivo experimentations need to be performed to provide scientific substantiation. In vitro studies are widely used because they are faster, cheaper, and more ethical compared to in vivo studies. However, in vitro studies faced difficulties in simulating the highly complex physiological and physiochemical events occurring in animal and human digestive tracts. Therefore, it is recommended that the results of in vitro studies be justified with in vivo experimentations to support their specific methodologies. Devised standard procedures for the evaluation and validation of prebiotic ingredients will boost confidence among the scientific community, approval of regulators, and acceptance from consumers on prebiotics and functional food science.     

益生元精准化研究进展

益生元在调节肠道菌群方面一直发挥着重要的作用。越来越多的研究数据、临床实验结果和报告表明益生 元在预防和干预治疗肠易激综合征、糖尿病、肥胖症等慢性代谢和免疫系统疾病方面均具有有益的效果。纵观精准 营养的发展趋势,可以预见益生元将对新兴的微生态健康医疗产业产生重要影响。本文通过回顾益生元最新的研究 发现和功能作用范例,着重探讨益生元概念的演变。对益生元生理作用机制的深入认识有助于定义和发展精准营养 分支之一的“精准益生元”概念。因此,有必要对益生元的特性、组成和结构进行更深入的研究,进一步探索益生 元、细菌种类、特定生理功能三者之间的关系。另外,在细胞生物学分子水平层面上明确益生元的作用机制将有助 于定制个性化益生元配方和营养摄入方案,从而促进与保障人类健康。     

Effect of the Lactobacillus rhamnosus strain GG and tagatose as a synbiotic combination in a dextran sulfate sodium-induced colitis murine model

Synbiotics, a combination of prebiotics and probiotics, produce synergistic effects to promote gastrointestinal health. Herein, we investigated the synbiotic interaction between the Lactobacillus rhamnosus strain GG (LGG; a probiotic strain) and tagatose (a prebiotic) in a dextran sulfate sodium (DSS)-induced colitis murine model. Initially, body weight, food intake, and clinical features were dramatically decreased after treatment with DSS, and the addition of LGG, tagatose, or both ameliorated these effects. In our pyrosequencing analysis of fecal microbiota, DSS treatment increased the abundance of Proteobacteria and decreased that of Firmicutes. When LGG and tagatose were administered as synbiotics, the gut microbiota composition recovered from the dysbiosis caused by DSS treatment. In particular, the abundance of Bacteroides, Lactobacillus, and Akkermansia was significantly associated with probiotic, prebiotic, and synbiotic treatments. Taken together, our results suggest that LGG and tagatose as synbiotics can alleviate colitis, and synbiotics could be applied as dietary supplements in dairy foods such as yogurt and cheese.     

Structural and rheological characterisation of heteropolysaccharides produced by lactic acid bacteria in wheat and sorghum sourdough

Hydrocolloids improve the volume, texture, and shelf life of bread. Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) during sourdough fermentation can replace hydrocolloids. It was the aim of this study to determine whether heteropolysaccharides (HePS) synthesized intracellularly from sugar nucleotides by glycosyltransferases are produced in wheat and gluten-free sorghum sourdough at effective levels. The HePS-producing strains Lactobacillus casei FUA3185, L. casei FUA3186, and Lactobacillus buchneri FUA3154 were used; Weissella cibaria 10M producing no EPS in the absence of sucrose served as control strain. Cell suspensions of L. buchneri in MRS showed the highest viscosity at low shear rate. Glycosyltransferase genes responsible of HePS formation in LAB were expressed in sorghum and wheat sourdough. However, only HePS produced by L. buchneri influenced the rheological properties of sorghum sourdoughs but not of wheat sourdoughs. Sorghum sourdough fermented with L. buchneri exhibited a low |G^∗| compared to the control, indicating a decrease in resistance to deformation. An increase in tan δ indicated decreased elasticity.The use of LAB producing HePS expands the diversity of EPS and increases the variety of cultures for use in baking.     

Bifidobacterium carbohydrases-their role in breakdown and synthesis of (potential) prebiotics

There is an increasing interest to positively influence the human intestinal microbiota through the diet by the use of prebiotics and/or probiotics. It is anticipated that this will balance the microbial composition in the gastrointestinal tract in favor of health promoting genera such as Bifidobacterium and Lactobacillus. Carbohydrates like non-digestible oligosaccharides are potential prebiotics. To understand how these bacteria can grow on these carbon sources, knowledge of the carbohydrate-modifying enzymes is needed. Little is known about the carbohydrate-modifying enzymes of bifidobacteria. The genome sequence of Bifidobacterium adolescentis and Bifidobacterium longum biotype longum has been completed and it was observed that for B. longum biotype longum more than 8% of the annotated genes were involved in carbohydrate metabolism. In addition more sequence data of individual carbohydrases from other Bifidobacterium spp. became available. Besides the degradation of (potential) prebiotics by bifidobacterial glycoside hydrolases, we will focus in this review on the possibilities to produce new classes of non-digestible oligosaccharides by showing the presence and (transglycosylation) activity of the most important carbohydrate modifying enzymes in bifidobacteria. Approaches to use and improve carbohydrate-modifying enzymes in prebiotic design will be discussed.     

Changes in polyphenol fractions and bacterial composition after in vitrofermentation of apple peel polyphenol by gut microbiota

The changes in polyphenol fractions after in vitro fermentation of apple peel polyphenol (APP) by gut microbiota as well as the effects of APP on the growth, pH value, short-chain fatty acids (SCFAs) production and intestinal flora composition of gut microbiota fermentation were firstly explored in this study. The relative abundance of Lactobacillus in the APP group was 49.55% with an increment of 49.40% compared with the blank group, while that of Bifidobacterium was 13.32%. Moreover, the flora produced 37.093 ± 0.478 mM of SCFAs including acetic acid, propionic acid, butyric acid and valeric acid during the process of fermentation, thus reduced the environmental pH value. In addition, polyphenol fractions in APP were altered by gut microbiota fermentation to some extent, for example, glycosides were hydrolysed to aglycones. These findings suggested APP as a potential prebiotic agent to alleviate the disorder of intestinal flora.     

Prevention and Control of Diseases by Use of Pro- and Prebiotics (Synbiotics)

Probiotics are microorganisms (bacteria or yeasts) that can reestablish and recolonize the human intestinal micro flora to give beneficial effect to a host. Prebiotics are the food ingredients that are nondigestible and affect the consumer by encouraging the number and activity of beneficial but selective colonic bacteria. The probiotics perform more efficiently in the presence of prebiotics, with the enhanced beneficial potential of live microorganisms having additional benefits of the prebiotic. Due to the concept, recently much research attention is focused on the combined use of probiotics and prebiotics, generally known as synbiotics, to get their synergistic health properties. This article provides an overview of possible synbiotic combinations, and their mode of action and health benefits upon consumption. In addition, research trends are also elaborated.     

Prebiotics: A Potential Treatment Strategy for the Chemotherapy-damaged Gut?

Mucositis, characterized by ulcerative lesions along the alimentary tract, is a common consequence of many chemotherapy regimens. Chemotherapy negatively disrupts the intestinal microbiota, resulting in increased numbers of potentially pathogenic bacteria, such as Clostridia and Enterobacteriaceae, and decreased numbers of “beneficial” bacteria, such as Lactobacilli and Bifidobacteria. Agents capable of restoring homeostasis in the bowel microbiota could, therefore, be applicable to mucositis. Prebiotics are indigestible compounds, commonly oligosaccharides, that seek to reverse chemotherapy-induced intestinal dysbiosis through selective colonization of the intestinal microbiota by probiotic bacteria. In addition, evidence is emerging that certain prebiotics contribute to nutrient digestibility and absorption, modulate intestinal barrier function through effects on mucin expression, and also modify mucosal immune responses, possibly via inflammasome-mediated processes. This review examines the known mechanisms of prebiotic action, and explores their potential for reducing the severity of chemotherapy-induced mucositis in the intestine.     

Effects of deep frying vegetable oils rich in PUFAs on gut microbiota in rats

Vegetable oils rich in PUFAs are widely used in daily cooking and food industry, and PUFAs could be utilised by gut microbiota and present prebiotic effects. However, PUFAs are unstable in high-temperature cooking like frying. In the current study, we aimed to explore the influence of thermally oxidised oils rich in PUFA on gut microbiota. Two vegetable oils: omega-3 alpha-linolenic acid (ALA)-rich perilla oil or omega-6 linoleic acid-rich sunflower oil were heated at 180 °C for 10 h, and then fed to male SD rats for 14 weeks. Administration of heated perilla oil dramatically increased the relative abundance of Akkermansia muciniphila, a recent identified probiotics which may weaken intestinal mucus barrier, and inhibited the expression of several tight junction-related genes including occludin and claudin-1 in colon. Consumption of thermally oxidised sunflower oil stimulated the proliferation of Bifidobacterium. Our findings suggested that thermally processing has complicated effects on the prebiotic effects of vegetable oils rich in PUFAs, and perilla oil fried foods may be potential sources to stimulate Akkermansia proliferation in gut.     

膳食纤维与肠道微生物互作调节食物过敏的研究进展

食物过敏的发病率逐步上升,遗传之外的影响因素如饮食受到密切关注.其中,高膳食纤维的食物摄入可能通过与肠道菌群互作和调节肠道黏膜免疫的方式来诱导口服耐受和降低食物过敏发生率.本文在阐述膳食纤维、肠道菌群和食物过敏三者的联系及研究现状的基础上,重点讨论膳食纤维通过调节肠道菌群影响食物过敏的发病机制,旨在为研究过敏人群的合理...