Galactooligosaccharides: novel components of designer foods

Since introduction of functional foods, commercialization of the traditionally used probiotics has ushered in more followers into the new fraternity of sophisticated, health-conscious consumers. In 1995, this was followed by the first introduction of prebiotics. Prebiotics are defined as "a non-digestible feed supplement, beneficially affecting the host by selectively stimulating growth and/or activity in one or a limited number of bacteria in the colon." The number of new product introductions with prebiotics has steeply increased over the last few years. Paradoxically, probiotics have limited applications as these cannot be used in wide range of food products because of their viability issue. Fortunately, prebiotics do not suffer from any such constraint and can be used in a wide range of food products. Probiotics do not have a long shelf life in their active form. In most cases, refrigeration is required to maintain the shelf life. While probiotics are predominantly used in fermented dairy products, the use of prebiotics has expanded into other food categories. Prebiotics have successfully been incorporated in a wide variety of human food products such as baked goods, sweeteners, yoghurts, nutrition bars, and meal replacement shakes. For instance, the introduction of galacto-oligosaccharides (GOS) into baby foods has been very successful. GOS, which are identical to the human milk oligosaccharides, has emerged with strong clinical support for both digestive and immune health. Various aspects related to GOS such as types and functions of functional food constituents with special reference to GOS, their role as prebiotics, and enhanced industrial production through microbial intervention are dealt in this review.     

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.     

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.     

Importance of food in probiotic efficacy

Foods are carriers for the delivery of probiotics to the human body. In addition, foods help to buffer the probiotic through the gastrointestinal tract, regulate their colonization and contain other functional ingredients, such as bioactive components, which may interact with probiotics to alter their functionality and efficacy. The growth and survival of probiotics during gastric transit is affected by the physico-chemical properties of food carriers. Gastric acid, juices and bile tolerance, adherence to gastrointestinal epithelium and the acid production of probiotics are also affected by the food ingredients used in probiotic delivery. Same probiotic strains could vary in functional and technological properties in the presence of different food ingredients. Prebiotic food ingredients encourage the growth of probiotic bacteria. The appropriate combination of prebiotics and probiotics manifest higher potential for a synergistic effect. Originally, probiotic delivery was consistently associated with foods, particularly dairy foods. But nowadays, there is an increasing trend toward using probiotics in different food systems despite its original sources and even as nutraceuticals, such as in capsules. This changing trend in delivering probiotics may lead to a reduction in functional efficacy due to the exclusion of the potential synergistic effect of the food. Thus, selection of suitable food systems to deliver probiotics is a vital factor that should be considered in developing functional probiotic foods. This review focuses on information related to the effect of processed food products on functional efficacy of probiotics.     

Prevention of infections by probiotics

'Viable bacteria that exhibit beneficial effects for health based on improvement of balance of intestinal bacterial flora' was the most common definition of probiotics, but the diversity of their action mechanisms, including immune regulation, has been clarified, and probiotics have recently been broadly defined as 'live microorganisms which when administered in adequet amounts confer a health benefit on the host'. Coined words such as prebiotics, describing non-digestible food fiber components that contribute to host health by activating proliferation and function of beneficial intestinal bacteria, and synbiotics, describing a combination of probiotics and prebiotics have also been established as medical expressions. In this report, clinical studies of probiotics, prebiotics, and synbiotics on prevention of infection by various infectious diseases in humans are reviewed. The effects of and action mechanisms against sporadic intestinal infectious diseases that are difficult to investigate in humans (enterohemorrhagic Escherichia coli and Salmonellosis) in experimental animal models are also reviewed. Finally, points necessary for clarification of the role of probiotics in health care, and their functions in health care foods are discussed.     

The Beneficial Use of Cereal and Cereal Components in Probiotic Foods

Cereals and cereal components can be used as fermentation substrates for probiotic organisms imparting prebiotic effects. Consumer interest in healthy functional foods has resulted in the need for food products with versatile health-benefiting properties. The conventional choice for probiotic food applications has been dairy-based products, but whole grain-based probiotic functional foods have debuted in Japan and Europe. In the US, pro- and prebiotics are mainly marketed as dietary supplements, but are moving towards inclusion in the diet as mainstream foods. Cereal constituents, such as wheat bran-based ingredients fermented with probiotics, would enhance consumer health with the benefits of probiotics, bran fiber, and healthful bioactive components.     

Development of functional ingredients for gut health

Microbial reactions in the gut have an essential role not only in gut health, but in general human health. The gut is the site of active fermentation of non-digestible diet components, as well as bioconversions and absorption of plant-derived compounds, such as phenolics. When developing nutritionally designed foods that promote health through gut microbial reactions, three different types of food ingredients can be used: living micro-organisms (probiotics), non-digestible carbohydrates (dietary fiber and prebiotics) and bioactive plant secondary metabolites (e.g. phenolics).     

Review on potential non-dairy synbiotic beverages: a preliminary approach using legumes

In the past few years, certain functional foods have gained consumer acceptance like those containing synbiotics (a blend of both prebiotics and probiotics) in different food systems. Synbiotics enhance gut functionality and confer health benefits to humans. However, due to the limitations exerted by dairy-based matrices like lactose intolerance, milk allergies, limited shelf life and inclination towards veganism, consumer’s interest in non-dairy foods has increased. Among the non-dairy matrices, legumes (such as chickpeas, kidney beans, lupin) are the less explored areas with the majority focus on only soya beans. The present review gives brief information about the different research associating with various legume-based probiotics, prebiotics and synbiotic foods narrowing down specifically to beverages. The integration of such information will allow the researchers to explore product development using new prebiotic ingredients that have not been studied in much detail and hold an exceptional potential to be employed in the synbiotic food industry.     

Probiotics and prebiotics--perspectives and challenges

Owing to their health benefits, probiotics and prebiotics are nowadays widely used in yogurts and fermented milks, which are leader products of functional foods worldwide. The world market for functional foods has grown rapidly in the last three decades, with an estimated size in 2003 of ca US$ 33 billion, while the European market estimation exceeded US$ 2 billion in the same year. However, the production of probiotics and prebiotics at industrial scale faces several challenges, including the search for economical and abundant raw materials for prebiotic production, the low-cost production of probiotics and the improvement of probiotic viability after storage or during the manufacturing process of the functional food. In this review, functional foods based on probiotics and prebiotics are introduced as a key biotechnological field with tremendous potential for innovation. A concise state of the art addressing the fundamentals and challenges for the development of new probiotic- and prebiotic-based foods is presented, the niches for future research being clearly identified and discussed.     

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.     

Production, health aspects and potential food uses of dairy prebiotic galactooligosaccharides

Galactooligosaccharides are sugars composed of 3-10 molecules of galactose and glucose via a transgalactosylation reaction mediated by the enzyme β-galactosidase. Prebiotics are non-digestible food ingredients that pass through the upper digestive system relatively intact and ferment in the lower colon, producing short-chain fatty acids that support the growth of supplemented or indigenous colonic microbiota. Galactooligosaccharides and other prebiotic ingredients are increasingly being recognized as useful dietary tools for the modulation of the colonic microflora toward a healthy balance. Galactooligosaccharides compare well to other oligosaccharides in terms of their prebiotic, immunomodulation, and functional properties in foods. This review elucidates the galactooligosaccharide production process from refined lactose and/or cheese whey permeates, galactooligosaccharide market share and economic value, their health properties, and potential food applications.     

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 as functional foods: A review

Prebiotics are short chain carbohydrates that are non-digestible by digestive enzymes in humans and selectively enhance the activity of some groups of beneficial bacteria. In the intestine, prebiotics are fermented by beneficial bacteria to produce short chain fatty acids. Prebiotics also render many other health benefits in the large intestine such as reduction of cancer risk and increase calcium and magnesium absorption. Prebiotics are found in several vegetables and fruits and are considered functional food components which present significant technological advantages. Their addition improves sensory characteristics such as taste and texture, and enhances the stability of foams, emulsions and mouthfeel in a large range of food applications like dairy products and bread. This contribution reviews bioactives from food sources with prebiotic properties. Additionally, food application of bioactive prebiotics, stimulation of the viability of probiotics, health benefits, epidemiological studies, and safety concerns of prebiotics are also reviewed.     

Application of cereals and cereal components in functional foods: a review

The food industry is directing new product development towards the area of functional foods and functional food ingredients due to consumers' demand for healthier foods. In this respect, probiotic dairy foods containing human-derived Lactobacillus and Bifidobacterium species and prebiotic food formulations containing ingredients that cannot be digested by the human host in the upper gastrointestinal tract and can selectively stimulate the growth of one or a limited number of colonic bacteria have been recently introduced into the market. The aim of these products is to affect beneficially the gut microbial composition and activities. Cereals offer another alternative for the production of functional foods. The multiple beneficial effects of cereals can be exploited in different ways leading to the design of novel cereal foods or cereal ingredients that can target specific populations. Cereals can be used as fermentable substrates for the growth of probiotic microorganisms. The main parameters that have to be considered are the composition and processing of the cereal grains, the substrate formulation, the growth capability and productivity of the starter culture, the stability of the probiotic strain during storage, the organoleptic properties and the nutritional value of the final product. Additionally, cereals can be used as sources of nondigestible carbohydrates that besides promoting several beneficial physiological effects can also selectively stimulate the growth of lactobacilli and bifidobacteria present in the colon and act as prebiotics. Cereals contain water-soluble fibre, such as beta-glucan and arabinoxylan, oilgosaccharides, such as galacto- and fructo-oligosaccharides and resistant starch, which have been suggested to fulfil the prebiotic concept. Separation of specific fractions of fibre from different cereal varieties or cereal by-products, according to the knowledge of fibre distribution in cereal grains, could be achieved through processing technologies, such as milling, sieving, and debranning or pearling. Finally, cereal constituents, such as starch, can be used as encapsulation materials for probiotics in order to improve their stability during storage and enhance their viability during their passage through the adverse conditions of the gastrointestinal tract. It could be concluded that functional foods based on cereals is a challenging perspective, however, the development of new technologies of cereal processing that enhance their health potential and the acceptability of the food product are of primary importance.     

Introduction to pre- and probiotics

During the last 2–3 decades, attempts for improving the human health status, are focusing on ways for modulating the indigenous intestinal flora by live microbial adjuncts, now called “probiotics”. Comprising ca. 65% of the functional food world market, probiotics represent the major and still growing segment of this huge market, estimated to exceed a total volume of US $ 75 billion. The most typical active components of probiotic products are lactic acid bacteria, including bifidobacteria, lactobacilli and enterococci. Health claims related to probiotics are numerous, but include maintenance of normal/healthy intestinal flora and protection against infections, alleviation of lactose intolerance, and stimulation of the immune system. Strains with proven beneficial effects may be consumed in relatively high numbers in products, and are collectively called probiotics. In addition. bifidobacteria and lactobacilli, typical inhabitants of the human GIT, are considered beneficial, and may be stimulated by non-digestible food ingredients such as oligosaccharides, collectively called prebiotics. Probably aimed at the two “target regions” of the GIT, pre- and probiotics may be combined in a food product, called a synbiotic. Confirmed health claims are discussed and reference will be made to open questions and research challenges.     

低聚半乳糖的生理功能研究进展

低聚半乳糖作为一种益生元越来越受到人们的关注,在功能性食品方面应用越加广泛。低聚半乳糖能够在肠道内选择性增殖益生菌发酵生成短链脂肪酸,与肠道微生物协同参与生理功能机制调节,在保障肠道健康、免疫系统调节、抑制肿瘤细胞生成、改善人体矿物质吸收、改善心血管疾病等机制方面发挥重要的作用。本文从分子水平出发,全面剖析了低聚半乳糖及其代谢产物短链脂肪酸在维持肠道微生物平衡、抵抗肠道病毒感染、免疫机制调节、结直肠癌的抑制、脂质代谢的调节及血糖水平控制等功效方面的作用机理。为低聚半乳糖在功能性食品开发及健康保健领域的应用提供参考。     

New trends in food processing

In this work some of the newest trends in food processing are reviewed. This revision intends to provide an updated overview (including works published until February 2001) on the newest food processes, including food manufacturing, preservation, and control. Modern processes for food and food ingredients manufacturing based on membrane technology, super-critical fluid technology, and some applications of biotechnology are presented, mainly applied to obtain functional foods, "all-natural" enriched foods, probiotics and prebiotics. Also included is a critical assessment concerning non-thermal preservation techniques used for food preservation, such as high hydrostatic pressure, pulsed electric fields, ultrasound, pulsed light, hurdle systems, etc. Finally, a group of new analytical techniques (i.e., molecular techniques such as Polymerase Chain Reaction (PCR), food image analysis, and biosensors) and their use for food and process control is reviewed.     

4 种哺乳动物乳中低聚糖的定性和定量分析研究进展

低聚糖是乳中的一类生物活性成分,具有益生元、抗病毒、抗炎及免疫调节等功能,可作为一种新型食品组分添加至特殊医学用途配方食品或功能性食品中,近年来受到了人们的广泛关注。哺乳动物乳是低聚糖的主要来源,前人围绕哺乳动物的初乳及成熟乳中的低聚糖种类及含量开展了相关研究,但是不同物种间低聚糖种类和含量的对比还鲜有报道。本文对4 种哺乳动物乳（山羊、牛、猪、骆驼）中的低聚糖种类和含量进行了总结及对比,旨在为动物乳源低聚糖的应用提供参考。     

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。