Fermented products with probiotic qualities

For several centuries, fermented products derived from plant or animal materials have been an acceptable and essential part of the diet in most parts of the world. Health benefits have also often been associated with them. Probiotics can be defined as fermented food containing specific live microorganisms or a live microbial food or feed supplement, which beneficially effects the human or the host animal by improving its intestinal microbial balance. Nearly all probiotics currently on the market contain Lactobacilli, Streptococci, Enterococci or Bifidobacteria. In contrast to Japan, where freeze-dried microorganisms are consumed by a substantial part of the human population, in Europe, probiotic action towards humans are only claimed for certain fermented dairy products (e.g. yoghurts). Those species that have been extensively studied so far, with several experimental trials on man, are the two yoghurt bacteria Streptocaccus thermophilus and Lactobacillus bulgaricus, L. casei and Bifidobacteria. L. acidophilus has also received important scientific interest, however, only a few human studies have been carried out. From the technological point of view a good probiotic should be stable and viable for long periods under storage, should be able to survive the low pH levels of the stomach, be able to colonise the epithelium of the gastro-intestinal tract of the host, should not be pathogenic and, last but not least, must be capable of exerting a growth promoting effect or a resistance to infectious diseases. The beneficial effects of probiotics are mainly contributed to a direct antagonistic effect against specific groups of microorganisms (Enteropathogenes), by an effect on the metabolism in the gut or by a stimulation of systemic or mucosal immunity. We will present major proven health benefits of milks fermented with those bacterial species and discuss, where possible, the impact of the specific selection and utilisation of particular strains.     

Survival and therapeutic potential of probiotic organisms with reference to Lactobacillus acidophilus and Bifidobacterium spp

The present paper provides an overview on the use of probiotic organisms as live supplements, with particular emphasis on Lactobacillus acidophilus and Bifidobacterium spp. The therapeutic potential of these bacteria in fermented dairy products is dependent on their survival during manufacture and storage. Probiotic bacteria are increasingly used in food and pharmaceutical applications to balance disturbed intestinal microflora and related dysfunction of the human gastrointestinal tract. Lactobacillus acidophilus and Bifidobacterium spp. have been reported to be beneficial probiotic organisms that provide excellent therapeutic benefits. The biological activity of probiotic bacteria is due in part to their ability to attach to enterocytes. This inhibits the binding of enteric pathogens by a process of competitive exclusion. Attachment of probiotic bacteria to cell surface receptors of enterocytes also initiates signalling events that result in the synthesis of cytokines. Probiotic bacteria also exert an influence on commensal micro-organisms by the production of lactic acid and bacteriocins. These substances inhibit growth of pathogens and also alter the ecological balance of enteric commensals. Production of butyric acid by some probiotic bacteria affects the turnover of enterocytes and neutralizes the activity of dietary carcinogens, such as nitrosamines, that are generated by the metabolic activity of commensal bacteria in subjects consuming a high-protein diet. Therefore, inclusion of probiotic bacteria in fermented dairy products enhances their value as better therapeutic functional foods. However, insufficient viability and survival of these bacteria remain a problem in commercial food products. By selecting better functional probiotic strains and adopting improved methods to enhance survival, including the use of appropriate prebiotics and the optimal combination of probiotics and prebiotics (synbiotics), an increased delivery of viable bacteria in fermented products to the consumers can be achieved.     

Microbial ecology and quality assurance in food fermentation systems. The case of kefir grains application

Fermentation technology has become a modern method for food production the last decades as a process for enhancing product stability, safety and sensory standards. The main reason for this development is the increasing consumers’ demand for safe and high quality food products. The above has led the scientific community to the thorough study for the appropriate selection of specific microorganisms with desirable properties such as bacteriocin production, and probiotic properties. The main food products produced through fermentation activity are bread, wine, beer cheese and other dairy products. The microorganisms conducting the above processes are mainly yeasts and lactic acid bacteria. The end products of carbohydrate catabolism by these microorganisms contribute not only to preservation as it was believed years ago, but also to the flavour, aroma and texture and to the increase of the nutritional quality by thereby helping determine unique product characteristics. Thus, controlling the function of specific microorganisms or the succession of microorganisms that dominate the microflora is therefore advantageous, because it can increase product quality, functionality and value. Throughout the process of the discovery of microbiological diversity in various fermented food systems, the development of starter culture technology has gained more scientific attention, and it could be used for the control of the manufacturing operation, and management of product quality. In the frame of this review the presentation of the quality enhancement of most consumed fermented food products around the world is attempted and the new trends in production of fermented food products, such as bread is discussed. The review is focused in kefir grains application in bread production.     

Lactic acid bacteria in meat fermentation

Abstract The main fermented meat products are fermented sausages in which lactic acid bacteria (LAB) are the essential agents of the ripening process. During indigenous fermentations Lactobacillus curvatus and L. sake are the dominating LAB. Their application as starter organisms ensures the dominance of the starter during the whole ripening process. The suppression of the competing fortuitous LAB depends on the quality of the raw materials and on technological factors. The physiological properties of lactic starters do not suffice to ensure a sensory quality which can be found in traditionally produced dry fermented sausages. Additional activities required are present in micrococci and yeasts which, therefore, are further components of starter culture preparations. Some strains of meat-borne lactobacilli exhibit the essential activities like nitrate reductase, nitrite reductase, catalase, lipase, and protease, respectively. To create the optimal starter cultures composed of lactobacilli, these activities have to be studied and optimized in strains of high competitiveness in the fermenting substrate.     

Probiotic bacterium prevents cytokine-induced apoptosis in intestinal epithelial cells

Probiotic bacteria are microorganisms that benefit the host by preventing or ameliorating disease. However, little information is known regarding the scientific rationale for using probiotics as alternative medicine. The purpose of this paper is to investigate the mechanisms of probiotic beneficial effects on intestinal cell homeostasis. We now report that one such probiotic, Lactobacillus rhamnosus GG (LGG), prevents cytokine-induced apoptosis in two different intestinal epithelial cell models. Culture of LGG with either mouse or human colon cells activates the anti-apoptotic Akt/protein kinase B. This model probiotic also inhibits activation of the pro-apoptotic p38/mitogen-activated protein kinase by tumor necrosis factor, interleukin-1alpha, or gamma-interferon. Furthermore, products recovered from LGG culture broth supernatant show concentration-dependent activation of Akt and inhibition of cytokine-induced apoptosis. These observations suggest a novel mechanism of communication between probiotic microorganisms and epithelia that increases survival of intestinal cells normally found in an environment of pro-apoptotic cytokines.     

Probiotic properties of yeasts in traditional fermented foods and beverages

The interest in potentiality and functionality of probiotic yeasts from fermented foods has increased drastically over the years. In many fermented foods and beverages, lactic acid bacteria and yeasts exist synergistically by stimulating their growth and survival. Probiotic strains of lactic acid bacteria are more widely studied than potential probiotic yeasts. Saccharomyces cerevisiae variety boulardii is the only commercialized probiotic yeast, which are extensively studied. This review article provides information on the presence of potential probiotic yeasts in some traditional fermented foods and beverages.     

The Probiotic Bacterial Strain Lactobacillus fermentum D3 Increases In Vitro the Bioavailability of Ca, P, and Zn in Fermented Goat Milk

We determined calcium, magnesium, phosphorus and zinc levels in a total of 27 samples of commercial goat- and cow-milk fermented products and 9 samples of a goat-milk fermented product with addition of a probiotic bacterial strain, Lactobacillus fermentum D3, manufactured experimentally by our research group. Atomic absorption spectroscopy with flame atomization and UV/VIS spectrophotometry were used as analytic techniques. The results of an in vitro digestion process showed that the bioavailability of calcium, phosphorus, and zinc was significantly higher in our fermented milk containing the probiotic bacterial strain than it was in commercial goat-milk fermented products. Furthermore, our product showed a significantly higher bioavailability of calcium and zinc compared to goat- and cow-milk fermented products made with other microorganisms. We conclude that, in in vitro assays, strain D3 seems to increase the bioavailability of these minerals and that this new product may constitute a better source of bioavailable minerals compared to other products already on the market.     

传统发酵肉制品中微生物菌群对风味形成的研究进展

我国传统发酵肉制品种类丰富、风味独特。本文主要介绍参与肉制品发酵的微生物,从蛋白质、脂质和碳水化合物代谢途径的角度概述微生物对发酵肉制品呈香物质形成的作用机制,以及发酵过程中微生物的演替与风味变化的关系。     

Occurrence and taxonomic characteristics of strains of Saccharomyces cerevisiae predominant in African indigenous fermented foods and beverages

Indigenous fermented foods and beverages play a major role in the diet of African people. The predominant yeast species seen is Saccharomyces cerevisiae, involved in basically three groups of indigenous fermented products: non-alcoholic starchy foods, alcoholic beverages and fermented milk. These products are to a great extent made by spontaneous fermentation and consequently S. cerevisiae often coexists with other microorganisms even though a microbiological succession usually takes place both between and within species. The functions of S. cerevisiae are mainly related to formation of alcohols and other aroma compounds, but stimulation of e.g. lactic acid bacteria, improvement of nutritional value, probiotic effects, inhibition of undesired microorganisms and production of tissue-degrading enzymes may also be observed. Several different isolates of S. cerevisiae have been shown to be involved in the fermentations and some of the isolates show pheno- and genotypic characteristics that deviate from those normally recognised for S. cerevisiae.     

Immunobiosis and probiosis: antimicrobial activity of lactic acid bacteria with a focus on their antiviral and antifungal properties

Lactic acid bacteria (LAB), a heterogeneous group of bacteria that produce lactic acid as the main product of carbohydrate degradation, play an important role in the production and protection of fermented foods. Moreover, beside the technological use of these microorganisms added to control and steer food fermentations, their beneficial healthy properties are largely overt. Thus, numerous LAB strains have obtained the probiotic status, which entails the ability to maintain and promote a good health of consumers. In particular, increasing consideration is being focused on probiotic microorganisms that can improve the human immune response against dangerous viral and fungal enemies. For such beneficial microbes, the term “immunobiotics” has been coined. Together with an indirect host-mediated adverse effect against undesirable microorganisms, also a direct antagonistic activity of several LAB strains has been largely demonstrated. The purpose of this review is to provide a fullest possible overview of the antiviral and antifungal activities ascribed to probiotic LAB. The interest in this research field is substantiated by a large number of studies exploring the potential application of these beneficial microorganisms both as biopreservatives and immune-enhancers, aiming to reduce and/or eliminate the use of chemical agents to prevent the development of pathogenic, infectious, and/or degrading causes.

     

Traditional healthful fermented products of Japan

A variety of fermentation products, such as foods containing probiotic bacteria, black rice vinegar (kurosu), soy sauce (shoyu), soybean-barley paste (miso), natto and tempeh, are sold in food stores in Japan. These fermented food products are produced by traditional methods that exploit mixed cultures of various non-toxic microorganisms. These microorganisms include lactic acid bacteria, acetic acid bacteria, sake yeast, koji molds and natto bacteria. Many traditional fermented foods have been studied and their effects on metabolism and/or immune system have been demonstrated in animal and/or human cells. This review summarizes the scientific basis for the effects of these traditional food products, which are currently produced commercially in Japan.     

Probiotic bacteria may become dormant during storage

The determination of bacterial viability in probiotic products is of economic, technological, and clinical significance. We compared four methods to enumerate three Bifidobacterium strains in fermented oat products during storage. A subpopulation of nonculturable cells retained a functional cell membrane typical of viable cells, indicating that probiotic bacteria become dormant during storage.     

Use of green fluorescent protein to monitor Lactobacillus sakei in fermented meat products

Lactobacillus sakei is a lactic acid bacterium naturally found on meat and often used as starter for the production of dry sausages or other fermented meat products. The gene encoding the green fluorescent protein (GFP) was cloned downstream from the constitutive L-lactate dehydrogenase promoter (pldhL) of L. sakei. The pldhL::gfp fusion was introduced in L. sakei either on a replicative plasmid or by double crossover integration into the chromosome, as a single copy. Both constructions were stable. Expression of GFP did not alter growth and was detectable by epifluorescence microscopy allowing the detection and monitoring of the development of GFP+ specific L. sakei strains both under growth laboratory conditions and in dry sausage samples.     

The improvement of probiotics efficacy by synergistically acting components of natural origin: a review

The protection of human health as well as the quality and safe food assurance becomes the priority of European research in the sphere of animal production. The negative experiences with the using of antibiotic growth promoters lead to subsequent reduction of their application. It is necessary to replace them by the growth promoters of natural origin, which are able to provide the comparable efficacy and will not contribute to the cumulative contamination of the environment. The probiotics represent an effective alternative to antibiotics and current research should be aimed at improving of their efficacy. This may be achieved by several methods. From the practical point of view, combination with synergistically acting components of natural origin seems to be the best way. Potentiated probiotics are defined as biopreparations containing production strains of microorganisms and synergistically acting components of natural origin which exert their intensified effect through effects on probiotic and gut microorganisms, the gut mucosa and the intestinal environment or immune system. A number of suitable components may be used for this purpose, such as prebiotics, non-specific substrates, plants and their extracts, metabolites of microorganisms and polyunsaturated fatty acids. In this report, the results of application of natural feed additives in animals are reviewed and their valuation for the enhancement of probiotic effectiveness is discussed. Presented at the Second Probiotic Conference, Košice, 15–19 September 2004, Slovakia.     

Assuring the continued safety of lactic acid bacteria used as probiotics

Lactic acid bacteria have long been used to improve the safety of foods through fermentation. Some fermented products were also early used for their perceived health benefits, which lead to the development of probiotics as we now know them. Probiotics mainly belong to the genera Lactobacillus and Bifidobacterium. Most members of these genera are not considered pathogens or even opportunistic pathogens. Nevertheless, rare cases of Lactobacillus and Bifidobacterium infection have been reported, possibly even associated with the consumption of probiotic products. Such cases are extremely rare and the subjects always had severe underlying conditions most often affecting the immune system. There does not seem to be any risk for the general population. Safety assessments can be performed and many possible tests exist. It is, however, not certain these tests will prevent rare case of Lactobacillus infection in certain high-risk patients. The benefits of probiotic use should be weighed against the possible small risk. Such an evaluation will, in most cases, be favourable and should therefore not discourage consumption of probiotics. Presented at the Second Probiotic Conference, Košice, 15–19 September 2004, Slovakia.     

Bacteriocinogenic LAB Strains for Fermented Meat Preservation: Perspectives,Challenges, and Limitations

Over the last decades, much research has focused on lactic acid bacteria (LAB) bacteriocins because of their potential as biopreservatives and their action against the growth of spoilage microbes. Meat and fermented meat products are prone to microbial contamination, causing health risks, as well as economic losses in the meat industry. The use of bacteriocin-producing LAB starter or protective cultures is suitable for fermented meats. However, although bacteriocins can be produced during meat processing, their levels are usually much lower than those achieved during in vitro fermentations under optimal environmental conditions. Thus, the direct addition of a bacteriocin food additive would be desirable. Moreover, safety and technological characteristics of the bacteriocinogenic LAB must be considered before their widespread applications. This review describes the perspectives and challenges toward the complete disclosure of new bacteriocins as effective preservatives in the production of safe and “healthy” fermented meat products.     

Probiotic Bacteria May Become Dormant during Storage

The determination of bacterial viability in probiotic products is of economic, technological, and clinical significance. We compared four methods to enumerate three Bifidobacterium strains in fermented oat products during storage. A subpopulation of nonculturable cells retained a functional cell membrane typical of viable cells, indicating that probiotic bacteria become dormant during storage.     

Probiotics from an industrial perspective

Probiotic products have gained popularity with consumers that expect that the products they consume are healthy and help them maintain health. Hence, the need and preferences of the consumers are translated into a product format concept. Probiotics have been used for a long time as natural components in supplements and functional foods, mainly in fermented dairy products. Most of the strains used as probiotics belong to the genera Lactobacillus and Bifidobacterium. By definition, a strain has to have documented health benefits, in order to be called a probiotic. Although each bacterial strain is unique, there are some points that are essential when selecting a probiotic regarding the genetic stability, survival, and technical properties of a strain. Proper components, food matrices and production processes need to be selected since the matrices may affect the viability of the strain in the product and the intestine. Survival in the product is considered a requirement for the beneficial effects of probiotics.     

Multiplex PCR and a chromogenic DNA macroarray for the detection of Listeria monocytogens, Staphylococcus aureus, Streptococcus agalactiae, Enterobacter sakazakii, Escherichia coli O157:H7, Vibrio parahaemolyticus, Salmonella spp. and Pseudomonas fluorescens in milk and meat samples

Food products, such as milk and meat products including cheese, milk powder, fermented milk, sausage, etc. are susceptible to the contamination by pathogenic and deteriorative bacteria. These bacteria include Listeria monocytogens, Staphylococcus aureus, Enterobacter sakazakii, Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Streptococcus agalactiae and Pseudomonas fluorescens, etc. Traditional methods for the detection of these microorganisms are laborious and time consuming. Therefore, rapid and accurate diagnostic methods are needed. In this study, we designed the DNA probes and PCR primers for the detection of aforementioned microorganisms. By using two sets of multiplex PCR, followed by a chromogenic macroarray system, these organisms in milk or other food products could be simultaneously detected. When the system was used for the inspection of milk or meat homogenate containing 10(0) target cells per milliliter or gram of the sample, all these bacterial species could be identified after an 8h pre-enrichment step. The system consisting of a multiplex PCR step followed by macroarray allowed us to detect multiple target bacterial species simultaneously without the use of agarose gel electrophoresis. Compared to the commonly used multiplex PCR method, this approach has the additional advantage of detecting more bacterial strains because some bacterial strains generate PCR products with the same molecular sizes which can be differentiated by macroarray but not by electrophoresis.     

Probiotic bacteria: safety, functional and technological properties

During the past two decades probiotic (health promoting) micro-organisms have been increasingly included in various types of food products, especially in fermented milks. Several aspects, including safety, functional and technological characteristics, have to be taken into consideration in the selection process of probiotic micro-organisms. Safety aspects include specifications such as origin (healthy human GI-tract), non-pathogenicity and antibiotic resistance characteristics. Functional aspects include viability and persistence in the GI-tract, immunomodulation, antagonistic and antimutagenic properties. Before probiotic strains, chosen on the basis of their good safety and functional characteristics, can benefit the consumer, they must first be able to be manufactured under industrial conditions. Furthermore, they have to survive and retain their functionality during storage, and also in the foods into which they are incorporated without producing off-flavours. Factors related to the technological and sensory aspects of probiotic food production are of utmost importance since only by satisfying the demands of the consumer can the food industry succeed in promoting the consumption of functional probiotic products in the future.