Effect of encapsulation methods and materials on the survival and viability of Lactobacillus acidophilus: A review

Consumption of probiotics is an area of research that has rapidly expanded in the last years. Lactobacilli are one of the most important probiotic bacteria owing to their beneficial impacts on human health. The most important challenge is the survival of probiotics against several conditions during processing, as well as harsh environments during gastrointestinal digestion. As an alternative to the preservation of probiotic bacteria, different encapsulation processes have been proved. Several methods and materials are currently used for probiotic encapsulation, which influences the survivability of probiotics. Thus, this review aims to understand and summarise the effects of the methods and materials used in the encapsulation of Lactobacillus acidophilus, and its consequences on their survival and viability under simulated gastrointestinal conditions. Among several studies reported, the alginate capsules obtained by external ionic gelation through extrusion and chitosan coating showed the highest encapsulation yield of 99.33%. Lastly, future research directions on the topic are suggested.     

Probiotic Fermented Sausage: Viability of Probiotic Microorganisms and Sensory Characteristics

Probiotics are from functional foods that bring health benefits for humans. Nowadays, a major development in functional foods is related to food containing probiotic cultures, mainly lactic acid bacteria or bifidobacteria. Probiotics must be alive and ingested in sufficient amounts to exert the positive effects on the health and the well-being of the host. Therefore, viability of probiotic products (the minimum viable probiotic cells in each gram or milliliter of product till the time of consumption) is their most important characteristic. However, these organisms often show poor viability in fermented products due to their detrimental conditions. Today, the variety of fermented meat products available around the world is nearly equal to that of cheese. With meat products, raw fermented sausages could constitute an appropriate vehicle for such microorganisms into the human gastrointestinal tract. In present article, the viability of probiotic microorganisms in fermented sausage, the main factors affect their viability, and the sensorial characteristics of final product are discussed.     

Probiotics in fermented sausages

Probiotic foods receive market interest as health-promoting, functional foods. They have been introduced in a wide range of food industries. However, commercial application of probiotic microorganisms in fermented sausages is not common yet. There are both advantages and disadvantages connected to fermented meat matrices. They are adequate for the carriage of probiotic bacteria since they are usually not or only mildly heated and may promote the survival of probiotic bacteria in the gastrointestinal tract. In contrast, bacterial viability may be reduced due to the high content in curing salt and the low water activity and pH. Therefore, results are expected to be strain-dependent. Up till now, several approaches have been followed but most results are too preliminary to be able to evaluate the effect of probiotic fermented meats on human health. Candidate probiotic strains have been obtained through screening for technological requirements among bacteria that are naturally present in the meat or that originate from meat starter cultures. Alternatively, existing probiotic bacteria have been applied in meat products. Finally, the evaluation of the end-products needs to deal with both health effects and technological characteristics, for instance through human intervention studies and taste panels, respectively.     

Issues deserve attention in encapsulating probiotics: Critical review of existing literature

Probiotic bacteria are being increasingly added to food for developing products with health-promoting properties. However, the efficacy of probiotics in commercial products is often questioned due to the loss of their viability during shelf storage and in human gastrointestinal tracts. Encapsulation of probiotics has been expected to provide protection to probiotics, but not many commercial products contain encapsulated and viable probiotic cells owing to various reasons. To promote the development and application of encapsulation technologies, this paper has critically reviewed previous publications with a focus on the areas where studies have fallen short, including insufficient consideration of structural effects of encapsulating material, general defects in encapsulating methods and issues in evaluation methodologies and risk assessments for application. Corresponding key issues that require further studies are highlighted. Some emerging trends in the field, such as current treads in encapsulating material and recently advanced encapsulation techniques, have also been discussed.     

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.     

Protective approaches and mechanisms of microencapsulation to the survival of probiotic bacteria during processing,storage and gastrointestinal digestion: A review

Abstract

In recent years, there is a rising interest in the number of food products containing probiotic bacteria with favorable health benefit effects. However, the viability of probiotic bacteria is always questionable when they exposure to the harsh environment during processing, storage, and gastrointestinal digestion. To overcome these problems, microencapsulation of cells is currently receiving considerable attention and has obtained valuable effects. According to the drying temperature, the commonly used technologies can be divided into two patterns: high temperature drying (spray drying and fluid bed drying) and low temperature drying (ultrasonic vacuum spray drying, spray chilling, electrospinning, supercritical technique, freeze drying, extrusion, emulsion, enzyme gelation, and impinging aerosol technique). Furthermore, not only should the probiotic bacteria maintain high viability during processing but they also need to keep alive during storage and gastrointestinal digestion, where they additionally suffer from water, oxygen, heat as well as strong acid and bile conditions. This review focuses on demonstrating the effects of different microencapsulation techniques on the survival of bacteria during processing as well as protective approaches and mechanisms to the encapsulated probiotic bacteria during storage and gastrointestinal digestion that currently reported in the literature.     

Protecting probiotic bacteria by microencapsulation: challenges for industrial applications

The use of probiotic bacteria in novel foods to provide beneficial health effects is today of increasing interest in the food industry. The process stability of probiotics is, however, not always optimal. Microencapsulation technology can be used to maintain the viability of probiotic bacteria during food product processing and storage. Both true microcapsules with coating as well as microspheres where the bacteria are evenly spread in the coating material are discussed. It is important that encapsulation keeps the probiotics active through the gastrointestinal tract and releases them in their target organ. The survival of microencapsulated cells in simulated gastric conditions is therefore also reviewed. Polysaccharides like alginate, gellan, κ-carrageenan and starch are the most commonly used materials in microencapsulation of bifidobacteria and lactobacilli. Techniques commonly applied for probiotic microencapsulation are emulsion, extrusion, spray drying, and adhesion to starch. Bead stability can be improved by using different coating materials, e.g. chitosan. Future challenges in the field include recognition of new potent applications, selection of appropriate techniques, materials and bacterial strains, and minimizing the extra costs incurred by microencapsulation.     

Anhydrobiotics: The challenges of drying probiotic cultures

There is accumulating clinical data supporting the role of probiotics in human health particularly in benefiting the immune system, strengthening the mucosal barrier and suppressing intestinal infection. Fermented and unfermented dairy products enriched with probiotic bacteria have developed into one of the most successful categories of functional foods. From a functional ingredient perspective, the generation of these live cultures in dried formats is particularly attractive, however, it does present challenges in terms of retaining probiotic functionality during powder manufacture and storage. Both freeze-dying and spray-drying can be used for manufacture of probiotic powders on a large-scale, however, both approaches expose the cultures to extreme environmental conditions. Methods of production of dried probiotic powders should be such that viability is maintained in the dried powders following manufacture, and storage to ensure that an adequate number of bacteria can be delivered in the final product. This review will focus on how this can be achieved through approaches such as optimizing drying technology, and the drying matrix, and by manipulating probiotic bacteria by classical (microbiological) or genetic approaches.     

Probiotic bacteria: selective enumeration and survival in dairy foods

A number of health benefits have been claimed for probiotic bacteria such as Lactobacillus acidophilus, Bifidobacterium spp., and Lactobacillus casei. Because of the potential health benefits, these organisms are increasingly incorporated into dairy foods. However, studies have shown low viability of probiotics in market preparations. In order to assess viability of probiotic bacteria, it is important to have a working method for selective enumeration of these probiotic bacteria. Viability of probiotic bacteria is important in order to provide health benefits. Viability of probiotic bacteria can be improved by appropriate selection of acid and bile resistant strains, use of oxygen impermeable containers, two-step fermentation, micro-encapsulation, stress adaptation, incorporation of micronutrients such as peptides and amino acids and by sonication of yogurt bacteria. This review will cover selective enumeration and survival of probiotic bacteria in dairy foods.     

动物双歧杆菌RH对消化道的耐受性及其微胶囊制备的研究

采用耐胃酸、耐胆盐、模拟胃液和模拟肠液的独立影响实验和连续模拟消化道实验考察动物双歧杆菌对消化道环境的耐受性,结果表明:动物双歧杆菌RH经各独立实验后活菌数仍保持在10~7 CFU/mL,经连续模拟消化道实验后活菌数为10~6 CFU/mL。采用单因素试验和正交试验对动物双歧杆菌RH微胶囊壁材进行优化,结果表明:动物双歧杆菌RH最佳冻干保护剂各组成质量分数分别为甘油10%、海藻酸钠0.5%、乳清蛋白1.5%、阿拉伯胶1.25%和大豆卵磷脂1.25%,该条件下制备的冻干微胶囊活菌数为1.80×10~(12) CFU/g,平均包埋效率为96.04%。结论:动物双歧杆菌RH对人工模拟消化道具有较好的耐受性,经壁材优化后制备的冻干微胶囊有较高的活菌数和较好的肠溶性。本研究为动物双歧杆菌RH益生菌产品的开发提供理论基础和技术支撑。     

微胶囊包埋技术在益生菌制品中的应用

益生菌对人体具有保健功效，在乳制品中的应用日趋广泛，但制品中益生菌的存活率很低。微胶囊包埋是保护益生菌免受外界环境侵害的常用方法，综述了益生菌的微胶囊包埋技术及在生产中的应用。     

Olive paste as vehicle for delivery of potential probiotic Lactobacillus plantarum 33

Use of probiotic bacteria and consumes in large — in novel foods to provide beneficial health effects has attracted an increasing interest by the food industry and fermented olives are an excellent example of a new generation of those foods from plant origin so as to assure maximum viability by the time of ingestion during processing and storage of food products, as well as during transit through the gastrointestinal tract.Our study focused on production, characterization and assessment of efficacy of microencapsulation upon survival of probiotic strains and sensory properties of the final olive paste throughout refrigerated storage. Microencapsulation appears to be an effective technique for strain survival, depending on the operating temperature and experimental results on tolerance to gastrointestinal-like conditions, and ability to adhere to intestinal epithelium is thereby presented and discussed. The sensory panel rated all experienced matrices as good, including overall acceptance without significant preference between them. However, the success of microencapsulation was more limited when incorporated into olive paste. Free cells of Lactobacillus plantarum 33 proved able to survive in olive paste during storage at refrigerated temperatures.     

Effect of Microencapsulation on Viability of Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-12 During Kasar Cheese Ripening

The viability of encapsulated Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-12 by emulsion or extrusion techniques in Kasar cheese was investigated. The microbiological, biochemical and organoleptic properties of cheeses were assessed throughout 90-day storage. Results showed that the viability of probiotic bacteria was maintained to a great extent by microencapsulation. No difference was noted between the two encapsulation techniques with regard to bacterial counts, proteolysis and organoleptical properties of the final products. Scalding caused a drastic decline in the counts of probiotic bacteria in all cheeses. Following scalding, while the numbers of nonencapsulated probiotic bacteria decreased continuously in the control cheese, the numbers of encapsulated bacteria remained well above the threshold for a minimum probiotic effect (10⁷ cfu/g).     

益生乳酸菌在乳制品中的应用研究进展

益生乳酸菌是一类能利用碳水化合物发酵产生大量乳酸,且对宿主有益的微生物。乳制品在人类膳食结构中占有十分重要的地位,随着消费者对乳品品质和健康要求的提升,具有各种健康功能的益生乳酸菌在乳品中的应用及相关加工技术和功能产品的研发日益受到关注。通过添加益生乳酸菌等活性因子获得功能性乳制品,是增强乳品健康功效的有效方法。本文综述了近年来有关益生乳酸菌在发酵乳、干酪、乳饮料、冰淇淋和奶粉等乳制品中的应用研究现状,重点介绍了益生乳酸菌发挥功能的主要代谢产物酶类和胞外多糖的应用研究,包括在不同乳制品中益生乳酸菌及其产物发挥的作用,常用的益生乳酸菌菌株种类,生产加工过程中存在的主要问题及解决方法,为益生乳酸菌在乳制品中的应用开发提供参考。     

Probiotics,prebiotics, and microencapsulation: A review

The development of a suitable technology for the production of probiotics is a key research for industrial production, which should take into account the viability and the stability of the organisms involved. Microbial criteria, stress tolerance during processing, and storage of the product constitute the basis for the production of probiotics. Generally, the bacteria belonging to the genera Lactobacillus and Bifidobacterium have been used as probiotics. Based on their positive qualities, probiotic bacteria are widely used in the production of food. Interest in the incorporation of the probiotic bacteria into other products apart from dairy products has been increasing and represents a great challenge. The recognition of dose delivery systems for probiotic bacteria has also resulted in research efforts aimed at developing probiotic food outside the dairy sector. Producing probiotic juices has been considered more in the recent years, due to an increased concern in personal health of consumers. This review focuses on probiotics, prebiotics, and the microencapsulation of living cells.     

Survival of Microencapsulated Probiotic Bacteria after Processing and during Storage: A Review

The use of live probiotic bacteria as food supplement has become popular. Capability of probiotic bacteria to be kept at room temperature becomes necessary for customer's convenience and manufacturer's cost reduction. Hence, production of dried form of probiotic bacteria is important. Two common drying methods commonly used for microencapsulation are freeze drying and spray drying. In spite of their benefits, both methods have adverse effects on cell membrane integrity and protein structures resulting in decrease in bacterial viability. Microencapsulation of probiotic bacteria has been a promising technology to ensure bacterial stability during the drying process and to preserve their viability during storage without significantly losing their functional properties such acid tolerance, bile tolerance, surface hydrophobicity, and enzyme activities. Storage at room temperatures instead of freezing or low temperature storage is preferable for minimizing costs of handling, transportation, and storage. Concepts of water activity and glass transition become important in terms of determination of bacterial survival during the storage. The effectiveness of microencapsulation is also affected by microcapsule materials. Carbohydrate- and protein-based microencapsulants and their combination are discussed in terms of their protecting effect on probiotic bacteria during dehydration, during exposure to harsh gastrointestinal transit and small intestine transit and during storage.     

Lactose-free skim milk and prebiotics as carrier agents of Bifidobacterium BB-12 microencapsulation: physicochemical properties,survival during storage and in vitro gastrointestinal condition behaviour

Bifidobacterium BB-12 was microencapsulated by spray drying using lactose-free milk, lactose-free milk and inulin, and lactose-free milk and oligofructose, resulting in powders 1, 2 and 3, respectively. The highest encapsulation yield (88.01%) and the highest bifidobacteria viability during 120 days of storage were noted for spray-dried powder 2. Spray-dried powders 1 and 3 show a higher tendency to yellow colour. After being submitted to in vitro-simulated gastrointestinal conditions, the best probiotic survival rate result was found for spray-dried powder 3 (87.59%). Therefore, spray-dried powders containing prebiotics were the most appropriate combinations for microencapsulation of Bifidobacterium BB-12 and maintenance of cell viability during storage and gastrointestinal system, showing great potential to be used in lactose-free dairy products.     

Technologies with free and immobilised cells for probiotic bifidobacteria production and protection

Interest in the incorporation of bifidobacteria into fermented products has developed considerably over recent years, with many studies reporting human health benefits associated with the consumption of these bacteria. Due to their slow growth in milk, bifidobacteria are generally propagated in pure cultures and eventually mixed thereafter with other lactic acid bacteria. Data on production of bifidobacteria with conventional free-cell cultures are reviewed, as well as new fermentation processes allowing cell productivity enhancement. Bifidobacteria are sensitive microorganisms with low survival to stresses occurring during their production, storage and consumption. Until now, little work has been published on improving the survival of bifidobacteria to these conditions, but new techniques, such as cell incubation under sublethal conditions and cell propagation in an immobilised biofilm state, are very promising. Combined with encapsulation, these techniques will allow better incorporation of bifidobacteria into established probiotic products, as well as the emergence of new applications.     

The effects of probiotics in lactose intolerance: A systematic review

Over 60 percent of the human population has a reduced ability to digest lactose due to low levels of lactase enzyme activity. Probiotics are live bacteria or yeast that supplements the gastrointestinal flora. Studies have shown that probiotics exhibit various health beneficial properties such as improvement of intestinal health, enhancement of the immune responses, and reduction of serum cholesterol. Accumulating evidence has shown that probiotic bacteria in fermented and unfermented milk products can be used to alleviate the clinical symptoms of lactose intolerance (LI). In this systematic review, the effectiveness of probiotics in the treatment of LI was evaluated using 15 randomized double-blind studies. Eight probiotic strains with the greatest number of proven benefits were studied. Results showed varying degrees of efficacy but an overall positive relationship between probiotics and lactose intolerance.     

Encapsulation in an alginate–goats’ milk–inulin matrix improves survival of probiotic Bifidobacterium in simulated gastrointestinal conditions and goats’ milk yoghurt

In this work, a new encapsulating matrix, alginate–goats’ milk–inulin, was used to encapsulate Bifidobacterium animalis subsp. lactis BB‐12. The addition of inulin resulted in capsules with a compact structure, and a higher probiotic cell count under simulated gastrointestinal conditions and in probiotic goats’ milk yoghurt during refrigerated storage. Encapsulation of the probiotic bacteria led to slower post‐acidification yoghurts. The results of this study showed that the alginate–goats’ milk–inulin matrix has potential to be used as a new encapsulation material to encapsulate probiotics for use in goats’ milk‐based probiotic fermented dairy products, avoiding the cross‐contamination caused by using capsules based on cows’ milk.