Lactic acid fermentation as a tool for increasing the folate content of foods

Folate is an essential micronutrient involved in numerous vital biological reactions. The dietary consumption of naturally occurring vitamin B9 is often inadequate in many countries, and supplementation or fortification programs (using synthetic folic acid) are implemented to alleviate folate deficiency. Other food-based alternatives are possible, such as the use of lactic acid bacteria (LAB) to synthesize folate during fermentation. Many studies have been conducted on this topic, and promising results were reported for some fermented dairy products. However, in other studies, folate consumption by LAB or rather low folate production were observed, resulting in fermented foods that may not significantly contribute to the recommended B9 intake. In addition, the optimum conditions for folate biosynthesis by LAB are still not clear. The aim of this review was thus to (i) clarify the ability of LAB to produce folate in food products, (ii) check if the production of folate by LAB in various fermented foods is sufficient to meet human vitamin B9 requirements and (iii) suggest ways to optimize folate production by LAB in fermented food products.     

Dietary Folate in a Changing Environment: Bioavailability, Fortification, and Requirements

ABSTRACT: The US and several other countries have instituted mandatory inclusion of folic acid in many enriched cereal grain products, and certain other countries allow optional addition. Nutritional surveys in the US now indicate that folate deficiency is infrequent, and vitamin B12 status is often a primary determinant of plasma homocysteine concentration. Thus, the current situation in the US is markedly different from that of the pre-fortification era and from countries that do not allow the addition of folic acid to foods. Recent analytical studies have indicated that food composition databases may underestimate naturally occurring folate, although folate intakes calculated from database values have allowed accurate ranking of intakes among population groups in many epidemiological studies. Published analyses of cereal grain foods in the US indicate that added folic acid exceeds intended ranges. Studies comparing folate nutritional status in the US before and after fortification indicate that the fortification program has contributed about 200 micrograms of folic acid to the average person per day. This increment is twice that predicted due, in part, to a greater than anticipated intake as well as the higher bioavailability of folic acid than most naturally occurring forms of food folate. More precise information is needed regarding the actual difference in bioavailability between natural folate and added folic acid.     

Screening of a natural biodiversity of lactic and propionic acid bacteria for folate and vitamin B12 production in supplemented whey permeate

Lactic acid bacteria (LAB) and propionic acid bacteria (PAB) are known for the production of several important nutraceuticals. We screened 151 LAB and 100 PAB of different origins (fermented foods and feeds) for extracellular folate and intracellular vitamin B12 production in supplemented whey permeate using a standardized microbiological assay (folate) and HPLC (vitamin B12). Five LAB strains belonging to the species Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus brevis and Lactobacillus fermentum exhibited high extracellular folate productions, with a maximum yield of 397 ± 60 ng mL^?1 for L. plantarum SM39. The highest vitamin B12 production was measured for Propionibacterium freudenreichii DF15 with 2.5 μg mL^?1. Screening a large biodiversity of LAB and PAB led to a representative image of the distribution of folate and vitamin B12 production by these genera and enabled the identification of high natural folate and vitamin B12 producing strains with high potential for applications in fermented foods.     

Folates in fermented vegetables—a pilot study

The present work aimed to evaluate whether lactic acid fermentation can increase folate concentrations in vegetables making these foods superior to similar foods produced by the more common preservation techniques. The concentrations of folates present in raw vegetables, usually root vegetables, were followed during pre-treatment and fermentation with the purpose to improve the folate retention. Commercial starter cultures aimed for manufacture of fermented dairy products were subjected to mixtures of grated and blanched root vegetables, mainly beetroots and turnips. The results indicate that among 10 different lactic acid bacteria (LAB) cultures, one mixture was superior, resulting in almost a doubling of folate concentration, mainly as 5-methyl-tetrahydrofolic acid (5-CH₃-H₄folate), a native and bioavailable folate form. Interestingly, one species of propionibacteria produced vitamin B₁₂. The retention of folate during the overall fermentation process varied between 50% and 75% when calculated on wet weight. The concentration of the folate was similar in the surrounding liquid medium as in the solids of the final fermented product. Sauerkraut, a classical fermented vegetable, did not have significantly increased folate content. Some commercial canned samples of sauerkraut contained between 50 and 200 μg/kg, mainly as 5-CH₃-H₄folate.     

Health benefits of fermented foods

In the past, the beneficial effects of fermented foods on health were unknown, and so people primarily used fermentation to preserve foods, enhance shelf life, and improve flavour. Fermented foods became an important part of the diet in many cultures, and over time fermentation has been associated with many health benefits. Because of this, the fermentation process and the resulting fermented products have recently attracted scientific interest. In addition, microorganisms contributing to the fermentation process have recently been associated with many health benefits, and so these microorganisms have become another focus of attention. Lactic acid bacteria (LAB) have been some of the most studied microorganisms. During fermentation, these bacteria synthesize vitamins and minerals, produce biologically active peptides with enzymes such as proteinase and peptidase, and remove some non-nutrients. Compounds known as biologically active peptides, which are produced by the bacteria responsible for fermentation, are also well known for their health benefits. Among these peptides, conjugated linoleic acids (CLA) have a blood pressure lowering effect, exopolysaccharides exhibit prebiotic properties, bacteriocins show anti-microbial effects, sphingolipids have anti-carcinogenic and anti-microbial properties, and bioactive peptides exhibit anti-oxidant, anti-microbial, opioid antagonist, anti-allergenic, and blood pressure lowering effects. As a result, fermented foods provide many health benefits such as anti-oxidant, anti-microbial, anti-fungal, anti-inflammatory, anti-diabetic and anti-atherosclerotic activity. However, some studies have shown no relationship between fermented foods and health benefits. Therefore, this paper aims to investigate the health effects of fermented foods.     

Folate intake of older adults before and after fortification of grain products.

PURPOSE: To determine whether fortification allowed older adults in the Kingston, Frontenac, and Lennox & Addington (KFL&A) Public Health area to obtain adequate amounts of food folate, and the proportion at risk of consuming more than the upper limit (UL) of folic acid (1,000 mcg). METHODS: Dietary intake of a convenience sample of 103 healthy, active older adults (age range: 65 to 95 years) was measured using three 24-hour recalls. Dietary folate pre- and post-fortification was estimated. RESULTS: Mean dietary folate increased from pre- to post-fortification, but 43.4% of women and 20% of men still consumed less than the Estimated Average Requirement of 320 mcg dietary folate equivalent. No intakes exceeded the UL. Participants whose diet met grain products and vegetable and fruit recommendations of Canada's Food Guide to Healthy Eating consumed significantly more folate. CONCLUSIONS: Despite fortification, some older adults in the KFL&A area may not be obtaining enough folate to meet their nutritional needs, and may be at risk for health problems associated with folate deficiency. However, without concomitant serum folate measurements, the proportion is not known. Dietitians need to continue promoting foods naturally rich in folate, along with folic acid-fortified foods. While none of the older adults consumed more than the UL, some could exceed this amount if folic acid supplements were added to a folic acid-rich diet.     

Bacterial Production of Conjugated Linoleic and Linolenic Acid in Foods: A Technological Challenge

Conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) isomers are present in foods derived from ruminants as a result of the respective linoleic acid (LA) and α-linolenic acid (LNA) metabolism by ruminal microorganisms and in animals’ tissues. CLA and CLNA have isomer-specific, health-promoting properties, including anticarcinogenic, antiatherogenic, anti-inflammatory, and antidiabetic activity, as well as the ability to reduce body fat. Besides ruminal microorganisms, such as Butyrivibrio fibrisolvens, many food-grade bacteria, such as bifidobacteria, lactic acid bacteria (LAB), and propionibacteria, are able to convert LA and LNA to CLA and CLNA, respectively. Linoleate isomerase activity, responsible for this conversion, is strain-dependent and probably related to the ability of the producer strain to tolerate the toxic effects of LA and LNA. Since natural concentrations of CLA and CLNA in ruminal food products are relatively low to exert their health benefits, food-grade bacteria with linoleate isomerase activity could be used as starter or adjunct cultures to develop functional fermented dairy and meat products with increased levels of CLA and CLNA or included in fermented products as probiotic cultures. However, results obtained so far are below expectations due to technological bottlenecks. More research is needed to assess if bacterial production kinetics can be increased and can match food processing requirements.     

海藻乳酸菌发酵的研究进展

海藻是一类重要的海洋资源,富含大量营养元素如蛋白质、碳水化合物、维生素和矿物质,以及多糖、酚类等生物活性物质。由于海藻营养价值极高,利用乳酸菌发酵海藻促进生物活性化合物的产生和释放,具有良好的健康效益。因此,本文根据国内外近年来利用乳酸菌发酵海藻的相关研究报道,对乳酸菌发酵类型、乳酸菌发酵海藻的可行性和乳酸菌主要种类、以及乳酸菌在海藻发酵中的效果和作用进行阐述,同时综述了乳酸菌发酵海藻在食品行业中的开发应用现状,并对今后发展趋势和前景进行展望,为藻类乳酸菌发酵制品的开发提供一定参考。     

酵母与乳酸菌的相互作用模式及其在发酵食品中的应用研究进展

酵母与乳酸菌作为被广泛应用的微生物在发酵食品的生产过程中起着举足轻重的作用,二者在发酵体系中的作用方式直接决定了产品的品质。研究发酵体系中酵母-乳酸菌间的相互作用模式有助于揭示微生物与食品功能的关系,对发酵进程的正向调控具有重要意义。本文综述了酵母与乳酸菌在发酵过程中发生的协同/拮抗作用、营养代谢产物交换、群体感应及生物膜包被等相互作用模式,探讨了酵母-乳酸菌相互作用对改善发酵食品风味质构、缩短发酵周期、提升产品益生特性等的积极作用。最后,对酵母-乳酸菌作为组合发酵剂进行强化发酵的应用前景进行了总结与展望。     

Production of Bioactive Peptides from Lactic Acid Bacteria: A Sustainable Approach for Healthier Foods

Traditional fermented foods where lactic acid bacteria (LAB) are present have been associated with beneficial effects on human health, and some of those benefits are related to protein‐derived products. Peptides produced by LAB have attracted the interest of food industries because of their diverse applications. These peptides include ribosomally produced (bacteriocins) and protein hydrolysates by‐products (bioactive peptides), which can participate as natural preservatives and nutraceuticals, respectively. It is essential to understand the biochemical pathways and the effect of growth conditions for the production of bioactive peptides and bacteriocins by LAB, in order to suggest strategies for optimization. LAB is an important food‐grade expression system that can be used in the simultaneous production of peptide‐based products for the food, animal, cosmetic, and pharmaceutical industries. This review describes the multifunctional proteinaceous compounds generated by LAB metabolism and discusses a strategy to use a single‐step production process, using an alternative protein‐based media. This strategy will provide economic advantages in fermentation processes and will also provide an environmental alternative to industrial waste valorization. New technologies that can be used to improve production and bioactivity of LAB‐derived peptides are also analyzed.     

Physiology of Acetic Acid Bacteria and Their Role in Vinegar and Fermented Beverages

Acetic acid bacteria (AAB) have, for centuries, been important microorganisms in the production of fermented foods and beverages such as vinegar, kombucha, (water) kefir, and lambic beer. Their unique form of metabolism, known as “oxidative” fermentation, mediates the transformation of a variety of substrates into products, which are of importance in the food and beverage industry and beyond; the most well‐known of which is the oxidation of ethanol into acetic acid. Here, a comprehensive review of the physiology of AAB is presented, with particular emphasis on their importance in the production of vinegar and fermented beverages. In addition, particular reference is addressed toward Gluconobacter oxydans due to its biotechnological applications, such as its role in vitamin C production. The production of vinegar and fermented beverages in which AAB play an important role is discussed, followed by an examination of the literature relating to the health benefits associated with consumption of these products. AAB hold great promise for future exploitation, both due to increased consumer demand for traditional fermented beverages such as kombucha, and for the development of new types of products. Further studies on the health benefits related to the consumption of these fermented products and guidelines on assessing the safety of AAB for use as microbial food cultures (starter cultures) are, however, necessary in order to take full advantage of this important group of microorganisms.     

乳酸菌胞外多糖生理功能及合成途径的研究进展

乳酸菌(Lactic acid bacteria,LAB)是一类重要的益生微生物,同时也是一类重要的工业发酵菌,在食品发酵生产上应用广泛,它的代谢产物也受到极大关注。本文总结了乳酸菌代谢合成的胞外多糖(Exopolysaccharide,EPS)的主要生理生化功能以及胞外多糖合成的四个主要过程,以期为乳酸菌EPS的应用、产量提高及结构改造提供指导。      

乳酸菌在发酵肉制品中的应用研究进展

发酵肉制品因其独特的风味、较高的营养价值、易消化等优势成为人们生活中不可缺少的食品。乳酸菌通常是兼性厌氧菌,在肉制品发酵过程中具有不可替代的作用。本文检索并总结乳酸菌在发酵肉制品研究领域的具体应用,如抑菌作用、改善风味、抗氧化、降低生物胺生成量、抑制亚硝胺积累及赋予健康功能,以期为乳酸菌在发酵肉制品中的应用研究提供理论参考。     

Bacteriocins of lactic acid bacteria: Their potentials as food biopreservative

Abstract

Numerous strains of lactic acid bacteria used in the fermentation of foods are known to produce bacteriocins. In general, bacteriocins are a group of proteinaceous antimicrobial substances that inhibit the growth of closely related bacteria. However, some bacteriocins produced by lactic acid bacteria (LAB) exhibit a relatively broad antimicrobial spectrum and are active against several food‐spoilage and health‐threatening microorganisms. Many investigators have reported on the use of bacteriocins as food preservative to extend the shelflife of various foods. This review decribes the research that has been conducted on bacteriocinogenic lactic acid bacteria— isolated from a wide variety of foods and in some instances of animal origin—and the characteristics of bacteriocins. Special emphasis is placed on their potentials for use as food preservative and on their physicochemical nature, antibacterial spectrum, and genetic behavior.     

A review on selection of fermentative microorganisms for functional foods and beverages: the production and future perspectives

Fermentation has been employed as a traditional means of improving the shelf life and nutritional contents of foods, thus making fermented foods and beverages functional and therapeutic. Lactic acid bacteria (LAB) plays a major role in determining the health benefits of fermented milk and related products. This review takes into cognizance numerous investigations reporting certain microbial strains and mixes to contribute safety, quality, stability, health and organoleptic properties to fermented foods, due to increased consumers’ awareness of food products with health claims. A look was taken at selection criteria for the ideal fermentative microbial species and strains, their usefulness and prospective ‘OMICS‘-based approaches to elucidating fermentative complex communities in relation to their effects on fermented food products. Moreover, recommendations were given for improved fermentation of beverages and functional foods. It is projected that fermented foods and beverages will continually be a paramount in the global food and emerging functional food market.     

Preservation and fermentation: past,present and future

Preservation of food and beverages resulting from fermentation has been an effective form of extending the shelf-life of foods for millennia. Traditionally, foods were preserved through naturally occurring fermentations, however, modern large scale production generally now exploits the use of defined strain starter systems to ensure consistency and quality in the final product. This review will mainly focus on the use of lactic acid bacteria (LAB) for food improvement, given their extensive application in a wide range of fermented foods. These microorganisms can produce a wide variety of antagonistic primary and secondary metabolites including organic acids, diacetyl, CO2 and even antibiotics such as reuterocyclin produced by Lactobacillus reuteri. In addition, members of the group can also produce a wide range of bacteriocins, some of which have activity against food pathogens such as Listeria monocytogenes and Clostridium botulinum. Indeed, the bacteriocin nisin has been used as an effective biopreservative in some dairy products for decades, while a number of more recently discovered bacteriocins, such as lacticin 3147, demonstrate increasing potential in a number of food applications. Both of these lactococcal bacteriocins belong to the lantibiotic family of posttranslationally modified bacteriocins that contain lanthionine, beta-methyllanthionine and dehydrated amino acids. The exploitation of such naturally produced antagonists holds tremendous potential for extension of shelf-life and improvement of safety of a variety of foods.     

Fermented Milks and Milk Products as Functional Foods—A Review

Fermented foods and beverages possess various nutritional and therapeutic properties. Lactic acid bacteria (LAB) play a major role in determining the positive health effects of fermented milks and related products. The L. acidophilus and Bifidobacteria spp are known for their use in probiotic dairy foods. Cultured products sold with any claim of health benefits should meet the criteria of suggested minimum number of more than 10⁶ cfu/g at the time of consumption. Yoghurt is redefined as a probiotic carrier food. Several food powders like yoghurt powder and curd (dahi) powder are manufactured taking into consideration the number of organisms surviving in the product after drying. Such foods, beverages and powders are highly acceptable to consumers because of their flavor and aroma and high nutritive value. Antitumor activity is associated with the cell wall of starter bacteria and so the activity remains even after drying. Other health benefits of fermented milks include prevention of gastrointestinal infections, reduction of serum cholesterol levels and antimutagenic activity. The fermented products are recommended for consumption by lactose intolerant individuals and patients suffering from atherosclerosis. The formulation of fermented dietetic preparations and special products is an expanding research area. The health benefits, the technology of production of fermented milks and the kinetics of lactic acid fermentation in dairy products are reviewed here.     

Application of the Key Events Dose-response Framework to Folate Metabolism

Folate is a vitamin that plays a role as a cofactor and coenzyme in many essential reactions. These reactions are interrelated and any change in folate homeostasis could affect other reactions. With food fortified with folic acid, and use of multivitamin, unmetabolized folic acid (UMFA) has been detected in blood circulation, particularly among older adults. This has raised concern about the potential harmful effect of high folic acid intake and UMFA on health conditions such as cognitive dysfunction and cancer. To examine what is known about folate metabolism and the release of circulating UMFA, the Key Events Dose-Response Framework (KEDRF) was used to review each of the major key events, dose-response characteristics and homeostatic mechanisms of folate metabolism. The intestine, liver and kidneys each play essential roles in regulating body folate homeostasis. But the determining event in folate metabolism leading to the release of UMFA in circulation appears to be the saturation of dihydrofolate reductase in the liver. However, at each of the key events in folate metabolism, limited information is available on threshold, homeostatic regulation and intracellular effects of folic acid. More studies are needed to fill in the knowledge gaps for quantitatively characterizing the dose-effect relationship especially in light of the call for extending folate fortification to other foods.     

The 'buttery' attribute of wine--diacetyl--desirability, spoilage and beyond

The diketone, diacetyl, is a major flavour metabolite produced by lactic acid bacteria (LAB). Of the LAB associated with wine, Oenococcus oeni is encouraged during the malolactic (ML) fermentation, a biodeacidification of wine during which the metabolism of diacetyl occurs. Diacetyl, which imparts a buttery aroma and flavour to many fermented foods and beverages, is a key flavour compound of most fermented dairy products. In wine, diacetyl has important stylistic implications. The biosynthesis of diacetyl is dependent upon citric acid metabolism and diacetyl is an intermediate metabolite which can be further reduced to acetoin and the alcohol, 2,3-butanediol. This review will focus on the sensory perception, metabolism, genetics and analysis of diacetyl during wine production. The extensive knowledge of diacetyl metabolism in dairy LAB is used to enhance the understanding of diacetyl metabolism of wine LAB. Factors which can effect the formation and concentration of diacetyl in wine are discussed. These include malolactic bacterial strain, wine chemical and physical parameters (pH, temperature, citric acid, sulfur dioxide, aeration) and the presence of yeast lees. Finally, the affects of other wine components, such as phenolics, are discussed.     

The importance of lactic acid bacteria for the prevention of bacterial growth and their biogenic amines formation: A review

Foodborne pathogens (FBP) represent an important threat to the consumers' health as they are able to cause different foodborne diseases. In order to eliminate the potential risk of those pathogens, lactic acid bacteria (LAB) have received a great attention in the food biotechnology sector since they play an essential function to prevent bacterial growth and reduce the biogenic amines (BAs) formation. The foodborne illnesses (diarrhea, vomiting, and abdominal pain, etc.) caused by those microbial pathogens is due to various reasons, one of them is related to the decarboxylation of available amino acids that lead to BAs production. The formation of BAs by pathogens in foods can cause the deterioration of their nutritional and sensory qualities. BAs formation can also have toxicological impacts and lead to different types of intoxications. The growth of FBP and their BAs production should be monitored and prevented to avoid such problems. LAB is capable of improving food safety by preventing foods spoilage and extending their shelf-life. LAB are utilized by the food industries to produce fermented products with their antibacterial effects as bio-preservative agents to extent their storage period and preserve their nutritive and gustative characteristics. Besides their contribution to the flavor for fermented foods, LAB secretes various antimicrobial substances including organic acids, hydrogen peroxide, and bacteriocins. Consequently, in this paper, the impact of LAB on the growth of FBP and their BAs formation in food has been reviewed extensively.