Fermentation Microorganisms and Flavor Changes in Fermented Foods

ABSTRACT: Food fermentation processes often result in profound changes in flavor relative to the starting ingredients. However, fermenting foods are typically very complex ecosystems with active enzyme systems from the ingredient materials interacting with the metabolic activities of the fermentation organisms. Factors such as added salt, particle sizes, temperature, and oxygen levels will also have important effects on the chemistry that occurs during fermentation. This is a brief review of recent research on flavor changes in food fermentations. The emphasis will be on the role of lactic acid bacteria in changing the compounds that help determine the character of fermented foods from plant-based substrates.     

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。     

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.     

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.     

Lactic acid bacteria in traditional fermented Chinese foods

Food fermentation is a widely practiced and ancient technology in China. Lactic acid bacteria (LAB) are involved in many fermentation processes of Chinese traditional foods, demonstrating their profound effects on improving food quality and food safety. This review article outlines the main types of LAB fermentation as well as their typical fermented foods such as koumiss, suan-tsai, stinky tofu and Chinese sausage. The roles of LAB and the reasons for their common presence are also discussed.     

市场上发酵蔬菜中乳酸菌数量的调查研究

乳酸菌（Lactic Acid Bacteria）是一类能发酵碳水化合物产生乳酸的细菌,广泛应用于发酵食品中,是发酵蔬菜中的有益菌群。泡菜主要是由乳酸菌发酵形成的发酵蔬菜。从食品安全的角度出发,研究市售的20种发酵菜样品（白菜类、黄瓜类、萝卜、类、辣椒类）中乳酸菌的数量多少,得出其与蔬菜种类、加工和包装方法的关系。不同类别中,黄瓜类的乳酸菌数量较多,萝卜、类的乳酸菌数量较少;同一类别中,散装的较袋装的乳酸菌数量多。     

Lactic acid bacteria and yeasts associated with spontaneous fermentations during the production of sour cassava starch in Brazil

Sour cassava starch is a traditional fermented food used in the preparation of fried foods and baked goods such as traditional cheese breads in Brazil. Thirty samples of sour cassava starch were collected from two factories in the state of Minas Gerais. The samples were examined for the presence of lactic acid bacteria, yeasts, mesophilic microorganisms, Bacillus cereus and faecal coliforms. Lactic acid bacteria and yeasts isolates were identified by biochemical tests, and the identities were confirmed by molecular methods. Lactobacillus plantarum and Lactobacillus fermentum were the prevalent lactic acid bacteria in product from both factories, at numbers between 6.0 and 9.0 log cfu g(-)(1). Lactobacillus perolans and Lactobacillus brevis were minor fractions of the population. Galactomyces geothricum and Issatchenkia sp. were the prevalent yeasts at numbers of 5.0 log cfu g(-)(1). A species similar to Candida ethanolica was frequently isolated from one factory. Mesophilic bacteria and amylolytic microorganisms were recovered in high numbers at all stages of the fermentation. B. cereus was found at low numbers in product at both factories. The spontaneous fermentations associated with the production of sour cassava starch involve a few species of lactic acid bacteria at high numbers and a variety of yeasts at relatively low numbers.     

发酵蔬菜中乳酸菌抑菌性的研究

乳酸菌(Lactic Acid Bacteria)是一类能发酵碳水化合物产生乳酸的细菌,他广泛应用于发酵食品中,是发酵蔬菜中的有益菌群。乳酸菌的抑菌功能是通过产生各种代谢产物包括酸性物质、二氧化碳、过氧化氢和细菌素等来实现的。通过分析发酵蔬菜中微生物菌群结构的组成,介绍了乳酸菌对病原菌和腐败菌的抑制作用特点及作用机理,旨在为乳酸菌制品的加工、储藏提供理论依据,更好地将乳酸菌这一益生菌应用于各类食品加工的实践操作中。     

Food biotechnology review: traditional solid-state fermentations of plant raw materials--application, nutritional significance, and future prospects

This review on the use of indigenous solid-state fermentations (SSF) describes the microbiological transformation of plant raw materials into highly nutritious foods and flavor-enhancing ingredients. Traditional fermented foods from most countries of the world may be classified into the following categories: fungal fermentation followed by brining, SSF principally using bacteria, lactic acid fermentation followed by fungal fermentation, production of fermented doughs, alcoholic fermentation, and fermented food ingredients. Scientific studies of the principles behind SSF, identification of the essential microorganisms, development of suitable and versatile equipment, control of the process, and quality control of the substrate and final product can very well lead to a substantial increase at a world level in the availability and consumption of these fermented foods. The application of modern biotechnology in some countries is already changing the ancient methods of making fermented foods.     

乳酸菌耐盐分子机制研究进展

乳酸菌广泛应用于食品和发酵行业。在酱油、熏肉、泡菜等发酵食品的生产过程中,乳酸菌的生长常受到 高盐浓度的影响。盐胁迫引起的渗透压变化会引起乳酸菌细胞结构损伤,导致细胞生理代谢活动紊乱甚至死亡。因 此,乳酸菌在盐胁迫条件下生存、生长和代谢的能力在食品发酵过程中是非常重要的。本文就乳酸菌的耐盐机制进 行阐释,以期为乳酸菌科学研究及食品发酵工业应用提供参考。     

Nitric Oxide (NO) and Lactic Acid Bacteria-Contributions to Health, Food Quality, and Safety

In this article, the effects of nitric oxide (NO) and nitric oxide producer bacteria on food quality, safety, and human health care high lighted. NO, which was previously recognized as a toxic gas, has attracted attention in the last two decades due to its vital role in many physiological processes of animals and plants. Particularly, it is important to note from the point of view of food quality and safety that lactic acid bacteria, which are used as starter cultures in foods, also have the capability of producing NO. There have been several studies on the color development of meat products that originated from NO production of lactic acid bacteria. For this reason, it is also important to emphasize the different aspects of interactions between food and NO.     

乳酸菌发酵在谷物产品中的应用及研究进展

谷物食品是人类能量摄入的主要来源之一，随着人们生活水平的提高，谷物食品的营养价值和食用品质受到了广泛关注。发酵是改善食品性质、功能及营养缺陷的重要方法，也是谷物加工的重要手段。乳酸菌能够利用碳水化合物进行生长代谢，在食品工业中被广泛应用于各种发酵制品，其发酵产生的代谢产物有许多重要的生理功能，包括调节肠道菌群平衡、提高免疫力、抗菌和抗肿瘤等。因此，乳酸菌发酵在谷物食品中的研究与应用，对提升食品品质具有重要意义。本文综述了乳酸菌发酵对谷物营养成分、生物功能和结构、理化性质的影响，总结了乳酸菌发酵谷物产品的优势以及乳酸菌发酵在多种谷物产品中的应用，分析了乳酸菌发酵谷物食品目前研究的不足及可能的发展方向, 拟为乳酸菌发酵在谷物中的研究与开发提供参考。     

乳酸菌降低过敏食物致敏性的研究进展

食物过敏的患病率在近几十年内急剧上升,越来越多的证据表明机体内微生物的生态失调是引起食物过敏的主要原因,因此乳酸菌等益生菌对过敏症状的潜在预防和治疗效果引起了人们的广泛关注。大量研究表明乳酸菌不仅能够通过发酵降低食物过敏原的致敏性,而且有可能通过调节肠道菌群的平衡在宿主免疫系统的发育和调节中发挥作用,从而改变过敏性疾病的发病风险。本文综述了乳酸菌的分类和生物特性,乳酸菌发酵在降低牛奶、大豆、花生、小麦等主要食物过敏原中发挥的作用,乳酸菌发挥免疫调节作用的主要机制,包括改变抗原递呈细胞的表型、调节Th1/Th2平衡、诱导调节性T细胞、增强肠道屏障功能。以期通过乳酸菌及其发酵作用达到预防和/或治疗食物过敏的效果,为乳酸菌的研究及应用提供参考。     

乳酸菌拮抗食源性致病菌的研究及应用进展

食品在生产加工、物流运输和贮存消费过程中均可能出现被食源性致病菌污染的风险,造成安全隐患,目前通过热加工、辐照、电解水和等离子体等方法来控制食品中食源性致病菌,但在食品感官、规模化应用和安全生产等方面存在部分缺点.乳酸菌因其丰富的生物活性常作为生物发酵剂和保鲜剂广泛应用于食品中,并且可在食品中拮抗致病菌.本文主要从竞争...     

乳酸菌产共轭亚油酸研究现状

共轭亚油酸(conjugated linoleic acid, CLA)是十八碳二烯酸的异构体。通过食物摄入的CLA不能达到每日推荐摄入量,而CLA又具有减肥、抗癌、抗Ⅱ型糖尿病等多种生理功能,故CLA逐渐成为研究热点。与化学合成CLA相比,微生物合成CLA更具有优势。乳酸菌(lactic acid bacteria, LAB)具有安全性和益生功能,利用乳酸菌合成CLA是一个理想的途径。目前已发现多种产CLA乳酸菌,人们使用乳酸菌发酵油酸、牛乳、植物油合成CLA,并取得了良好的效果。亚油酸异构酶(linoleate isomerase, LAI)对乳酸菌合成CLA起重要作用,但其对乳酸菌合成CLA的作用机理还不明确。一些学者对乳酸菌合成CLA的中间产物进行了研究,发现乳酸菌合成CLA有多种中间产物。乳酸菌合成CLA的代谢机制目前尚不清楚。乳酸菌合成CLA对食品工业有重要意义,也为功能性食品的开发提供了新机遇。本文主要对CLA的生理功能、产CLA乳酸菌、乳酸菌合成CLA的底物、乳酸菌合成CLA的途径进行了概述。     

乳酸菌发酵对淀粉类食品品质的影响

馒头、面包、米粉和面条等淀粉类食品是常见的主食，提高该类食品品质对保证营养摄入、促进健康具有重要意义。乳酸菌发酵是改善淀粉类食品品质的有效手段，该文将乳酸菌发酵对上述淀粉类产品的质构、感官和老化等方面的影响进行了总结，并对其应用前景进行了展望。     

Traditional and novel fermented foods and beverages from tropical root and tuber crops: review

Tropical root and tuber crops [cassava, sweet potato, yams, colocasia (taro), etc] are important staples for food security for about a fifth of the world population. Bulk of cassava in Africa and Latin America are processed into fermented foods and food additives such as organic (acetic, citric and lactic) acids, mono-sodium glutamate, etc. The fermented foods from cassava are gari , fufu , lafun , chickwanghe , agbelima , attieke and kivunde in Africa, tape in Asia and ' cheese ' bread , and ' coated peanut ' in Latin America. Lactic acid bacteria and yeasts are the major group of micro-organisms associated with cassava fermentation. Similarly, sweet potatoes can be fermented into soy sauce, vinegar, lacto-juices, lacto-pickles and sochu (an alcoholic drink produced in Japan), and yams into fermented flour. Most of these fermented food products are functional foods rich in phytochemicals, dietary fibres, anti-oxidant compounds (β-carotene, anthocyanin, etc) and probiotic components (lactic acid bacteria and yeasts).     

乳酸菌在果蔬及谷物制品中的应用

乳酸菌作为一种益生菌,具有多种生理功能,用其发酵食品更是具有改善风味、延长保质期等特点,因此乳酸菌在各类食品中得到了广泛应用.鉴于乳酸菌在乳制品中的应用历史较为悠久,且有广泛的报导,本文仅列举了近些年乳酸菌较新的应用领域,阐述了其应用现状及益处, 并对今后发展提出了建议.乳酸菌可实现多种果汁、蔬菜汁及谷物制品的发酵,通过乳酸发酵,实现了菠萝皮、麦麸等的利用,改善了原料口味,提高了利用价值。     

Characterization of Cucumber Fermentation Spoilage Bacteria by Enrichment Culture and 16S rDNA Cloning

Commercial cucumber fermentations are typically carried out in 40000 L fermentation tanks. A secondary fermentation can occur after sugars are consumed that results in the formation of acetic, propionic, and butyric acids, concomitantly with the loss of lactic acid and an increase in pH. Spoilage fermentations can result in significant economic loss for industrial producers. The microbiota that result in spoilage remain incompletely defined. Previous studies have implicated yeasts, lactic acid bacteria, enterobacteriaceae, and Clostridia as having a role in spoilage fermentations. We report that Propionibacterium and Pectinatus isolates from cucumber fermentation spoilage converted lactic acid to propionic acid, increasing pH. The analysis of 16S rDNA cloning libraries confirmed and expanded the knowledge gained from previous studies using classical microbiological methods. Our data show that Gram‐negative anaerobic bacteria supersede Gram‐positive Fermincutes species after the pH rises from around 3.2 to pH 5, and propionic and butyric acids are produced. Characterization of the spoilage microbiota is an important first step in efforts to prevent cucumber fermentation spoilage. Practical Application An understanding of the microorganisms that cause commercial cucumber fermentation spoilage may aid in developing methods to prevent the spoilage from occurring.     

Liquid sourdough fermentation: industrial application perspectives

Sourdough fermentation is considered to play a key role to get improved flavour, texture, nutritional and shelf-life properties of bakery products. Since few years Barilla R&D has been focusing on liquid sourdough fermentation which may deserve several advantages with respect to traditional processes. The results showed that the micro-biota of sourdough markedly influences flavour and texture of bakery products. Particular attention has been paid to lactic acid bacteria and yeasts. Selected lactic acid bacteria and yeasts were tested in sourdough liquid fermentation as single strain or in association. The parameters of fermentations were optimized and standardized to set up a laboratory plant liquid fermentation. Only a few strains of lactic acid bacteria were found to be suitable for liquid fermentation alone or in association with yeasts. Fermentations were carried out at pilot plant and an industrial technology was developed. This work describes the results found for the organoleptic profile of an industrial bread started with liquid sourdough with respect to bakers' yeast bread without sourdough addition.