Solid-state (solid-substrate) food/beverage fermentations involving fungi

“Solid-substrate” fermentation developed in the Orient is a very useful fermentation method. It is presently used to produce a variety of foods, beverages and related products. Solid-substrate fermentation products utilizing fungi including soy sauce, miso and tempe, ontjom, sake, and bread have been produced for centuries at the home and village level. They are examples of economical methods of preserving and improving the flavor, texture and nutritive values of cereal/legume substrates. “Solid-substrate” fermentation is also applied to animal products such as milk to produce Roquefort and Camembert cheeses which diversify the food flavors available to man “Solid-substrate”fermentation has certain advantages. The substrate is concentrated; the product can be extracted with relatively small quantities of solvent; the product can be easily dehydrated; moisture level can be controlled favoring the desired organisms; enzyme concentration is generally higher than is submerged fermentation; product concentration is generally higher than in submerged cultures; it is the only technique that yields true mushroom fruiting bodies and it can be used not only for production of crude enzyme concentrates (koji) but also for raising the protein content of high starch substrates. It also can be used to increase the content of vitamins at low cost. Disadvantages of “solid-substrates”from the modern industrial processing view point are the greater difficulty of handling solid substrate and the greater difficulty of controlling the fermentation parameters, temperature, pH and oxygen, and rate of microbial growth compared with liquid submerged fermentations.     

Bioactivity of soy-based fermented foods: A review

For centuries, fermented soy foods have been dietary staples in Asia and, now, in response to consumer demand, they are available throughout the world. Fermentation bestows unique flavors, boosts nutritional values and increases or adds new functional properties. In this review, we describe the functional properties and underlying action mechanisms of soy-based fermented foods such as Natto, fermented soy milk, Tempeh and soy sauce. When possible, the contribution of specific bioactive components is highlighted. While numerous studies with in vitro and animal models have hinted at the functionality of fermented soy foods, ascribing health benefits requires well-designed, often complex human studies with analysis of diet, lifestyle, family and medical history combined with long-term follow-ups for each subject. In addition, the contribution of the microbiome to the bioactivities of fermented soy foods, possibly mediated through direct action or bioactive metabolites, needs to be studied. Potential synergy or other interactions among the microorganisms carrying out the fermentation and the host's microbial community may also contribute to food functionality, but the details still require elucidation. Finally, safety evaluation of fermented soy foods has been limited, but is essential in order to provide guidelines for consumption and confirm lack of toxicity.     

Changes in microflora and biochemical composition during the Baceman stage of traditional indonesian Kecap (soy sauce) production

Indonesian soy sauce (kecap) is made from black soybeans in a traditional way which involves two microbiological stages: a solid-state fermentation and a brine fermentation. This study is concerned with the brine fermentation, called baceman. Samples from different kecap producers were analyzed for (bio)chemical content and micro-organisms. It was found that the final composition of the baceman differed from manufacturer to manufacturer, and even within companies large differences were found in microflora and the amounts of fermentation products, formol nitrogen and salt concentration. The main fermentation products were lactate, acetate, glycerol and ethanol. Pediococcus halophilus, staphylococci, a coryneform bacterium and yeasts belonging to Candida, Debaromyces and Sterigmatomyces were isolated from the brines. Compared to Japanese soy sauce production, fermentation by yeasts does not play an important role in Indonesian kecap production. This is due to the fact that kecap is made from whole soybeans only, which are poor in sugars. After fermentation by P. halophilus no substrates are left for growth and ethanol production by yeasts. The presence of film forming yeasts can even lead to spoilage of the product.     

Tempe fermentation: some aspects of formation of gamma-linolenic acid, proteases and vitamins

During a tempe fermentation the concentrations of linoleic, and alpha-linolenic acids (ALA) decreased while the concentration of oleic acid increased. During fatty acid synthesis Rhizopus sp. produced only gamma-linolenic acid (GLA) instead of ALA. The amount of GLA in tempe were influenced by varying external parameters.The proteolytic capacity of 36 strains of the genus Rhizopus isolated from Indonesian tempe or tempe inocula was examined. There was a distinct increase in the amount of free amino acids during tempe fermentation. Fermentations with mixed populations of bacteria and Rhizopus yielded a lower level of free amino acids, but an increase in total amount of amino acids. In comparison to intracellular, and extracellular proteases the proteases of the cell wall fraction are most responsible for proteolytic capacity of the different Rhizopus strains.Two isolated strains of Citrobacter freundii were found to be the best vitamin B(12) producers during the soaking of soybeans. In the solid substrate fermentation the Rhizopus molds formed vitamin B(6), riboflavin, and nicotinic acid. The addition of bacteria to the solid substrate fermentation resulted in a strong increase of active vitamin B(12) in tempe. In the presence of the Rhizopus mold, the vitamin B(12) formation by C. freundii was three times higher than that of a fermentation without the mold.     

Traditional fermented foods

For centuries, diverse plant and animal materials have been fermented by various bacteria, yeasts, and fungi to make excellent foods. The kinds of micro organisms used in traditional fermentation are restricted to a relatively few genera, including Aspergillus, Rhizopus, Mucor, Actinomucor, Monascus, Saccharomyces, Neurospora, Acetobacler, Bacillus, and Lactobacillus. The two principal advantages of food fermentations over other processes are to add flavor and to prevent spoilage. Fermented fish is a common food in the Orient and may have been the first product made by fermentation. Flavor is especially important in vegetable diets based on bland foods such as rice. Shoyu is the best, known oriental food fermentation, and it is very widely used as a flavoring agent. Be sides this fermentation, there are a large number of additional ones not so well known outside the Orient, whose products serve as seasoning or flavoring agents. Miso and natto are prepared from soybeans in Japan. Sufu is a cheese like product made from soybean milk in China. Tempeh and ontjom are Indonesian foods prepared from soybeans and peanuts, respectively. These food fermentations are discussed with emphasis on how they are produced and the flavor formed.     

Hydrolytic activity of Virgibacillus sp. SK37, a starter culture of fish sauce fermentation, and its cell-bound proteinases

Fish sauce production relies on a natural fermentation process requiring 12-18 months for process completion. Virgibacillus sp. SK37 has been shown to be a potential strain for fish sauce acceleration. However, hydrolytic activity of proteinases bound at cell surface of this strain has not been well elucidated. Addition of 0.2 % CaCl(2) (w/w) in conjunction with starter cultures of Virgibacillus sp. SK 37 increased protein hydrolysis as measured by α-amino group content throughout fermentation (P < 0.05). Cell-bound proteinases from Virgibacillus sp. SK 37 were extracted into a free form by incubating the washed cells in Ca(2+)-free buffer at 37 °C for 2 h. Cell-bound proteinases revealed molecular mass of 19, 20, 22, 32, 34, and 44 kDa based on a synthetic peptide zymogram. The proteinases showed subtilisin-like serine characteristics with the highest activity at 50 °C and pH 8 and 11. Activity of the extracted proteinases increased ~4 times at ≥100 mM CaCl(2). In addition, CaCl(2) enhanced thermal stability of the extracted proteinases. Enzymes showed proteolytic activity in either the absence or presence of 10 and 25 % NaCl toward fish muscle, soy protein isolate, and casein substrates. Cell-bound proteinases were likely to play an important role in protein hydrolysis during fish sauce fermentation.     

Formation of vitamins by pure cultures of tempe moulds and bacteria during the tempe solid substrate fermentation

The formation of water soluble vitamins (vitamin B₁₂, vitamin B₆, riboflavin, thiamine, nicotinic acid and nicotinamide) during the tempe solid substrate fermentation was investigated. The role of several strains of Rhizopus oligosporus, R. arrhizus , and R. stolonifer and the role of several bacteria in the vitamin formation process were checked. All fungal and bacterial strains were isolated from Indonesian tempe and soaking water samples. The Rhizopus strains formed riboflavin, nicotinic acid, nicotinamide and vitamin B₆. The final concentrations of these substances depended on the different strains involved and on the fermentation time. Isolates of R. oligosporus were generally the best vitamin formers. The moulds did not produce physiologically active vitamin B₁₂. The thiamine content decreased during fermentation. The addition of bacteria, which had been selected in a screening for vitamin B₁₂ production, resulted in an increase of physiologically active vitamin B₁₂. Citrobacter freundii and Klebsiella pneumoniae showed the best formation capabilities. Furthermore, the bacteria produced riboflavin and vitamin B₆ in addition to the moulds. The influence of Rhizopus on the vitamin B₁₂ formation of Cit. freundii was also investigated. The vitamin content of tempe that was fermented with the mould and the bacterium was three times as high as a control fermentation with Cit. freundii only.     

Fermented foods, feeds and beverages

There has been a proliferation of books and papers dealing with the indigenous fermented foods/beverages of the world. It is anticipated that these foods/beverages will play an ever-increasingly important role in feeding both the developing and the developed world as population increases from approximately 4.5 billion to 6 billion by the year 2000 and to 8 to 12 billion people in the 21st century. The indigenous fermented foods consist of microbial protein grown on edible substrates. Microbial or single cell protein (SCP) per se continues to receive research and development attention. It is likely to play an important role in feeding animals in the future when it becomes competitive with soy protein. It may play a direct role in feeding humans in the future after its safety for feeding animals has been adequately demonstrated and it has been shown that it can be processed into foods acceptable to humans. At the present time, mushrooms, a form of microbial protein highly acceptable to humans, which can be grown readily on ligno-cellulosic and other agricultural and food processing wastes, offer considerable opportunity for expanding man's food supply.     

酱醪中魏斯氏菌的分离及特性分析

【背景】魏斯氏菌广泛存在于发酵食品中,它们与食品发酵进程和风味物质的形成密切相关。酱油发酵过程酱醪中细菌的优势菌属是魏斯氏菌,研究魏斯氏菌的生理和代谢特性对于揭示菌株对环境的适应性和与酱油发酵相关的功能具有重要意义。【目的】从酱油酱醪中分离获得魏斯氏菌属中主要种的菌株,研究它们在酱油发酵过程的数量变化以及菌株的生理和生化特性,阐明菌株对酱油发酵体系的适应性和与酱油发酵相关的特性。【方法】通过菌株绝对数量的定量分析和耐受性比较,以及考察高盐条件下魏斯氏菌合成短链脂肪酸、胞外多糖、生物胺和氨基甲酸乙酯或其前体等特性,研究各类魏斯氏菌对酱油发酵和其安全性的影响。【结果】从高盐稀态酱油的酱醪中共分离得到16株魏斯氏菌,分别属于融合魏斯氏菌(Weissella confusa)、类肠膜魏斯氏菌(Weissellaparamesenteroides)和食窦魏斯氏菌(Weissellacibaria)。其中类肠膜魏斯氏菌可耐受高盐条件,是酱醪中魏斯氏菌属的主要菌种。它们合成短链脂肪酸的能力高于融合魏斯氏菌和食窦魏斯氏菌。酱醪来源的魏斯氏菌合成氨(胺)类危害物的特性区别较大,类肠膜魏斯氏菌的部分菌株产生物胺并可利用精氨酸积累瓜氨酸,食窦魏斯氏菌则能够降解多种生物胺。【结论】揭示了酱醪中主要魏斯氏菌的耐盐特性、在较低温度下生长情况和物质代谢规律,对于阐明魏斯氏菌与酱油发酵相关的功能和特性以及对酱油加工过程安全控制具有重要意义。     

Lactic-acid fermentation as a low-cost means of food preservation in tropical countries

Abstract The range of traditional lactic-acid-fermented foods in tropical countries is briefly reviewed. Recent studies on the lactic acid fermentation of fish and cassava products are described. Lactic-acid-fermented fish products may offer considerable scope for the development of new food products and for the use of under-utilised fish species. Lactic-acid-fermented fish products are common in parts of Asia; methods to improve the product and shelf-life quality, to reduce microbial risks and to accelerate the process are described. This work is based on fish/salt/carbohydrate model systems. The nutritional aspects of cassava fermentation are discussed with respect to factors involved in determining residual cyanide levels; the possible anti-nutritional rôle of condensed tannins is mentioned. The increasing consumption of meat products in tropical countries emphasises the need for a preservation method that does not depend on refrigeration. The possible production of sausage ingredients preserved by lactic acid fermentation, and the associated research needs are described.     

液质发酵食品中微生物群落及与乳酸菌间相互作用研究进展

液质发酵食品发酵过程中微生物组成复杂,复杂的微生物发酵体系会影响微生物的生长和代谢,继而改变微生物的群落结构与功能,最终影响液质发酵食品的品质.乳酸菌在食品发酵中对形成风味物质、提高营养价值、抑制腐败菌生长具有重要的作用.本文主要对近年来食醋、酱油和饮料酒等液质发酵食品中微生物群落及与乳酸菌间相互作用关系进行综述,了解...     

Halobacterium sp. SP1(1) as a starter culture for accelerating fish sauce fermentation

Aims: Application of Halobacterium sp. SP1(1) for the acceleration of fish sauce fermentation. Methods and Results: Traditional fish sauce fermentation was mimicked using Halobacterium sp. SP1(1) as starter culture. Protease activity, peptide release and α‐amino content (parameters used to monitor the progress of the fermentation) were high at day 10 in tests and day 20 in un‐inoculated controls. The total protein and nitrogen contents were also high in tests compared with controls. The amino acid profile observed at the end of fermentation in experimental samples, when compared with the commercial sauce preparation, was found to be better with respect to flavour and aroma contributing amino acids as well as essential amino acid lysine. Microflora analysis of the final fish sauce revealed the absence of any nonhalophilic or halotolerant micro‐organisms. The protease‐producing halophilic isolates obtained from the fish sauce of eviscerated and uneviscerated controls were identified as Halobacterium sp. F1 and F2, respectively, by 16S rDNA sequence analysis. Conclusions: Exogenous augmentation of Halobacterium sp. SP1(1) accelerated the fish sauce fermentation process with an additive effect on the existing natural microflora present in the fish during fermentation. Halobacterium sp SP1(1), therefore, can be used as an important starter culture for accelerating the fish fermentation process, which is attributed to its extracellular protease. Significance and Impact of the Study: The present study is the first report on use of Halobacterium species as a starter culture for accelerating fish sauce fermentation. Use of halobacterial starter cultures may revolutionize the process in fish sauce industries by reducing the fermentation time and making the process more economical with improved nutritive value of product.     

Occurrence and function of yeasts in Asian indigenous fermented foods

In the Asian region, indigenous fermented foods are important in daily life. In many of these foods, yeasts are predominant and functional during the fermentation. The diversity of foods in which yeasts predominate ranges from leavened bread-like products such as nan and idli, to alcoholic beverages such as rice and palm wines, and condiments such as papads and soy sauce. Although several products are obtained by natural fermentation, the use of traditional starter cultures is widespread. This minireview focuses on the diversity and functionality of yeasts in these products, and on opportunities for research and development.     

Identification and Quantitation of New Glutamic Acid Derivatives in Soy Sauce by UPLC/MS/MS

Glutamic acid is an abundant amino acid that lends a characteristic umami taste to foods. In fermented foods, glutamic acid can be found as a free amino acid formed by proteolysis or as a non‐proteolytic derivative formed by microorganisms. The aim of the present study was to identify different structures of glutamic acid derivatives in a typical fermented protein‐based food product, soy sauce. An acidic fraction was prepared with anion‐exchange solid‐phase extraction (SPE) and analyzed by UPLC/MS/MS and UPLC/TOF‐MS. α‐Glutamyl, γ‐glutamyl, and pyroglutamyl dipeptides, as well as lactoyl amino acids, were identified in the acidic fraction of soy sauce. They were chemically synthesized for confirmation of their occurrence and quantified in the selected reaction monitoring (SRM) mode. Pyroglutamyl dipeptides accounted for 770 mg/kg of soy sauce, followed by lactoyl amino acids (135 mg/kg) and γ‐glutamyl dipeptides (70 mg/kg). In addition, N‐succinoylglutamic acid was identified for the first time in food as a minor compound in soy sauce (5 mg/kg).     

Food technology: challenge for health promotion

The food technology has brought countless benefits to today's food supply. Despite its many positive contributions, it has also brought unintended negative consequences. It is the time to mobilize the food technology to help the food supply more secure, safer and healthier, and here three possible approaches are foreseeable: First, we should continue to improve the conventional technologies. Many wholesome foods have been prepared and preserved using natural materials simply by fermentation. Second, we have to enhance the minimal processing as much as applicable. Third, new ingredients, intelligent packaging and functional foods should be explored to improve food supply and health. Today, consumer interest in the functional foods has been increased tremendously, and the future of food lies in the functional foods. However, the situations in the developing world are different from this. As food resource is limited in this region, food technology has to be emphasized to increase food supply. To help solve such complex problems, not only new technologies, but also conventional technologies have to be mobilized. Simultaneously, even higher technical capabilities have to be built up by applying new findings from the related disciplines to allow the food technology to play its vital role.     

New developments in the field of protein enrichment of foods and feeds (P.E.F.F)

Up to the year 2000 the total demand of protein for animal feeding will rise by 146%. This demand can not be covered by agriculture alone. According to FAO data it will be an expected deficit of some 400 million tons of cereals at this time all over the world. Therefore the large scale industrial production of SCP from alkanes, methanol and other raw materials will undoubtely become soon an absolute necessity. On the other hand, a new process of solid state fermentation (ORSTOM/IRCHA process) having special interest for the developing countries has been recently set-up in France. Based on dried and crushed potatoes or cassava (manioc or tapioca) protein enrichment by fermentation of feeds of foods (PEFF) in a simple manner without aseptic conditions with the filamentous fungus Aspergillus hennebergii is carried out. The process is presently optimized and scaled-up to the size of a 700 kg (dry weight) fermenter. Nutrititional and toxicological assays have demonstrated complete safety and excellent nutrititional value of the product, which is applicable as a feedstuff for breading of e.g. pigs or chickens.     

Determination of bioactive compounds in fermented soybean products using GC/MS and further investigation of correlation of their bioactivities

The active ingredients and bioactivities (anti-oxidant, anti-tyrosinase, anti-proliferative and estrogenic activities) of soybean and soybean products (Cheonggukjang, Meju, Makjang, Doenjang and soy sauce) produced by different fermentation processes were compared. There were high correlations between active ingredients and bioactivities. Free phenolic acids extracted from soybean products were identified and quantified by gas chromatography/mass spectrometry (GC/MS). Overall, the components and activities in fermented soybean products were different than those in soybeans. Total phenolic content (TPC), protein content (PC) and anti-oxidant activity increased as fermentation time increased. TPC and PC showed strong negative correlations with anti-oxidant activity. Doenjang and soy sauce, two long-term fermented products, showed lower total flavonoid content (TFC) and estrogenic activities than short-term fermented soybean products. This might be explained by the decomposition and hydrolysis of flavonoids due to the long fermentation time and high temperature. Strong anti-proliferative activity against cancer cell lines, which was highly correlated with TFC, was found in Meju and Cheonggukjang. Soybean and all fermented products except Meju exhibited effective tyrosinase inhibitory activities. Fermented products showed stronger estrogenic activity than soybeans, which was highly correlated with syringic acid.     

Importance of lactic acid bacteria in Asian fermented foods

Lactic acid bacteria play important roles in various fermented foods in Asia. Besides being the main component in kimchi and other fermented foods, they are used to preserve edible food materials through fermentation of other raw-materials such as rice wine/beer, rice cakes, and fish by producing organic acids to control putrefactive microorganisms and pathogens. These bacteria also provide a selective environment favoring fermentative microorganisms and produce desirable flavors in various fermented foods. This paper discusses the role of lactic acid bacteria in various non-dairy fermented food products in Asia and their nutritional and physiological functions in the Asian diet.     

Food processing by high hydrostatic pressure

High hydrostatic pressure (HHP) process, as a nonthermal process, can be used to inactivate microbes while minimizing chemical reactions in food. In this regard, a HHP level of 100 MPa (986.9 atm/1019.7 kgf/cm²) and more is applied to food. Conventional thermal process damages food components relating color, flavor, and nutrition via enhanced chemical reactions. However, HHP process minimizes the damages and inactivates microbes toward processing high quality safe foods. The first commercial HHP-processed foods were launched in 1990 as fruit products such as jams, and then some other products have been commercialized: retort rice products (enhanced water impregnation), cooked hams and sausages (shelf life extension), soy sauce with minimized salt (short-time fermentation owing to enhanced enzymatic reactions), and beverages (shelf life extension). The characteristics of HHP food processing are reviewed from viewpoints of nonthermal process, history, research and development, physical and biochemical changes, and processing equipment.     

Anaerobic solid-phase fermentation of plant substrates by <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

Solid-phase growth of Bacillus subtilis 8130 on cellulose-rich plant substrates (presscakes or pulp) under hypoxic conditions was accompanied by cellulose depolymerization, protein hydrolysis, and degradation of other plant components, including some processes of mixed-type carbohydrate fermentation. The bacterial fermentation yielded propionic, butyric, hexanoic acids and butyric acid derivatives. The bacterial metabolism and fermentation degree can be characterized by the proportions of fatty acids in the reaction mixture. The product of sea buckthorn cake fermentation has a good sorption quality.