A review on traditional Turkish fermented non-alcoholic beverages: Microbiota,fermentation process and quality characteristics

Shalgam juice, hardaliye, boza, ayran (yoghurt drink) and kefir are the most known traditional Turkish fermented non-alcoholic beverages. The first three are obtained from vegetables, fruits and cereals, and the last two ones are made of milk. Shalgam juice, hardaliye and ayran are produced by lactic acid fermentation. Their microbiota is mainly composed of lactic acid bacteria (LAB). Lactobacillus plantarum, Lactobacillus brevis and Lactobacillus paracasei subsp. paracasei in shalgam fermentation and L. paracasei subsp. paracasei and Lactobacillus casei subsp. pseudoplantarum in hardaliye fermentation are predominant. Ayran is traditionally prepared by mixing yoghurt with water and salt. Yoghurt starter cultures are used in industrial ayran production. On the other hand, both alcohol and lactic acid fermentation occur in boza and kefir. Boza is prepared by using a mixture of maize, wheat and rice or their flours and water. Generally previously produced boza or sourdough/yoghurt are used as starter culture which is rich in Lactobacillus spp. and yeasts. Kefir is prepared by inoculation of raw milk with kefir grains which consists of different species of yeasts, LAB, acetic acid bacteria in a protein and polysaccharide matrix. The microbiota of boza and kefir is affected from raw materials, the origin and the production methods.     

藏灵菇牦牛酸乳发酵过程中乳酸菌和酵母菌对品质的作用

藏灵菇酸乳是由乳酸菌、酵母菌、醋杆菌和霉菌共同发酵形成的一种发酵乳制品,其品质特征与普通酸乳有显著差异。为研究藏灵菇发酵酸乳中乳酸菌和酵母菌分别发挥的作用,利用放线菌酮和青链霉素分别抑制发酵过程中的酵母菌和乳酸菌,测定并比较正常发酵酸乳、抑制乳酸菌发酵酸乳和抑制酵母菌发酵酸乳的风味、口感和质构等相关指标。实验结果显示抑制酵母菌发酵的酸乳中乙醇含量由1.85g/kg上升为2.77g/kg,VB2含量由168μg/100g下降为157μg/100g,与正常发酵组差异较大;抑制乳酸菌发酵的酸乳中酸度由18°T上升为28°T,氨基酸态氮由65mg/100g下降为53mg/100g,乳酸含量持续2mg/g,乙酸由1mg/g下降为0.7mg/g,VB1含量由20μg/100g下降为18μg/100g,与正常发酵组差异较大。乳酸菌在酸乳发酵过程中,对酸度、氨基酸态氮、质构、乳酸、乙酸与VB1的生成贡献较大;酵母菌对乙醇、VB2的生成贡献较大。     

Microbiology and biochemistry of natural fermentation of coconut palm sap

The micro-organisms appearing during natural fermentation of coconut sap were identified and the physical and chemical changes occuring in the sap were studied by analysing samples collected at intervals of time during the traditional fermentation process.A total of 166 isolates of yeasts and 39 isolates of bacteria were identified. Seventeen species of yeasts belonging to eight genera were recorded. The largest number of isolates (72%) belonged to genera Candida, Pichia and Saccharomyces. Saccharomyces chevalieri was the most dominant yeast species and accounted for 35% of the total isolates. Seven genera of bacteria were isolated. The predominant Genera was Bacillus. Others included Enterobacter, Leuconostoc, Micrococcus and Lactobacillus.The major physical, chemical and microbiological changes occurring in the fermenting sap indicated that a natural fermentation of coconut sap consist of an initial lactic acid fermentation, a middle alcoholic fermentation and a final acetic acid fermentation. It also appeared that activities brought about by micro-organisms of early phase helped the activities of the micro-organisms in each of the later phases.     

Aeration and Its Influence on the Microbial Sequence in Cacao Fermentations in Bahia, with Emphasis on Lactic Acid Bacteria

Three aeration treatments on cacao fermentations in Bahia produced a basically similar microbial sequence which was influenced by the time and intensity of aeration. An initial, low temperature, semi-anaerobic phase dominated by yeasts and lactic acid bacteria, was superceded by aerobic and thermophyllic bacteria when the fermentations gained heat after aeration. Delay in aeration retarded this change in flora while over aeration accelerated it and, in addition, provoked a second lactic acid bacteria phase towards the end of fermentation. Lactobacillaceae were predominant during the anaerobic period and Streptococeaceae under aerated conditions. This marked, lactic acid bacteria population during the early stages of fermentation is not usual and would account for the lactic and acetic acids produced during this period.     

Lactic acid fermentation of<Emphasis Type="Italic"> Brassica rapa</Emphasis>: chemical and microbial evaluation of a typical Italian product (<Emphasis Type="Italic">brovada</Emphasis>)

Brovada is an ancient traditional product from the northeast Italian region, included in any list of typical Italian products, which is obtained by natural fermentation of turnips (Brassica rapa). Turnips are cleaned and put in vats, alternating them with a layer of grape skins. Before covering the vat a mix of water and salt or water only is added. The vegetable fermentation is a spontaneous process caused by the microorganisms present on the various components (turnip and grape skins). A total 225 lactic acid bacteria (LAB) and 63 yeasts were isolated during this natural fermentation process. The main heterofermentative population was identified as Lactobacillus spp. while the major homofermentative LAB were Pediococcus spp., Candida spp. was the main yeast present. During the first 24 h of fermentation, the pH decreased rapidly to 3.7. At different steps of fermentation the headspace aroma compounds of brovada were analyzed by solid-phase-micro-extraction/gas chromatography/flame ionization detection to define the characteristic aroma profile of this particular product.     

Preservation of Acidified Cucumbers with a Natural Preservative Combination of Fumaric Acid and Allyl Isothiocyanate that Target Lactic Acid Bacteria and Yeasts

ABSTRACT: Without the addition of preservative compounds cucumbers acidified with 150 mM acetic acid with pH adjusted to 3.5 typically undergo fermentation by lactic acid bacteria. Fumaric acid (20 mM) inhibited growth of Lactobacillus plantarum and the lactic acid bacteria present on fresh cucumbers, but spoilage then occurred due to growth of fermentative yeasts, which produced ethanol in the cucumbers. Allyl isothiocyanate (2 mM) prevented growth of Zygosaccharomyces globiformis, which has been responsible for commercial pickle spoilage, as well as the yeasts that were present on fresh cucumbers. However, allyl isothiocyanate did not prevent growth of Lactobacillus plantarum. When these compounds were added in combination to acidified cucumbers, the cucumbers were successfully preserved as indicated by the fact that neither yeasts or lactic acid bacteria increased in numbers nor were lactic acid or ethanol produced by microorganisms when cucumbers were stored at 30 °C for at least 2 mo. This combination of 2 naturally occurring preservative compounds may serve as an alternative approach to the use of sodium benzoate or sodium metabisulfite for preservation of acidified vegetables without a thermal process.     

传统发酵泡菜优势微生物及其代谢特性

采用平板计数法分析泡菜发酵过程中主要微生物的变化规律,并利用高效液相色谱仪、pH计等仪器分析底物、代谢产物和pH值的变化。结果表明：我国传统泡菜发酵过程中的主要微生物有乳酸菌、醋酸菌、酵母菌及霉菌;发酵7 d后,卤水的最终pH值由初始的5.7降至3.2;蔗糖作为发酵体系内的主要碳源,在整个发酵过程中被大量代谢利用,发酵7 d后,蔗糖浓度由初始的74.4 mmol/L变为18.4 mmol/L;而葡萄糖和果糖在发酵过程中没有明显被利用,其浓度分别维持在28.1 mmol/L和23.2 mmol/L;柠檬酸与苹果酸分别在24 h和12 h时达到最大浓度（3.4 mmol/L和8.9 mmol/L）,然后下降,最后维持稳定,因此,发酵微生物对柠檬酸和苹果酸有一定的利用能力;乳酸是发酵过程中的主要代谢产物并且呈现稳定的增长趋势,其浓度由初始的5.6 mmol/L增长至149.6 mmol/L;乙酸和乙醇的产生则主要发生在泡菜的发酵前期。     

Biochemical characteristics,virulence traits and antifungal resistance of two major yeast species isolated from kefir: Kluyveromyces marxianus and Saccharomyces unisporus

Kefir yeasts were investigated for their possible virulence using an in vitro system. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis of 46 biochemical traits showed that all kefir isolates formed clusters distinct from Candida albicans. No isolate showed N‐acetylglucosaminidase activity, which is involved in resistance against host immune systems. All Kluyveromyces marxianus isolates formed pseudohyphae and grew at 42 °C, whereas Saccharomyces unisporus isolates did not. None of the kefir yeasts had proteolytic or haemolytic activities. All K. marxianus isolates were susceptible to fluconazole, whereas S. unisporus isolates were classified as resistant.     

Daqu— A Traditional Chinese Liquor Fermentation Starter

Chinese liquor is one of the world's oldest distilled alcoholic beverages, and it is typically obtained with the use of Daqu fermentation starters. Daqu is a saccharifying and fermenting agent, having a significant impact on the flavour of the product. Daqu can be categorized according to maximum incubation temperatures (high, medium and low) and flavour (sauce, strong, light and miscellaneous). Most Daqu are prepared by solid‐state fermentation from wheat, barley and/or peas with ingredient formulation, grinding and mixing, shaping, incubation and maturation. Although there is a wealth of artisanal experience in the production of a range of different types of Daqu, the scientific knowledge base—including the microbiota, their enzymes and their metabolic activities—needs further development. Daqu as a specific alcoholic starter is compared with other Asian amylolytic fermentation starters in terms of microbial diversity and function. Filamentous fungi (Rhizopus, Rhizomucor, Aspergillus and other genera), yeasts (Saccharomyces, Candida, Hansenula and other genera) and bacteria (acetic acid bacteria, lactic acid bacteria and Bacillus spp.), are considered to be the functional microbiota, responsible for the formation of a range of lytic enzymes, formation of substrates for alcoholic fermentation and formation of flavour compounds. However, the knowledge about the microbiota composition and their function is still fragmentary information, so further research is required to establish the functionality and growth kinetics of the microbiota in diverse types of Daqu.     

Microbial composition of Korean kefir and antimicrobial activity of Acetobacter fabarum DH1801

Kefir is a probiotic dairy product containing multiple species of lactic acid bacteria, acetic acid bacteria, and yeast, with varying microbial composition depending on geographical origin. In the present study, we characterized the acetic acid bacterial population in Korean kefir by next-generation sequencing-based community analysis and isolated a novel acetic acid bacterial strain, Acetobacter fabarum DH1801. To evaluate its potential application in the food industry, the antimicrobial activity of A. fabarum DH1801 against seven foodborne pathogens (Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Cronobacter sakazakii, Salmonella Enteritidis, enterotoxigenic Escherichia coli, and Shigella flexneri) was analyzed by growth curve analysis. Remarkably, the culture filtrate of the novel isolate inhibited the growth of all seven pathogenic bacteria in a dose-dependent manner, which was superior to acetic acid solution of same pH value. Our findings suggest that the A. fabarum DH1801 strain forms a protective barrier during kefir fermentation against contamination by foodborne pathogens.     

Microbiological, physicochemical, and sensory characteristics of kefir during storage

Changes in certain microbiological, physicochemical, and sensory parameters of kefir were studied during refrigerated storage. Kefir batches were prepared using 1% and 5% added kefir grains, and samples for analysis were taken 24 h after inoculation and then after 2, 7, 14, 21, and 28 days of storage at 5 ± 1 °C. After fermentation for 24 h after inoculation, lactobacilli and lactococci were present at levels of 10⁸ cfu/ml, and yeasts and acetic acid bacteria were present at levels of 10⁵ and 10⁶ cfu/ml, respectively. The lactic acid flora decreased by about 1.5 log units between days 7 and 14 and then stabilized at that level. Yeast and acetic acid bacterial counts, lactose, and pH all remained constant over the storage period, while the total fat content and dry matter decreased. The percentage inoculate did exert an influence, and the sample batches made using 1% added kefir grains had higher lactic acid bacterial counts, lactose, and pH, while the sample batches made using 5% added kefir grains had higher yeast and acetic acid bacterial counts and viscosity. The total fat and dry matter contents were similar in both sample batches. Sensory analysis of the kefir samples revealed maximum acceptability levels in the first 2 days of storage.     

Microbiological and physicochemical changes of naturally black olives fermented at different temperatures and NaCl levels in the brines

The effect of different temperatures (25°C, 18°C and ambient temperature) and NaCl levels in brines (4%, 6% and 8%) on the microbiological and physicochemical characteristics of naturally black olives of Conservolea variety was studied for up to 190 days. Fermentation was carried out according to the traditional anaerobic method. The initial microflora consisted of Gram-negative bacteria, lactic acid bacteria and yeasts. Inhibition of Gram-negative bacteria was evident in all fermentations. The prevailing micro-organisms were lactic acid bacteria and yeasts, the association of which was dependent on the conditions of fermentation. At 25°C and 18°C in brines containing 4% and 6% NaCl, the growth of lactic acid bacteria was favoured resulting in a lactic acid fermentation, as indicated by the high free acidity levels and low pH values in the brines. On the contrary, 8% NaCl concentration affected the growth of lactic acid bacteria and enhanced the activity of fermentative yeasts, producing a final product with lower free acidity and higher pH value. At ambient temperature, the counts of lactic acid bacteria followed the fluctuation of temperature regardless of salt concentration, while yeasts did not seem to be affected. The lactic acid bacteria identified belonged to the species Lactobacillus mesenteroides, Lactobacillus brevis, Lactobacillus plantarum and Lactobacillus pentosus. The best conditions for fermentation were at 25°C and 6% NaCl, developing free acidity of 142 mM (1·28% w/v) lactic acid and pH value of 3·8. After 5 months of brining, olives fermented at 25°C were judged by panelists as being debittered and ready to eat. No off-odour development was detected in any case due to anomalous fermentation. The HPLC analysis revealed that citric, malic, tartaric, succinic, lactic and acetic were among the end products of fermentation.     

Resistance to aerobic deterioration of total mixed ration silage inoculated with and without homofermentative or heterofermentative lactic acid bacteria

Wet brewers grains were stored as a total mixed ration (TMR) in laboratory silos with lucerne hay, cracked maize, sugar beet pulp, soya bean meal and molasses at 5:1:1:1:1:1 on fresh weight basis. The TMR mixture was inoculated with or without Lactobacillus casei or Lactobacillus buchneri to obtain silages with differing fermentation and stability after exposure to air. In the first experiment, ensiling was stopped at 10, 20 and 60 days, and the stability was tested for the following 7 days. Ethanol and lactic acid were the main products in untreated TMR silage, while addition of L. casei and L. buchneri increased lactic and acetic acid, respectively. No silages deteriorated in the presence of air over 7 days, regardless of inoculation, ensiling period and the level of yeasts determined at unloading. In the second experiment, silos were opened at 14 days and then subjected to aerobic stability test for 14 days. Resistance to deterioration was sustained in the untreated control, even with a high population (>10⁴ cfu g^?1) of yeasts throughout the 14‐day test. Spoilage was found in L. casei‐treated silage at about 5 days, while increase of yeasts preceded the distinct heating (degradation). In L. buchneri‐treated silage, no yeasts were detected at unloading or after exposure to air. These results suggest that substantial stability can be expected in TMR silage with or without inoculation of lactic acid bacteria. This property is not associated with the counts of yeasts at loading and the characteristics of silage such as alcoholic and lactic acid fermentation. Copyright © 2007 Society of Chemical Industry     

Inhibitory activity of cheese whey fermented with kefir grains

We investigated the chemical and microbiological compositions of three types of whey to be used for kefir fermentation as well as the inhibitory capacity of their subsequent fermentation products against 100 Salmonella sp. and 100 Escherichia coli pathogenic isolates. All the wheys after fermentation with 10% (wt/vol) kefir grains showed inhibition against all 200 isolates. The content of lactic acid bacteria in fermented whey ranged from 1.04 × 10(7) to 1.17 × 10(7) CFU/ml and the level of yeasts from 2.05 × 10(6) to 4.23 × 10(6) CFU/ml. The main changes in the chemical composition during fermentation were a decrease in lactose content by 41 to 48% along with a corresponding lactic acid production to a final level of 0.84 to 1.20% of the total reaction products. The MIC was a 30% dilution of the fermentation products for most of the isolates, while the MBC varied between 40 and 70%, depending on the isolate. The pathogenic isolates Salmonella enterica serovar Enteritidis 2713 and E. coli 2710 in the fermented whey lost their viability after 2 to 7 h of incubation. When pathogens were deliberately inoculated into whey before fermentation, the CFU were reduced by 2 log cycles for E. coli and 4 log cycles for Salmonella sp. after 24 h of incubation. The inhibition was mainly related to lactic acid production. This work demonstrated the possibility of using kefir grains to ferment an industrial by-product in order to obtain a natural acidic preparation with strong bacterial inhibitory properties that also contains potentially probiotic microorganisms.     

Microbiological and physicochemical characterisation of green table olives of Halkidiki and Conservolea varieties processed by the Spanish method on industrial scale

The microbiological and physicochemical changes of industrially fermented Halkidiki and Conservolea green table olives were determined. Samples were analysed to monitor the population of lactic acid bacteria (LAB), yeasts and Enterobacteriaceae, together with changes in pH, acidity, salinity, colour, lactic acid, acetic acid and ethanol. LAB and yeast species diversity was evaluated at the beginning (1 day), middle (75 days) and final (135 days) stages of fermentation by RAPD-PCR genomic fingerprinting. Results revealed vigorous lactic acid processes as indicated by the dominance of LAB over yeasts. No Enterobacteriaceae could be detected after 30 days. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) dominated in the beginning of fermentation in both varieties. In the end, Lactiplantibacillus pentosus (formerly Lactobacillus pentosus) and Pediococcus ethanolidurans prevailed in Halkidiki and Conservolea varieties, respectively. As for yeasts, Kluyveromyces lactis/marxianus and Pichia manshurica prevailed at the onset of fermentation in Halkidiki and Conservolea varieties, whereas in the end Pichia membranifaciens dominated in both varieties.     

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.     

INCIDENCE OF INDIGENOUS MICROBIAL FLORA FROM UTENSILS AND SURROUNDING AIR IN TRADITIONAL FRENCH CIDER MAKING

Lactic acid bacteria and yeasts were numerated, isolated and identified from two ciders obtained from similar raw materials used under different conditions. One cider was produced in a cellar of a traditional producer while the second one was produced under laboratory conditions. In both ciders alcoholic fermentation was achieved mainly by Saccharomyces cerevisiae. In the traditional cider, among the lactic acid bacteria (LAB) the species Leuconostoc oenos was predominant and malolactic conversion was observed. By contrast no development of LAB occurred in the second cider and therefore malolactic conversion was not achieved .     

Metabolic activity and symbiotic interactions of lactic acid bacteria and yeasts isolated from water kefir

Water kefir is a mildly sour and alcoholic drink fermented by a stable microbial multispecies community. With its high sugar content and low amino acid concentration water kefir medium represents a demanding habitat. In this ecological niche only well adapted microorganisms which are fit to the consortium are able to grow and mutually provide essential nutrients. The synergism between main representatives of water kefir yeasts and lactobacilli was studied in a co-culture model system. Co-cultivation of yeasts and lactobacilli in water kefir medium significantly increased cell yield of all interaction partners, delineating the interaction of these water kefir isolates as mutualism. The support of Zygotorulaspora (Z.) florentina was due to the acidification of the medium by the lactobacilli, whereas lactobacilli are improved in growth by the disposal of essential nutrients produced by yeasts. The trophic interaction between Lactobacillus (Lb.) hordei and yeasts is constituted by the release of amino acids and Vitamin B₆ from yeasts, whereas Lb. nagelii is supported in growth by their production of amino acids. The interaction of Z. florentina and Lb. nagelii was further examined to reveal that co-cultivation induced the yeast to release arginine, which was essential for Lb. nagelii.     

Microbiological and chemical properties of kefir manufactured by entrapped microorganisms isolated from kefir grains

In this study, various yeasts (Kluyveromyces marxianus, Saccharomyces turicensis, Pichia fermentans) and lactic acid bacteria (Lactobacillus kefiranofaciens, Lactobacillus kefiri, Leuconostoc mesenteroides) were entrapped in 2 different microspheres using an entrapment ratio for the strains that was based on the distribution ratio of these organisms in kefir grains. The purpose of this study was to develop a new technique to produce kefir using immobilized starter cultures isolated from kefir grains. An increase in cell counts with fermentation cycles was observed for both the lactic acid bacteria (LAB) and yeasts, whereas the cell counts of kefir grains were very stable during cultivation. Scanning electron microscopy showed that the short-chain lactobacilli and lactococci occupied the surface of the LAB microspheres, whereas the long-chain lactobacilli were inside the microspheres. When the yeasts were analyzed, cells at a high density were entrapped in cracks on the surface and within the microspheres, where they were surrounded by the short-chain lactobacilli. The distribution of the LAB and yeast species in kefir produced from grains and microspheres showed that there was no significant difference between the kefirs produced by the 2 methods; moreover, Leu. mesenteroides and K. marxianus were the predominating microflora in both types of kefir. There was no significant difference in the ethanol and exopolysaccharide contents between the 2 kefirs, although the acidity was different.     

Microbial Populations and Malolactic Fermentation of Apple Cider using Traditional and Modified Methods

The evolution of yeasts and lactic acid bacteria was examined during two methods of cider making: the traditional employed unwashed apples of different varieties and the modified used a sole washed acidic apple variety with temperature control during the cider making process. The alcoholic fermentation was carried out mainly by Kloeckera apiculata and Sacharomyces cerevisiae species, and their distributions were similar in the two methods. In the traditional, the malolactic fermentation proceeded at the same time as alcoholic fermentation and the “piqure lactique” occurred. In the modified method, no malolactic fermentation took place. In all musts, a fundamentally heterofermentative lactic flora was found, with Lactobacillus species most abundant in the traditional process.