Gamma aminobutyric acid (GABA) is a non-protein amino acid that is widely distributed in nature and its physiological importance goes beyond its role as an inhibitory neurotransmitter of the central ...nervous system in mammals. Since microbial fermentation is one of the most promising methods to obtain GABA, the production of this metabolite by several strains of lactic acid bacteria isolated from quinoa and amaranth sourdoughs was investigated. Lactobacillus brevis CRL 2013 produced the highest GABA levels, reaching 265 mM when optimal culture conditions were set up. The fermentative profile showed that CRL 2013 was able to catabolize carbohydrates through the phosphoketolase pathway yielding variable amounts of lactic acid, acetate and ethanol, which depended on the type of carbon source available and the presence of external electron acceptors such as fructose. Enhanced growth parameters and low GABA synthesis were associated to pentose fermentation. This impairment on GABA production machinery was partially overpassed by the addition of ethanol to the culture media. These results support the potential use of L. brevis CRL 2013 as a starter culture for the manufacture of GABA-enriched functional foods and provide further insights to the understanding of the GAD system regulation in lactic acid bacteria.
•L. brevis CRL 2013, isolated from quinoa sourdough, produced high levels of GABA.•Final GABA production is among the highest for lactobacilli grown in batch culture.•Enhanced growth rates and low GABA synthesis were associated to pentose fermentation.•The impairment on GABA production was partially restored by the addition of ethanol.
The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes.
Ice cream manufacture commonly results in the ...accumulation of wasted product that contains valuable food-grade quality components, including fat, carbohydrates, and protein. Methods have been developed for recovering the fat from this waste stream, but this results in the generation of a co-product rich in fermentable carbohydrates. This study aimed to investigate the potential for using this co-product as a fermentation substrate for production of antimicrobial peptides, called bacteriocins, by dairy starter cultures. Results showed that Streptococcus thermophilus B59671 and Lactococcus lactis 11454 produced the broad-spectrum bacteriocins thermophilin 110 and nisin, respectively, when the fermentation substrate was melted ice cream, or a co-product generated by a modified butter churning technique. Bacteriocin production varied depending on the brand and variety of vanilla ice cream used in this study. When an alternate enzyme-assisted fat extraction technique was used, S. thermophilus metabolism was impaired within the resulting co-product, and thermophilin 110 production was not observed. Lactococcus lactis was still able to grow in this co-product, but antimicrobial activity was not observed. Results from this study suggest the co-product generated when using the churning technique is a better choice to use as a base medium for future studies to optimize bacteriocin production.
Among the innovative trends in the wine sector, the continuous exploration of enological properties associated with wine microbial resources represents a cornerstone driver of quality improvement. ...Since the advent of starter cultures technology, the attention has been focused on intraspecific biodiversity within the primary species responsible for alcoholic fermentation (
) and, subsequently, for the so-called 'malolactic fermentation' (
). However, in the last decade, a relevant number of studies proposed the enological exploitation of an increasing number of species (e.g., non-
yeasts) associated with spontaneous fermentation in wine. These new species/strains may provide technological solutions to specific problems and/or improve sensory characteristics, such as complexity, mouth-feel and flavors. This review offers an overview of the available information on the enological/protechnological significance of microbial resources associated with winemaking, summarizing the opportunities and the benefits associated with the enological exploitation of this microbial potential. We discuss proposed solutions to improve quality and safety of wines (e.g., alternative starter cultures, multistrains starter cultures) and future perspectives.
Using the antagonistic competitive interaction of the microbiological cultures has become one of the potential and modern ways to improve the quality of dry-cured meat products. These studies aim to ...substantiate the use of the starter cultures for producing fermented pork meat products. The studies' physicochemical, microbiological, organoleptic, and statistical methods were used for their implementation. Two starter cultures were used on the basis of Lactobacillus plantarum, L. rhamnosus and Kocuria rosea (SC 1); Staphylococcus carnosus, L. plantarum, L. Rhamnosus and L. paracasei (SC 2). The dynamics of microbiota development, the dynamics of acidity, the content of sodium nitrite, parameters of water activity, the dynamics of moisture changes, the content of nitrogen-containing substances, the accumulation of free cyclic and acyclic amino acids, as well as the organoleptic characteristics were studied. It had been established that the undesirable microflora is suppressed due to the active development of the starter cultures in fermented meat products. The study results confirm that using the starter cultures while producing the dry-cured meat contributes to their dehydration and reduction of the parameters of water activity. Based on the tasting results, the samples with the addition of the compositions of the starter cultures received a total score higher than the control sample, in particular, they had a beautiful appearance, a cut of red color, an elastic consistency, a delectable flavor with a characteristic sour after-taste. The use of the starter culture based on the combination of Staphylococcus carnosus, L. plantarum, L. rhamnosus, and L. paracasei (SC 2) for the dry-cured meat products to be produced activates the microbiological processes, which improves the structural-mechanical properties of the meat product, increases the water-binding power and, as a whole, positively influences on the quality of the finished product. It has been shown that the use of the drugs SC 2 and SC 1, when the dry-cured pork balyks are produced, decreases the duration of the technological cycle by 3-4 days, as well as ensures a high degree of sanitary and epidemic safety of the finished product: the absence of pathogenic and opportunistic microorganisms, the low residual content of sodium nitrite of up to 0.003%.
Water kefir is a sparkling, slightly acidic fermented beverage produced by fermenting a solution of sucrose, to which dried fruits have been added, with water kefir grains. These gelatinous grains ...are a symbiotic culture of bacteria and yeast embedded in a polysaccharide matrix. Lactic acid bacteria, yeast and acetic acid bacteria are the primary microbial members of the sugary kefir grain. Amongst other contributions, species of lactic acid bacteria produce the exopolysaccharide matrix from which the kefir grain is formed, while yeast assists the bacteria by a nitrogen source that can be assimilated. Exactly which species predominate within the grain microbiota, however, appears to be dependent on the geographical origin of the grains and the fermentation substrate and conditions. These factors ultimately affect the characteristics of the beverage produced in terms of aroma, flavour, and acidity, for example, but can also be controlled and exploited in the production of a beverage of desired characteristics. The production of water kefir has traditionally occurred on a small scale and the use of defined starter cultures is not commonly practiced. However, as water kefir increases in popularity as a beverage – in part because of consumer lifestyle trends and in part due to water kefir being viewed as a health drink with its purported health benefits – the need for a thorough understanding of the biology and dynamics of water kefir, and for defined and controlled production processes, will ultimately increase. The aim of this review is to provide an update into the current knowledge of water kefir.
•Water kefir is a sparkling, acidic fermented beverage produced by fermenting a sucrose solution, to which dried fruits and water kefir grains are added.•Lactic acid bacteria, yeast and acetic acid bacteria are the primary microbial members of the sugary kefir grain.•Which species predominate within the kefir grain appears dependent on the geographical origin of the grains and substrate and fermentation conditions.•Water kefir is seen as a vegan alternative to milk kefir and purported health benefits related to the presence live microorganisms.•As water kefir increases in popularity there is a need for a thorough understanding of the biology and dynamics of water kefir fermentation.
Summary
In this research, effects of maturation times on volatiles of Mucor‐type Douchi were investigated. Results showed that 2‐year matured sample exhibited higher concentrations of characteristic ...flavours including alcohols, esters, phenols, ketones and pyrazines. Additionally, effects of starter cultures addition on volatiles were investigated, and results demonstrated that inoculated fermented samples presented higher amounts of aldehydes, ketones, phenols and pyrazines compared with that of naturally fermented sample. Analysis of odour activity value (OAV) suggested that increased OAVs of eight compounds that mainly contributed to the flavour of Douchi ranged from onefold to 6.5‐fold in the Tetragenococcus halophilus, Zygosaccharomyces rouxii and Candida versatilis co‐cultured sample. Furtherly, by comparing the characteristic flavour of co‐cultured and 2‐year matured samples, no significant difference was observed in the OAV of flavour except rose‐like and soapy flavour, which indicated that co‐culture of the three strains during Douchi fermentation may facilitate the formation of flavours and shorten the fermentation process.
In the present study, the effects of maturation times and starter cultures on volatile compounds of Mucor‐type Douchi were investigated. By comparing the characteristic flavour of co‐cultured and 2‐years matured samples, no significant difference was observed in the OAV of characteristic flavour except rose‐like and soapy flavour among these samples. These findings revealed that the co‐culture of the Tetragenococcus halophilus, Zygosaccharomyces rouxii and Candida versatilis during Douchi fermentation may promote the formation of characteristic flavour and shorten the process.
The use of starter cultures (Tetragenococcus halophilus TS71, Zygosaccharomyces rouxii A22, and Meyerozyma (Pichia) guilliermondii EM1Y52) in reduced-salt moromi fermentation was investigated. ...Reduced-salt moromi fermentation (12%NaCl) with starter cultures was monitored for changes of microbiological and biochemical properties including volatile flavor compounds (VFCs) and biogenic amines (BAs) during three months. The inoculation was done after one-month fermentation with two combinations: TS71 and A22 (L2); and TS71, A22 and EM1Y52 (L3). Controls were 12% salt (CL) and 18% salt traditional (CT) without inoculation. Total bacteria counts significantly increased (P < 0.05) in CL. Total lactic acid bacteria and total yeasts in the reduced-salt moromi with inoculation (L2 and L3) were significantly higher than both controls. Key VFCs including ethanol, 2-methyl-1-propanol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) and 3-hydroxy-2-methyl-4H-pyran-4-one (maltol) were detected in L2 and L3 at higher levels than the traditional CT. Lower amount of BAs was accumulated in the reduced-salt moromi fermentation, particularly with lactic acid bacterium (L3) than other fermentations. Hence, the reduced-salt moromi fermentation with using starter cultures was therefore feasible for the soy sauce production without undesirable impact on formation of VFCs and safety levels of BAs.
•Comparison of microbiological and biochemical properties of reduced salt and traditional soy sauce.•Zygosaccharomyces rouxii and Meyerozyma guilliermondii starter enhanced formation of volatile flavor compounds in soy sauce.•Low biogenic amines formation was observed in reduced salt soy sauce fermentation with Tetragenococcus halophilus starter.
Starter cultures are selected microbial strains intentionally added to food to obtain a product with desired organoleptic characteristics. The most important group of microorganisms used in starter ...cultures are bacteria, mostly lactic acid bacteria (LAB). For many years the safety criteria for the use of starter cultures in food production were based mainly on their long history of safe use. However, recent research indicates that starter culture microorganisms are able to acquire antibiotic resistance genes. Starter culture microorganisms can carry variously sized plasmids with resistance determinants. These strains have a high potential for transmitting resistance genes, which raises concerns regarding the antibiotic resistance of food-related bacteria. It should be noted that the antibiotic resistance of starter culture bacteria does not pose a direct risk to consumers because they are not pathogenic. However, they can act as environmental reservoirs of antibiotic resistance determinants. Therefore, bacteria that harbor antibiotic resistance genes on mobile genetic elements should not be used in food production. In addition, it is reported that stress factors associated with the production and storage of food may affect the changes in the antibiotic resistance profile of these microorganisms. Research indicates that the acquisition of antibiotic resistance in starter cultures is not a critical problem, but it poses a concern that cannot be disregarded.
•Antibiotic resistance is one of the biggest global health and food safety threats.•Starter cultures are highly capable to acquire antibiotic resistance genes.•Resistance genes can be horizontally transferred by mobile genetic elements.•Microorganisms considered as a component of starter culture must have safety status.
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