Genomic exploration of the fermented meat isolate Staphylococcus shinii IMDO-S216 with a focus on competitiveness-enhancing secondary metabolites.

BACKGROUND: Staphylococcus shinii appears as an umbrella species encompassing several strains of Staphylococcus pseudoxylosus and Staphylococcus xylosus. Given its phylogenetic closeness to S. xylosus, S. shinii can be found in similar ecological niches, including the microbiota of fermented meats where the species may contribute to colour and flavour development. In addition to these conventional functionalities, a biopreservation potential based on the production of antagonistic compounds may be available. Such potential, however, remains largely unexplored in contrast to the large body of research that is available on the biopreservative properties of lactic acid bacteria. The present study outlines the exploration of the genetic basis of competitiveness and antimicrobial activity of a fermented meat isolate, S. shinii IMDO-S216. To this end, its genome was sequenced, de novo assembled, and annotated. RESULTS: The genome contained a single circular chromosome and eight plasmid replicons. Focus of the genomic exploration was on secondary metabolite biosynthetic gene clusters coding for ribosomally synthesized and posttranslationally modified peptides. One complete cluster was coding for a bacteriocin, namely lactococcin 972; the genes coding for the pre-bacteriocin, the ATP-binding cassette transporter, and the immunity protein were also identified. Five other complete clusters were identified, possibly functioning as competitiveness factors. These clusters were found to be involved in various responses such as membrane fluidity, iron intake from the medium, a quorum sensing system, and decreased sensitivity to antimicrobial peptides and competing microorganisms. The presence of these clusters was equally studied among a selection of multiple Staphylococcus species to assess their prevalence in closely-related organisms. CONCLUSIONS: Such factors possibly translate in an improved adaptation and competitiveness of S. shinii IMDO-S216 which are, in turn, likely to improve its fitness in a fermented meat matrix.

Growth of methicillin-resistant Staphylococcus aureus during raw milk soft cheese-production and the inhibitory effect of starter cultures.

The consumption of raw milk or raw milk products might be a potential risk factor for the transmission of methicillin-resistant Staphylococcus aureus (MRSA). Therefore, we studied MRSA growth during raw milk soft cheese-production. Furthermore, we investigated the inhibitory effect of four starter cultures (Lactococcus lactis, Lacticaseibacillus rhamnosus, Lactiplantibacillus plantarum, Lactobacillus helveticus) on the growth of MRSA in a spot-agar-assay and in raw milk co-culture following a cheesemaking temperature profile. During the initial phases of raw milk cheese-production, MRSA counts increased by 2 log units. In the ripening phase, MRSA counts only dropped slightly and remained high up to the end of the storage. Comparable MRSA counts were found in the rind and core and strain-specific differences in survival were observed. In the spot-agar-assay, all four starter cultures showed strong or intermediate inhibition of MRSA growth. In contrast, in raw milk, only Lactococcus lactis strongly inhibited MRSA, whereas all other starter cultures only had minor inhibitory effects on MRSA growth. Our results indicate that MRSA follow a similar growth pattern as described for other S. aureus during raw milk soft cheese-production and illustrate the potential use of appropriate starter cultures to inhibit MRSA growth during the production of raw milk cheese.

Developing defined starter culture for reproducible profile of flavour compound in Chinese xiaoqu baijiu fermentation.

Defined starter cultures, containing selected microbes could reduce the complexity of natural starter, are beneficial for controllable food fermentations. However, there are challenges in identifying key microbiota and constructing synthetic microbiota for traditional food fermentations. Here, we aimed to develop a defined starter culture for reproducible profile of flavour compounds, using Chinese Xiaoqu Baijiu fermentation as a case. We classified all microbes into 4 modules using weighted correlation network analysis. Module 3 presented significant correlations with flavour compounds (P < 0.05) and the highest gene abundance related with flavour compound production. 13 dominant species in module 3 were selected for mixed culture fermentation, and each species was individually deleted to analyse the effect on flavour compound production. Ten species, presenting significant effects (P < 0.05) on flavour compound production, were selected for developing the starter culture, including Rhizopus oryzae, Rhizopus microsporus, Saccharomyces cerevisiae, Pichia kudriavzevii, Wickerhamomyces anomalus, Lactobacillus acetotolerans, Levilactobacillus brevis, Weissella paramesenteroides, Pediococcus acidilactici, and Leuconostoc pseudomesenteroides. After optimising the structure of the starter culture, the profile similarity of flavour compounds produced by the starter culture reached 81.88% with that by the natural starter. This work indicated feasibility of reproducible profile of flavour compounds with defined starter culture for food fermentations.

Optimization of lactic acid bacterial starter culture to improve the quality and flavor characteristics of traditional Hurood.

Hurood is a traditional fermented milk product prepared by traditional Mongolian techniques of fermenting raw milk, partial degreasing, heating, whey drainage, emulsification of curd, and molding. Currently, Hurood available in the market is generally prepared by small-scale enterprises at home or in open air. Therefore, lack of standardization of bacterial starter culture leads to variation in the flavor and sensory properties of Hurood from batch to batch. In this study, we aimed to assess the best starter culture combination obtained from 37 lactic acid bacterial strains isolated from traditional Hurood. The solidification state and sensory quality were used as indexes for determining the fermentation efficiency of the bacterial starter culture combinations. The yield and texture characteristics were used to determine the optimal ratio of bacterial strains in a combination and the processing conditions for traditional Hurood production. The most optimal bacterial culture combination was observed to be NF 9-3:NF 10-4:CH 3-1 in 5:4:1 ratio and in 3% amount. The most optimal whey temperature and heating-stirring temperature were observed to be 55°C to 60°C and 85°C to 90°C, respectively. Hurood prepared with the optimal combination of bacterial strains exhibited significantly enhanced sensory quality, flavor, and contents of AA and fatty acids. Therefore, the use of optimal starter culture of lactic acid bacteria could produce Hurood with significantly superior sensory qualities, making the product more acceptable to consumers.

A review on fermented vegetables: Microbial community and potential upgrading strategy via inoculated fermentation.

Fermentation is a traditional method utilized for vegetable preservation, with microorganisms playing a crucial role in the process. Nowadays, traditional spontaneous fermentation methods are widely employed, which excessively depend on the microorganisms attached to the surface of raw materials, resulting in great difficulties in ideal control over the fermentation process. To achieve standardized production and improve product quality, it is essential to promote inoculated fermentation. In this way, starter cultures can dominate the fermentation processes successfully. Unfortunately, inoculated fermentation has not been thoroughly studied and applied. Therefore, this paper provides a systematic review of the potential upgrading strategy of vegetable fermentation technology. First, we disclose the microbial community structures and succession rules in some typical spontaneously fermented vegetables to comprehend the microbial fermentation processes well. Then, internal and external factors affecting microorganisms are explored to provide references for the selection of fermented materials and conditions. Besides, we widely summarize the potential starter candidates with various characteristics isolated from spontaneously fermented products. Subsequently, we exhibited the inoculated fermentation strategies with those isolations. To optimize the product quality, not only lactic acid bacteria that lead the fermentation, but also yeasts that contribute to aroma formation should be combined for inoculation. The inoculation order of the starter cultures also affects the microbial fermentation. It is equally important to choose a proper processing method to guarantee the activity and convenience of starter cultures. Only in this way can we achieve the transition from traditional spontaneous fermentation to modern inoculated fermentation.

Transcriptomic profiling reveals differences in the adaptation of two Tetragenococcus halophilus strains to a lupine moromi model medium.

BACKGROUND: Tetragenococcus (T.) halophilus is a common member of the microbial consortia of food fermented under high salt conditions. These comprises salty condiments based on soy or lupine beans, fish sauce, shrimp paste and brined anchovies. Within these fermentations this lactic acid bacterium (LAB) is responsible for the formation of lactic and other short chain acids that contribute to the flavor and lower the pH of the product. In this study, we investigated the transcriptomic profile of the two T. halophilus strains TMW 2.2254 and TMW 2.2256 in a lupine moromi model medium supplied with galactose. To get further insights into which genomic trait is important, we used a setup with two strains. That way we can determine if strain dependent pathways contribute to the overall fitness. These strains differ in the ability to utilize L-arginine, L-aspartate, L-arabinose, D-sorbitol, glycerol, D-lactose or D-melibiose. The lupine moromi model medium is an adapted version of the regular MRS medium supplied with lupine peptone instead of casein peptone and meat extract, to simulate the amino acid availabilities in lupine moromi. RESULTS: The transcriptomic profiles of the T. halophilus strains TMW 2.2254 and TMW 2.2256 in a lupine peptone-based model media supplied with galactose, used as simulation media for a lupine seasoning sauce fermentation, were compared to the determine potentially important traits. Both strains, have a great overlap in their response to the culture conditions but some strain specific features such as the utilization of glycerol, sorbitol and arginine contribute to the overall fitness of the strain TMW 2.2256. Interestingly, although both strains have two non-identical copies of the tagatose-6P pathway and the Leloir pathway increased under the same conditions, TMW 2.2256 prefers the degradation via the tagatose-6P pathway while TMW 2.2254 does not. Furthermore, TMW 2.2256 shows an increase in pathways required for balancing out the intracellular NADH/NADH+ ratios. CONCLUSIONS: Our study reveals for the first time, that both versions of tagatose-6P pathways encoded in both strains are simultaneously active together with the Leloir pathway and contribute to the degradation of galactose. These findings will help to understand the strain dependent features that might be required for a starter strain in lupine moromi.

Decolorization potential of malachite green by Ralstonia mannitolilytica isolated from Indonesian cassava-based fermented food tapai.

Pollution due to textile dye effluent mishandling is hazardous to ecosystems and to the living beings inhabiting them. This can cause retarded photosynthesis, disrupted fish day/night cycles, unbalanced bacterial populations, and decreased oxygen concentration in contaminated water, leading to low habitability. In this study, we aimed to isolate and characterize the microorganisms found in Indonesian cassava-based fermented food tapai starter cultures as a source of potential microbes for the biological remediation of textile dye pollutants. Microorganisms in the tapai starter culture were screened for their decolorization activity via spread-culture inoculation on a solid growth medium supplemented with textile dyes. Isolated microorganisms were selected based on their ability to secrete textile dye-decolorizing extracellular enzymes via increased light penetration after incubation of the cell-free supernatant (CFS) containing extracellular enzymes in textile dye solutions. Isolate JSP1 was the only bacterium capable of producing malachite green (MG)-decolorizing extracellular enzymes, which enabled it to survive and decolorize MG up to 375 ppm. Moreover, isolate JSP1 CFS was able to optimally decolorize 75% of MG at 100 ppm, but its activity was diminished at concentrations > 350 ppm. Colony and cellular morphology, biochemistry, and 16S rRNA tests revealed that the isolate was of Ralstonia mannitolilytica. Therefore, R. mannitolilytica isolate JSP1 may be a potential bioremediation agent for MG.

Role of microbiota and its ecological succession on flavor formation in traditional dry-cured ham: a review.

Traditional dry cured ham (DCH) is favored by consumers for its distinctive flavor, derived from an array of volatile organic compounds (VOCs). Microbiota play a pivotal role in the formation of VOCs. To fully comprehend the pathway by which the microbiota enhance the flavor quality of DCH, it is imperative to elucidate the flavor profile of DCH, the structural and metabolic activities of the microbiota, and the intricate relationship between microbial and VOCs. Thus far, the impact of microbiota on the flavor profile of DCH has not been comprehensively discussed or reviewed, and the succession of bacteria, especially at distinct phases of processing, has not been adequately summarized. This article aims to encapsulate the considerable potential of ferments in shaping the flavor characteristics of DCH, while elucidating the underlying mechanisms through which VOCs are generated in hams via microbial metabolism. Throughout the various stages of DCH processing, the composition of microbiota undergoes dynamic changes. Furthermore, they directly participate in the formation of VOCs in DCH through the catabolism of amino acids, metabolism of fatty acids, and the breakdown of carbohydrates. Several microorganisms, including Lactobacillus, Penicillium, Debaryomyces, Pediococcus, and Staphylococcus, exhibit considerable potential as fermenters in ham production.

Isolation and characterization of yogurt starter cultures from traditional yogurts and growth kinetics of selected cultures under lab-scale fermentation.

The development of new starter cultures is a crucial task for the food industry to meet technological requirements and traditional products are important reservoirs for new starter cultures. In this respect, this study aimed to isolate, identify, and determine the technological characteristics of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains originated from traditional yogurt samples. Genotypic discrimination of 200 isolates revealed the presence of distinct 19 S. thermophilus and 11 Lb. delbrueckii subsp. bulgaricus strains as potential starter cultures. Strain-specific properties determined the acidification capacity of the yogurt starter cultures and a higher acidification capacity was observed for S. thermophilus strains compared to Lb. delbrueckii subsp. bulgaricus strains. Proteolytic activity was found between 0.012-0.172 and 0.078-0.406 for S. thermophilus and Lb. delbrueckii subsp. bulgaricus strains, respectively. 4 of S. thermophilus and 3 of Lb. delbrueckii subsp. bulgaricus strains were found resistant to all tested bacteriophages. The antibiotic susceptibility tests of the isolates revealed that a very low antibiotic resistance was observed for the yogurt starter cultures. Finally, the growth kinetics of selected strains were determined and the maximum specific growth rate of selected S. thermophilus and Lb. delbrueckii subsp. bulgaricus was calculated as 0.527 h-1 and 0.589 h-1, respectively.

Influence of Different Ratios of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus on Fermentation Characteristics of Yogurt.

Lactic acid bacteria (LAB) are industrially important bacteria that are widely used in the fermented food industry, especially in the manufacture of yogurt. The fermentation characteristics of LAB are an important factor affecting the physicochemical properties of yogurts. Here, different ratios of L. delbrueckii subsp. bulgaricus IMAU20312 and S. thermophilus IMAU80809 were compared with a commercial starter JD (control) for their effects on viable cell counts, pH values, titratable acidity (TA), viscosity and water holding capacity (WHC) of milk during fermentation. Sensory evaluation and flavour profiles were also determined at the end of fermentation. All samples had a viable cell count above 5.59 × 107 CFU/mL at the end of fermentation, and a significant increase in TA and decrease in pH were observed. Viscosity, WHC and the sensory evaluation results of one treatment ratio (A3) were closer to the commercial starter control than the others. A total of 63 volatile flavour compounds and 10 odour-active (OAVs) compounds were detected in all treatment ratios and the control according to the results from solid-phase micro-extraction-gas chromatography-mass spectrometry (SPME-GC-MS). Principal components analysis (PCA) also indicated that the flavour characteristics of the A3 treatment ratio were closer to the control. These results help us understand how the fermentation characteristics of yogurts are affected by the ratio of L. delbrueckii subsp. bulgaricus to S. thermophilus in starter cultures; this is useful for the development of value-added fermented dairy products.

Combined effects of lipase and Lactiplantibacillus plantarum 1-24-LJ on physicochemical property, microbial succession and volatile compounds formation in fermented fish product.

BACKGROUND: Studies have shown that either the addition of starter culture or enzyme can improve fermentation in fish or other products. However, little research has been carried out on the effects of coupling starter cultures with lipase on the microbial community and product quality. Suanzhayu is a Chinese fermented fish product that mainly relies on spontaneous fermentation, resulting in an unstable flavor and quality. The present study investigated the impact of lipase and Lactiplantibacillus plantarum 1-24-LJ on the quality of Suanzhayu. RESULTS: Inoculation decreased pH and 2-thiobarbituric acid reactive substances (TBARS) values, and also helped the dominance of the strain in the ecosystem, whereas lipase addition raised TBARS values and had little effect on pH, water activity (aw ) and microbiota. The addition of lipase and/or Lpb. plantarum increased the content of alcohols, aldehydes, ketones, esters and umami amino acids. The co-additions with the most significant effect and the total contents of volatile compounds (VCs) and free amino acids (FAAs) were 1801.92 g per 100 g and 21 357.05 mg per 100 g, respectively. Former-Lactobacillus was negatively correlated with pH, aw and Prevotella, but positively with VCs (ethyl ester of heptanoic acid, ethyl ester of octanoic acid) and FAAs (Tyr, Phe). Furthermore, adding Lpb. plantarum 1-24-LJ alone or in combination with lipase shortened the fermentation process. CONCLUSION: The present study provides a recommended Suanzhayu process approach for improving product quality and flavor, as well as shortening fermentation time, by adding Lpb. plantarum 1-24-LJ with or without lipase. © 2023 Society of Chemical Industry.

A comprehensive review on yogurt syneresis: effect of processing conditions and added additives.

Yogurt, produced by the lactic fermentation of milk base, is an important dairy product worldwide. One of the essential sensory properties of yogurt is the texture, and some textural defects such as weak gel firmness and syneresis likely occur in various types of yogurts, affecting consumer acceptance. In this regard, various strategies such as enrichment of milk-based with different additives and ingredients such as protein-based components (skimmed milk powder (SMP), whey protein-based powders (WP), casein-based powders (CP), and suitable stabilizers, as well as modification of processing conditions (homogenization, fermentation, and cooling), can be applied in order to reduce syneresis. The most effective proteins and stabilizers in syneresis reduction are CP and gelatin, respectively. Furthermore, yogurt's water holding capacity and syneresis can be affected by the type of starter cultures, the protolithic activity, production of extracellular polysaccharides, and inoculation rate. Moreover, optimizing the heat treatment process (85 °C/30 min and 95 °C/5 min), homogenization (single or dual-stage), incubation temperature (around 40 °C), and two-step cooling process can decrease yogurt syneresis. This review is aimed to investigate the effect of fortification of the milk base with various additives and optimization of process conditions on improving texture and preventing syneresis in yogurt.

Chronic Release of Tailless Phage Particles from Lactococcus lactis.

Lactococcus lactis strains residing in the microbial community of a complex dairy starter culture named "Ur" are hosts to prophages belonging to the family Siphoviridae. L. lactis strains (TIFN1 to TIFN7) showed detectable spontaneous phage production and release (109 to 1010 phage particles/ml) and up to 10-fold increases upon prophage induction, while in both cases we observed no obvious cell lysis typically described for the lytic life cycle of Siphoviridae phages. Intrigued by this phenomenon, we investigated the host-phage interaction using strain TIFN1 (harboring prophage proPhi1) as a representative. We confirmed that during the massive phage release, all bacterial cells remain viable. Further, by monitoring phage replication in vivo, using a green fluorescence protein reporter combined with flow cytometry, we demonstrated that the majority of the bacterial population (over 80%) is actively producing phage particles when induced with mitomycin C. The released tailless phage particles were found to be engulfed in lipid membranes, as evidenced by electron microscopy and lipid staining combined with chemical lipid analysis. Based on the collective observations, we propose a model of phage-host interaction in L. lactis TIFN1 where the phage particles are engulfed in membranes upon release, thereby leaving the producing host intact. Moreover, we discuss possible mechanisms of chronic, or nonlytic, release of LAB Siphoviridae phages and its impact on the bacterial host. IMPORTANCE In complex microbial consortia such as fermentation starters, bacteriophages can alter the dynamics and diversity of microbial communities. Bacteriophages infecting Lactococcus lactis are mostly studied for their detrimental impact on industrial dairy fermentation processes. In this study, we describe a novel form of phage-bacterium interaction in an L. lactis strain isolated from a complex dairy starter culture: when the prophages harbored in the L. lactis genome are activated, the phage particles are engulfed in lipid membranes upon release, leaving the producing host intact. Findings from this study provide additional insights into the diverse manners of phage-bacterium interactions and coevolution, which are essential for understanding the population dynamics in complex microbial communities like fermentation starters.

Functional yeast starter cultures for cocoa fermentation.

The quest to develop a performant starter culture mixture to be applied in cocoa fermentation processes started in the 20th century, aiming at achieving high-quality, reproducible chocolates with improved organoleptic properties. Since then, different yeasts have been proposed as candidate starter cultures, as this microbial group plays a key role during fermentation of the cocoa pulp-bean mass. Yeast starter culture-initiated fermentation trials have been performed worldwide through the equatorial zone and the effects of yeast inoculation have been analysed as a function of the cocoa variety (Forastero, Trinitario and hybrids) and fermentation method (farm-, small- and micro-scale) through the application of physicochemical, microbiological and chemical techniques. A thorough screening of candidate yeast starter culture strains is sometimes done to obtain the best performing strains to steer the cocoa fermentation process and/or to enhance specific features, such as pectinolysis, ethanol production, citrate assimilation and flavour production. Besides their effects during cocoa fermentation, a significant influence of the starter culture mixture applied is often found on the cocoa liquors and/or chocolates produced thereof. Thus, starter culture-initiated cocoa fermentation processes constitute a suitable strategy to elaborate improved flavourful chocolate products.

Effect of grape pomace from red cultivar 'Nero d'Avola' on the microbiological, physicochemical, phenolic profile and sensory aspects of ovine Vastedda-like stretched cheese.

AIMS: The purpose of this study was to functionalize an ovine stretched cheese belonging to 'Vastedda' typology with red grape pomace powder (GPP) of Nero d'Avola cultivar and to characterize the microbiological, physicochemical, phenolic profile and sensory characteristics of the final cheeses. METHODS AND RESULTS: Before cheeses production, GPP was characterized for its microbiological profile, antibacterial activity and polyphenolic content. No colonies of bacteria and yeasts were detected in the GPP. GPP showed a large inhibition spectrum against spoilage and pathogenic bacteria. Three classes of polyphenolic compounds belonging to flavan-3-ols, flavonol and phenolic acids were identified. Two cheeses [0 and 1% (w w-1 ) of GPP] were produced with pasteurized ewe's milk and commercial starter cultures. Plate counts and randomly amplified polymorphic DNA analysis demonstrated the ability of the starter strains to drive the fermentation process in the presence of GPP. GPP enrichment resulted in an increase of protein, phenolic compounds, sensory traits and reduced fat. CONCLUSIONS: GPP addition to cheese represents an optimal strategy for the valorization of winemaking by-products and to obtain polyphenol-enriched cheese. SIGNIFICANCE AND IMPACT OF THE STUDY: This study allowed to achieve an ovine cheese with specific physicochemical, nutraceutical and sensorial characteristics able to enlarge the functional dairy product portfolio.

Resistant Lactic Acidemia Due to Accidental Cheese Starter Culture Ingestion.

Lactic acid is the end-product of anaerobic glycolysis. It is generally believed that elevated blood lactate levels are associated with poor patient outcomes. Literature reports that lactic acidosis can be related to supplementary food intake in the pediatric age group however, in adult patients, it is not common to see lactic acidosis due to oral ingestion unless the patient has a history of short bowel syndrome or jejunoileal bypass surgery. With the current case presentation, we report an accidental cheese starter culture intake that resulted in resistant lactic acidosis with no signs of critical illnesses.

Effect of Penicillium candidum and Penicillium nalgiovense and their combination on the physicochemical and sensory quality of dry-aged beef.

This study was designed to investigate the effect of starter culture on the improvement of physicochemical and sensory properties of dry-aged beef. Penicillium nalgiovense and Penicillium candidum were used as single starter cultures and mixed suspensions (1:1) to determine the effect of mixed starter culture. Starter cultures were spray-inoculated on the surface of beef samples, and samples were dry-aged for 0, 7, 10, 14, and 21 days. Dry-aged samples were then analyzed for microbial population, physicochemical properties (pH, water content, and color), proteolytic activity on sarcoplasmic and myofibrillar proteins, and flavor compounds (free amino acids, nucleotides, and volatile compounds). The microbial activities of starter cultures affected the physicochemical traits and enhanced sensory quality. Penicillium candidum particularly influenced proteolytic activity and volatile compounds, whereas P. nalgiovense affected free amino acid and nucleotide content, with the most significant effect on day 7. Combination of the two strains resulted in different patterns when compared to the single strains. Therefore, the inoculation of mold starter cultures significantly affected the physicochemical properties and improved the sensory qualities of dry-aged beef, and the effect differed between single and mixed strains.

Microbial ecology and functional coffee fermentation dynamics with Pichia kudriavzevii.

Specialty coffee can be developed by the application of explicit microorganisms or starters to obtain desired fermentation. In the present study, natural fermentation (NF) of Arabica coffee was carried out spontaneously, the other set was inoculated with Pichia kudriavzevii (Y) starter culture (isolated, identified and mass cultured). The effect of microbial fermentation, metagenomics, production of functional metabolites, volatiles and their sensorial aspects were studied. The bioprocess illustrated cohesive interface of coffee nutrients and microbial communities like Mycobacterium, Acinetobacter, Gordonia, etc., in NF, Lactobacillus and Leuconostoc were prevailing in Y. The Pichia and Rhodotorula dominated in both the groups. The bioactivity of bacteria and fungi induced complex changes in physicochemical features like pH (4.2-5.2), Brix° (9.5-3.0), and metabolic transition in sugar (3.0-0.7%), alcohol (1.4-2.7%), organic acids modulating flavour precursors and organoleptics in the final brew. In the roasted bean, Y exhibited higher sugar (42%), protein (25%), polyphenol (3.5%), CGA (2.5%), caffeine (17.2%), and trigonelline (2.8%) than NF. The volatile profile exhibited increased flavour molecules like furans, ketones, and pyrazines in Y, besides lactone complexes. The organoleptics in Y were highlighted with honey, malt and berry notes. P. kudriavzevii coffee fermentation could be beneficial in specialty coffee production and enhancement of distinct characteristic flavours.

Bioprospecting of indigenous yeasts involved in cocoa fermentation using sensory and chemical strategies for selecting a starter inoculum.

Cocoa fermentation is the key and most relevant process in the synthesis of aroma and flavor precursor molecules in dry beans or raw material for producing chocolate. Because this process occurs in an uncontrolled manner, the chemical and sensory quality of beans can vary and be negatively affected. One of the strategies for the standardization and improvement of the sensory quality of chocolate is the introduction of microbial starter cultures. Among these, yeasts involved in fermentation have been studied because of their pectinolytic and metabolic potential in the production of volatile compounds. This study was aimed at isolating and characterizing, both sensory and chemically, yeasts involved in cocoa fermentation that could be used as starter cultures from two agro-ecological regions for the cultivation of cocoa in Colombia. The microbiological analyses identified 22 species represented mostly by Saccharomyces cerevisiae, Wickerhamomyces anomalus and Pichia sp. The preliminary sensory analysis of eight of these species showed that Hanseniaspora thailandica and Pichia kluyveri presented sensory profiles characterized by high intensity levels of fruity notes, which could be ascribed to the production of ethyl acetate, isoamyl acetate, and 2-phenylethyl acetate.

Lactiplantibacillus plantarum 299v as starter culture suppresses Enterobacteriaceae more efficiently than spontaneous fermentation of carrots.

Fermentation, especially spontaneous fermentation, has become from an ancient food preservation method to a stylish cooking trend in very recent years. Accordingly, the associated food safety should be revisited, particularly since inexperienced people increasingly performing spontaneous fermentation on an ad hoc basis. In this study, three lactic acid bacteria (LAB) strains were tested. Lactiplantibacillus plantarum 299v at high initial inoculation levels (>6 log CFU/mL brine water) effectively eliminated Salmonella spiked in a carrot fermentation system from 4.6 ± 0.2 log CFU/mL to < 1 log CFU/mL after 7 days fermentation at 20 °C. Next, the bacterial enumeration and 16s rRNA gene sequencing results between spontaneous fermentation and fermentation samples using L. plantarum 299v as the starter culture were compared. It was found that the inhibiting effect of L. plantarum 299v could be extended beyond Salmonella spp. to the entire Enterobacteriaceae family during the carrot fermentation. Therefore, our study suggests that in comparison with spontaneous fermentation, selected starter culture such as L. plantarum 299v can consistently improve the safety and quality of fermented foods.