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Production of lactic acid bacteria starters for manufacturing food, probiotic, and chemical products requires the application of successive steps: fermentation, concentration, stabilization, and storage. Despite process optimization, losses of bacterial viability and functional activities are observed after stabilization and storage steps due to cell exposure to environmental stresses (thermal, osmotic, mechanical, and oxidative). Bacterial membrane is the primary target for injury and its damage is highly dependent on its physical properties and lipid organization. Membrane fluidity is a key property for maintaining cell functionality, and depends on lipid composition and cell environment. Extensive evidence has been reported on changes in membrane fatty acyl chains when modifying fermentation conditions. However, a deep characterization of membrane physical properties and their evolution following production processes is scarcely reported. Therefore, the aims of this mini-review are (i) to define the membrane fluidity and the methods used to assess it and (ii) to summarize the effect of environmental conditions on membrane fluidity and the resulting impact on the resistance of lactic acid bacteria to the stabilization processes. This will make it possible to highlight existing gaps of knowledge and opens up novel approaches for future investigations.

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.

Description of the subject. The use of non-Saccharomyces yeast for improving fine cocoa flavor perception has been poorly explored. Objectives. In this study, we investigated the contribution of the non-Saccharomyces yeasts producing β-glycosidase isolated from the spontaneous fermentation of cocoa to the quality and production of aromas during the alcoholic fermentation of a medium based on cocoa pulp.Method. The screening for β-glycosidase activity and molecular identification of non-Saccharomyces yeast isolates from Amazonian cocoa bean fermentations were performed on agar plates with esculin as a substrate and by 5.8S ITS rDNA sequence analysis, respectively. The yeasts producing β-glycosidases were used as a starter culture for alcoholic micro-fermentations of a medium based on cocoa pulp, incubated at 30 °C for 48 h. The quantification of organic acids, ethanol, and sugars was obtained by HPLC, and aroma compounds after cocoa pulp fermentation were identified by GC-FID and GC-MS.Results. Twenty-six non-Saccharomyces yeast isolates were selected by β-glycosidase activity, comprising species such as Pichia kudriavzevii (n = 15), Pichia sp. (n = 2), Pichia sporocuriosa (n = 1), Candida orthopsilosis (n = 3), Issatchenkia sp. (n = 1), I. orientalis (n = 1), and P. kudriavzevii/I. orientalis (n = 3). All yeast strains exhibited rapid growth in cocoa pulp medium, low ethanol production, high organic acid production, and higher glucose consume than fructose. These yeasts produced thirty different volatile compounds. The main groups included alcohols (3), esters (19), terpenes (4), phenols (2), organic acids (2), and aldehydes (3), with 67% of these having fruity and floral aromas. Pichia sp., P. kudriavzevii/I. orientalis and Issatchenckia sp. were the largest producers of volatile compounds. Notably, this study identified volatile compounds with fruity aromas previously unassociated with cocoa fermentations for the first time.Conclusions. These data demonstrate the potential of β-glycosidase-producing non-Saccharomyces yeasts to improve floral and fruity aromas, suggesting their promising use as a starter culture for cocoa fermentation. Activité de β-glycosidase associée à la formation de composés aromatiques parmi les levures natives non-Saccharomyces isolées de la fermentation du cacaoDescription du sujet. L'utilisation de levures non-Saccharomyces pour améliorer la perception des saveurs fines du cacao a été peu explorée.Objectifs. Dans cette étude, nous avons étudié l'apport des levures non-Saccharomyces productrices de β-glycosidase isolées de la fermentation spontanée du cacao à la qualité et à la production d'arômes lors de la fermentation alcoolique d'un milieu à base de pulpe de cacao.Méthode. Le criblage de l'activité β-glycosidase et l'identification moléculaire d'isolats de levures non-Saccharomyces provenant de fermentations de fèves de cacao amazoniennes ont été réalisés sur des plaques de gélose avec de l'esculine comme substrat et par analyse de séquence d'ADNr 5,8S ITS, respectivement. Les levures productrices de β-glycosidases ont été utilisées comme starter pour des micro-fermentations alcooliques d'un milieu à base de pulpe de cacao, incubées à 30 °C pendant 48 h. La quantification des acides organiques, de l'éthanol et des sucres a été obtenue par HPLC et les composés aromatiques après fermentation de la pulpe de cacao ont été identifiés par GC-FID et GC-MS.Résultats. Vingt-six isolats de levures non-Saccharomyces ont été sélectionnés par activité β-glycosidase, comprenant des espèces telles que Pichia kudriavzevii (n = 15), Pichia sp. (n = 2), Pichia sporocuriosa (n = 1), Candida orthopsilosis (n = 3), Issatchenkia sp. (n = 1), I. orientalis (n = 1) et P. kudriavzevii/I. orientalis (n = 3). Toutes les souches de levure ont présenté une croissance rapide dans un milieu de pulpe de cacao, une faible production d'éthanol, une production élevée d'acide organique et une consommation de glucose plus élevée que le fructose. Ces levures produisaient trente composés volatils différents. Les principaux groupes comprenaient les alcools (3), les esters (19), les terpènes (4), les phénols (2), les acides organiques (2) et les aldéhydes (3), dont 67 % avaient des arômes fruités et floraux. Pichia sp., P. kudriavzevii/I. orientalis et Issatchenckia sp. étaient les plus grands producteurs de composés volatils. Notamment, cette étude a identifié pour la première fois des composés volatils aux arômes fruités auparavant non associés aux fermentations du cacao.Conclusions. Ces données démontrent le potentiel des levures non-Saccharomyces productrices de β-glycosidase pour améliorer les arômes floraux et fruités, suggérant leur utilisation prometteuse comme culture de départ pour la fermentation du cacao.

The purpose of this study was two-fold: (1) to describe weekly average values for training monotony (TM) and training strain (TS) and their variations across the full soccer season, based on the number of accelerations and decelerations; (2) to analyze the differences between starter and non-starter players on weekly average TM and TS values for the pre-season and three in-season periods. In total, 21 professional soccer players were evaluated over 48 weeks during the full-season. The TM and TS were calculated based on the number of accelerations and decelerations at zone 1, zone 2 and zone 3, respectively. The results revealed that starters presented higher values compared to non-starters throughout the full season for all variables analyzed (all, p < 0.05). Generally, there were higher values in the pre-season. Specifically, accelerations at zones 1, 2 and 3 revealed moderate to very large significance of the starters compared to non-starters over the full-season. Decelerations at zone 1, 2 and 3 presented moderate to nearly optimally significant greater weekly averages for starters compared to non-starters during the full season. In conclusion, the TM and TS values were higher for starters compared to non-starters through the full-season, which confirms that the training session does not provide a sufficient load to non-starter soccer players during the full-season.

Saccharomycopsis fibuligera, also known as Endomyces fibuliger or Saccharomyces fibuligera, is a yeast that produces ascospores and is widely found in all types of fermentation starters. It secretes α-amylase, β-glucosidase and acid protease with high efficiency and is an important functional microorganism in the fermentation of grains. Hence, S. fibuligera has high industrial application value; for example, it has a high starch conversion capacity and can synthesise trehalose from starch and it can decompose and synthesise single-cell proteins from starch and use proteins as a protein feed. It also produces aromas, esters and alcohols via fermentation; thereby, improving liquor quality. Moreover, S. fibuligera exerts an inhibitory effect on guava grey mould and can synthesise fungicides. Because S. fibuligera has excellent development potential and research value in industrial production, it has attracted considerable attention. In this study, the physicochemical, enzymatic and ester-producing properties of S. fibuligera and its effect on liquor flavour were examined. These findings will help screen excellent strains, optimise liquor fermentation conditions and improve liquor production quality.

Sanchuan ham is a kind of popular fermented meat product in China. To understand the role of microorganisms in reducing the accumulation of Biogenic amine (BA) during ham fermentation. Biogenic amine oxidase-producing strains were screened and identified using color development method on double-layered plate, oxidase test, high-performance liquid chromatography (HPLC), physiological, biochemical methods, and 16 S rDNA. And then a model for simulated fermentation of Sanchuan ham was developed using the strains as single or mixed starter cultures. The results showed that two biogenic amine oxidase-producing strains were identified as Enterococcus faecium and Enterococcus faecalis from Sanchuan ham by compared to the NCBI database. And the mixed starter cultures showed a more remarkable effect on the decreased production of BA compared to single starter cultures, especially cadaverine and tyramine. The cadaverine was decreased from 92.74 ± 2.44 mg/Kg to 53.95 ± 2.69 mg/Kg and tyramine was decreased from 94.23 ± 3.42 mg/kg to 57.24 ± 3.51 mg/kg in mixed starter cultures than the control group. These results indicate exist biogenic amine oxidase-producing strains could decrease the accumulation of BA in Sanchuan ham. This study reveals important findings for improving the safety and health of Sanchuan ham and other fermented meat products.

The soft starters of ABB company are used in a pumped storage power station. Sometimes, a phase absent fault was reported during the process of the motor starting and then led to starting failure. To solve this problem, this article first explained the working principle of the device, and then analyzed the design of the control circuit and the characteristics of the components. Combined with the actual inspection results to find the crux of the problem, It proposed optimization and improvement methods for the soft starter control circuit, and achieved the desired results.

Cheese is a fermented dairy product that is made from animal milk and is considered to be a healthy food due to its available nutrients and potential probiotic characteristics. Since the microbes in the cheese matrix directly contribute to the quality and physicochemical properties of cheese, it is important to understand the microbial properties of cheese. In this study, Cheddar cheeses produced on three different dates at the Arbuthnot Dairy Center at Oregon State University were collected to determine the microbial community structure. A total of 773,821 sequencing reads and 271 amplicon sequence variants (ASVs) were acquired from 108 samples. Streptococcus and Lactococcus were observed as the most abundant ASVs in the cheese, which were used as the starter lactic acid bacteria (SLAB). Escherichia coli was detected in the raw milk; however, it was not detected after inoculating with SLAB. According to an alpha diversity analysis, SLAB inoculation decreased the microbial richness by inhibiting the growth of other bacteria present in the milk. A beta diversity analysis showed that microbial communities before the addition of SLAB clustered together, as did the samples from cheese making and aging. Non-starter lactic acid bacteria (NSLAB) were detected 15 weeks into aging for the June 6th and June 26th produced cheeses, and 17 weeks into aging for the cheese produced on April 26th. These NSLAB were identified as an unidentified group of Lactobacillaceae. This study characterizes the changes in the Cheddar cheese microbiome over the course of production from raw milk to a 6-month-aged final product.Key points• 271 ASVs were acquired from cheese production from raw milk to 6-month aging.• Addition of SLAB changed the microbial diversity during Cheddar cheese making procedure.• NSLAB were detected more than 15 weeks after aging.

ABSTRACT Preservation of cheese microbiota biodiversity is central to the sensory quality of traditional and PDO cheeses. Lyophilized commercial selected starters, being advantageous in terms of cells concentration, are supplanting natural cultures causing important loss of microbial biodiversity in the dairy environment. Biodiversity could be recovered using natural starter cultures, however their cells concentration after propagation is lower than the commercial ones. Two autochthonous and biodiverse starter cultures (MixA and MixB) coming from scotta (residual whey from Ricotta cheese manufacture), collected in the 1960 s from Pecorino Romano PDO cheese manufactures, were revitalized in reconstituted commercial powder scotta. The aim of this study was the propagation of the microbial starter mixes increasing their bacterial concentration in the pellet, reducing nonessential scotta components by a fast and not-expensive method, without changing the microbial community balance. The behaviour of each mix inoculated in scotta was compared to that in half-concentrated, clarified, and half-concentrated-clarified scotta. Higher cells concentration in the pellets from the modified scotta was obtained, without changing technological performances and microbial fingerprint. The pellets obtained were reinoculated in commercial scotta for the preparation of the scotta-innesto (the typical starter for Pecorino Romano), and no differences were observed among the treatments after incubation. The reduction of nonessential scotta's components could help the reproduction of natural starter cultures preserving their properties. The modified scotta, removing non-essential components, could be a fast and not-expensive method to reproduce natural starter cultures with high cells concentration, without affecting their technological performances and microbial balance.