In this paper, we study skew frame starters, which are strong frame starters that satisfy an additional “skew” property. We prove three new non-existence results for cyclic skew frame starters of ...certain types. We also construct several small examples of previously unknown cyclic skew frame starters by computer.
Traditional fermented foods are a significant source of starter and/or non‐starter lactic acid bacteria (nsLAB). Moreover, these microorganisms are also known for their role as probiotics. The ...potential of nsLAB is huge; however, there are still challenges to be overcome with respect to characterization and application. In the present review, the most important steps that autochthonous lactic acid bacteria isolated from fermented foods need to overcome, to qualify as novel starter cultures, or as probiotics, in food technology and biotechnology, are considered. These different characterization steps include precise identification, detection of health‐promoting properties, and safety evaluation. Each of these features is strain specific and needs to be accurately determined. This review highlights the advantages and disadvantages of nsLAB, isolated from traditional fermented foods, discussing safety aspects and sensory impact.
Many traditional fermented foods and beverages in both eastern and western countries are produced with the addition of starter cultures. Daqu is the undefined starter used for Chinese liquor, which ...contributed many fermentation functional fungal and bacterial communities to liquor fermentation process. However, the sources of these microbial communities and how these microorganisms formed in Daqu are still unclear. In this study, high-throughput sequencing combined with microbial source tracking analysis were applied to analyze the sources of the microbial communities in Daqu. We found fungal communities in Daqu were mainly originated from Daqu making environments (mainly tools and indoor ground), including Saccharomycopsis fibuligera, Pichia kudriavzevii, Rhizopus oryzae, Sterigmatomyces elviae, Aspergillus flavus/oryzae, Hyphopichia burtonii and Lichtheimia corymbifera. Meanwhile, most of bacterial communities in Daqu were from raw materials, including Gammaproteobacteria, Alphaproteobacteria and Bacilli. During Daqu-making process, the abundance of Gammaproteobacteria and Alphaproteobacteria that were not beneficial to liquor fermentation declined, but the abundance of the fermentation functional yeasts and Bacilli increased. Moreover, network analysis showed the bacteria in Daqu might be the drivers for the microbial succession during the Daqu-making process. This study shows that the Daqu production technology is a good way to screen fermentation functional microorganisms from complex environmental microbial communities.
•Raw materials were the main sources of bacteria in Daqu.•Daqu-making environment was the main source of fungi in Daqu.•Bacteria drove the microbial succession during Daqu-making process.
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.
Moutai is a world-famous traditional Chinese liquor with complex taste and aroma, which are considered to be strongly influenced by the quality of fermentation starters (Daqu). However, the role of ...microbial communities in the starters has not been fully understood. In this study, we revealed the microbial composition of 185 Moutai starter samples, covering three different types of starters across immature and mature phases, and functional gene composition of mature starter microbiome. Our results showed that microbial composition patterns of immature starters varied, but they eventually were similar and steady when they became mature starters, after half-year storage and subsequent mixing. To help identify two types of immature starters, we selected seven operational taxonomic unit (OTU) markers by leave-one-out cross validation (LOOCV) and an OTU classified as
was the most decisive one. For mature starters, we identified a total of 16 core OTUs, one of which annotated as
was found positively associated with saccharifying power. We also identified the functional gene and microbial composition in starch and cellulose hydrolysis pathways. Microbes with higher abundances of alpha-glucosidase, alpha-amylase, and glucoamylase probably contributed to high saccharifying power. Overall, this study reveals the features of Moutai starter microbial communities in different phases and improves understanding of the relationships between microbiota and functional properties of the starters.
Undefined strain starters are used for the production of many traditional and artisanal cheeses. Composition of undefined starters depends on several factors, and the diversity in strains and species ...significantly affects cheese quality and features. Culture-dependent approaches have long been used for the microbial profiling and functionalities of undefined cultures but underestimate their diversity due to culturability biases. Recently, culture-independent methods, based on high-throughput sequencing (HTS), have been preferred, with a significant boost in resolution power and sensitivity level. Amplicon targeted (AT) metagenomics, based on 16S rRNA sequencing, returned a larger microbiota diversity at genus and, sometimes, at species levels for artisanal starters of several PDO cheeses, but was inappropriate for populations with high strain diversity, and other gene targets were tested in AT approaches. Shotgun metagenomics (total DNA) and metatranscriptomics (total RNA), although are more powerful in depicting diversity and functionality of undefined cultures, have been rarely applied because of some limitations (e.g., high costs and laboriousness, need for bioinformatics skills). The advantages of HTS technologies are undoubted, but some hurdles need to be still overcame (e.g., resolution power, discrepancy between active and inactive cells, robust analytic pipelines, cost and time reduction for integrated approaches) so that HTS become routinary and convenient for defining complexity, microbial interactions (including host-phage relationships) and evolution in cheeses of undefined starters.
Lactic acid bacteria (LAB) communities shape the sensorial and functional properties of artisanal hard-cooked and long-ripened cheeses made with raw bovine milk like Parmigiano Reggiano (PR) cheese. ...While patterns of microbial evolution have been well studied in PR cheese, there is a lack of information about how this microbial diversity affects the metabolic and functional properties of PR cheese.
To fill this information gap, we characterized the cultivable fraction of natural whey starter (NWS) and PR cheeses at different ripening times, both at the species and strain level, and investigated the possible correlation between microbial composition and the evolution of peptide profiles over cheese ripening.
The results showed that NWS was a complex community of several biotypes belonging to a few species, namely,
,
, and
subsp.
. A new species-specific PCR assay was successful in discriminating the cheese-associated species
,
,
, and
. Based on the resolved patterns of species and biotype distribution,
and
were most frequently isolated after 24 and 30 months of ripening, while the number of biotypes was inversely related to the ripening time. Peptidomics analysis revealed more than 520 peptides in cheese samples. To the best of our knowledge, this is the most comprehensive survey of peptides in PR cheese. Most of them were from β-caseins, which represent the best substrate for LAB cell-envelope proteases. The abundance of peptides from β-casein 38-88 region continuously increased during ripening. Remarkably, this region contains precursors for the anti-hypertensive lactotripeptides VPP and IPP, as well as for β-casomorphins. We found that the ripening time strongly affects bioactive peptide profiles and that the occurrence of
species is positively linked to the incidence of eight anti-hypertensive peptides. This result highlighted how the presence of specific LAB species is likely a pivotal factor in determining PR functional properties.
Xiaoqu starter serves as the saccharifying and fermenting agent in the production of Cantonese soybean-flavor (Chi-flavor) Baijiu , and the complex microbial communities determine the flavor and ...quality of the product. Round-Koji-mechanical starter (produced by using an automated starter-making disk machine) is advantageous as it decreases operator influence, labor costs, and fermentation time, but the product quality is lower compared to traditional starter. Thus, two types of starters (traditional and Round-Koji-mechanical starter) from a Cantonese Baijiu factory were compared in a metagenomic analysis to investigate the differences in microbial community composition and core microbes. The results showed that several core microbes related to carbohydrate metabolism, amino acid metabolism and lipid metabolism, were differentially enriched in the traditional starter. Mucor lusitanicus and Rhizopus delemar were significantly positively correlated with the three key metabolic pathways. Saccharomyces cerevisiae, Cyberlindnera fabianii, Kluyveromyces marxianus, Lactobacillus fermentum, Mucor ambiguous, Rhizopus microspores, Rhizopus azygosporus, Mucor circinelloides, and Ascoidea rubescens were significantly positively correlated with two of the three key metabolic pathways. The results of this study provide a basis for understanding the differential core microbes in traditional and Round-Koji-mechanical starters of Chi-flavor Baijiu , and they also provide guidance for improving Round-Koji-mechanical starter.
Abstract
Gambling harms are disproportionately experienced among disadvantaged groups and as such, adult social care (ASC) practitioners are well-placed to identify and support affected individuals. ...There exists no evidence-based ‘introductory’ question for practitioners to identify those at risk of gambling harms, which includes family and friends (‘affected others’). To develop an ‘introductory’ question for use in English ASC, we conducted a scoping review that identified fifteen potential questions. Questions were refined through expert panel review groups (n = 13), cognitive interviewing (n = 18), test–retest reliability checks (n = 20) and validity testing (n = 2,100) against gold-standard measures of problem gambling behaviour. The question development process produced two questions suitable for testing in local authority (LA) ASC departments. These were (i) ‘Do you feel you are affected by any gambling, either your own or someone else’s?’ and (ii) ‘If you or someone close to you gambles, do you feel it is causing you any worries?’ Each had good face validity, strong test–retest reliability, correlated highly with well-being measures and performed reasonably against validated measures of problem gambling. These two questions are currently being piloted by ASC practitioners in three English LAs to assess their feasibility for adoption in practice.
Gambling harms are recognised as a serious problem for which a public health approach is recommended. Harms may be experienced by the gambler, their family and friends, and the wider community. Adult social care services within English local authorities (LAs) have been suggested as an appropriate location to ask people about gambling-related harms, offer brief advice and signpost to support services. No evidence-based ‘introductory’ question exists for use in these settings for practitioners to identify both gamblers and affected others at risk of gambling harms. We report findings from a National Institute for Health and Care Research (NIHR)-funded study that developed and piloted an ‘introductory’ question and trained staff about gambling harms within three LAs in England. This article focuses on the development of the ‘introductory’ question, and testing it for reliability, validity and comprehensibility in readiness for testing in three LA settings. Findings regarding the testing of the question in practice are reported elsewhere. This project was co-developed with People with lived experience partners (Betknowmore UK), GamCare (who delivered the training) and LA practitioners.
PDF
