Fermented Dairy Products Research Articles

Genetic diversity and phylogenetic relationships of Streptococcus thermophilus isolates from traditional Turkish yogurt: multilocus sequence typing (MLST).

Yogurt, a globally consumed fermented dairy product, is recognized for its taste and potential health benefits attributed to probiotic bacteria, particularly Streptococcus thermophilus. In this study, we employed Multilocus Sequence Typing (MLST) to investigate the genetic diversity and phylogenetic relationships of 13 S. thermophilus isolates from traditional Turkish yogurt samples. We also assessed potential correlations between genetic traits and geographic origins. The isolates were identified as S. thermophilus using VITEK® MALDI-TOF MS, ribotyping, and 16S rRNA analysis methods. MLST analysis revealed 13 different sequence types (STs), with seven new STs for Turkey. The most prevalent STs were ST/83 (n = 3), ST/135 (n = 2), and ST/134 (n = 2). eBURST analysis showed that these isolates mainly were singletons (n = 7) defined as sequence types (STs) that cannot be assigned to any group and differ at two or more alleles from every other ST in the sample. This information suggests that the isolates under study were genetically distinct from the other isolates in the dataset, highlighting their unique genetic profiles within the population. Genetic diversity analysis of ten housekeeping genes revealed polymorphism, with some genes showing higher allelic variation than others. Tajima's D values suggested that selection pressures differed among these genes, with some being more conserved, likely due to their vital functions. Phylogenetic analysis revealed distinct genetic diversity between Turkish isolates and European and Asian counterparts. These findings demonstrate the genetic diversity of S. thermophilus isolates in Turkish yogurt and highlight their unique evolutionary patterns. This research contributes to our understanding of local microbial diversity associated with yogurt production in Turkey and holds the potential for identifyic strains with enhanced functional attributes.

Oral Administration of Fermented Milk from Co-Starter Containing Lactobacillus plantarum Y44 Shows an Ameliorating Effect on Hypertension in Spontaneously Hypertensive Rats.

Fermented dairy foods such as yogurt exhibit some beneficial effects on consumers, including relieving the symptoms of hypertension. This study aims to obtain fermented dairy products from a co-starter that have a great flavor and the auxiliary function of reducing blood pressure after longtime consumption. Commercial starter cultures composed of Lactobacillus delbrueckii subsp. bulgaricus CICC 6047 and Streptococcus thermophilus CICC 6038 were combined with Lactobacillus plantarum strains Y44, Y12, and Y16, respectively, as a combined starter culture to ferment the mixed milk of skim milk and soybean milk. The fermented milk produced using the combined starter culture mixed with L. plantarum Y44 showed an angiotensin-converting-enzyme (ACE) inhibitory activity (53.56 ± 0.69%). Some peptides that regulate blood pressure were released in the fermented milk, such as AMKPWIQPK, GPVRGPFPII, LNVPGEIVE, NIPPLTQTPV, and YQEPVL. In spontaneously hypertensive rat (SHR) oral-administration experiments compared with the gavage unfermented milk group, the gavage feeding of SHRs with the fermented milk produced using the combined starter culture mixed with L. plantarum Y44 significantly reduced the blood pressure of the SHRs after long-term intragastric administration, shown with the systolic blood pressure (SBP) and diastolic blood pressure (DBP) decreasing by 23.67 ± 2.49 mmHg and 15.22 ± 2.62 mmHg, respectively. Moreover, the abundance of short-chain fatty acids (SCFA), bacterial diversity in the gut microbiota, and SCFA levels including acetic acid, propionic acid, and butyric acid in the feces of the SHRs were increased via oral administration of the fermented milk produced using the combined starter culture containing L. plantarum Y44. Furthermore, the ACE-angiotensin II (Ang II)-angiotensin type 1 (AT 1) axis was downregulated, the angiotensin-converting-enzyme 2 (ACE 2)-angiotensin(1-7) (Ang1-7)-Mas receptor axis of the SHRs was upregulated, and then the RAS signal was rebalanced. The fermented milk obtained from the combined starter culture shows the potential to be a functional food with antihypertension properties.

Phenotypic, Technological, Safety, and Genomic Profiles of Gamma-Aminobutyric Acid-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow's Milk.

Gamma-aminobutyric acid (GABA)-producing lactic acid bacteria (LAB) can be used as starters in the development of GABA-enriched functional fermented foods. In this work, four GABA-producing strains each of Lactococcus lactis and Streptococcus thermophilus species were isolated from cow's milk, and their phenotypic, technological, and safety profiles determined. Genome analysis provided genetic support for the majority of the analyzed traits, namely, GABA production, growth in milk, and the absence of genes of concern. The operon harboring the glutamate decarboxylase gene (gadB) was chromosomally encoded in all strains and showed the same gene content and gene order as those reported, respectively, for L. lactis and S. thermophilus. In the latter species, the operon was flanked (as in most strains of this species) by complete or truncated copies of insertion sequences (IS), suggesting recent acquisition through horizontal gene transfer. The genomes of three L. lactis and two S. thermophilus strains showed a gene encoding a caseinolytic proteinase (PrtP in L. lactis and PrtS in S. thermophilus). Of these, all but one grew in milk, forming a coagulum of good appearance and an appealing acidic flavor and taste. They also produced GABA in milk supplemented with monosodium glutamate. Two L. lactis strains were identified as belonging to the biovar. diacetylactis, utilized citrate from milk, and produced significant amounts of acetoin. None of the strains showed any noticeable antibiotic resistance, nor did their genomes harbor transferable antibiotic resistance genes or genes involved in toxicity, virulence, or pathogenicity. Altogether these results suggest that all eight strains may be considered candidates for use as starters or components of mixed LAB cultures for the manufacture of GABA-enriched fermented dairy products.

The Relationship Between Fermented Dairy Consumption with Cognitive Function Among Older US Adults: Data from the NHANES 2011-2014.

The aging global population has led to an increased burden of cognitive impairment in older adults. This study examined the relationship between fermented dairy intake and cognitive function in this population. Yogurt, cheese, and fermented dairy consumption were assessed through two 24-hour dietary recall interviews, categorized into low, medium, and high intake groups. Multivariate linear regression was employed to examine the relationship between fermented dairy intake and cognitive tests, including the Alzheimer's Disease Word Learning Immediate Recall Test (CERAD-IRT), CERAD Delayed Recall Test (CERAD-DRT), Animal Fluency Test (AFT), Digit Symbol Substitution Test (DSST), and global cognitive z-scores, adjusting for potential confounding factors. The study comprised 2,462 participants (average age 69.34±6.75 years, 52.07% female). Among yogurt consumers, global cognition and AFT z-scores are notably higher than non-consumers. Conversely, individuals who consume cheese display significantly lower CERAD-DRT z-scores. Compared to participants not intake fermented dairy, consumers of fermented dairy show significantly higher AFT and DSST z-scores and lower CERAD-DRT z-scores. Moreover, when categorizing individuals based on their intake of fermented dairy, those with low and medium consumption show significantly higher AFT and DSST z-scores, as well as significantly lower CERAD-DRT z-scores compared to non-consumers. Our study suggests that moderate consumption of fermented dairy products is associated with better executive function and verbal fluency in the elderly.

Effect of different isolation sources of Lactococcus lactis subsp. lactis on volatile metabolites in fermented milk

Lactococcus lactis subsp. lactis (L. lactis subsp. lactis) is a commonly used starter cultures in fermented dairy products, contributing distinct flavor and texture characteristics with high application value. However, the strains from different isolates have different contributions to milk fermentation. Therefore, this study aimed to investigate the influence of L. lactis subsp. lactis isolated from various sources on the volatile metabolites present in fermented milk. In this study, L. lactis subsp. lactis from different isolation sources (yogurt, koumiss and goat yogurt) was utilized as a starter culture for fermentation. The volatile metabolites of fermented milk were subsequently analyzed by headspace solid phase microextraction gas chromatography-mass spectrography (HS-SPME-GC-MS). The results indicated significant differences in the structure and abundance of volatile metabolites in fermented milk produced with different isolates (R2Y = 0.96, Q2 = 0.88). Notably, the strains isolated from goat yogurt appeared to enhance the accumulation of ketones (goat yogurt vs yogurt milk: 50 %; goat yogur vs koumiss: 27.3 %)and aldehydes (goat yogurt vs yogurt milk: 21.4 %; goat yogurt vs koumiss: 54.5 %) in fermented milk than strains isolated from koumiss and yogurt milk. It significantly promoted the production of 8 flavor substances (1 substance with OAV ≥ 1 and 6 substances with OAV > 0.1) and enhanced the biosynthesis of valine, leucine, and isoleucine. This study provides valuable insights for the application of Lactococcus lactis subsp. lactis isolated from different sources in fermented dairy production and screening of potential starter cultures.

The relationship between fermented and nonfermented dairy products consumption and hypertension among premature coronary artery disease patients: Iran premature coronary artery disease study.

Dairy products may affect hypertension (HTN) risk. The aim of this study was to examine the association between fermented and nonfermented dairy foods and HTN in a sample of premature coronary artery disease (PCAD) subjects. This cross-sectional study was performed on 1854 PCAD patients. A 110-item food frequency questionnaire was used to assess dietary intakes. HTN was considered if systolic blood pressure was 140 mmHg and higher and/or diastolic blood pressure was 90 mmHg and higher. The odds ratio of HTN across the quartiles of different types of dairy products was evaluated by binary logistic regression. The mean (SD) of dairy products consumption was 339.8 (223.5) g/day, of which 285.4 g/day was fermented dairy products. In the crude model, participants in the fourth quartile of fermented dairy products had lesser risk of HTN compared to the bottom quartile (OR = 0.70, 95% CI: 0.52, 0.96; p for trend = .058). However, after considering the possible confounders, the significance disappeared. Subjects in the top quartile of high-fat fermented dairy products had 34% lower risk for HTN compared to the bottom quartile (95% CI: 0.49, 0.88; p for trend < .001). Adjustment for potential risk factors weakened the association but remained significant (OR = 0.73, 95% CI: 0.53, 1.01; p for trend = .001). Nonsignificant relation was detected between low-fat fermented, low-fat nonfermented, and high-fat nonfermented dairy products and HTN. Moderate consumption of high-fat fermented dairy products, in a population with low consumption of dairy foods, might relate to reduced likelihood of HTN.

The effect of seed germination and Bacillus spp. on the ripening of plant cheese analogs.

The development of novel plant-based fermented food products for which no traditional templates exist requires the development of starter cultures. Although the principles of microbial flavor formation in plant-based analogs partially overlap with dairy fermentations, the composition of the raw materials and thus likely the selective pressure on the activity of starter cultures differs. Experiments that are described in this study explored the use of seed germination, the use of lactic acid bacteria, and the use of bacilli to reduce hygienic risks, to acidify plant milk, and to generate taste-active compounds through proteolysis and fermentative conversion of carbohydrates. The characterization of fermentation microbiota by culture-dependent and culture-independent methods also confirmed that the starter cultures used were able to control microbial communities throughout 90 d of ripening. Taken together, the results provide novel tools for the development of plant-based analogs of fermented dairy products.

Bifidobacterium species viability in dairy-based probiotic foods: challenges and innovative approaches for accurate viability determination and monitoring of probiotic functionality.

Bifidobacterium species are essential members of a healthy human gut microbiota. Their presence in the gut is associated with numerous health outcomes such as protection against gastrointestinal tract infections, inflammation, and metabolic diseases. Regular intake of Bifidobacterium in foods is a sustainable way of maintaining the health benefits associated with its use as a probiotic. Owing to their global acceptance, fermented dairy products (particularly yogurt) are considered the ideal probiotic carrier foods. As envisioned in the definition of probiotics as "live organisms," the therapeutic functionalities of Bifidobacterium spp. depend on maintaining their viability in the foods up to the point of consumption. However, sustaining Bifidobacterium spp. viability during the manufacture and shelf-life of fermented dairy products remains challenging. Hence, this paper discusses the significance of viability as a prerequisite for Bifidobacterium spp. probiotic functionality. The paper focuses on the stress factors that influence Bifidobacterium spp. viability during the manufacture and shelf life of yogurt as an archetypical fermented dairy product that is widely accepted as a delivery vehicle for probiotics. It further expounds the Bifidobacterium spp. physiological and genetic stress response mechanisms as well as the methods for viability retention in yogurt, such as microencapsulation, use of oxygen scavenging lactic acid bacterial strains, and stress-protective agents. The report also explores the topic of viability determination as a critical factor in probiotic quality assurance, wherein, the limitations of culture-based enumeration methods, the challenges of species and strain resolution in the presence of lactic acid bacterial starter and probiotic species are discussed. Finally, new developments and potential applications of next-generation viability determination methods such as flow cytometry, propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR), next-generation sequencing, and single-cell Raman spectroscopy (SCRS) methods are examined.

Safety evaluation of the food enzyme mucorpepsin from the non-genetically modified Rhizomucor miehei strain M19-21.

The food enzyme mucorpepsin (EC 3.4.23.23) is produced with the non-genetically modified Rhizomucor miehei strain M19-21 by Meito Sangyo Co., Ltd. The enzyme is chemically modified to produce a thermolabile form. The food enzyme was considered free from viable cells of the production organism. It is intended to be used in the processing of dairy products for the production of cheese and fermented dairy products. Based on the maximum use levels, dietary exposure was estimated to be up to 0.108 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 226 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, results in a margin of exposure of at least 2093. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and four matches to respiratory allergens and one match to a food allergen (mustard) were found. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to mustard proteins, cannot be excluded. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Use of hop extract in the biotechnology of kefir beverage

The shelf life of fermented dairy products is only 3-5 days and is extended by the addition of preservatives to the production process, but the biological value of the kefir beverage is reduced. The purpose of this study was to determine the feasibility of using hop extract in the biotechnology of fermented milk beverage. Three samples of kefir beverage were produced: control (K) – using traditional technology based on dry starter “Kefir VIVO”; experimental (D1) – with the above type of starter in the amount of 0.05% by weight of milk and hop extract in the amount of 5% by weight of milk. The experimental sample (D2) was fermented using hop extract (10% by weight of milk). It was found that when using only hop extract for fermentation of the prototype kefir beverage, the duration of the technological process of its production is the same as when using dry starter and does not exceed 7-8 hours. The number of beneficial viable lactic acid microorganisms (Lactococcus lactis ssp.) in the fermented milk beverage made based on hop extract was 1.0∙107 CFU/cm3 . These microorganisms have probiotic properties, which makes it possible to classify beverages enriched with hop extract as functional foods. In the experimental samples made using hop extract, yeast colonies were found in the amount of 3∙107 and 8∙107 CFU/cm3 , respectively. During the experimental storage period, the pH of all product samples was (4.71-4.46). Therewith, the acidity of the sample (D2) increased more slowly. Its organoleptic characteristics were improving. The shelf life has been extended to 10-15 days. The results of the study showed that milk can be fermented with hop extract, resulting in a new functional type of kefir beverage with high organoleptic characteristics, viability of beneficial microflora (lactic acid bacteria and yeast) and extended shelf life

Growth inhibition of Salmonella by Leuconostoc species isolated from buffalo milk curd

Traditional fermented products are considered to be a niche for microbial diversity. Probiotics offer a unique approach for addressing the threat of antibiotic resistance. Therefore, the aim of the present study was to isolate Leuconostoc spp. from Buffalo milk curd, an artisanal fermented dairy product in Bangladesh and assess their growth inhibition competence against Salmonella sp. A total of 50 isolates were isolated and purified from five freshly prepared buffalo milk curd samples using two different media, with glucose or sucrose as the carbon source. Among these pure isolates, 37 were identified as presumptive Leuconostoc spp. The biochemical identification using the VITEK 2 system confirmed that 59.5% of the isolates were Leuconostoc mesenteroides ssp. cremoris, while 40.5% were Leuconostoc pseudomesenteroides. Out of the identified isolates, twelve had a similarity of over 97%, and twenty-five had a similarity of less than 96%. Consequently, these twelve isolates were tested for their antimicrobial activity against Salmonella sp. using two in vitro methods, agar well diffusion and microbroth. The isolate M1L1 exhibited the highest inhibitory zone (15 mm) and showed 55.6% growth inhibition by the agar well diffusion and microbroth assay, respectively, suggesting a similar efficacy between the two methods. Notably, five other isolates also displayed inhibitory zones ranging from 13 to 15 mm and growth inhibition percentages of 37 to 52%. Overall, the isolated Leuconostoc spp. could be utilized as probiotics to combat pathogenic microorganisms. Ann. Bangladesh Agric. (2023) 27 (1): 93-104

Metagenomics reveals differences in the composition of bacterial antimicrobial resistance and antibiotic resistance genes in pasteurized yogurt and probiotic bacteria yogurt from China

Antimicrobial resistance has become a global public health concern, and antibiotic resistance genes (ARG) in food are a research focus. In China, probiotics and pasteurized yogurts are the 2 main types of commercially available yogurt, but the distribution and differences of antibiotic-resistant bacteria and gene types in these products are not well known. This study used a shotgun metagenomic approach to analyze 22 different types of yogurt collected from 9 main yogurt-producing areas in China; each type of yogurt included 8 different batches of samples. The abundance and diversity of bacteria identified in probiotic yogurt were significantly higher than those in pasteurized yogurt, with Acetobacter, Raoultella, and Burkholderia identified as unique and highly abundant genera in probiotic yogurt. Similarly, the abundance of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. was higher than that in pasteurized yogurt. A total of 1,149 ARG subtypes belonging to 16 ARG types were identified, with the highest abundance of rifampicin, multidrug efflux pumps, and quinolone resistance genes detected. Network analysis revealed significant nonrandom co-occurrence relationships between different types and subtypes of ARG in yogurt samples. A total of 44 ARG subtypes in pasteurized yogurt were potentially hosted by 36 bacterial genera, and in probiotic yogurt, 63 ARG were expected to be hosted by 86 bacterial species from 37 genera. These findings indicate potential safety issues in fermented dairy products and emphasize the need for a more hygienic environment when processing probiotic yogurt.

Synbiotic Combination between Lactobacillus paracasei VL8 and Mannan-Oligosaccharide Repairs the Intestinal Barrier in the Dextran Sulfate Sodium-Induced Colitis Model by Regulating the Intestinal Stem Cell Niche.

Previously, Lactobacillus paracasei VL8, a lactobacillus strain isolated from the traditional Finnish fermented dairy product Viili, demonstrated immunomodulatory and antibacterial effects. The prebiotic mannan-oligosaccharide (MOS) further promoted its antibacterial activity and growth performance, holding promise for maintaining intestinal health. However, this has not been verified in vivo. In this study, we elucidated the process by which L. paracasei VL8 and its synbiotc combination (SYN) with MOS repair the intestinal barrier function in dextran sodium sulfate (DSS)-induced colitis mice. SYN surpasses VL8 or MOS alone in restoring goblet cells and improving the tight junction structure. Omics analysis on gut microbiota reveals SYN's ability to restore Lactobacillus spp. abundance and promote tryptophan metabolism. SYN intervention also inhibits the DSS-induced hyperactivation of the Wnt/β-catenin pathway. Tryptophan metabolites from Lactobacillus induce intestinal organoid differentiation. Co-housing experiments confirm microbiota transferability, replicating intestinal barrier repair. In conclusion, our study highlights the potential therapeutic efficacy of the synbiotic combination of Lactobacillus paracasei VL8 and MOS in restoring the damaged intestinal barrier and offers new insights into the complex crosstalk between the gut microbiota and intestinal stem cells.

Peculiarities of development and metabolism of &lt;i&gt;Streptococcus thermophilus&lt;/i&gt; strains under different conditions of deep liquid phase cultivation

The microflora of most fermented dairy products, including cheeses, consists entirely of lactic acid bacteria, i. e., bacterial starter cultures with different species and strain composition that are specially introduced into the mixture. The species composition of the starter must ensure the intensity and direction of the microbiological and biochemical processes of the produced product and guarantee its safety, quality and storability. In particular, lactic acid bacteria transform the main components of milk (protein, milk fat, lactose) into taste, aromatic, and biologically active substances involved in the formation of identification and organoleptic characteristics of fermented dairy products. The number of starter microorganisms in fermented dairy products, including cheeses, significantly exceeds the content of any foreign microflora and can cause the appearance of organoleptic defects such as acid, bitterness, non-specific off-taste or excessive gas formation. The ability of microorganisms to form certain metabolic products is determined both by their species and strain properties, and by cultivation conditions. These include, first of all, the composition of the development environment and temperature conditions of cultivation. By combining the composition of the starter and selecting favorable modes for cultivating microorganisms, it is possible to achieve optimal development of the starter microflora, obtaining products with the desired quality characteristics. This article presents the results of a comparative assessment of the properties of production strains of Streptococcus thermophilus during their development in dairy environments at optimal temperatures (41 ± 1) °C, simulating conditions for the production of fermented milk products, as well as in modes simulating cheese ripening conditions (11 ± 1) °C and 4% table salt concentration. The nature of the enzymatic processes of glycolysis, proteolysis, lipolysis, and flavor formation as a result of the metabolism of these cultures was also assessed.

Nutritional and Food Safety Characteristics of Jameed—A Traditional Dairy Product of Drylands

Jameed is a traditional dried dairy product in Jordan that is known under different names in the Middle East, Turkey, Central Asia, China, and Mongolia. It has been produced in the region for centuries and makes a significant contribution (up to 20%) to the income of small-scale traditional dairy processors who are based in sheep-producing districts. This study aims to assess the nutritional value of Jameed as a model for traditional dried fermented dairy products and to highlight the safety of the product quality and some of the health risks that may arise. For this purpose, 80 samples of Jameed were collected from the market covering all regions of the Kingdom of Jordan. The samples were analyzed for nutritional value and health risks by standard and approved methods. Results show that the total solids were 84.57%, with a large variation from 73 to 92%. Producers use a lot of salt to control elevated acidity during the drying of Jameed. The salt concentrations in collected samples were 15.68%. The average acidity was 6.79%. Moreover, farmers heavily use antibiotics to control mastitis without observing milk withdrawal. The residues of antibiotics were detected in 50.65% of the analyzed samples. The samples show large variations in measured values, reflecting differences in processing methods, homogeneity, and standardization.

Evaluation of probiotic bifidobacteria strains from Iranian traditional dairy products for their anti-hyperlipidemic potential.

This study investigated the therapeutic potential of probiotic bifidobacteria, isolated from Iranian fermented dairy products, in a hyperlipidemic animal model. Bifidobacterium strains were extracted from traditional dairy samples and screened using physiological and phenotypic examinations, 16S rRNA analysis, and probiotic properties such as tolerance to gastrointestinal juice, antimicrobial activity, and antibiotic susceptibility. The ability of the screened bifidobacteria to reduce serum and liver lipids in vivo was tested using male Wistar rats. Six strains of bifidobacteria were isolated from traditional Iranian fermented dairy. These strains showed promising in vitro activity in lowering triglyceride and cholesterol, tolerance to simulated gastrointestinal juice, the ability to adhere to Caco-2 cells, acceptable antibiotic susceptibility, and a broad spectrum of antibacterial activity. The diet supplemented with isolated bifidobacteria significantly reduced serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), liver tissue lipid levels, and hepatic enzymes in animals when compared to a high-fat diet without strains (p < 0.01). Additionally, the potential probiotic-supplemented diet significantly increased bile acid excretion in the feces and upregulated hepatic CYP7A1 expression levels (p < 0.05), while NPC1L1, ACAT2, and MTP gene expressions in small intestinal cells were downregulated (p < 0.05). Bifidobacteria isolated from Iranian traditional dairy showed potential for use in the production of fermented foods that have hypolipemic activity in the host.

Dissecting the Genetic Basis of the Technological, Functional, and Safety Characteristics of Lacticaseibacillus paracasei SRX10.

Nonstarter lactic acid bacteria (NSLAB) are major contributors to the unique characteristics (e.g., aroma, flavor, texture) of dairy and nondairy fermented products. Lc. paracasei SRX10 is an NSLAB strain originally isolated from a traditional Greek cheese and previously shown to exhibit favorable biotechnological characteristics. More specifically, the strain showed tolerance to simulated gastrointestinal conditions, exopolysaccharide (EPS) biosynthetic capacity, and lack of hemolytic activity and was used in the production of yoghurt and feta cheese with distinct organoleptic characteristics. The aim of the present study was to investigate these traits at the genome level through whole-genome sequencing (WGS), annotation, and comparative genomics. Functional annotation of the genome revealed that Lc. paracasei SRX10 can utilize different carbon sources, leading to the generation of flavor compounds, including lactic acid, acetate, ethanol, and acetoin. Similarly, full clusters for fatty acid biosynthesis, protein and peptide degradation, as well as genes related to survival under extreme temperatures, osmotic shock, and oxidative stress were annotated. Importantly, no transferable antibiotic resistance genes or virulence factors were identified. Finally, strain-specific primers based on genome-wide polymorphisms were designed for the efficient and rapid identification of Lc. paracasei SRX10 via multiplex PCR in fermented products.

Safety evaluation of the food enzyme protein-glutamine γ-glutamyltransferase from the non-genetically modified Streptomyces mobaraensis strain M2020197.

The food enzyme protein-glutamine γ-glutamyltransferase (protein-glutamine: amine γ-glutamyltransferase; EC 2.3.2.13) is produced with the non-genetically modified Streptomyces mobaraensis strain M2020197 by Taixing Dongsheng Bio-Tech Co. Ltd. The identity of the production strain and the absence of viable cells could not be established. The food enzyme is intended to be used in eight food manufacturing processes: processing of cereals and other grains for the production of (1) baked products, (2) cereal-based products other than baked; processing of dairy products for the production of (3) fermented dairy products, (4) cheese, (5) dairy desserts; processing of plant- and fungal-derived products for the production of (6) meat analogues, (7) plant-based analogues of milk and milk products; processing of meat and fish products for the production of (8) modified meat and fish products. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 3.498 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 91 mg TOS/kg bw per day. The calculated margin of exposure for each age group was 36 (infants), 26 (toddlers), 50 (children), 99 (adolescents), 115 (adults) and 133 (the elderly). A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that a risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded, but the likelihood is low. The safety of the food enzyme could not be established given the derived margins of exposure. Therefore, the Panel concluded that the food enzyme could not be considered safe under the intended conditions of use.

Biotechnology factors influence on formation of curd cheese quality indicators

Considering the growing interest of the Russian society in fermented dairy products, in particular, cream cheese enriched with probiotic cultures and biologically active substances (BAS), it is relevant to conduct research aimed at scientifically justifying the choice of biotechnology of curd production as a raw material for cream cheese by studying the influence of biotechnological and technological factors on the formation of properties of the used curd. The generally accepted methods of qualitative prediction were used. The study of consumer opinion revealed the demand of Russian buyers for curd products enriched with BAS and probiotic cultures. The analysis of the regulatory documentation allowed us to form a set of mandatory requirements for the quality of curd cheese and the curd used, as well as a list of raw materials, biotechnological and technological factors required in the technology of curd cheese production. The study of the influence of each type of biotechnological and technological factors on the properties of the finished product has shown that in the biotechnology of enriched cream cheese it is necessary to use starter from pure cultures of lactococci or a mixture of lactococci and thermophilic lactic acid streptococci, acid method of coagulation of milk protein, whey separation by separation or ultrafiltration, introduction of BAS and flavoring fillers with cream in a separate method of normalization, as well as to exclude the use of milkclotting enzyme, and also to eliminate the use of milk-clotting enzymes. The results obtained are the basis for the development of new biotechnologies of curd cheese enriched with BAS and/or probiotic cultures.

Intake of the different types of dairy products, genetic predisposition, and the risks of nonalcoholic fatty liver disease and cirrhosis: a prospective cohort study.

Background: The association of dairy product consumption with nonalcoholic fatty liver disease (NAFLD) and cirrhosis remains controversial. This study aimed to prospectively investigate the associations between the consumption of the different types of dairy products, genetic predisposition, and the risks of NAFLD and cirrhosis. Methods: This cohort study included 190 145 participants from the UK Biobank Study. The consumption of the different types of dairy products was assessed based on the Oxford WebQ at baseline and defined as the sum of milk, yogurt, and cheese. NAFLD and cirrhosis were evaluated using hospital inpatient records and death data in the UK Biobank. The weighted genetic risk score (GRS) for NAFLD and cirrhosis was constructed using 5 and 6 single-nucleotide variants (SNVs), respectively. Cox proportional hazards regression models were utilized to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between genetic factors and different types of dairy products with the incidence of NAFLD and cirrhosis. Results: During a median follow-up of 11.6 years, 1512 NAFLD and 556 cirrhosis cases were ascertained. After adjusting for several potential confounders, the HRs (95% CIs) (Q4 vs. Q1) of NAFLD were 0.86 (0.74, 0.995) for total dairy products, 0.96 (0.84, 1.09) for high-fat dairy products, 0.78 (0.67, 0.92) for low-fat dairy products, 0.86 (0.74, 0.99) for unfermented dairy products, and 0.79 (0.68, 0.91) for fermented dairy products. The multivariable-adjusted HRs (95% CIs) (Q4 vs. Q1) of cirrhosis were 0.75 (0.59, 0.96) for total dairy products, 0.97 (0.78, 1.19) for high-fat dairy products, 0.67 (0.51, 0.89) for low-fat dairy products, 0.75 (0.59, 0.96) for unfermented dairy products, and 0.71 (0.56, 0.90) for fermented dairy products. The associations of high-fat dairy products and fermented dairy products with NAFLD and cirrhosis were found to be nonlinear (P for nonlinear <0.05). No interaction was observed between dairy product consumption and NAFLD or cirrhosis genetic susceptibility. Conclusions: Higher consumption of dairy products, except for high-fat dairy, was correlated with lower risks of NAFLD and cirrhosis, regardless of their differences in genetic susceptibility.