The quality and flavor profile of fermented milk produced by Streptococcus thermophilus ABT-T is influenced by the pfs gene in the quorum sensing system.

The luxS/AI-2 quorum sensing (QS) system of Streptococcus thermophilus regulates strain acid tolerance, yet its impact on milk fermentation remains unclear. This study aimed to elucidate the mechanism of luxS and pfs gene overexpression in the luxS/AI-2 system of S. thermophilus ABT-T on fermented milk quality using metabolomics. Results showed that pfs gene overexpression had a greater impact on milk quality than the wild-type strain or luxS gene overexpression strain. Overexpression of the pfs gene significantly enhanced AI-2 secretion, reducing fermented milk pH, increasing acidity, improving fermented milk protein hydrolysis, and altering texture and water-holding capacity. Nineteen volatile flavor compounds were identified, with decreased ketone compounds due to the pfs gene overexpression. KEGG analysis suggested significant alterations in amino acid metabolism pathways due to the pfs gene overexpression. This study provides insights into the role of QS in fermented foods.

Biofunctional attributes and storage study of milk fermented by Enterococcus italicus.

Lactic acid bacteria are probiotics in the intestines and have been widely used as natural antioxidants in the food industry. In this study, Enterococcus italicus FM5 with strong antioxidant ability was isolated from fresh milk. The safety evaluation showed that E. italicus FM5 was sensitive to ampicillin, chloramphenicol, erythromycin, vancomycin, rifampicin, and tetracycline, and was not hemolytic. Meanwhile, the whole genome information and biofunctional attributes of this strain were determined and analyzed. Subsequently, E. italicus FM5 was co-cultured with traditional yogurt starters (Streptococcus thermophilus and Lactobacillus bulgaricus) to make fermented milk. The results showed that the addition of E. italicus FM5 could improve the oxygen free radical scavenging ability of the fermented milk, and the scavenging rates of DPPH, ABTS, OH-, and O2- radicals reaching up to 95.54 %, 88.35 %, 93.65 %, and 60.29 %, respectively. Furthermore, the addition of E. italicus FM5 reduced the curd time and improved the water holding capacity of the fermented milk. Besides, the growth of Lb. bulgaricus was significantly promoted when co-cultured with E. italicus FM5, thus the survival cells were increased compared with the traditional fermentation processes. Therefore, this study emphasized the potential to manufacture fermented milk by the co-cultivation of E. italicus with traditional yogurt starters.

Dung Beetle Optimizer Algorithm and Machine Learning-Based Genome Analysis of Lactococcus lactis: Predicting Electronic Sensory Properties of Fermented Milk.

In the global food industry, fermented dairy products are valued for their unique flavors and nutrients. Lactococcus lactis is crucial in developing these flavors during fermentation. Meeting diverse consumer flavor preferences requires the careful selection of fermentation agents. Traditional assessment methods are slow, costly, and subjective. Although electronic-nose and -tongue technologies provide objective assessments, they are mostly limited to laboratory environments. Therefore, this study developed a model to predict the electronic sensory characteristics of fermented milk. This model is based on the genomic data of Lactococcus lactis, using the DBO (Dung Beetle Optimizer) optimization algorithm combined with 10 different machine learning methods. The research results show that the combination of the DBO optimization algorithm and multi-round feature selection with a ridge regression model significantly improved the performance of the model. In the 10-fold cross-validation, the R2 values of all the electronic sensory phenotypes exceeded 0.895, indicating an excellent performance. In addition, a deep analysis of the electronic sensory data revealed an important phenomenon: the correlation between the electronic sensory phenotypes is positively related to the number of features jointly selected. Generally, a higher correlation among the electronic sensory phenotypes corresponds to a greater number of features being jointly selected. Specifically, phenotypes with high correlations exhibit from 2 to 60 times more jointly selected features than those with low correlations. This suggests that our feature selection strategy effectively identifies the key features impacting multiple phenotypes, likely originating from their regulation by similar biological pathways or metabolic processes. Overall, this study proposes a more efficient and cost-effective method for predicting the electronic sensory characteristics of milk fermented by Lactococcus lactis. It helps to screen and optimize fermenting agents with desirable flavor characteristics, thereby driving innovation and development in the dairy industry and enhancing the product quality and market competitiveness.

Combined Metabolomic and NIRS Analyses Reveal Biochemical and Metabolite Changes in Goat Milk Kefir under Different Heat Treatments and Fermentation Times.

Dairy products are an important source of protein and other nutrients in the Mediterranean diet. In these countries, the most common sources of milk for producing dairy products are cow, goat, sheep, and buffalo. Andalusia is traditionally the largest producer of goat milk in Spain. Kefir is a fermented product made from bacteria and yeasts and has health benefits beyond its nutritional properties. There is a lack of knowledge about the molecular mechanisms and metabolites that bring about these benefits. In this work, the combination of analytical techniques (GC-FID, UHPLC-MS-QToF, GC-QqQ-MS, and GC-ToF-MS) resulted in the detection of 105 metabolites in kefir produced with goat milk from two different thermal treatments (raw and pasteurized) fermented at four time points (12, 24, 36, and 48 h, using 0 h as the control). Of these, 27 metabolites differed between kefir produced with raw and pasteurized milk. These changes could possibly be caused by the effect of pasteurization on the microbial population in the starting milk. Some interesting molecules were identified, such as shikimic acid, dehydroabietic acid, GABA, and tyramine, which could be related to antibacterial properties, strengthening of the immune system, and arterial pressure. Moreover, a viability assay of the NIRS technique was performed to evaluate its use in monitoring the fermentation and classification of samples, which resulted in a 90% accuracy in comparison to correctly classified samples according to their fermentation time. This study represents the most comprehensive metabolomic analysis of goat milk kefir so far, revealing the intricate changes in metabolites during fermentation and the impact of milk treatment.

Mangosteen extracts: Effects on intestinal bacteria, and application to functional fermented milk products.

Mangosteen (Garcinia mangostana L.) is a tasty, polyphenol-rich tropical fruit. The edible part is highly appreciated by its aroma, taste and texture. The non-edible part, rich in polyphenols, has been traditionally used in Thai medicine. In this work, flavonoids and phenolic acid/derivatives were identified in mangosteen extracts (ME) from edible and non-edible portions. We first studied the effects of MEs on the growth, metabolism, antioxidant capacity, biofilm formation and antimicrobial capacity of eight bifidobacteria and lactobacilli strains from intestinal origin and two commercial probiotic strains (BB536 and GG). ME concentrations higher than 10-20 % were inhibitory for all strains. However, ME concentrations of 5 % significantly (P < 0.01) increased all strains antioxidant capacity, reduced biofilm-formation, and enhanced inhibition against Gram-positive pathogens. To apply these knowledge, bifunctional fermented milk products were elaborated with 5 % ME and individual strains, which were selected taking into account their growth with ME, and the widest range of values on antioxidant capacity, biofilm formation and antimicrobial activity (bifidobacteria INIA P2 and INIA P467, lactobacilli INIA P459 and INIA P708, and reference strain GG). Most strains survived well manufacture, refrigerated storage and an in vitro simulation of major conditions encountered in the gastrointestinal tract. As expected, products supplemented with ME showed higher polyphenol content and antioxidant capacity levels than control. After sensory evaluation, products containing strains INIA P2, INIA P708 and GG outstood as best.

Factors influencing conjugated linoleic acid content of dairy products: challenges and strategies.

Conjugated linoleic acid (CLA), a bioactive fatty acid that provides various physiological benefits, has gained increasing attention in the food industry, and various studies have focused on enhancing its content in dairy products. The factors influencing CLA content in dairy products vary significantly, including lactation stage, breed type, seasonality, feed, management methods of the animals, the manufacturing processes, storage, and ripening periods of the product. Additionally, the incorporation of CLA-producing probiotic bacteria, such as Lactobacillus, Lactococcus, Bifidobacterium, and Propionibacterium, is an emerging study in this field. Studies have revealed that factors affecting the CLA content in milk affect that in dairy products as well. Furthermore, the species and strains of CLA-producing bacteria, fermentation conditions, ripening period, and type of dairy product are also contributing factors. However, production of CLA-enhanced dairy products using CLA-producing bacteria while maintaining their optimal viability and maximizing exposure to free linoleic acid remains limited. The current review emphasized the factors affecting the CLA content and related mechanisms, challenges in the application of CLA-producing probiotic bacteria, and strategies to address these challenges and enhance CLA production in dairy products. Therefore, the development of functional dairy products with enhanced CLA levels is expected to be possible.

Metabolomic analysis reveals Ligilactobacillus salivarius CCFM 1266 fermentation improves dairy product quality.

Previous studies have demonstrated that Ligilactobacillus salivarius CCFM 1266 exhibits anti-inflammatory properties and the capability to synthesize niacin. This study aimed to investigate the fermentative abilities of L. salivarius CCFM 1266 in fermented milk. Metabonomic analysis revealed that fermentation by L. salivarius CCFM 1266 altered volatile flavor compounds and metabolite profiles, including heptanal, nonanal, and increased niacin production. Genomic investigations confirmed that L. salivarius CCFM 1266 possess essential genes for the metabolism of fructose and mannose, affirming its proficiency in utilizing fructooligosaccharides and mannan oligosaccharides. The addition of fructooligosaccharides and mannan oligosaccharides during the fermentation process significantly facilitated the proliferation of L. salivarius CCFM 1266 in fermented milk, with growth exceeding 107 colony-forming units (CFU)/mL. This intervention not only augmented the microbial density but also modified the metabolite composition of fermented milk, resulting in an elevated presence of advantageous flavor compounds such as nonanal, 2,3-pentanedione, and 3-methyl-2-butanone. However, its influence on improving the texture of fermented milk was observed to be minimal. Co-fermentation of L. salivarius CCFM 1266 with commercial fermentation starters indicated that L. salivarius CCFM 1266 was compatible, similarly altering metabolite composition and increasing niacin content in fermented milk. In summary, the findings suggest that L. salivarius CCFM 1266 holds substantial promise as an adjunctive fermentation starter, capable of enhancing the nutritional diversity of fermented milk products.

Shotgun metagenomic analysis of microbiota dynamics during long-term backslopping fermentation of traditional fermented milk in a controlled laboratory environment.

Traditional fermented milks are produced through an inoculation process that involves the deliberate introduction of microorganisms that have been adapted and perpetuated across successive generations. However, the changes in the microbiota of traditional fermented milk during long-term inoculation fermentation in a laboratory environment remain unclear. In this study, we collected 5 samples of traditional fermented milk samples from 5 different counties in Tibet (3 kurut products) and Xinjiang (2 tarag products) of China, which served as starter cultures for a 9-mo continuous inoculation fermentation experiment. We analyzed the inter- and intra-population variations in the microbial communities of the collected samples, representing their macrodiversity and microdiversity, using shotgun metagenomic sequencing. Across all samples, we obtained a total of 186 high-quality metagenomic-assembled genomes, including 7 genera and 13 species with a relative abundance of more than 1%. The majority of these genomes were annotated as Lactobacillus helveticus (60.46%), Enterococcus durans (9.52%), and Limosilactobacillus fermentum (6.23%). We observed significant differences in species composition and abundance among the 5 initial inoculants. During the long-term inoculation fermentation, we found an overall increasing trend in species diversity, composition, and abundances of carbohydrate metabolism module-encoding genes in the fermented milk bacterial metagenome, while the fermented milk virome exhibited a relatively narrow range of variation. Lactobacillus helveticus, a dominant species in traditional fermented milk, displayed high stability during the long-term inoculation fermentation. Our study provides valuable insights for the industrial production of traditional fermented milk.

Probiotic Bifidobacterium animalis ssp. lactis Probio-M8 improves the fermentation and probiotic properties of fermented milk.

Probiotics are increasingly used as starter cultures to produce fermented dairy products; however, few studies have investigated the role of probiotics in milk fermentation metabolism. The current study aimed to investigate whether adding Bifidobacterium animalis ssp. lactis Probio-M8 (Probio-M8) as a starter culture strain could improve milk fermentation by comparing the physico-chemical characteristics and metabolomes of fermented milks produced by a commercial starter culture with and without Probio-M8. Our results showed that adding Probio-M8 shortened the milk fermentation time and improved the fermented milk texture and stability. Metabolomics analyses revealed that adding Probio-M8 affected mostly organic acid, amino acid, and fatty acid metabolism in milk fermentation. Targeted quantitative analyses revealed significant increases in various metabolites related to the sensory quality, nutritive value, and health benefits of the probiotic fermented milk, including 5 organic acids (acetic acid, lactic acid, citric acid, succinic acid, and tartaric acid), 5 essential amino acids (valine, arginine, leucine, isoleucine, and lysine), glutamic acid, and 2 essential fatty acids (α-linolenic acid and docosahexaenoic acid). Thus, applying probiotics in milk fermentation is desirable. This study has generated useful information for developing novel functional dairy products.

Investigation on Fermented Milk Quality after the Addition of Flaxseed Mucilage and the Use of Lactobacillus delbrueckii subsp. bulgaricus and Lactiplantibacillus plantarum AG9.

BACKGROUND: Flaxseed mucilage (FSM) is one of the healthy components of flaxseed. FSM is an example of a material that can be used in the food, cosmetic, and pharmaceutical industries due to its rheological properties. FSM consists mainly of two polysaccharides, arabinoxylan, and rhamnogalacturonan I, and it also contains protein components and minerals. The prospect of using FSM in food is due to its gelling, water binding, emulsifying, and foaming properties. In addition, valuable natural sources of phenolic compounds such as lignans, phenolic acids, flavonoids, phenylpropanoids, and tannins are partially extracted from flaxseed in FSM. These antioxidant components have pharmacological properties, including anti-diabetic, anti-hypertensive, immunomodulatory, anti-inflammatory and neuroprotective properties. A combination of FSM and lactobacilli in dairy foods can improve their functional properties. This study aimed to develop dairy products by adding of FSM and using two lactic acid bacteria (LAB). FSM (0.2%) was used as an ingredient to improve both the texture and antioxidant properties of the product. METHODS: Skim milk was fermented with 0.2% flaxseed mucilage using Lactobacillus delbrueckii subs. bulgaricus and the probiotic Lactiplantibacillus plantarum AG9. The finished fermented milk products were stored at 4 °C for 14 days. Quantitative chemical, textural, and antioxidant analyses were carried out. RESULTS: Adding 0.2% FSM to the dairy product stimulated the synthesis of lactic acid. FSM increased the viscosity and water-holding capacity of L. bulgaricus or L. bulgaricus/L. plantarum AG9 fermented milk products. Combining these starter strains with FSM promoted the formation of a hard, elastic, resilient casein matrix in the product. When only L. plantarum AG9 was used for the fermentation, the dairy product had a high syneresis and a low viscosity and firmness; such a product is inferior in textural characteristics to the variant with commercial L. bulgaricus. The addition of FSM improved the textural properties of this variant. The use of L. plantarum AG9 and FSM makes it possible to obtain a fermented milk product with the highest content of polyphenolic compounds, which have the highest antioxidant properties and stimulate lipase and α-glucosidase inhibitor synthesis. Combining of L. bulgaricus and L. plantarum AG9 in the starter (20% of the total mass of the starter) and adding of 0.2% FSM is the optimal combination for obtaining a dairy product with high textural and antioxidant properties. CONCLUSIONS: The physicochemical properties (viscosity, syneresis, water holding capacity, texture) and antioxidant properties of fermented milk were improved. In the future, as part of the work to investigate the functional properties of dairy products with FSM, studies will be conducted using in in vivo models.

Fermented Milk Containing Lacticaseibacillus rhamnosus SNU50430 Modulates Immune Responses and Gut Microbiota in Antibiotic-Treated Mice.

Antibiotics are used to control infectious diseases. However, adverse effects of antibiotics, such as devastation of the gut microbiota and enhancement of the inflammatory response, have been reported. Health benefits of fermented milk are established and can be enhanced by the addition of probiotic strains. In this study, we evaluated effects of fermented milk containing Lacticaseibacillus rhamnosus (L. rhamnosus) SNUG50430 in a mouse model with antibiotic treatment. Fermented milk containing 2 × 105 colony-forming units of L. rhamnosus SNUG50430 was administered to six week-old female BALB/c mice for 1 week. Interleukin (IL)-10 levels in colon samples were significantly increased (P < 0.05) compared to water-treated mice, whereas interferon-gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) were decreased, of mice treated with fermented milk containing L. rhamnosus SNUG50430-antibiotics-treated (FM+LR+Abx-treated) mice. Phylum Firmicutes composition in the gut was restored and the relative abundances of several bacteria, including the genera Coprococcus and Lactobacillus, were increased in FM+LR+Abx-treated mice compared to PBS+Abx-treated mice. Interestingly, abundances of genus Coprococcus and Lactobacillus were positively correlated with IL-5 and IL-10 levels (P < 0.05) in colon samples and negative correlated with IFN-γ and TNF-α levels in serum samples (P < 0.001). Acetate and butyrate were increased in mice with fermented milk and fecal microbiota of FM+LR+Abx-treated mice were highly enriched with butyrate metabolism pathway compared to water-treated mice (P < 0.05). Thus, fermented milk containing L. rhamnosus SNUG50430 was shown to ameliorate adverse health effects caused by antibiotics through modulating immune responses and the gut microbiota.

Overview of Dairy-based Products with Probiotics: Fermented or Non-fermented Milk Drink.

Probiotic products have long been recognized for their health benefits. Additionally, milk has held a longstanding reputation as a dairy product that offers high-quality proteins and essential micronutrients. As awareness of the impact of food on health grows, interest in functional products such as probiotic dairy products is on the rise. Fermentation, a time-honored technique used to enhance nutritional value and food preservation, has been used for centuries to increase nutritional value and is one of the oldest food processing methods. Historically, fermented dairy products have been used as convenient vehicle for the consumption of probiotics. However, addressing the potential drawbacks of fermentation has recently led to increase in research on probiotic dairy drinks prepared without fermentation. These non-fermented dairy drinks have the advantage of maintaining the original flavors of milk drinks, containing potential health functional probiotics, and being an alternative dairy product that is helpful for probiotics intake. Currently, research on plant-based dairy products is rapidly increasing in the market. These developments might suggest the potential for novel forms of non-fermented dairy beverages with substantial prospects in the food market. This review aims to provide an overview of milk-based dairy beverages, both fermented and non-fermented, and discuss the potential of non-fermented dairy products. This exploration paves the way for innovative approaches to deliver probiotics and nutrition to consumers.

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.

Lactic acid bacteria and yeast co-fermented milk alleviate cow milk allergy.

Cow milk allergy is one of the common food allergies. Our previous study showed that the allergenicity of fermented milk is lower than that of unfermented skimmed milk in vitro, and the antigenicity of ß-lactoglobulin and α-lactalbumin in fermented milk was decreased by 67.54% and 80.49%, respectively. To confirm its effects in vivo, allergic BALB/C mice model was used to further study the allergenicity of fermented milk. It was found that compared with the skim milk (SM) group, the intragastrically sensitization with fermented milk had no obvious allergic symptoms and the fingers were more stable: lower levels of IgE, IgG, and IgA in serum, lower levels of plasma histamine and mast cell protein-1, and immune balance of Th1/Th2 and Treg/Th17. At the same time, intragastrically sensitization with fermented milk increased the α diversity of intestinal microbiota and changed the microbiota abundance: the relative abundance of norank-f-Muribaculaceae and Staphylococcus significantly decreased, and the abundance of Lachnospiraceae NK4A136 group, Bacteroides, and Turicibacter increased. In addition, fermented milk can also increase the level of short-chain fatty acids in the intestines of mice. It turns out that fermented milk is much less allergenicity than SM. PRACTICAL APPLICATION: Fermentation provides a theoretical foundation for reducing the allergenicity of milk and dairy products, thereby facilitating the production of low-allergenic dairy products suitable for individuals with milk allergies.

Milk and Lacticaseibacillus paracasei BL23 effects on intestinal responses in a murine model of colitis.

Probiotic-containing fermented dairy foods have the potential to benefit human health, but the importance of the dairy matrix for efficacy remains unclear. We investigated the capacity of Lacticaseibacillus paracasei BL23 in phosphate-buffered saline (BL23-PBS), BL23-fermented milk (BL23-milk), and milk to modify intestinal and behavioral responses in a dextran sodium sulfate (DSS, 3% wt/vol) mouse model of colitis. Significant sex-dependent differences were found such that female mice exhibited more severe colitis, greater weight loss, and higher mortality rates. Sex differences were also found for ion transport ex vivo, colonic cytokine and tight junction gene expression, and fecal microbiota composition. Measurements of milk and BL23 effects showed BL23-PBS consumption improved weight recovery in females, whereas milk resulted in better body weight recovery in males. Occludin and Claudin-2 gene transcript levels indicated barrier function was impaired in males, but BL23-milk was still found to improve colonic ion transport in those mice. Proinflammatory and anti-inflammatory gene expression levels were increased in both male and female mice fed BL23, and to a more variable extent, milk, compared with controls. The female mouse fecal microbiota contained high proportions of Akkermansia (average of 18.1%) at baseline, and females exhibited more changes in gut microbiota composition following BL23 and milk intake. Male fecal microbiota harbored significantly more Parasutterella and less Blautia and Roseburia after DSS treatment, independent of BL23 or milk consumption. These findings show the complex interplay between dietary components and sex-dependent responses in mitigating inflammation in the digestive tract.NEW & NOTEWORTHY Sex-dependent responses to probiotic Lacticaseibacillus paracasei and milk and the potential of the dairy matrix to enhance probiotic protection against colitis in this context have not been previously explored. Female mice were more sensitive than males to colonic injury, and neither treatment effectively alleviated inflammation in both sexes. These sex-dependent responses may result from differences in the higher baseline proportions of Akkermansia in the gut microbiome of female mice.

Technological and Enzymatic Characterization of Autochthonous Lactic Acid Bacteria Isolated from Viili Natural Starters.

Viili, a Finnish ropy fermented milk, is traditionally manufactured through spontaneous fermentation, by mesophilic lactic acid bacteria and yeast-like fungi, or back-slopping. This study evaluated four natural viili starters as sources of lactic acid bacteria for dairy production. Back-slopping activation of the studied viili samples was monitored through pH and titratable acidity measurements and enumeration of mesophilic lactic acid bacteria. Sixty lactic acid bacteria isolates were collected, molecularly identified, and assayed for acidification performance, enzymatic activities, production of exopolysaccharides (EPSs), presence of the histidine decarboxylase (hdcA) gene of Gram-positive bacteria, and production of bacteriocins. A neat predominance of Lactococcus lactis emerged among the isolates, followed by Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, Enterococcus lactis, and Lactococcus cremoris. Most isolates exhibited proteolytic activity, whereas only a few enterococci showed lipase activity. Five isolates identified as L. cremoris, L. lactis, and E. faecalis showed a good acidification performance. Most of the isolates tested positive for leucine arylamidase, whereas only one E. durans and two L. lactis isolates were positive for valine arylamidase. A few isolates also showed a positive reaction for beta-galactosidase and alpha- and beta-glucosidase. None of the isolates produced EPSs or bacteriocins. The hdcA gene was detected in five isolates identified as L. lactis and E. faecium. A few L. cremoris and L. lactis isolates for potential use as starter or adjunct cultures for dairy processing were finally identified.

Lactobacillus paracasei ZFM54 alters the metabolomic profiles of yogurt and the co-fermented yogurt improves the gut microecology of human adults.

Gut microbiota imbalance could lead to various diseases, making it important to optimize the structure of the gut flora in adults. Lactobacillus paracasei ZFM54 is a bacteriocin- and folic acid-producing Lactobacillus strain. Herein, L. paracasei ZFM54 was used as the potentially probiotic bacterium to ferment milk together with a yogurt starter. We optimized the fermentation conditions, and the obtained yogurts were then subjected to volatile and nonvolatile metabolome analysis, showing that L. paracasei ZFM54 can not only improve the acidity, water holding capacity and live lactic acid bacteria counts, but also improve many volatile acid contents and increase some beneficial nonvolatile metabolites, such as N-ethyl glycine and l-lysine, endowing the yogurt with more flavor and better function. The regulatory effects of the co-fermented yogurt on the intestinal microecology of volunteers were investigated by 16S rRNA sequencing and short-chain fatty acid (SCFA) analysis after consuming the yogurt for a 2-wk period, showing a better effect to increase the relative abundance of beneficial bacteria such as Ruminococcus and Alistipes, decrease harmful bacteria (Escherichia-Shigella and Enterobacter), and enhance the production of SCFA (acetate, propionate, and butyric acid) compared with the control yogurt. We found that L. paracasei ZFM54 can significantly improve the health benefits of yogurt, laying the foundation for its commercial application in improving gut microbiota.

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.

Exploring the Effect of Milk Fat on Fermented Milk Flavor Based on Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) and Multivariate Statistical Analysis.

Milk fat is a premium nutritional health product, yet there is a lack of high-fat dairy products for daily consumption in the current market. This study investigated the influence of different milk fat contents on the physicochemical and textural properties of fermented milk. The research revealed that an increase in milkfat content significantly improved the water-holding capacity, syneresis, color, hardness, springiness, gumminess, and chewiness of fermented milk, while showing minimal changes in pH and total titratable acidity. Response surface analysis indicated that fermented milk with 25% milk fat, 2.5% inoculum, a fermentation time of 16 h, and a fermentation temperature of 30 °C exhibited the highest overall acceptability. Using GC-IMS technology, 36 volatile compounds were identified, with an increase in milk fat content leading to elevated levels of ketone compounds, and 14 compounds were defined as key aroma compounds (ROAV > 1). Electronic nose distinguished samples with different milk fat contents. The results demonstrate that an increase in milk fat content enhances the physicochemical and flavor attributes of fermented milk. This work provides theoretical references for the production and development of high-fat fermented milk.

Effect of Fermented Milk Supplemented with Nisin or Plantaricin Q7 on Inflammatory Factors and Gut Microbiota in Mice.

Lactic-acid-bacteria-derived bacteriocins are used as food biological preservatives widely. Little information is available on the impact of bacteriocin intake with food on gut microbiota in vivo. In this study, the effects of fermented milk supplemented with nisin (FM-nisin) or plantaricin Q7 (FM-Q7) from Lactiplantibacillus plantarum Q7 on inflammatory factors and the gut microbiota of mice were investigated. The results showed that FM-nisin or FM-Q7 up-regulated IFN-γ and down-regulated IL-17 and IL-12 in serum significantly. FM-nisin down-regulated TNF-α and IL-10 while FM-Q7 up-regulated them. The results of 16S rRNA gene sequence analysis suggested that the gut microbiome in mice was changed by FM-nisin or FM-Q7. The Firmicutes/Bacteroides ratio was reduced significantly in both groups. It was observed that the volume of Akkermansia_Muciniphila was significantly reduced whereas those of Lachnospiraceae and Ruminococcaceae were increased. The total number of short-chain fatty acids (SCFAs) in the mouse feces of the FM-nisin group and FM-Q7 group was increased. The content of acetic acid was increased while the butyric acid content was decreased significantly. These findings indicated that FM-nisin or FM-Q7 could stimulate the inflammation response and alter gut microbiota and metabolic components in mice. Further in-depth study is needed to determine the impact of FM-nisin or FM-Q7 on the host's health.