A UPLC-Q-TOF-MS-based metabolomics approach for the evaluation of fermented mare’s milk to koumiss

A UHPLC-QE-MS-based metabolomics approach for the evaluation of fermented lipase by an engineered Escherichia coli

Using an engineered Escherichia coli to produce lipase and can easily achieve high-level expression. The investigation of biochemical processes during lipase fermentation, approached from a metabolomics perspective, will yield novel insights into the efficient secretion of recombinant proteins. In this study, the lipase batch fermentation was carried out first with enzyme activity of 36.83 U/mg cells. Then, differential metabolites and metabolic pathways were identified using an untargeted metabolomics approach through comparative analysis of various fermentation periods. In total, 574 metabolites were identified: 545 were up-regulated and 29 were down-regulated, mainly in 153 organic acids and derivatives, 160 organoheterocyclic compounds, 64 lipids and lipid-like molecules, and 58 organic oxygen compounds. Through metabolic pathways and network analysis, it could be found that tryptophan metabolism was of great significance to lipase production, which could affect the secretion and synthesis of recombinant protein. In addition, the promotion effects of cell growth by varying concentrations of indole acetic acid serve to validate the results obtained from tryptophan metabolism. This study offers valuable insights into metabolic regulation of engineered E. coli, indicating that its fermentation bioprocess can be systematically designed according to metabolomics findings to enhance recombinant protein production.

Analysis of differential metabolites in Liuyang douchi at different fermentation stages based on untargeted metabolomics approach

The quality and flavor of Liuyang Douchi are usually closely related to the metabolites compostion. This work described the metabolic profiles of Liuyang douchi during fermentation. Obvious hydrolysis of carbohydrates, proteins and slight lipids degradation were observed. Notably, the qu-making and pile-fermentation stage of douchi could be easily distinguished according to their metabolites profile, and pile-fermentation stage showed the most abundant metabolites. Specifically, organic acid, such as succinic acid and lactic acid, accumulated during pile-fermentation, as well as amino acids and derivatives. Especially glutamate (Glu), which contributed to the umami taste, increased form 0.82 mg/g to 15.90 mg/g after fermentation. Meanwhile, metabolisms related to amino acids were also the main enrichment metabolic pathways. Among them, some flavor compunds such as phenylacetaldehyde might drived from phenylalanine metabolism. These results could provide a new understanding on the metabolic characteristics during Liuyang douchi fermentation.

Rapid identification method of milk powder from different animals based on Raman spectroscopy

This study developed an efficient method for identifying and quantitatively analyzing animal-origin milk powders using Raman spectroscopy combined with chemometrics. By employing the MultiClassClassifier model, the method achieved high accuracy in distinguishing various types of animal-origin milk powders, with sensitivity and specificity both exceeding 80% and an overall accuracy of 93%. Furthermore, the quantitative models based on partial least squares regression and support vector machine regression exhibited excellent linear correlations, with both root mean square error and mean relative error below 0.2. These models successfully quantified adulteration in camel, mare, and donkey milk powders in comparison to goat and cow milk powders. The study's approach not only holds significant promise for detecting adulteration in specialty milk powders but also demonstrates wide applicability in analyzing other powdered adulterants.

Microbiological and clinical effects of probiotic-related Zeger therapy on gingival health: a randomized controlled clinical trial

BACKGROUND

This single-blind randomized controlled trial was aimed to evaluate the microbiological and clinical effects of Zeger therapy on gingival health.

METHODS

Twenty-four adults with gingivitis were recruited and monitored micro-biologically and clinically at baseline (Day 0), 4 weeks (Day 29) after therapy. All volunteers received one-stage full-mouth supragingival scaling as basic oral health care for baseline, and then randomly divided into experimental (koumiss, n = 12) or control (none, n = 12) group. The koumiss was used once a day for 4 weeks.

RESULTS

The microbial diversity of the experimental group increased significantly after drinking koumiss (p < 0.05), mainly owing to increasing of Gram-positive bacteria (p = 0.038) and oral health-related microbes (Rothia, Corynebacterium, Actinomyces, Saccharibacteria_TM7, etc.), decreasing of Gram-negative bacteria (p = 0.009) and periodontal disease-related microbes (Porphyromonas, Fusobacterium, Veillonella, etc.), while the microbial diversity of the control group had no significant change (p > 0.05). However, there was no significant difference between the two groups in the clinical parameters (p > 0.05).

CONCLUSIONS

Zeger therapy promotes the diversity of supragingival microbiome in adults with gingivitis and increases the abundance of some beneficial flora while decreasing some harmful without clinical parameters marked changing, which holds promise for improving of gingivitis and may be a valuable oral health care approach in the future.

TRIAL REGISTRATION

The clinical trial was approved by the Medical Ethics Committee of West China Hospital of Stomatology, Sichuan University, batch No. WCHSIRB-D-2021-428. Before patient registration began, the prospective clinical trial was registered in www.

CLINICALTRIALS

gov public repository in China under the registration number ChiCTR2200060555 on 04/06/2022.

Metabolite profiling of different Iranian traditional yogurts using an untargeted metabolomics approach

We used gas chromatography-mass spectrometry (GC-MS) with an untargeted metabolomics approach to look at the metabolite profiles of traditional Iranian yogurts made from cow, goat, buffalo, and sheep milk. Results showed that different animal milks significantly influenced physicochemical properties and fatty acid (FA) composition, resulting in diverse metabolites. Over 80 % of all the fatty acids in the yogurt samples were saturated. The main fatty acids found were myristic acid (C14:0), palmitic acid (C16:0), and oleic acid + petroselenic acid (cis-9 C18:1 + cis-6 C18:1). In total, 36 metabolites, including esters, aldehydes, alcohols, and acids, were detected. Some important metabolites that changed yogurt profiles were 2-heptanone, methyl acetate, 2-propanone, butyl formate, and 4-methyl benzal. Associations between metabolite profiles and milk compositional traits were also observed, with statistical models showing a strong correlation between metabolite profiles and FA content. This study is the first to explore the impact of different animal sources and regions in Iran on the metabolome profiles of traditional yogurts. These results give us useful information about how metabolites differ between species and can be used to make new dairy products based on milk compositions and metabolites, which will help with future formulations of autochthonous starters.

Uncovering the antiinflammatory potential of Lactiplantibacillus Plantarum fermented Cannabis Sativa L seeds

Inflammation acts as a dual role in disease initiation and progression, while Cannabis sativa L. (hemp) seeds, known for their abundance of anti-inflammatory phytochemicals, present a promising food source. Additionally, fermentation may optimize the food matrix, thereby augmenting its developmental prospects. This study explores the anti-inflammatory potential of hemp seeds fermented with 10 different probiotic strains. Among these, Lactiplantibacillus plantarum fermented hemp seeds (FHS) demonstrated a significant anti-inflammatory ability, accompanied by a reduction in the expression of critical inflammatory markers such as TLR4, NF-κBp65, and iNOS. Moreover, there is a noteworthy dose-dependent inhibition of inflammatory cytokines TNF-α, IL-6, IL-1β, and NO within a concentration range of 50 to 500 µg/mL. Subsequently, metabolomics analysis using UHPLC-QTOF-MS highlighted significant metabolic alterations in FHS compared to raw hemp seeds (RHS). Through multivariate, univariate, and correlation analyses, indolelactic acid (IA) and homovanillic acid (HVA) emerged as the main anti-inflammatory metabolites in FHS. Validation via HPLC confirmed the concentration of IA and HVA in RHS and FHS and both organic acids demonstrated lower IC50 values for TNF-α, IL-1β, IL-6, IL-18, and NO inhibition, showcasing their potent anti-inflammatory abilities. Furthermore, in vitro gastro-intestinal digestion coupled with the Caco-2 cell monolayer model validates the uptake and bioaccessibility of FHS, further affirming IA and HVA as major anti-inflammatory compounds. Overall, this research sets the stage for the development of novel hemp seed-based products targeting inflammation-associated disorders.

Exploring the effects of the fermentation method on the quality of Lycium barbarum and Polygonatum cyrtonema compound wine based on LC-MS metabolomics

This study aimed to examine the effect of fermentation methods on the quality of Lycium barbarum and Polygonatum cyrtonema compound wine (LPW) by combining non-targeted metabolomic approaches with chemometrics and path profiling to determine the chemical and metabolic properties of LPW. The results demonstrated that SRA had higher leaching rates of total phenols and flavonoids, reaching 4.20 ± 0.10 v/v ethanol concentration. According to LC-MS non-targeting genomics, the metabolic profiles of LPW prepared by different mixtures of fermentation methods (Saccharomyces cerevisiae RW; Debaryomyces hansenii AS2.45) of yeast differed significantly. Amino acids, phenylpropanoids, flavonols, etc., were identified as the differential metabolites between different comparison groups. The pathways of tyrosine metabolism, biosynthesis of phenylpropanoids, and metabolism of 2-oxocarboxylic acids enriched 17 distinct metabolites. SRA stimulated the production of tyrosine and imparted a distinctive saucy aroma to the wine samples, providing a novel research concept for the microbial fermentation-based production of tyrosine.

Mass spectrometry-based techniques for identification of compounds in milk and meat matrix

Food including milk and meat is often viewed as the mixture of different components such as fat, protein, carbohydrates, moisture and ash, which are estimated using well-established protocols and techniques. However, with the advent of metabolomics, low-molecular weight substances, also known as metabolites, have been recognized as one of the major factors influencing the production, quality and processing. Therefore, different separation and detection techniques have been developed for the rapid, robust and reproducible separation and identification of compounds for efficient control in milk and meat production and supply chain. Mass-spectrometry based techniques such as GC-MS and LC-MS and nuclear magnetic resonance spectroscopy techniques have been proven successful in the detailed food component analysis owing to their associated benefits. Different metabolites extraction protocols, derivatization, spectra generated, data processing followed by data interpretation are the major sequential steps for these analytical techniques. This chapter deals with not only the detailed discussion of these analytical techniques but also sheds light on various applications of these analytical techniques in milk and meat products.

Donkey Colostrum and Milk: How Dietary Probiotics Can Affect Metabolomic Profile, Alkaline Sphingomyelinase and Alkaline Phosphatase Activity

Positive results on animal health, feed efficiency, and milk's nutritional content have been obtained after oral administration of probiotics. The aim of the present study was therefore to evaluate the effect of dietary supplementation with high numbers of multispecies probiotic formulations on the milk metabolomic profiles of alkaline sphingomyelinase (alk-SMase) and alkaline phosphatase (ALP) in donkeys. Twenty animals were randomly allocated to receive either a normal diet (group B) or a supplemented diet (group A). Colostrum and milk samples were obtained within 48 h, at 15 days (supplementation start), and at 45 days after parturition. Different metabolomic profiles were observed between colostrum and milk, as were the concentrations of 12 metabolites that changed following 30 days of probiotic supplementation. Alk-SMase activity was found to be higher in donkey colostrum (vs. milk at 15 days); this enzyme, together with ALP, increased in milk after 30 days of probiotic supplementation. The results of the present study provide new insight into the complex changes in donkey colostrum and milk composition in the first 45 days of lactation and how the milk metabolome can be modulated by probiotic supplementation.

The "Crosstalk" between Microbiota and Metabolomic Profile of Kefalograviera Cheese after the Innovative Feeding Strategy of Dairy Sheep by Omega-3 Fatty Acids

The purpose of this study was to examine the effects of two different feeding systems, a control or a flaxseed and lupin diet (experimental), for a sheep flock, on the microbiota and metabolome of Kefalograviera cheese samples produced by their milk. In particular, the microbiota present in Kefalograviera cheese samples was analyzed using 16S rRNA gene sequencing, while ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) was applied to investigate the chemical profile of the cheeses, considering the different feeding systems applied. The metagenomic profile was found to be altered by the experimental feeding system and significantly correlated to specific cheese metabolites, with Streptococcaceae and Lactobacillaceae establishing positive and negative correlations with the discriminant metabolites. Overall, more than 120 features were annotated and identified with high confidence level across the samples while most of them belonged to specific chemical classes. Characteristic analytes detected in different concentrations in the experimental cheese samples including arabinose, dulcitol, hypoxanthine, itaconic acid, L-arginine, L-glutamine and succinic acid. Therefore, taken together, our results provide an extensive foodomics approach for Kefalograviera cheese samples from different feeding regimes, investigating the metabolomic and metagenomic biomarkers that could be used to foresee, improve, and control cheese ripening outcomes, demonstrating the quality of the experimental Kefalograviera cheese.

Soy protein degradation drives diversity of amino-containing compounds via Bacillus subtilis natto fermentation

Food fermentation has been playing an important role in producing bioactive components (e.g., peptides), which exert many healthy effects. In this study, it was observed that natto possessed significantly higher angiotensin I-converting enzyme (ACE) inhibitory effect than soybean. Meanwhile, a total of 246 amino-containing compounds were identified via LC-Q-TOF-MS/MS, including amino acids, dipeptides, tripeptides, O-methyl-peptide, and biogenic amines, 187 of them were only detected in natto. Of the list, dipeptides, with ACE inhibitory abilities or potentials, were found to be the most significantly up-regulated class and positively correlated with significantly increased ACE inhibitory activity of natto. Moreover, dynamic profiling elucidated the increased dipeptides were generated from water soluble and insoluble protein via Bacillus subtilis natto fermentation. Taken together, this study enriches the chemical diversity of natto and provides an in-depth insight into the degradation mechanism of soy protein during natto fermentation, which can be extended to other functional foods.

Comprehensive identification of molecular profiles related to sensory and nutritional changes in Mongolian cheese during storage by untargeted metabolomics coupled with quantification of free amino acids

Non-targeted metabolomics was used to study metabolites with low molecular weight which may contribute to quality deterioration of Mongolian cheese during storage. Microbiological analysis, pH, FAAs (free amino acids), volatile compounds, and sensory evaluation of the cheese during storage were also studied. A total of 278 metabolites were identified in Mongolian cheese, of which 51 metabolites were used as differential metabolites, including amino acids, peptides, organic acids, lipids, and carbohydrates. Bitter amino acids, bitter peptide (Phe-Ile), and organic acids (sinapic acid, butyric acid) increased during storage. Metabolic pathway analysis showed that differential metabolites were mainly related to amino acid metabolism, such as β-alanine metabolism and glycine, serine, and threonine metabolism. Moreover, accompanied with the increased contents of short-chain fatty acids, 2-undecanone and ethyl esters, strength of odor and unpleasant smell increased but overall acceptability decreased during Mongolian cheese storage. This research provides suitable strategies for quality control of Mongolian cheese during shelf life.

Changes in the Fatty Acid Composition of Milk of Lipizzaner Mares during the Lactation Period

The composition and properties of the milk fat of mares’ milk is interesting from a nutritional standpoint. The aim of this study was to determine the nutritional value of Lipizzaner mare’s milk for possible human consumption and identity the influence of the parity and stage of lactation on its fatty acid (FA) composition. This study was conducted on 17 Lipizzaner mares from a state stud farm in the Slavonian region (eastern Croatia). Mares were hand-milked twice during lactation in the fourth and sixth months. Significantly higher contents of MUFAs (monounsaturated fatty acids) and PUFAs (polyunsaturated fatty acids) and lower ratios of n-6/n-3 were found in the fourth month of lactation. This parity significantly affected the PUFA/SFA ratio (polyunsaturated fatty acids/saturated fatty acids), with lower values found in older mares. The fatty acid composition of mare’s milk that is especially high in UFAs (unsaturated fatty acids) is considered to be beneficial for consumers.

Comprehensive Metabolomic Comparison of Five Cereal Vinegars Using Non-Targeted and Chemical Isotope Labeling LC-MS Analysis

Vinegar is used as an acidic condiment and preservative worldwide. In Asia, various black vinegars are made from different combinations of grains, such as Sichuan bran vinegar (SBV), Shanxi aged vinegar (SAV), Zhenjiang aromatic vinegar (ZAV), and Fujian Monascus vinegar (FMV) in China and Ehime black vinegar in Japan (JBV). Understanding the chemical compositions of different vinegars can provide information about nutritional values and the quality of the taste. This study investigated the vinegar metabolome using a combination of GC-MS, conventional LC-MS, and chemical isotope labeling LC-MS. Different types of vinegar contained different metabolites and concentrations. Amino acids and organic acids were found to be the main components. Tetrahydroharman-3-carboxylic acid and harmalan were identified first in vinegar. Various diketopiperazines and linear dipeptides contributing to different taste effects were also detected first in vinegar. Dipeptides, 3-phenyllactic acid, and tyrosine were found to be potential metabolic markers for differentiating vinegars. The differently expressed pathway between Chinese and Japanese vinegar was tryptophan metabolism, while the main difference within Chinese vinegars was aminoacyl-tRNA biosynthesis metabolism. These results not only give insights into the metabolites in famous types of cereal vinegar but also provide valuable knowledge for making vinegar with desirable health characteristics.

Effects of Koumiss on Intestinal Immune Modulation in Immunosuppressed Rats

Koumiss is a traditional fermented dairy product with health and medicinal benefits. It is very popular in the Inner Mongolia Autonomous Region of China. The results of relevant studies have shown that koumiss can regulate the gastrointestinal environment, improve the absorption of nutrients, improve the body's intolerance to lactose, enhance the body's immunity, prevent scurvy and atherosclerosis, and aid in the treatment of tuberculosis. However, there are no systematic reports on the effects of koumiss on immunity. In this study, we aimed to decipher the effects of koumiss on intestinal immune modulation. We used liquid chromatography-tandem mass spectrometry (LC-MS) analysis to determine the composition of Koumiss. Using Compound Discoverer software, we compared the mass spectrometry data with the compound information in the online databases ChemSpider and mzCloud to intelligently identify the main chemical components of koumiss. Additionally, we used Mass Frontier small molecule fragmentation library^TM to determine the structure of fragment ions. A total of 21 components were identified, which clarified the chemical basis of koumiss. These 21 compounds were then used to perform molecular docking with immune-related targets, such as TNF, IL2, IL10, etc. The results indicated good docking activity between most of the compounds and the targets. Then, an immunosuppressive rat model was used to determine the therapeutic effect of koumiss. The results of this study showed that koumiss could, to a certain extent, correct the atrophy of the thymus and spleen in immunosuppressed model rats. The number of leukocytes, lymphocytes, and the CD4⁺/CD8⁺ ratio of peripheral blood lymphocytes was also increased. In addition, it could effectively improve the structure of the small intestinal mucosa, which shows that koumiss has a positive effect on the intestinal immune function of immunosuppressed rats. These findings provide an experimental basis for the development and utilization of koumiss as a therapeutic product.

The Application of FTIR Spectroscopy and Chemometrics for the Authentication Analysis of Horse Milk

Expensive milk such as horse's milk (HM) may be the target of adulteration by other milk such as goat's milk (GM) and cow's milk (CM). FTIR spectroscopy in combination with chemometrics of linear discriminant analysis (LDA) and multivariate calibrations of partial least square regression (PLSR) and principal component regression (PCR) was used for authentication of HM from GM and CM. Milk was directly subjected to attenuated total reflectance (ATR) spectral measurement at midinfrared regions (4000-650 cm-1). Results showed that LDA could make clear discrimination between HM and HM adulterated with CM and GM without any misclassification observed. PLSR using 2nd derivative spectra at 3200-2800 and 1300-1000 cm-1 provided the best model for the relationship between actual values of GM and FTIR predicted values than PCR. At this condition, R 2 values for calibration and validation models obtained were 0.9995 and 0.9612 with RMSEC and RMSEP values of 0.0093 and 0.0794. PLSR using normal FTIR spectra at 3800-3000 and 1500-1000 cm-1 offered R 2 for the relationship between actual values of CM and FTIR predicted values of >0.99 in calibration and validation models with low errors of RMSEC of 0.0164 and RMSEP of 0.0336 during authentication of HM from CM. Therefore, FTIR spectroscopy in combination with LDA and PLSR is an effective method for authentication of HM from GM and CM.

Comparative metabolomics and microbial communities associated network analysis of black and white horse- sourced koumiss

The quality and formation of bioactive components in fermented koumiss are based on the complex metabolism of the microbial community. In the present study, changes in the bioactive metabolites and microbial communities in black and white horse-sourced koumiss were evaluated during the fermentation process. 74 and 69 differential metabolites were formed when BLM and WHM were fermentated into koumiss. Lactobacillus and Dekkera grew rapidly and became the dominant genera in the koumiss. Bioactive compounds (e.g., adenine, d-proline) were significantly enhanced after natural fermentation and were positively correlated with Lactobacillus, Dekkera and Acetobacter. The microbial metabolic network showed that Lactobacillus and Dekkera were the functional core microbiota and played significant roles in the formation of bioactive compounds, followed by Acetobacter, Streptococcus and Leuconostoc. The current study results provide new insight into the formation of bioactive components in koumiss, which is useful for directionally isolating functional microorganisms suitable for koumiss fermentation.

Effect of Coix Seed Extracts on Growth and Metabolism of Limosilactobacillus reuteri

Coix seed (Coix lachryma-jobi L.) is an important nourishing food and traditional Chinese medicine. The role of their bioactive constituents in physiology and pharmacology has received considerable scientific attention. However, very little is known about the role of coix seed bioactive components in the growth of Limosilactobacillus reuteri (L. reuteri). This study aimed to evaluate the effects of coix seed extract (CSE) on the growth, acidifying activity, and metabolism of L. reuteri. The results showed that CSE can increase the growth and acidifying activity of L. reuteri compared with the control group. During the stationary phase, the viable bacteria in the medium supplemented with coix seed oil (CSO, 13.72 Log₁₀ CFU/mL), coix polysaccharide (CPO, 12.24 Log₁₀ CFU/mL), and coix protein (CPR, 11.91 Log₁₀ CFU/mL) were significantly higher (p < 0.05) than the control group (MRS, 9.16 Log₁₀ CFU/mL). CSE also enhanced the biosynthesis of lactic acid and acetic acid of L. reuteri. Untargeted metabolomics results indicated that the carbohydrate metabolism, amino acid metabolism, and nucleotide metabolism activities of L. reuteri were increased after adding CSE. Furthermore, CSE increased the accumulation of bioactive metabolites, such as phenyl lactic acid, vitamins, and biotin. Overall, CSE may have prebiotic potential and can be used to culture L. reuteri with high viable bacteria.

Impact of lactic acid bacteria and their metabolites on the techno-functional properties and health benefits of fermented dairy products

After conversion of lactose to lactic acid, several biochemical changes occur such as enhanced protein digestibility, fatty acids release, and production of bioactive compounds etc. during the fermentation process that brings nutritional and quality improvement in the fermented dairy products (FDP). A diverse range of lactic acid bacteria (LAB) is being utilized for the development of FDP with specific desirable techno-functional attributes. This review contributes to the knowledge of basic pathways and changes during fermentation process and the current research on techniques used for identification and quantification of metabolites. The focus of this article is mainly on the metabolites responsible for maintaining the desired attributes and health benefits of FDP as well as their characterization from raw milk. LAB genera including Lactobacillus, Streptococcus, Leuconostoc, Pediococcus and Lactococcus are involved in the fermentation of milk and milk products. LAB species accrue these benefits and desirable properties of FDP producing the bioactive compounds and metabolites using homo-fermentative and heterofermentative pathways. Generation of metabolites vary with incubation and other processing conditions and are analyzed and quantified using highly advanced and sophisticated instrumentation including nuclear magnetic resonance, mass-spectrometry based techniques. Health benefits of FDP are mainly possible due to the biological roles of such metabolites that also cause technological improvements desired by dairy manufacturers and consumers.

A novel strategy for D-psicose and lipase co-production using a co-culture system of engineered Bacillus subtilis and Escherichia coli and bioprocess analysis using metabolomics

To develop an economically feasible fermentation process, this study designed a novel bioprocess based on the co-culture of engineered Bacillus subtilis and Escherichia coli for the co-production of extracellular D-psicose and intracellular lipase. After optimizing the co-culture bioprocess, 11.70 g/L of D-psicose along with 16.03 U/mg of lipase was obtained; the glucose and fructose were completely utilized. Hence, the conversion rate of D-psicose reached 69.54%. Compared with mono-culture, lipase activity increased by 58.24%, and D-psicose production increased by 7.08%. In addition, the co-culture bioprocess was explored through metabolomics analysis, which included 168 carboxylic acids and derivatives, 70 organooxygen compounds, 34 diazines, 32 pyridines and derivatives, 30 benzene and substituted derivatives, and other compounds. It also could be found that the relative abundance of differential metabolites in the co-culture system was significantly higher than that in the mono-culture system. Pathway analysis revealed that, tryptophan metabolism and β-alanine metabolism had the highest correlation and played an important role in the co-culture system; among them, tryptophan metabolism regulates protein synthesis and β-alanine metabolism, which is related to the formation of metabolic by-products. These results confirm that the co-cultivation of B. subtilis and E. coli can provide a novel idea for D-psicose and lipase biorefinery, and are beneficial for the discovery of valuable secondary metabolites such as turanose and morusin.

Integrated metabolomics and lipidomics profiling reveals beneficial changes in sensory quality of brown fermented goat milk

Fermentation and thermal processing can improve the sensory properties of foods. Chemical composition of fermented brown goat milk was investigated using an integrated lipomics and metabonomic method while the effects of changes in chemical composition on sensory quality were also explored. After fermentation, organic acid, peptide and medium- and long-chain fatty acid contents in brown goat milk samples increased significantly. A total of 108 metabolites and 174 lipids related to sensory quality were identified. Heterocyclic compounds, as intermediates of Maillard reaction, modified colour, taste, and aroma, while changes in triglyceride content reduced the impact of off-odour, greatly improving sensory quality of fermented brown goat milk. This study provided new approaches for examining goat milk sensory quality and insights into how these can be modified to further diversify dairy products on the market.

Gas chromatography-mass spectrometry based metabolomic approach to investigate the changes in goat milk yoghurt during storage

The overall goal was to utilize a gas chromatography spectrometry based metabolomics approach to investigate the metabolite changes in goat milk yoghurt during storage. A total of 129 metabolites were identified in goat milk yoghurt during 28 days refrigerated storage. Among 129, 39 metabolites were differentially regulated (p < 0.05) wherein 22 were upregulated (UR) and 17 were downregulated (DR). 17 (9 UR, 8 DR), 20 (11 UR, 9 DR) and 2 (both UR) differential metabolites were identified during storage period of 0-14, 14-28, and 0-28 days, respectively. Metabolic pathway analysis revealed that aminoacyl-tRNA biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis and phenylalanine metabolism altered during 0-14 days storage; while fatty acid biosynthesis, and propanoate metabolism altered during 14-28 days of storage. Metabolite-gene interaction analysis identified genes regulated by differentially expressed metabolites. Functional annotation of interacted genes in corroboration with that of KEGG pathway analysis provided the probable mechanisms that altered the metabolites during storage. These findings reveal comprehensive insights into the metabolite alterations during storage. This research provides practical information for developing goat milk yoghurt with enhanced bio-activities and would aid in future investigations into the nutritional research and isolation of functional compounds.