Untargeted metabolic footprinting reveals key differences between fermented brown milk and fermented milk metabolomes

Metabolomics study on fermentation of Lactiplantibacillus plantarum ST-III with food grade proliferators in milk

Milk is a naturally complex medium that is suitable for the growth of most lactic acid bacteria. Unfortunately, Lactiplantibacillus plantarum ST-III grow poorly in milk without supplementation. To solve this problem, we use fresh pineapple and mung beans juice to develop an edible proliferator for L. plantarum ST-III. Our comparative analysis of metabolomics changes before and after fermentation reveals that amino acids and dipeptides are the most consumed compounds, with other substances including nucleotides and vitamins, implying the mechanism of proliferation. Combining the KEGG metabolic pathway analysis, substances that may promote the growth of L. plantarum ST-III in milk were screened. To explore which component of the proliferator is required for L. plantarum ST-III cultivate, we supplemented with several combinations of molecules aforementioned in milk. The simulation addition experiment results of L. plantarum ST-III in milk show that if any additions are missing, the concentration of viable bacteria is lower. Only when it contains all additives can the highest concentration of viable bacteria be obtained. Compared with the control, the fold change of the viable bacteria is about 32. Thus, it proves that milk primarily lacked available amino acids, dipeptides, uracil, xanthine, nicotinamide, and manganese for the growth of L. plantarum ST-III.

Comparison of the targeted metabolomics and nutritional quality indices of the probiotic cheese enriched with microalgae

The objective of this study is to evaluate the influence of mixed L. acidophilus LA-5 and enrichment with microalgae (C. vulgaris and A. platensis) on metabolomic formation in a brined cheese matrix. Microbiological, compositional, and metabolomic characterization were investigated during the ripening. It was found that the nutritional quality indices of the samples were based on amino acid and fatty acid characterization. Fifty-six metabolomics including fatty acids, amino acids, organic acids, minerals, and vitamins were detected using the HPLC-DAD, GC-MS, and ICP-OES-based methods. The results indicated that the enrichment with probiotic strain and microalgae led to an increase in the nutritional quality indices such as EAAI, NI, BV, MUFA/SFA, h/H, and DFA. The chemometric analysis (e.g. HCA and PCA) presented the variance between the cheese samples based on their attributes. The identification of cheese metabolomics throughout the ripening could be used for a better understanding of the functional ingredients-cheese matrix relationships and as a directive approach for novel dairy products in other metabolomic-related studies.

Methods for detection and quantification of gelatin from different sources

Gelatin is a water-soluble protein obtained from the collagen of various animal origins (porcine, bovine, fish, donkey, horse, and deer hide) and has diverse applications in the food, pharmaceutical, and cosmetics industries. Porcine and bovine gelatins are extensively used in food and non-food products; however, their acceptance is limited due to religious prohibitions, whereas fish gelatin is accepted in all religions. In Southeast Asia, especially in China, gelatin obtained from donkey and deer skins is used in medicines. However, both sources suffer from adulteration (mixing different sources of gelatin) due to their limited availability and high cost. Unclear labeling and limited information about actual gelatin sources in gelatin-containing products cause serious concern among societies for halal and fraud authentication of gelatin sources. Therefore, authenticating gelatin sources in gelatin-based products is challenging due to close similarities between the composition differences and degradation of DNA and protein biomarkers in processed gelatin. Thus, different methods have been proposed to identify and quantify different gelatin sources in pharmaceutical and food products. To the best of our knowledge, this systematic and comprehensive review highlights different authentication techniques and their limitations in gelatin detection and quantification in various commercial products. This review also describes halal authentication and adulteration prevention strategies of various gelatin sources, mainly focussing on research gaps, challenges, and future directions in this research area.

The probiotic fermented milk of Lacticaseibacillus paracasei JY062 and Lactobacillus gasseri JM1 alleviates constipation via improving gastrointestinal motility and gut microbiota

Constipation is directly related to the intestinal microenvironment, in which the promotion of gastrointestinal (GI) motility and improvement of gut microbiota distribution are important for alleviating symptoms. Herein, after the intervention of probiotic fermented milk (FMMIX) containing Lacticaseibacillus paracasei JY062 and Lactobacillus gasseri JM1 for 14 d in Kunming mice with loperamide-induced constipation, the results indicated that FMMIX significantly increased the secretion of serum motilin, gastrin and 5-hydroxytryptamine, as well as decreased the secretion of peptide YY, vasoactive intestinal peptide, and nitric oxide in mice. As determined by immunohistochemical analysis, FMMIX promoted an augmentation in the quantity of Cajal interstitial cells. In addition, the mRNA and protein expression of c-kit and stem cell factor (SCF) were upregulated to facilitate intestinal motility. High-throughput sequencing and gas chromatography techniques revealed that FMMIX led to an increase in the relative abundance of beneficial bacteria (Lactobacillus, Oscillospira, Ruminococcus, Coprococcus, and Akkermansia), reduced the presence of harmful bacteria (Prevotella), and resulted in elevated levels of short-chain fatty acids (SCFA) with a superior improvement compared with unfermented milk. Untargeted metabolomics revealed significant upregulation of functional metabolites such as l-pipecolinic acid, dl-phenylalanine, and naringenin in FMMIX, presumably playing a potential role in constipation relief. Overall, our results showed that FMMIX had the potential to alleviate constipation symptoms in mice by improving the secretion of serum GI regulatory peptides and neurotransmitters, increasing the expression of c-kit and SCF proteins, and modulating the gut microbiota structure and SCFA levels, and may be associated with an increase in these functional metabolites. This suggested that FMMIX could be a promising adjunctive strategy for managing constipation symptoms and could contribute to the development of functional foods aimed at improving gut health.

The cross-linking ability of dialdo-galactose in food processing condition

Cross-linking is a popular strategy to tailor the mechanical profile of foods and materials. Dialdo-galactose (DAG) is a hetero-sugar bearing two aldehyde groups that could potentially cross-link amino-group rich systems. In this study, we proved even in undesirable Maillard reaction condition, DAG is a very reactive Maillard substrate that could effectively cross-link all the tested foods, enhance their mechanical strength, and generate brown pigments during cross-linking. In particular, DAG treated sea cucumber exhibited good stability against heat-induced deterioration. In addition, DAG treated collagen sausage casing was more elastic and flexible then glutaraldehyde (GA) treated ones. DAG also outperformed GA in generating stronger chitosan hydrogels with higher G', and the DAG cross-linked chitosan film was more robust against acid-catalyzed decompositions. These results have not only confirmed DAG's cross-linking ability in food processing condition, but also provided useful information for the development of new food cross-linking agents based on oxidized saccharides.

Untargeted Metabolomics and Physicochemical Analysis Revealed the Quality Formation Mechanism in Fermented Milk Inoculated with Lactobacillus brevis and Kluyveromyces marxianus Isolated from Traditional Fermented Milk

Traditional fermented milk from the western Sichuan plateau of China has a unique flavor and rich microbial diversity. This study explored the quality formation mechanism in fermented milk inoculated with Lactobacillus brevis NZ4 and Kluyveromyces marxianus SY11 (MFM), the dominant microorganisms isolated from traditional dairy products in western nan. The results indicated that MFM displayed better overall quality than the milk fermented with L. brevis NZ4 (LFM) and K. marxianus SY11 (KFM), respectively. MFM exhibited good sensory quality, more organic acid types, more free amino acids and esters, and moderate acidity and ethanol concentrations. Non-targeted metabolomics showed a total of 885 metabolites annotated in the samples, representing 204 differential metabolites between MFM and LFM and 163 between MFM and KFM. MFM displayed higher levels of N-acetyl-L-glutamic acid, cysteinyl serine, glaucarubin, and other substances. The differential metabolites were mainly enriched in pathways such as glycerophospholipid metabolism, arginine biosynthesis, and beta-alanine metabolism. This study speculated that L. brevis affected K. marxianus growth via its metabolites, while the mixed fermentation of these strains significantly changed the metabolism pathway of flavor-related substances, especially glycerophospholipid metabolism. Furthermore, mixed fermentation modified the flavor and quality of fermented milk by affecting cell growth and metabolic pathways.

Exopolysaccharide-Producing Lacticaseibacillus rhamnosus Space Mutant Improves the Techno-Functional Characteristics of Fermented Cow and Goat Milks

Lacticaseibacillus rhamnosus Probio-M9 (Probio-M9) is increasingly used as a co-fermentation culture in fermented milk production. Recently, a capsular polysaccharide (CPS)- and exopolysaccharide (EPS)-producing mutant of Probio-M9, HG-R7970-3, was generated by space mutagenesis. This study compared the performance of cow and goat milk fermentation between the non-CPS/-EPS-producing parental strain (Probio-M9) and the CPS/EPS producer (HG-R7970-3), and the stability of products fermented by the two bacteria. Our results showed that using HG-R7970-3 as the fermentative culture could improve the probiotic viable counts, physico-chemical, texture, and rheological properties in both cow and goat milk fermentation. Substantial differences were also observed in the metabolomics profiles between fermented cow and goat milks produced by the two bacteria. Comparing with Probio-M9-fermented cow and goat milks, those fermented by HG-R7970-3 were enriched in a number of flavor compounds and potential functional components, particularly acids, esters, peptides, and intermediate metabolites. Moreover, HG-R7970-3 could improve the post-fermentation flavor retention capacity. These new and added features are of potential to improve the techno-functional qualities of conventional fermented milks produced by Probio-M9, and these differences are likely imparted by the acquired CPS-/EPS-producing ability of the mutant. It merits further investigation into the sensory quality and in vivo function of HG-R7970-3-fermented milks.

Sensory attributes and functional properties of maillard reaction products derived from the crassosotrea gigas (Ostrea rivularis gould) enzymatic hydrolysate and xylose system

To improve the flavor of Ostrea rivularis Gould, enzymatic hydrolysis was conducted and xylose-OEH Maillard reaction products were prepared. Then, their physicochemical properties and metabolites were determined by UHPLC-MS-MS, and volatile compounds were determined by GC-MS to investigate the changes. The results showed that His, Gln, Lys, Asp, and Cys were the major amino acids consumed. After being heated at 120 °C for up to 150 min, the DPPH (2,2-Diphenyl-1-picrylhydrazyl) was 85.32 ± 1.35% and the reducing capacity was 1.28 ± 0.12. Both were the highest in the groups. Additionally, 45 volatile compounds, including 2-ethyl-5-methyl-pyrazine and 2-ethyl-3,5-dimethyl-pyrazine, and 678 compounds were identified. We also found that 18 metabolites with significant differences (VIP ≥2) were differential metabolites, which involved lipid oxides and amino acid derivatives. The content of lipids favored the regulation of Maillard products and affected the lower threshold of the flavor of aldehydes, which contributed to the flavor and antioxidant activity. These results suggested the potential of xylose-OEH MRPs as a natural antioxidant for further processing oysters.

Brown goat yogurt: Metabolomics, peptidomics, and sensory changes during production

Brown goat milk products have gained popularity for their unique taste and flavor. The emergence of chain-reversal phenomenon makes the design and development of goat milk products gradually tend to a consumer-oriented model. However, the precise mechanism of how browning and fermentation process causes characteristics is not clear. In an effort to understand how the treatments potentially lead to certain metabolite profile changes in goat milk, comprehensive, quantitative metabolomics and peptidomics analysis of goat milk samples after browning and fermentation were undertaken. An intelligent hybrid z-score standardization-principal components algorithm-multimodal denoizing autoencoder was used for feature fusion and hidden layer fusion in high-dimensional variable space. The fermentation process significantly improved the flavor of brown goat yogurt through the tricarboxylic acid-urea-glycolysis composite pathway. Bitter peptides HPFLEWAR, PPGLPDKY, and PPPPPKK have strong interactions with both putative dipeptidyl peptidase IV and angiotensin-converting enzyme, proving that brown goat yogurt can be considered as effective provider of potential putative dipeptidyl peptidase IV and angiotensin-converting enzyme inhibitors. The level of health-promoting bioactive components and sensory contributed to consumer selection. The proposed multimodal data integrative analysis platform was applicable to explain the effect of the dynamic changes of metabolites and peptides on consumer preferences.

Evaluating the effect of lactic acid bacteria fermentation on quality, aroma, and metabolites of chickpea milk

Legumes are an attractive choice for developing new products since their health benefits. Fermentation can effectively improve the quality of soymilk. This study evaluated the impact of Lactobacillus plantarum fermentation on the physicochemical parameters, vitamins, organic acids, aroma substances, and metabolites of chickpea milk. The lactic acid bacteria (LAB) fermentation improved the color, antioxidant properties, total phenolic content, total flavonoid content, lactic acid content, and vitamin B6 content of raw juice. In total, 77 aroma substances were identified in chickpea milk by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME-GC-MS); 43 of the 77 aroma substances increased after the LAB fermentation with a significant decrease in beany flavor content (p < 0.05), improving the flavor of the soymilk product. Also, a total of 218 metabolites were determined in chickpea milk using non-targeted metabolomics techniques, including 51 differentially metabolites (28 up-regulated and 23 down-regulated; p < 0.05). These metabolites participated in multiple metabolic pathways during the LAB fermentation, ultimately improving the functional and antioxidant properties of fermented soymilk. Overall, LAB fermentation can improve the flavor, nutritional, and functional value of chickpea milk accelerating its consumer acceptance and development as an animal milk alternative.