Evaluation of milk photooxidation based on peptidomics.

Photooxidation is one of the main causes of the deterioration of milk quality during processing and marketing. This study aimed to investigate the variation in peptides after photooxidation using peptidomic techniques, and how cow species, oxygen content, and light intensity affect photooxidation. The different peptides were identified and quantified using ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Eighteen milk samples were subjected to light treatment. Seven types of peptides were identified as photooxidation markers. Subsequently, the effects of milk variety, oxygen content, and light intensity on photooxidation were studied, and sensory evaluations were performed. Dairy cow breed, oxygen content, and light intensity all affect photooxidation. Sensory evaluation verified that light and oxygen are necessary for the photooxidation of milk. The peptide m/z+ 529.2783 (LLDEIKEVV), both in different varieties of milk and in different brands of commercially available milk, showed a large variation in multiplicity, and its content was closely related to oxygen and light. This peptide was not produced in the absence of oxygen and light, and its relative content increased with the duration of light exposure. These results suggest that the peptidomics method is an effective tool for distinguishing between normal and photooxidized milk.

Differentiating ultra-high temperature milk and reconstituted milk using an untargeted peptidomic approach with chemometrics.

An untargeted peptide profiling based on ultra-performance liquid chromatography quadrupole time-of flight mass spectrometry with chemometrics was performed to differentiate ultra-high temperature processed milk and reconstituted milk. Thirty-three marker peptides were identified, primarily released from the C- or N-terminal of ß-casein and αs1-casein. These peptides were produced by heating and protease hydrolysis. Additional heating and storage time experiments showed that the level of 18 marker peptides increased with heat load and storage time, whereas 15 peptides were solely influenced by heat load. The peptides from ß-casein showed higher sensitivity to thermal stress compared to those from αs1-casein. Additionally, eight modified peptides of casein were identified as indicators of milk thermal processing. The identified marker peptides can distinguish ultra-high temperature processed milk and reconstituted milk, and are suitable for monitoring heating processes and storage of milk.

Milk lipids characterization in relation to different heat treatments using lipidomics.

Heat treatment is an important processing technique related to milk quality and nutritional value in the dairy industry. In this study, changes in milk lipids in response to different heat treatments were comprehensively characterized using a lipidomic approach. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) were used to identify and quantify 29 classes and 788 different lipids. In general, heat treatment promoted milk lipid hydrolysis and oxidation; in particular, ultra-high temperature (UHT) treatment resulted in more phospholipid hydrolysis than did pasteurization and extended shelf-life (ESL) treatment. Heat treatment resulted in further lipid oxidation reactions and a reduction in the amount of mild oxidation products. Moreover, the levels of lysophospholipids and free fatty acids (including oxidized free fatty acids) can be used to distinguish UHT-treated milk. In turn, oxidized phosphatidylcholine, oxidized phosphatidylethanolamine, ether-linked phosphatidylethanolamine, diacylglycerol, triacylglycerol, and oxidized triacylglycerol can be used to differentiate raw, pasteurized, and ESL milk. These biomarkers can potentially be used in the dairy industry to monitor the degree and method of heat treatment of milk.

Effects of the Oxygen Content and Light Intensity on Milk Photooxidation Using Untargeted Metabolomic Analysis.

Photooxidation is the main cause of milk quality deterioration during processing and transportation. Oxygen and light are responsible for dairy milk photooxidation. The objective of this study was to determine the characteristic metabolites after photooxidation and how they are affected by oxygen exposure and light intensity. Ultra-performance liquid chromatography coupled with triple time-of-flight mass spectrometry and multivariate data analysis were used for the high-throughput evaluation of milk photooxidation. Four products were identified as biomarkers: uric acid, riboflavin, lumichrome, and indole-3-carboxaldehyde. Afterward, the effects of oxygen content and light intensity on the biomarkers were investigated, and a sensory evaluation was performed. Both oxygen exposure and light intensity affected the contents of photooxidation biomarkers in milk samples. The sensory score correlated well with the oxygen content but not with the light intensity. The untargeted metabolomic method was an effective tool to identify biomarkers for milk photooxidation evaluation.

Establishing an untargeted-to-MRM liquid chromatography-mass spectrometry method for discriminating reconstituted milk from ultra-high temperature milk.

The counterfeit use of reconstituted milk to simulate fresh milk in some countries is largely driven by profiteering; hence, establishing a robust market-surveillance method is an important objective. In this study, an untargeted metabolomics approach that uses ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was established to discover biomarkers that can be used to classify UHT and reconstituted milk. Furthermore, 36 positive- and 24 negative-ionization mode features were selected as candidate markers to establish a UPLC-tandem mass spectrometry (UPLC-MS/MS) multiple reaction monitoring (MRM) method. The support vector machine (SVM) method was used to process the responses of the selected potential markers, and 100% classifiability was observed. The marker metabolites could be divided into three categories by hierarchical clustering analysis: peptides, lipids, and nucleic acids. The results suggest that the untargeted-to-MRM metabolomics method is an effective tool for distinguishing between UHT and reconstituted milk.

Endogenous Indole Pyruvate Pathway for Tryptophan Metabolism Mediated by IL4I1.

l-tryptophan (Trp) is widely used in food and feed enforcement to play an important role in biological processes. Various metabolites of Trp perform its potent function. The indole pyruvate pathway is one of the main pathways of Trp metabolism in the gut microbiota, providing numerous indole-derivatives, which can modulate intestinal homeostasis and mucosal immunity by activating the aryl hydrocarbon receptor (AHR) signaling pathway. In this study, we constructed an IL4I1-overexpressed 293T cell line and found that IL4I1 can catalyze Trp to produce indole-3-acetic acid (IAA) and indole-3-carboxaldehyde (IAld). Moreover, both IAA and IAld are accumulated in dendritic cells (DCs) and can stimulate the expression of CYP1A1. Our results demonstrate the existence of the indole pyruvate pathway in host cells with IL4I1 as the key enzyme. The IL4I1-mediated Trp metabolism implies the role of dietary impact on immunity.

The combined use of 1 H and 2D NMR-based metabolomics and chemometrics for non-targeted screening of biomarkers and identification of reconstituted milk.

BACKGROUND: The illegal undeclared addition of reconstituted milk powder to ultra-heat treated (UHT) milk to lower production costs is an example of economically motivated adulteration. This activity not only defrauds consumers but also places honest traders at a disadvantage, which could damage the reputation of milk producers and reduce the integrity of the markets. In this research, a non-targeted analytical strategy that combines proton (1 H) nuclear magnetic resonance (NMR) spectroscopy with a chemometrics data mining tool was developed for the authentication of bovine UHT milk. RESULTS: Unsupervised principal component analysis was used to distinguish UHT and tap-water-reconstituted powdered milk. Partial least squares-discriminant analysis (PLS-DA) with R2 (Y) and Q2 equal to 0.859 and 0.748, respectively, was used to differentiate UHT and reconstituted milk samples. Three compounds were selected as biomarkers to distinguish UHT and reconstituted milk and identified according to the standard NMR-spectra database. Finally, a PLS-DA model was established, according to the characteristic spectral bands, to identify UHT milk and reconstituted milk. CONCLUSION: This procedure demonstrated the feasibility of using non-targeted NMR profiling combined with chemometric analysis to combat mislabeling and fraudulent practices in milk production. © 2019 Society of Chemical Industry.

Effects of low-levels of three hexabromocyclododecane diastereomers on the metabolic profiles of pak choi leaves using high-throughput untargeted metabolomics approach.

The ecological toxicity of hexabromocyclododecane (HBCD) on animals, including fish and mice, has been reported, but its effects in plants, particularly its toxic mechanism, have rarely been investigated. An untargeted metabolomics approach for comprehensive assessment was selected to study the alterations in the metabolic profiles in pak choi leaves induced by exposure to trace-level amounts of HBCD diastereomers over 30 days. A supervised orthogonal partial least-squares-discriminant analysis (OPLS-DA) was performed to investigate differences between the HBCD and control groups. The discriminating metabolites were identified using public databases. The results indicated that the toxicity of the HBCD diastereomers was ordered as γ-HBCD > α-HBCD > ß-HBCD. 13 metabolites were identified as potential biomarkers to discriminate the presence of HBCD toxicity. The lipid, carbohydrate, nucleotide and amino acid metabolic pathways affected were found in accordance with animals and humans, and also HBCD could induce the interference of the secondary metabolite pathways. The system of the stress defences was activated, including signalling pathway, antioxidant defence system, shikimate and phenylpropanoid metabolism. The carbohydrate and amino acid metabolism were disturbed by HBCD intervention, and the lipid, amino acid and secondary metabolite metabolism were regulated for HBCD stress prevention. These results provide insights into the mechanism and degree of HBCD phytotoxicity.

Perfluorinated Compounds in Greenhouse and Open Agricultural Producing Areas of Three Provinces of China: Levels, Sources and Risk Assessment.

Field investigations on perfluoroalkyl acid (PFAA) levels in various environmental matrixes were reported, but there is still a lack of PFAA level data for agricultural environments, especially agricultural producing areas, so we collected soil, irrigation water and agricultural product samples from agricultural producing areas in the provinces of Liaoning, Shandong and Sichuan in China. The background pollution from instruments was removed and C4-C18 PFAAs were detected by LC-MS/MS. The concentrations of PFAAs in the top and deep layers of soil were compared, and the levels of PFAAs in different agricultural environments (greenhouses and open agriculture) were analyzed. We found the order of PFAA levels by province was Shandong > Liaoning > Sichuan. A descending trend of PFAA levels from top to deep soil and open to greenhouse agriculture was shown and perfluorobutanoic acid (PFBA) was considered as a marker for source analysis. Bean vegetables contribute highly to the overall PFAA load in vegetables. A significant correlation was shown between irrigation water and agricultural products. The EDI (estimated daily intake) from vegetables should be of concern in China.

[An experimental study(II) on the inhibition of prostatic hyperplasia by extract of seeds of Brassica alba].

OBJECTIVE: To study the active components and their functionary mechanism of the extract of Brassica alba seeds, which inhibits experimental mice prostatic hyperplasia. METHOD: Prostatic hyperplasia of castrated male mice induced by testosterone propionate, the penetrability of capillary vessel of mice skin induced by histamine and the endermic flesh bud of rat induced by filter paper were used as experimental models. Sinalbin and beta-sitosterol separated from seeds of Brassica alba were used to test the activities. RESULT: Sinalbin and beta-sitosterol(16.0 mg.kg-1.d-1 and 8.0 mg.kg-1.d-1) could significantly inhibit mice prostatic hyperplasia induced by testosterone propionate and activity of serum acid phosphatase(P < 0.01 or P < 0.05), Sinalbin(16.0 mg.kg-1.d-1)could significantly inhibit the hyperplasia of endermic flesh bud in rat induced by filter paper(P < 0.05), beta-sitosterol(16.0 mg.kg-1.d-1 and 8.0 mg.kg-1.d-1) could significantly decrease the penetrability of capillary vessel of mice skin induced by histamine. CONCLUSION: Sinalbin and beta-sitosterol have anti-androgen and anti-inflammation activities.

[An experimental study(I) on the inhibition of prostatic hyperplasia with extract of seeds of Brassica alba].

OBJECTIVE: To study the effective fraction of the extract of seeds of Brassica alba, which inhibits experimental mice prostatic hyperplasia. METHOD: An experimental model of prostatic hyperplasia of castrated male mice induced by testosterone propionate was made. Fractions I, II and III were prepared by extracting the seeds of Brassica alba successively with ether, ethanol and water under reflux. Total extract was prepared by extracting the seeds of Brassica alba with 60% ethanol under reflux. The total extract and the three fractions were used to test the activities. RESULT: Total extract, fractions I and II could not only significantly inhibit mice prostatic hyperplasia induced by testosterone propionate and activity of serum acid phosphatase, but also decrease wet weight of preputial glands, while fraction III is inactive. CONCLUSION: Extract from seeds of Brassica alba can significantly inhibit mice prostatic hyperplasia induced by exterior hormone, possessing an activity of anti-androgen. Fractions I and II show an equivalent activity of total extract, which indicate that these fractions contain active components of seeds of Brassica alba which can inhibit prostatic hyperplasia.