High resolution mass approach to characterize refrigerated black truffles stored under different storage atmospheres

Changes in Black Truffle (Tuber melanosporum) Aroma during Storage under Different Conditions

The enticing aroma of truffles is a key factor for their culinary value. Although all truffle species tend to be pricy, the most intensely aromatic species are the most sought after. Research into the aroma of truffles encompasses various disciplines including chemistry, biology, and sensory science. This study focusses on the chemical composition of the aroma of black truffles (Tuber melanosporum) and the changes occurring under different storage conditions. For this, truffle samples were stored under different treatments, at different temperatures, and measured over a total storage time of 12 days. Measurements of the truffle aroma profiles were taken with SPME/GC-MS at regular intervals. To handle the ample data collected, a systematic approach utilizing multivariate data analysis techniques was taken. This approach led to a vast amount of data which we made publicly available for future exploration. Results reveal the complexity of aroma changes, with 695 compounds identified, highlighting the need for a comprehensive understanding. Principal component analyses offer initial insights into truffle composition, while individual compounds may serve as markers for age (formic acid, 1-methylpropyl ester), freshness (2-Methyl-1-propanal; 1-(methylthio)-propane), freezing (tetrahydrofuran), salt treatment (1-chloropentane), or heat exposure (4-hydroxy-3-methyl-2-butanone). This research suggests that heat treatment or salt contact significantly affects truffle aroma, while freezing and cutting have less pronounced effects in comparison. The enrichment of compounds showing significant changes during storage was investigated with a metabolomic pathway analysis. The involvement of some of the enriched compounds on the pyruvate/glycolysis and sulfur pathways was shown.

Transcriptome and metabolome analysis reveals stage-specific metabolite accumulation during maturity of Chinese black truffle Tuber indicum

Tuber indicum is the most economically important member of Tuber, with the highest production and widest distribution in China. However, the overexploitation of immature ascocarps not only has driven wild resources of the species toward extinction, but also has caused enconomic losses and a decline in the reputation of T.indicum quality. In this study, stage-specific metabolites of T. indicum in relation to nutritional quality and the mechanism of their accumulations were explored by transcriptome and metabolome analysis at five harvest times, representing four maturation stages. A total of 663 compounds were identified in T. indicum ascocarps by a widely targeted metabolomic approach. Lipid compounds are the most prominent metabolites (18%) in our samples and also are higher accumulation at the immature stage than at mature stage, representing 30.16% differential accumulated metabolites in this stage. Levels of some of the amino acids, such as S-(methyl) glutathione, S-adenosylmethionine, which are known truffle aroma precursors, were increased at the mature stage. The gene expression level related to the biosynthesis of volatile organic compounds were verified by qPCR. This study contributes to the preliminary understanding of metabolites variations in T. indicum ascocarps during maturity for quality evaluation and truffle biology.

Different maturities drive proteomic and metabolomic changes in Chinese black truffle

Chinese black truffle (Tuber indicum) is rich in nutrition. However, commercial interests lead to the aroma components and nutrients of T. indicum being greatly affected by overexploitation without consideration of their maturity. This study investigated the proteomic and metabolomic profiles of truffle fruiting bodies at different maturities using a meta-proteomic approach. Among the 3007 identified proteins, the most up-expressed protein in the mature ascocarps was involved in the peptidyl-diphthamide biosynthetic process, while thiamine metabolism was the most differentially expressed pathway. Furthermore, a total of 54 metabolites identified upon LC-MS differed significantly, with 30 being up-expressed in the mature ascocarps, including organic acids, carnitine substances and polysaccharides. Additionally, the ash, protein, fat, crude fiber and total sugar contents were all higher in the mature ascocarps. Overall, our findings reveal that mature truffles have a higher nutritional value, providing a basis for further exploring protein functionality of T. indicum at different maturities.

Anti-angiogenic and anti-inflammatory activity of the summer truffle (Tuber aestivum Vittad.) extracts and a correlation with the chemical constituents identified therein

Fungi are a huge source of unexplored bioactive compounds. Owing to their biological activities, several fungi have shown commercial application in the health industry. Tuber aestivum Vittad. is one such edible fungi with an immense scope for practical biological applications. In the present study, the anti-angiogenic activity of petroleum ether and ethanol extracts of T. aestivum was investigated using the chick chorioallantoic membrane assay and compared to the positive controls silibinin and lenalidomide. Both the extracts showed a dose-dependent anti-angiogenic response. The extracts were also assessed for their anti-inflammatory potential by lipoxygenase-inhibition assay. The IC₅₀ values for LOX inhibition assay, computed by the Boltzmann plot, were 368.5, 147.3 and 40.2 µg/mL, for the petroleum ether extract, ethanol extract, and the positive control ascorbic acid, respectively. The ethanol extract of T. aestivum showed superior anti-angiogenic and anti-inflammatory activity than the petroleum ether extract. Compositional investigation of the extracts by GC-MS revealed the presence of various bioactive compounds. The compounds were correlated to their anti-angiogenic and anti-inflammatory activity based on a meticulous literature search.

Hypobaric Packaging Prolongs the Shelf Life of Refrigerated Black Truffles (Tuber melanosporum)

Black truffle (Tuber melanosporum Vitt.) is a fine agro-food product known for its unique aroma and very limited shelf life (maximum of 5-7 days, room temperature). Hypobaric packaging at 30 kPa, a mix of 1% O₂/99% N₂, and 40% CO₂/60% N₂ were studied to prolong the shelf life of black truffle at 4 °C in sealed polypropylene vessels, compared to normal atmosphere. Epiphytic microbial population, firmness, weight loss, CO₂ formation, and sensory properties were monitored weekly up to 35 days of storage and were related to the volatile profile. Principal components analysis revealed good correlation between the storage time and the decrease of firmness, and the increase of the microbial count and CO₂ production. Only truffles stored under hypobaric conditions showed an acceptable quality after 14 days storage. Hypobaric packaging is a cheap strategy to prevent the swelling of vessels caused by respiration and can reduce the deviation from the high-quality level of the fresh product from one to at least two weeks.

Non-Extractable Polyphenols from Food By-Products: Current Knowledge on Recovery, Characterisation, and Potential Applications

Non-extractable polyphenols (NEPs), or bound polyphenols, are a significant fraction of polyphenols that are retained in the extraction residues after conventional aqueous organic solvent extraction. They include both high molecular weight polymeric polyphenols and low molecular weight phenolics attached to macromolecules. Current knowledge proved that these bioactive compounds possess high antioxidant, antidiabetic, and other biological activities. Plant-based food by-products, such as peels, pomace, and seeds, possess high amount of NEPs. The recovery of these valuable compounds is considered an effective way to recycle food by-products and mitigate pollution, bad manufacturing practice, and economic loss caused by the residues management. The current challenge to valorise NEPs from plant-based by-products is to increase the extraction efficiency with proper techniques, choose appropriate characterising methods, and explore potential functions to use in some products. Based on this scenario, the present review aims to summarise the extraction procedure and technologies applied to recover NEPs from plant-based by-products. Furthermore, it also describes the main techniques used for the characterisation of NEPs and outlines their potential food, pharmaceutical, nutraceutical, and cosmetic applications.

Multi-platform metabolomic approach to discriminate ripening markers of black truffles (Tuber melanosporum)

Black truffle is characterized by a black ascocarp and white veins. This hypogeous fruit body is known for its aroma. Understanding metabolic variation during ripening can shed light on truffle biology. In this work, the comprehensive polar metabolome and the volatile organic compounds of T. melanosporum were studied at different ripening stages by means of a metabolomic approach using GC-MS. Multivariate statistical data analysis indicated that the metabolic profile changed during ripening and that the metabolites that mostly discriminated truffles in the early ripening stages belonged to the classes of carbohydrates, while free fatty acids and amino acids, among which precursors of VOCs, characterized the late stages of ripening. Principal component analysis of the volatilome indicated that dimethylsulfide and dimethyldisulfide characterized most of the samples collected in December-January, while 1-octen-3-ol samples collected in February-March.

LC-MS-Based Metabolomic Approach Revealed the Significantly Different Metabolic Profiles of Five Commercial Truffle Species

Truffles are ascomycetous ectomycorrhizal fungi that have elevated status in the culinary field due to their unique aroma and taste as well as their nutritional value and potential biological activities. Tuber melanosporum, T. indicum, T. panzhihuanense, T. sinoaestivum, and T. pseudoexcavatum are five commercial truffle species mainly distributed in Europe or China. In this study, an untargeted metabolomics technology based on an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was applied to analyze the metabolic profiles and variations among these five truffle species. In our results, a total of 2376 metabolites were identified under positive ion mode, of which 1282 had significantly differential amounts and covered 110 pathways or metabolisms. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) revealed a clear separation from each of these five truffles, indicating a significantly different metabolic profile among them, with the biggest difference between T. melanosporum and the other four truffles. The differential metabolites covered various chemical categories, and a detailed analysis was performed for nine metabolic categories, including amino acids, saccharides and nucleosides, organic acids, alkaloids, flavonoids, carnitines, phenols and alcohols, esters, and sulfur compounds. For each of the nine categories, most of metabolites predominantly accumulated in T. melanosporum compared with the other four truffles. Meanwhile, there were significant differences of the average ion intensity in each category among the five truffles, e.g., higher amounts of amino acids was detected in T. panzhihuanense and T. pseudoexcavatum; T. indicum contained significantly more carnitines, while there were more alkaloids in T. melanosporum. Additionally, some metabolites with biological activities were discussed for each category, such as acetyl-L-carnitine, adenine, neobavaisoflavone, and anandamide. Generally, this study may provide the valuable information regarding the variation of the metabolic composition of these five commercial truffle species, and the biological significance of these metabolites was uncovered to explore the metabolic mechanisms of truffles, which would be helpful for further research on the compounds and potential biological functions in truffles that have not yet been investigated.

Distribution of crown hexameric procyanidin and its tetrameric and pentameric congeners in red and white wines

Nineteen red and white wines were screened for the presence of crown (oligomeric cyclic) procyanidins with 4, 5 or 6 (epi)catechin monomers by means of HPLC-HRMS/MS. For the first time, the distribution of crown procyanidins in wines obtained from several grape varieties was discussed including white wines. The ratios between crown and non-cyclic procyanidins allowed the samples to be discriminated by grape variety. The crown hexameric procyanidin was present in the red wines and absent in the white wines analyzed. The crown pentameric procyanidin was absent in Gewürztraminer. In Chardonnay and Sauvignon Blanc, the pentameric procyanidin was present only in the cyclic form. Less oxidized high quality red wines displayed a higher fraction of crown to non-cyclic procyanidins than the other wines. These compounds are proposed as potential complement markers of wine quality and authenticity.

Manganese affects the growth and metabolism of Ganoderma lucidum based on LC-MS analysis

Background

As a metal-enriched edible fungus, Ganoderma lucidum is capable of adsorbing manganese effectively. And the manganese ion is demonstrated to play an important role in the synthesis of manganese peroxidase (Mnp) and other physiological activities during G. lucidum growth. Recently, the influence of manganese on the metabolites of G. lucidum fruiting bodies can be revealed through metabonomics technique.

Methods

In this study, we uncovered the changes between the control and 200 mg/kg Mn-treated fruiting bodies with liquid chromatography coupled to mass spectrometry (LC-MS).

Results

The mycelial growth rate, dry yield, Mnp activity , total polysaccharide content, triterpenoid content, and total manganese content in the mature fruiting bodies of G. lucidum changed between the control and different Mn-treated groups. Based on LC-MS method, a total of 16 significantly different metabolites were obtained and identified, among which, five presented significantly down-regulated and 11 up-regulated in Mn-treated samples. The metabolites chavicol and palmitoylethanolamide were particularly significantly up-regulated, and were found the strong promotion relationship. Dependent on the MetPA database, four KEGG pathways were detected and glycerophospholipid metabolism was most impacted, in which, choline was involved in.

Discussion

The added manganese ion in the substrate enhanced Mnp activities, and consequently promoted the mycelial growth, yield , metabolites in the fruiting bodies including triterpenoids, total manganese, chavicol, etc. Our finding can provide a theoretical reference to regulation of manganese on the physiological metabolism of G. lucidum.

Selective binding of potassium and calcium ions to novel cyclic proanthocyanidins in wine by HPLC-HRMS

RATIONALE

Cyclic B-type (referred also as crown) proanthocyanidins were recently identified in wines. An HPLC-HRMS/MS method was applied to study the binding of cyclic and non-cyclic PAC to potassium and calcium ions, which affect the chemico-physical stability of wines. Different binding affinities suggest that cyclic and non-cyclic analogues, despite the equal number of monomer units, influence the colloidal stability of wine and are related to the grape variety or winemaking conditions.

METHODS

Nineteen red and white wines were analysed by HPLC high resolution tandem mass spectrometry with positive electrospray ionization to investigate the distribution of novel cyclic proanthocyanidins and their calcium, potassium and sodium adducts. Principal Component Analysis was used to study the distribution of the wines and the relationships among proanthocyanidins with and without cation complexes.

RESULTS

A dependence on specific isomers (and conformations) was found for the non-cyclic procyanidin (PC) trimer whereas the cyclic tetrameric PAC were shown to bind better to potassium than their non-cyclic analogues. The binding to these metals appeared to be influenced not only be the number of monomer units but also by the conformation assumed by the molecules. Statistical analysis evidenced that the adducts distribution in different wines is less influenced by the grape variety used for winemaking than their associated [M+H]+ species studied earlier.

CONCLUSIONS

Wines from 19 grape varieties were investigated in order to identify potassium and calcium complexes of non- and cyclic B-type proanthocyanidins that were recently discovered. The results showed a dependence of the distribution of metal complexes according to the cyclic or non cyclic geometry of proanthocyanidins. The multivariate analysis of the mass spectrometric results showed a relationship with the grape variety, however not so straightforward as evidenced for the non-complexed species.

Oak wood extracts as natural antioxidants to increase shelf life of raw pork patties in modified atmosphere packaging

The use of antioxidants and refrigeration storage in modified atmosphere packaging, MAP, are the main strategies to slow down the oxidative and microbial deterioration of fresh meat. Synthetic antioxidants are commonly used for this purpose, however due to their controversial health effects, natural alternatives for their replacement are being looked for. The main aim of this work is the evaluation of pressurised aqueous extracts from oak wood as natural preservative of pork patties. The effect of different amounts of oak wood extracts (0.05, 0.5 and 1.0%) on the self-life of pork patties packed in MAP in refrigeration during 12 days were studied in comparison with the use of sodium ascorbate as synthetic preservative. Samples treated with oak wood extracts showed lower lipid oxidation, higher antioxidant capacity and an inhibitory effect on the enterobacteria growth. Furthermore, the addition of oak wood extracts resulted in a dramatically decrease of the volatile compounds coming from the lipid oxidation reactions. On the other hand, it is noteworthy that the use of oak wood extracts modified sensorial characteristics. Intensity colour was higher and new sensorial features such as oak wood and sweet spices appeared which were well appreciated.