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Hydroxytyrosol (HT) is a phenolic compound of recognized bioactivity that has been described in wines but little is known about its origin. This work demonstrates that yeast involved in wine making, i.e. Saccharomyces cerevisiae strains and the non-Saccharomyces Torulaspora delbrueckii, can synthesise HT, as this compound was identified in the intracellular media of three strains by means of a developed and validated UHPLC–HRMS method with LOQ and LOD of 0.108 and 0.035 ng mL−1 respectively. Controlled fermentations were performed with different varieties of grapes (Corredera, Moscatel, Chardonnay, Palomino fino, Sauvignon Blanc, Vijiriega, and Tempranillo) and synthetic must. The Saccharomyces cerevisiae strain QA23 was the most efficient producer of HT from tested yeasts. On the other hand, the grape variety influences HT wine concentrations. Furthermore, the maximum concentration of HT is reached between the fourth and sixth day of fermentation. This work reveals that yeasts have a great potential for the production of HT.

Derived fruit products such as strawberry-based fermented beverages, increase the fruit's conservation period and offer new alternatives for the non-alcoholic market. The influence of storage time and temperature on the anthocyanin composition, antioxidant activity and colour of a fermented strawberry beverage were studied and indicated that 60-days is the half-life for the tested beverage. Twenty-three anthocyanin compounds were analysed by ultra high-performance liquid chromatography Orbitrap (UHPLC-MS/MS). This is the first time that pelargonidin 3-sambubioside, delphinidin 3-arabinoside, cyanidin 3-(6-acetyl)-glucoside and delphinidin 3-galactoside have been reported in any products derived from strawberry. Additionally, the accurate mass of the following anthocyanins were reported: catechin-(4–8)-pelargonidin 3-glucoside, afzelechin-pelargonidin 3-glucoside, pelargonidin dissacharide-(hexose + pentose)-acylated with acetic acid, 5-carboxypyranopelargonidin 3-glucoside, pelargonidin 3-arabinoside, pelargonidin 3-malonylglucoside, pelargonidin 3-(6-acetyl)-glucoside and pelargonidin 3-(6-succynil)-arabinoside. Functional aspects of this drink rely on its bioactive compounds and lack of glucose due to its transformation to gluconic acid which makes it suitable for diabetic consumers.

Hydroxytyrosol is well known for its potent antioxidant activity and anticarcinogenic, antimicrobial, cardioprotective and neuroprotective properties. Main food sources are olive oil (formed from the hydrolysis of oleuropein) and wine. One possible explanation to its origin in wines is the synthesis from tyrosol, which in turn is produced from the Ehrlich pathway by yeasts. This work aims to explore the factors that could increase the content as the strain of yeast, the initial tyrosine concentrations as precursor and the effect of synthetic and sterilized natural grape musts. Alcoholic fermentations in synthetic must showed that hydroxytyrosol is produced by all the yeast strains under study. Commercial Saccharomyces cerevisiae yeasts were those which produced higher concentrations, being the Red Fruit strain the biggest producer (6.12 ng/mL). Once the strain was selected, alcoholic fermentations were performed in synthetic must, with different tyrosine concentrations. The amount of hydroxytyrosol did not increase in a proportional way as tyrosine does. On the other hand, higher concentrations of hydroxytyrosol were obtained in natural grape musts (10.46 ng/mL) than in synthetic must (4.03 ng/mL). This work confirms the capacity of winemaking yeasts to produce the bioactive hydroxytyrosol.

Melatonin supplements are used widely in Europe and the United States (US) to alleviate jet-lag and other sleep-delay disorders. Recently, the European Commission authorized two health claims for food containing melatonin, with a minimum dose per quantified portion. This study aimed to determine the dose of melatonin in food supplements marketed in Europe (Spain) and the US by validating a liquid chromatography method with diode array detection (LC-DAD). Additionally, contaminants present in melatonin supplements were analyzed using ultra-high-performance liquid chromatography coupled to an orbitrap mass spectrometer. We tentatively identified 8 tryptophan-related contaminants in melatonin supplements, suggesting tighter impurity control in melatonin supplements is necessary. The LC-DAD validated method achieved reliable results regarding recovery, precision, repeatability, limit of detection, limit of quantitation and linearity. Label melatonin dose varied from 1–1.95 mg/unit and 0.3–5 mg/unit for supplements marketed in Europe (Spain) and the US, respectively. Four out of seventeen supplements showed significant deviations from melatonin content declared on the label (from −60% to −20%). Regarding health claims, three out of the ten supplements purchased in Spain should not include the claim “reduction of time taken to fall asleep”, as their melatonin content is lower than 1 mg.

Strawberries are harvested in a short period of time frequently involving fruit surplus. This paper studies the impact of the strawberry purée elaboration process on the chemical composition of the final products. Thirty-two phenolic compounds were studied by Liquid Chromatography with Diode Array Detector (LC-DAD) and Mass Spectrometry (LC-MS). An LC-DAD method was set up and validated and the non-anthocyanin phenolic profile was quantified at the different steps of production, for three elaboration processes and two harvests (2011 and 2012). We have tentatively identified apigenin-7-O-glucoside, luteolin-3-O-glucuronide, malonyl caffeoylquinic acid, trans-resveratrol glucoside and caffeoylglucaric isomer. (+)-Catechin and HHDP-galloylglucose were the most abundant phenolic compounds. The most abundant flavonol was kaempferol-3-glucoside. The purée maintains the fruit's non-anthocyanin phenolic composition and in vitro antioxidant activity as determined by ORAC and DPPH methods. This fact suggests that strawberry purée could be considered a valuable ingredient for producing food derivatives.

Strawberry is widely harvested in Spain. It is a highly perishable fruit and surplus production may be used to produce innovative foods. This paper studies the influence of gluconic fermentation by Gluconobacter japonicus on the non-anthocyanin content and antioxidant activity of strawberry. A total of 43 non-anthocyanin phenolic compounds were identified. To the best of our knowledge, this paper reports five compounds for the first time in strawberry and its derivatives, tentatively identified as: monogalloyl diglucose, 5-hydroxy feruloyl hexose, dihydrokaempferol hexoside, kaempferol neohesperidoside and (−)chicoric acid. It was further observed that gluconic fermentation leaves in vitro antioxidant activity practically unchanged. Gluconic fermentation by Gluconobacter japonicus can be considered a potential tool for producing fermented beverages. It transforms glucose into gluconic acid, which allows diabetics to consume the drink, while maintaining bioactive compound concentration and antioxidant activity. Industrial relevance As strawberry is a highly perishable product, fruits spoil quickly, leading to substantial economic losses. Therefore, the transformation of strawberry surplus into new, longer-lasting products is a financially worthwhile solution for the industry and producers. Our gluconic beverages were elaborated by traditional process using exclusively strawberry as raw material easily transferable to industrial scale. The main innovation aspect relies on developing an innovative product, aiming to fulfill consumers demand who are permanently seeking for different taste and flavors. At the same time its composition in sugars (non-glucose, original fructose content) makes these products very suitable for dietetic purposes.

International audience; Preventing the abnormal assembly of α-synuclein (α-Syn) and the correct modulation of vitagenes system exercise strong neuroprotective effects. It has been reported that melatonin (MEL), protocatechuic acid (PCA) and hydroxytyrosol (HT) reduce α-Syn toxicity. Their effect on the vitagenes system of PC12 cells have not been explored yet. These bioactive can cross the blood brain barrier (BBB). Therefore, this work aims to evaluate the inhibitory and destabilising capacities of MEL, PCA, HT, and their combinations on α-Syn kinetics and effects on vitagenes system (sirtuin-1 (SIRT-1), sirtuin-2 (SIRT-2), heme oxygenase (HO-1) and heat shock protein 70 (Hsp-70)). In vitro techniques (Thioflavin T (ThT), Transmission Electronic Microscopy (TEM), electrophoresis, MTT assay and qPCR) were used. Compounds, both individually and simultaneously were able to decrease the toxicity induced by α-Syn. Concurrently, occurrence of PCA (100 μM) +HT (100 μM) showed the highest inhibitory effect against α-Syn fibril formation and destabilisation of α-Syn fibrils (88 and 62%, respectively). Moreover, these compounds increased the expression of SIRT-2, HO-1 and Hsp70, contributing to a neuroprotective effect. In addition, the most important result is the increase on the expression of SIRT-2 caused by the combination of MEL + HT + PCA in the absence of α-Syn fibrils.

Melatonin (N-acetyl-3-(2-aminoethyl)-5-methoxyindole) is biologically active as a neurohormone and a chronobiotic and antioxidant agent. Its concentration in plant material and foods is usually determined by ELISA. However, commercial ELISA kits are not validated for those matrixes. This paper aims to accurately detect melatonin in wines. The advantages and pitfalls of the methods currently used to assay melatonin in wines (ELISA, LC-fluorescence and LC-ESI-MS/MS) are presented. The LC-FL method was validated as reliable for the quantitative analysis of MEL in wine samples that met AOAC requirements: LOD = 51.72 ng/mL; LOQ = 172.39 ng/mL; intraday accuracy as RSD = 0.35% and interday accuracy as RSD = 13.46%. The linearity showed a correlation coefficient of 0.9999, and peak resolution ranged from 0.96 to 1.52. Melatonin in wines was identified by LC-ESI-MS/MS, comparing its MS and MS2 spectra with its corresponding authentic commercial marker. LC-ESI-MS/MS revealed another compound with an identical fragment pattern (positive-mode ESI) but a different retention time as melatonin. Major mass fragmentation ions were (m/z) 216 and 174, tentatively identified as a melatonin isomer not previously described in wines. This compound appears in certain monovarietal wines (Jaen Tinto, Merlot and Palomino Negro). Only melatonin is present in others (Petit Verdot and Syrah), and a third group contains both melatonin and the new compound (Cabernet Sauvignon, Prieto Picudo and Tempranillo).

Melatonin (N-acetyl-5-methoxytryptamine) is a neurohormone produced in the pineal gland. Its biological properties are related to the circadian rhythm. Recently, the European Food Safety Authority (EFSA) accepted the health claim related to melatonin and the alleviation of subjective feelings of jet lag. This molecule has been detected in some foods. In this work, 13 grape varieties were studied; 7 monovarietal wines were produced in an experimental winery under strictly controlled conditions and were sampled in different steps. The grape varieties used to make the wines were: Cabernet Sauvignon, Merlot, Syrah, Tempranillo, Tintilla de Rota, Palomino Fino and Alpha red. Liquid chromatography tandem mass spectrometry (LC-MS/MS) unequivocally confirmed the presence of melatonin in wines. The main contribution of this paper is the results that clearly show that melatonin is synthesised during the winemaking process, specifically after the alcoholic fermentation. Indeed, melatonin is absent in grapes and musts and is formed during alcoholic fermentation.

Vinegars elaborated from white wine can be characterized by their phenolic composition. Indeed, for authenticity purpose, phenolic composition can be used to identify Sherry and Balsamic vinegars. However, the phenolic composition of red wine vinegars has scarcely been studied. Anthocyanin compounds in particular remain largely unknown. This study focuses on the analysis of anthocyanin compounds in red wine vinegar and the effect of acetification with submerged culture on such vinegars. The vinegar used in this study was produced from a young Cabernet Sauvignon wine in a laboratory-scale fermenter. Subsequent analyses of both wine and vinegar included their anthocyanin profile (by LC/MS), and their non-anthocyanin phenolic profile (by LC/DAD). In addition, wine and vinegar anthocyanin extracts were fractionated by CCC to determine the contribution of the fractions to overall antioxidant activity (AA), using ORAC, FRAP and DPPH assays. A total of 20 anthocyanin compounds were identified in the vinegar. As far as we know, this is the first time that anthocyanin-derived pigments (pyranoanthocyanins and ethyl-linked compounds) have been identified in red vinegar in such detail. Moreover, an original contribution of this study is the identification for the first time of catechyl-pyranocyanidin-3-glucoside in vinegar and wine, as well as two anthocyanin compounds not previously reported in vinegar or Cabernet Sauvignon wine: acetyl vitisin B and coumaroyl vitisin B. After the acetification process, vitisin-type and ethyl-linked compounds increased and monomeric anthocyanins, phenolic acids (ferulic acid, caffeic acid and caftaric acid) and flavan-3-ol ((+)-catechin) decreased. Although the proportion by weight of the polymeric compound fraction is similar in wine and vinegar, the AA of these polymers in vinegar is significantly greater (p

A crucial step in the production of high-quality wine vinegars is ageing in wood. This study aims to determine how wood barrels affect vinegar quality. For this purpose, vinegars were aged in barrels made from acacia, cherry, chestnut and oak wood. Two kinds of vinegars were studied: balsamic and red-wine vinegars. Analysis of samples included total phenol index (TPI), total monomeric anthocyanins (TA), dry extract, and phenolic and furanic compounds by liquid chromatography with photodiode array detection (LC–DAD) in a total of 98 samples. The concentration of HMF, 2-furfuraldehyde, protocatechualdehyde and vanillin significantly increased during ageing. Taxifolin is present in vinegars aged in cherry wood, confirmed by liquid chromatography–mass spectrometry/mass (LC–MS/MS). Hence, it can be a marker of vinegars aged in cherry wood. This is the first time that this compound has been identified in wine vinegars. On the other hand, ellagic acid is a characteristic compound for samples aged in chestnut and oak barrels. An unknown peak was found in all vinegar samples (groups F, T and M) which were aged in acacia wood. Linear discriminant analysis was used to classify samples as a function of the type of wood and ageing time, with phenolic compounds as variables. The linear functions obtained correctly classified – at 100% – red vinegars according to the type of wood. If ageing time (0–365 days) is considered, 62.5% and 100% of the red and balsamic vinegar samples, respectively, were well classified. The effect of wood on vinegar quality is obvious enough to be perceived by the senses in triangle tests. Woody, sweet and vanilla descriptors presented the highest scores for vinegars aged in oak wood. On the other hand, ageing in cherry wood increased markers for red-fruit attributes. These results prove that wood used in vinegar ageing determines both the chemical composition and sensorial properties.

Melatonin (N-acetyl-5-methoxytriptamine), a neurohormone produced by the pineal gland, has recently been reported in foods, mainly of plant origin. Literature concerning the biological properties is extensive. However, little is known about melatonin presence in foods or the analytical methods suitable for assay in food matrices and the potential influence of dietetic intake on human health. The aim of this work is to review current knowledge and available data of dietary intake of melatonin as it has been proposed as a new bioactive food component. There are gaps in the knowledge and insufficiently standardised methods for its analysis. Advantages and disadvantages of analytical methods to assess melatonin in different food matrixes are discussed, as well as the effect of dietetic melatonin.

The presence of phenolic compounds has been extensively studied in Sherry and Balsamic vinegars due to their impact on quality but little work has been done on red wine vinegars. Phenolic compounds were monitored during the acetification of red wine vinegars produced by surface culture in different wood barrels (oak, chestnut, acacia and cherry). A total of 166 samples were analysed for phenolic compounds using LC-DAD, the total phenol index (TPI) and the total monomeric anthocyanins (TA). Twelve phenolic compounds were identified corresponding to phenolic acids, flavanols and stilbens. Most phenolic acids did not significantly change their concentrations in the different acetifications. (+)-Catechin and resveratrol glycoside underwent significant decreases during acetification while gallic acid and gallic ethyl ester increased substantially for those vinegars produced in chestnut wood. The concentrations of phenolic compounds were used to build the functions for discriminant analysis. Samples belonging to two wine substrates (groups F and T) were correctly classified with 98.6% (group F) and 100% (group T) for the four types of wood barrels. During acetification a decrease (∼50%) in the content of total monomeric anthocyanins was observed. According to the results of triangle difference test the panel was able to distinguish most of the vinegars according to the different woods they were made in. The results of descriptive sensory analysis show that oak and cherry gave the maximum scores for most of the descriptors.

A comparative study of the antioxidant activity of wine phenolics has been performed. Standards of phenolic compounds, including benzoic and cinnamic acids, flavanols, flavonols and resveratrol, as well as some of their metabolites have been analysed for their antioxidant activity. Antioxidant assays included the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods and the Oxygen Radical Absorbance Capacity method (ORAC). We compared the reactivity of standard phenolic compounds under selected tests and obtained a ranking order for each one. Both ABTS and DPPH methods were well correlated. Several new structure–activity relationships were observed. As the number of phenoxyl groups increases, the antioxidant capacity, determined by DPPH and ABTS tests, improves. In the case of the ORAC assay, the ortho-position of phenoxyl groups clearly determines the activity. The metabolites of phenolic compounds present antioxidant activity and their values are similar to those of the phenolic compounds themselves. The choice of solvent, the effect of concentration and the information provided by the three tests under study are considered.

Phenolic compounds are common constituents of wine. Due to their healthy properties the analysis in human fluids is interesting within bioavailability evaluation. They have been reported not to be stable in human plasma, particularly at room temperature. Most sample treatments have been reported for a single compound. Our aim in this paper is to study sample handling control conditions and improve phenolic stability in human plasma samples. We tested various sample treatments to determine whether they could be used for analysing a set of phenolic compounds usually present in wines. The compounds studied were six phenolic acids, five flavonoids, trans -resveratrol and tyrosol. The effect of the following factors was explored: temperature, pH, the addition of antioxidants and the addition of anticoagulants. The results suggest that the plasma samples should be kept at temperatures below −20 °C before analysis and that 1% ascorbic acid plus 10 μl/ml o -phosphoric acid should be added. Anticoagulants (heparin or EDTA) do not play a significant role in the stability of polyphenolic compounds. The recovery values of a number of sample treatments (solid phase extraction, extraction with methanol, deproteinization, inhibition of enzymatic plasma activity) were compared. The recovery values for most phenolic compounds were better if the enzymatic plasma activity was inhibited and acidified ethanol was used for deproteinization.

A widely-used method for the spectrophotometric determination of procyanidins in wines has been adapted to wine vinegar samples. Reagent concentrations have been established and the analytical method tested for possible matrix effects. The recovery of catechin was approximately 98% and the limit of reliable measurement was 0.48 mg l −1 . The within-day and between-day precisions were evaluated and according to the two-tailed F -test the precisions were statistically equivalent. Application to wine vinegars obtained by traditional and quick acetification methods showed differences in concentration between the two groups.