Acetic Acid Bacteria and the Production and Quality of Wine Vinegar

The production of vinegar depends on an oxidation process that is mainly performed by acetic acid bacteria. Despite the different methods of vinegar production (more or less designated as either “fast” or “traditional”), the use of pure starter cultures remains far from being a reality. Uncontrolled mixed cultures are normally used, but this review proposes the use of controlled mixed cultures. The acetic acid bacteria species determine the quality of vinegar, although the final quality is a combined result of technological process, wood contact, and aging. This discussion centers on wine vinegar and evaluates the effects of these different processes on its chemical and sensory properties

Synergism Effect between Phenolic Metabolites and Endogenous Antioxidants in Terms of Antioxidant Activity

Polyphenolic compounds, widely distributed in plant kingdom, have been exhaustively studied for their bioactive properties specially antioxidant activity. However, they are extensively metabolized by human organism and the resulting metabolites are largely responsible for their effects. Furthermore, they may interact with the endogenous antioxidant network being this possibility scarcely studied. Plasma antioxidant network encompasses antioxidant enzymes and other substances such as uric acid. In addition, ascorbic acid is the major compound representing water soluble compartment both in foods and human body. The interaction of this vitamin with phenolic compound is largely unexplored. This work aims to study if there is a synergic effect between phenolic metabolites and main antioxidants (uric and ascorbic acid). For this purpose, the antioxidant activity was evaluated in terms of ORAC (oxygen radical absorbance capac ity) and FRAP (ferricreducing antioxidant power) as these tests involved either HAT (Hydrogen Atom Transfer) or SET (Single Electron Transfer) mechanisms. Additionally, a kinetic studied was developed to test if the rate constant presented a synergic effect. Protocatechuic acid, 3, 4 -dihydroxyphenylacetic acid, 3,4 -dihydroxyphenylpropionic acid and 3 -hydroxyphenylacetic acid were selected as they were metabolites of polyphenol compounds such as anthocyanins, quercetin, neohesperidin, chlorogenic acid and hesperetin present in wines, orange and strawberries. A synergic effect was proved for the combination of ascorbic acid with 3,4 -dihydroxyphenylacetic acid, both in terms of antioxidant activity and potent increase of velocity of the antioxidant reaction that took place.Ministerio de Economía y Competitividad AGL-2010-22152-C03-0

Inhibition of VEGF-Induced VEGFR-2 Activation and HUVEC Migration by Melatonin and Other Bioactive Indolic Compounds

Excessive concentrations of vascular endothelial growth factor (VEGF) trigger angiogenesis, which causes complications such as the destabilization of atherosclerotic plaques and increased growth of tumors. This work focuses on the determination of the inhibitory activity of melatonin and other indolic related compounds on VEGF-induced VEGF receptor-2 (VEGFR-2) activation and an approximation to the molecular mechanism underlying the inhibition. Quantification of phosphorylated VEGFR-2 was measured by ELISA. Migration wound-healing assay was used to determine cell migration of human umbilical vein endothelial cells (HUVECs). This is the first time that melatonin, 3-indolacetic acid, 5-hydroxytryptophol, and serotonin are proved to significantly inhibit VEGF-induced VEGFR-2 activation in human umbilical vein endothelial cells and subsequent angiogenesis. 3-Indolacetic acid showed the highest inhibitory effect (IC50 value of 0.9704 mM), followed by 5-hydroxytryptophol (35% of inhibition at 0.1 mM), melatonin (30% of inhibition at 1 mM), and serotonin (24% of inhibition at 1 mM). An approximation to the molecular mechanism of the inhibition has been proposed, suggesting that indolic compounds might interact with the cell surface components of the endothelial membrane in a way that prevents VEGF from activating the receptor. Additionally, wound-healing assay revealed that exposure of HUVECs to melatonin and 3-indolacetic acid in the presence of VEGF significantly inhibited cell migration by 87% and 99%, respectively, after 24 h. These data demonstrate that melatonin, 3-indolacetic acid, 5-hydroxytryptophol, and serotonin would be good molecules for future exploitation as anti-VEGF signaling agents.España, Ministerio de Ciencia e Innovación AGL2013-47300-C3-2-

Time course of l-tryptophan metabolites when fermenting natural grape musts: effect of inoculation treatments and cultivar on the occurrence of melatonin and related indolic compounds

Background and Aims:Tryptophan is involved in the formation of bioactive compounds, such as melatonin (MEL) and3-indoleacetic acid (3-IAA), by yeast. Melatonin is a neurohormone whose occurrence in wine has been widely reported inrecent years. The occurrence, however, of MEL and other indolic compounds related to tryptophan metabolism by wineyeast strains has been scarcely reported in grape musts. This work examined the occurrence of these compounds during thealcoholic fermentation (AF) of musts from seven grape cultivars, Corredera, Chardonnay, Moscatel, Palomino Fino, Sau-vignon Blanc, Tempranillo and Vijiriega.Methods and Results:Must was fermented with threeSaccharomyces cerevisiaestrains and then in two cases an additionalsequential inoculation with the non-SaccharomycesyeastTorulaspora delbrueckiiwas carried out. Fermented must samples wereanalysed by UHPLC/HRMS to determine the concentration of:L-tryptophan, 5-hydroxytryptophan, 5-hydroxytryptamine,N-acetyl-5-hydroxytryptamine, MEL, 3-IAA, tryptamine, tryptophol andL-tryptophan ethyl ester. The profile of indoliccompounds during AF with the Aroma White strain depended on the cultivar. The yeast strain did not influence the profile ofindolic compounds; instead, fermentation time was found to be a more influential factor.Conclusions:The production of indolic compounds during the AF depends largely on the cultivar used and the day of fer-mentation on natural grape musts.Significance of the Study:This is thefirst study that quantifies 5-hydroxytryptophan andN-acetyl-5-hydroxytryptamineduring the AF of grape must. The occurrence of compounds with bioactive potential, for example 3-IAA and ML, during fer-mentation with commercial yeast strains is also described.Ministerio de Economía y Competitividad de España - AGL2013-47300-C3-2-R, 2014–16 y AGL2016-77505-C3-2-R, 2017–1

Impact of preharvest and postharvest treatment combinations on increase of stilbene content in grape

Aims : Stilbene-enriched grape is an interesting new food product with numerous health-promoting properties, mainly due to its high added-value compound content, notably resveratrol. The aim of this study was to evaluate the effects of different elicitors, alone or in combination with ultraviolet C light (UVC) postharvest treatment, on stilbene concentration in grapes. Methods and results : Three preharvest treatments were tested, namely benzothiadiazole, (BTH), methyl jasmonate (MEJA) and chitosan (CHIT). After harvesting, these treatments were combined with UVC postharvest treatment. The stilbene extraction method was validated method. Moreover, and grape quality was evaluated. Of the preharvest treatments, only BTH significantly increased trans-resveratrol concentration in grape, but this appears to be linked to a ripening delay. When pre- and postharvest treatments were combined, only the MEJA-UVC combination was successful in reducing by three days the day of maximum induction of stilbenes (trans resveratrol and piceatannol). Conclusion: The MEJA-UVC combination reached similar grape trans-resveratrol contents than UVC alone, but additionally the time to reach maximum trans-resveratrol after the UVC treatment was reduced by three days and therefore grape quality was preserved. Significance and impact of the study: The achieved results provide a potential treatment combination that allows functional grapes to be obtained in a shorter period than with UVC light alone, making it more applicable

Bioactive compounds derived from the yeast metabolism of aromatic amino acids during alcoholic fermentation

Metabolites resulting from nitrogen metabolism in yeast are currently found in some fermented beverages such as wine and beer. Their study has recently attracted the attention of researchers. Some metabolites derived from aromatic amino acids are bioactive compounds that can behave as hormones or even mimic their role in humans and may also act as regulators in yeast. Although the metabolic pathways for their formation are well known, the physiological significance is still far from being understood. The understanding of this relevance will be a key element in managing the production of these compounds under controlled conditions, to offer fermented food with specific enrichment in these compounds or even to use the yeast as nutritional complement

Isotopic labelling-based analysis elucidates biosynthesis pathways in Saccharomyces cerevisiae for Melatonin, Serotonin and Hydroxytyrosol formation

Yeasts can synthetise bioactive compounds such as Melatonin (MEL), Serotonin (SER) and Hydroxytyrosol (HT). Deciphering the mechanisms involved in their formation can lead to exploit this fact to increase the bioactive potential of fermented beverages. Quantitative analysis using labelled compounds, 15-N2 l-tryptophan and 13-C tyrosine, allowed tracking the formation of the above-mentioned bioactive compounds during the alcoholic fermentation of synthetic must by two different Saccharomyces cerevisiae strains. Labelled and unlabelled MEL, SER and HT were undoubtedly identified and quantified by High Resolution Mass Spectrometry (HRMS). Our results prove that there are at least two pathways involved in MEL biosynthesis by yeast. One starts with tryptophan as precursor being known for the vertebrates’ pathway. Additionally, MEL is produced from SER which in turn is consistent with the plants’ biosynthesis pathway. Concerning HT, it can be formed both from labelled tyrosine and from intermediates of the Erlich pathway.Ministerio de Economía y Competitividad AGL2016-77505-C3-2-RMinisterio de Ciencia, Innovación y Universidades PID2019-108722RB-C32Junta de Andalucía, Consejería de Economía y Conocimiento P18-RT-309

New Insights into the Exploitation of Vitis vinifera L. cv. Aglianico Leaf Extracts for Nutraceutical Purposes

The leaves of Vitis vinifera L. have been used for a long time in traditional medicine for the treatment of many ailments. Grape polyphenols, indeed, have been demonstrated to be able to defend against oxidative stress, responsible for various disorders such as cancer, diabetes and neurodegenerative diseases. The effects of different extraction techniques, Soxhlet (SOX), Accelerated Solvent (ASE 40, ASE 50) and Ultrasound Assisted Extraction (UAE) were studied in this work to evaluate their impact on the chemical profile and bioactive potential of Vitis vinifera L. (cv. Aglianico) leaf extracts. The phytochemical profile was investigated by HPLC-DAD and 9 phenolic compounds were identified and quantified in the extract. Moreover, the antioxidant, anticholinesterase and antityrosinase activities were evaluated. In detail, the total polyphenol content and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl, Oxygen Radical Absorbance Capacities and β-Carotene Bleaching assays) were evaluated and compared to assess the Relative Antioxidant Capacity Index (RACI). To test the inhibitory activity of extracts towards cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition assays were performed. SOX and ASE 50 have shown the highest value of RACI, 0.76 and 0.65, respectively. Regarding enzymatic inhibitory activity, ASE 50 (IC50 = 107.16 ± 8.12 μg/mL) and SOX (IC50 = 171.34 ± 12.12 μg/mL) extracts exhibited the highest AChE and BChE inhibitory activity, respectively, while UAE (IC50 = 293.2 ± 25.6 μg/mL, followed by SOX (IC50 = 302.5 ± 38.3 μg/mL) showed the highest tyrosinase inhibition value. Our results demonstrated for the first time that Aglianico leaves are important sources of phenols that could be used to prevent oxidative stress and be potentially helpful in diseases treatable with tyrosinase and cholinesterase inhibitors, like myasthenia gravis or Alzheimer’s.Italian Ministry of the Economic Development F/200099/03/X45—CUP, B31B19000590008 COR, C31G1800021000

Occurrence of melatonin and indolic compounds derived from L-tryptophan yeast metabolism in fermented wort and commercial beers

Melatonin and serotonin are bioactive compounds present in foods and beverages and related to neuroprotection and anti-angiogenesis, among other activities. They have been described in wines and the role of yeast in their formation is clear. Thus, this study evaluates the content of these bioactives and other related indolic compounds in beer. For this purpose, commercial beers were analyzed by a validated UHPLC-HRMS method and sample treatment optimized due to the low concentrations expected. Moreover, a wort was fermented with different commercial beer yeast (Abbaye, Diamond, SafAle, SafLager) in order to monitor the formation of these bioactives during the elaboration process. Results show that indolic compounds such as N-acetylserotonin and 3-indoleacetic acid are produced during the alcoholic fermentation of wort. Moreover, the occurrence of four indolic compounds (5-hydroxytryptophan, N-acetylserotonin, 3-indoleacetic acid, L-tryptophan ethyl ester) in commercial beers is reported for the first time.Ministerio de Economía y Competitividad AGL2013-47300-C3-2-R, AGL2016-77505-C3-2-

Anthocyanins in Blueberries Grown in Hot Climate Exert Strong Antioxidant Activity and May Be Effective Against Urinary Tract Bacteria

Anthocyanins are extensively studied for their health-related properties, including antibacterial activity against urinary tract infections (UTI). Among common fruits, blueberries, with their remarkable antioxidant capacity, are one of the richest sources. Anthocyanin-rich extracts were obtained from four varieties: Snowchaser, Star, Stella Blue and Cristina Blue, grown in the hot climate of Southern Spain. Their total anthocyanins contents (TAC) were determined spectrophotometrically, and the anthocyanin profile by ultra high performance liquid chromatography - tandem mass spectrometer (UHPLC-MS/MS). Their antioxidant activity was assessed by oxygen radical absorbance capacity (ORAC) assay, while antibacterial activity against strains isolated from UTI patients was assessed in vitro, helping to select the varieties with the highest bioactive potential. Star showed the highest TAC and antioxidant activity (1663 ± 159 mg of cyanidin-3-O-glucoside (cy-3-O-glu) equivalents/100 g fresh weight (FW), 6345 ± 601 μmol Trolox equivalents (TE)/100 g FW, respectively), followed by Cristina Blue, Stella Blue and Snowchaser. As far as we know, this is the first time that cyanidin-3-rutinoside has been identified in blueberries. The extracts inhibited all the tested strains, MICs ranging from 0.4 mg/mL (for Stella Blue extract against UTI P. aeruginosa) to 9.5 mg/mL (for all extracts against UTI K. pneumoniae ssp. pneumoniae). This is the first study that assessed in vitro the antibacterial activity of blueberries against Klebsiella pneumoniae, Providencia stuartii and Micrococcus spp. strains isolated from UTI.España, University of Sevilla, VI Plan Propio de Investigación y Transferencia (VIPPIT‐2019‐I.5