Daniela Fracassetti

Ellagic acid derivatives, ellagitannins, proanthocyanidins and other phenolics, vitamin C and antioxidant capacity of two powder products from camu-camu fruit (Myrciaria dubia)

The aims of this study were the evaluation of polyphenols and vitamin C content, and antioxidant capacity of dehydrated pulp powder and the dried flour obtained from the skin and seeds residue remaining after pulp preparation from camu-camu (Myrciaria dudia). Fifty-three different phenolics were characterised by HPLC-DAD-ESI-MS-MS and UPLC-HR-QTOF-MS-MS. The phenolic content of camu-camu flour was higher than that of the pulp powder (4007.95 mg/100 g vs. 48.54 mg/100 g). In both products the flavonol myricetin and conjugates, ellagic acid and conjugates and ellagitannins were detected. Cyanidin 3-glucoside, and quercetin and its glycosides were only found in the pulp powder, while proanthocyanidins were only present in the flour (3.5 g/100 g, mean degree of polymerisation 3). The vitamin C content was lower in pulp powder (3.5%) than in the flour (9.1%). The radical-scavenging capacity of both powders was determined by the DPPH, ABTS and ORAC assays, and was higher for camu-camu flour as could be expected for its higher phenolics and vitamin C content. Comparative analyses with fresh camu-camu berries indicate that some transformations occur during processing. Analysis of fresh berries showed that ellagic acid derivatives and ellagitannins were mainly present in the seeds, while proanthocyanidins were present both in the seeds and skin.

Sulphur dioxide affects culturability and volatile phenol production by Brettanomyces/Dekkera bruxellensis

The effect of different sulphur dioxide concentrations on culturability and viability of seven strains of Brettanomyces bruxellensis was tested in a synthetic wine medium (SWM) and a different response to molecular SO(2) among strains was detected. Sulphur dioxide induced a viable but non culturable (VBNC) state in all the strains. The greater percentage of VBNC cells were identified for five strains at molecular SO(2) concentrations of 0.2mg/L and for two strains at the concentration of 0.4mg/L. Vinyl phenols were detected in media containing VBNC or not viable B. bruxellensis, suggesting that its spoilage metabolism could be maintained during wine storage. Overall, this study indicates that SO(2) is a chemical stressor inducing VBNC state in B. bruxellensis grown in synthetic wine medium. Further studies are needed to evaluate the effects of SO(2) on the metabolism of this yeast in wine spoilage.

Differential Modulation of Human Intestinal Bifidobacterium Populations after Consumption of a Wild Blueberry (Vaccinium angustifolium) Drink

Bifidobacteria are gaining increasing interest as health-promoting bacteria. Nonetheless, the genus comprises several species, which can exert different effects on human host. Previous studies showed that wild blueberry drink consumption could selectively increase intestinal bifidobacteria, suggesting an important role for the polyphenols and fiber present in wild blueberries. This study evaluated the modulation of the most common and abundant bifidobacterial taxonomic groups inhabiting the human gut in the same fecal samples. The analyses carried out showed that B. adolescentis, B. breve, B. catenulatum/pseudocatelulatum, and B. longum subsp. longum were always present in the group of subjects enrolled, whereas B. bifidum and B. longum subsp. infantis were not. Furthermore, it was found that the most predominant bifidobacterial species were B. longum subsp. longum and B. adolescentis. The results obtained revealed a high interindividual variability; however, a significant increase of B. longum subsp. infantis cell concentration was observed in the feces of volunteers after the wild blueberry drink treatment. This bifidobacterial group was shown to possess immunomodulatory abilities and to relieve symptoms and promote the regression of several gastrointestinal disorders. Thus, an increased cell concentration of B. longum subsp. infantis in the human gut could be considered of potential health benefit. In conclusion, wild blueberry consumption resulted in a specific bifidogenic effect that could positively affect certain populations of bifidobacteria with demonstrated health-promoting properties.

Immunomodulatory effect of a wild blueberry anthocyanin-rich extract in human Caco-2 intestinal cells.

Intestinal inflammation is a natural process crucial for the maintenance of gut functioning. However, abnormal or prolonged inflammatory responses may lead to the onset of chronic degenerative diseases, typically treated by means of pharmacological interventions. Dietary strategies for the prevention of inflammation are a safer alternative to pharmacotherapy. Anthocyanins and other polyphenols have been documented to display anti-inflammatory activity. In the present study, three bioactive fractions (anthocyanin, phenolic, and water-soluble fractions) were extracted from a wild blueberry powder. The Caco-2 intestinal model was used to test the immunomodulatory effect of the above fractions. Only the anthocyanin-rich fraction reduced the activation of NF-κB, induced by IL-1β in intestinal epithelial Caco-2 cells. Specifically, concentrations of 50 and 100 μg mL(-1) decreased NF-κB activation by 68.9 and 85.2%, respectively (p ≤ 0.05). These preliminary results provide further support for the role of food bioactives as potential dietary anti-inflammatory agents.

Effect of Time and Storage Temperature on Anthocyanin Decay and Antioxidant Activity in Wild Blueberry (Vaccinium angustifolium) Powder

This study evaluated the effects of storage on total and single anthocyanin (ACN) content, and total antioxidant activity (TAA) of freeze-dried wild blueberry (WB) powder maintained at 25, 42, 60, and 80 °C for 49 days. Storage reduced single and total ACN content at all of the temperatures; it was slower at 25 °C (-3% after 2 weeks), whereas it was faster at 60 °C (-60%) and at 80 °C (-85%) after 3 days. The values of half-life time (t1/2) were found to be 139, 39, and 12 days at 25, 42, and 60 °C, respectively, utilizing the Arrhenius equation. No significant effects were detected on TAA by temperature increase. In conclusion, this study provides important information on the stability of WB powder at 25 °C; this is interesting scientific research for the food industry.

Determination of Reduced Cysteine in Oenological Cell Wall Fractions of Saccharomyces cerevisiae

Compounds containing cysteine residues, such as glutathione, can affect the redox potential of must and wine by reduction of o-quinones and hydrogen peroxide. The oenological yeast cell wall fractions contain cysteine residues in their protein structure, and they could affect both oxidative and odor properties of wine. An analytical approach based on the derivatization of cysteinyl residues with p-benzoquinone followed by reversed-phase high-performance liquid chromatography separation was developed to quantify glutathione and free and protein cysteine in 16 Saccharomyces cerevisiae strains and 12 commercial samples of yeast mannoproteins, hulls, and lysates. The chemical modifications induced by the Maillard reaction following the industrial preparation of such fractions were evaluated as well. Lysates showed the highest protein cysteine content and high contents of glutathione and free cysteine. Mannoproteins showed an intense Maillard reaction (furosine >60 mg/100 g protein), and most of the samples were able to bind thiol compounds with a potentially detrimental effect toward the thiol-related odors in wine.

Yeast contribution to melatonin, melatonin isomers and tryptophan ethyl ester during alcoholic fermentation of grape musts

Melatonin (MEL) has been found in some medicinal and food plants, including grapevine, a commodity of particular interest for the production of wine, a beverage of economic relevance. It has also been suggested that MEL in wine may, at least in part, contribute to the health‐promoting properties attributed to this beverage and, possibly, to other traditional Mediterranean foodstuffs. After a preliminary screening of 9 yeast strains in laboratory medium, three selected strains (Saccharomyces cerevisiae EC1118, Torulaspora delbrueckii CBS1146T and Zygosaccharomyces bailii ATCC36947T) were inoculated in experimental musts obtained from 2 white (Moscato and Chardonnay) and 2 red (Croatina and Merlot) grape varieties. The production of MEL, melatonin isomers (MIs) and tryptophan ethyl ester (TEE) was monitored during the alcoholic fermentation. The screening showed that the three investigated strains produced the highest concentrations of MEL and two MIs in optimal growth conditions. However, MEL and MIs were not produced in oenological conditions, but the three strains synthesized high concentrations of a new MI and TEE in musts.

Comparison of DNA damage by the comet assay in fresh versus cryopreserved peripheral blood mononuclear cells obtained following dietary intervention

Endogenous and oxidatively induced DNA damage, as evaluated by the comet assay, are widely used as biomarkers of oxidative stress in numerous dietary intervention studies. This analysis can be performed on fresh peripheral blood mononuclear cells (PBMCs) or on cryopreserved cells. However, information pertaining to the effects of cryopreservation on DNA damage is often missing, and this may be crucial in studies in which samples are analysed before and after intervention. The purpose of this study was to compare DNA damage in fresh versus cryopreserved PBMCs obtained from subjects following a 6-week intervention with wild blueberry drink or placebo drink. Fresh and 12-month-stored PBMCs were analysed for formamidopyrimidine-DNA glycosylase (FPG)-sensitive sites and H2O2-induced DNA damage. The levels of FPG-sensitive sites were significantly higher in the cryopreserved compared with the fresh cells (P < 0.001), while H2O2-induced DNA damage was significantly lower after storage (P < 0.001). Both the fresh and cryopreserved samples showed reductions in FPG-sensitive sites following the wild blueberry treatment (fresh PBMCs: from 12.50 ± 5.61% to 9.62 ± 3.52%, P = 0.039; cryopreserved PBMCs: from 22.7 ± 6.1% to 19.1 ± 7.0%, P = 0.012). In contrast, the decrease in H2O2-induced DNA damage observed in the cryopreserved cells masked the protective effect of the wild blueberry drink documented in the fresh samples (fresh PBMCs: from 44.73 ± 7.46% to 36.34 ± 9.27%, P < 0.001; cryopreserved PBMCs: from 25.8 ± 4.6% to 23.9 ± 4.6%, P = 0.414). In conclusion, our results suggest that FPG-sensitive sites, and more importantly, H2O2-induced DNA damage could be significantly modified following the long-term storage of samples obtained from individuals participating in a dietary intervention study. Because storage may affect the assessment of the protective role of diet against DNA damage as a marker of oxidative stress, further research is needed.

Polymorphisms of Saccharomyces cerevisiae Genes Involved in Wine Production

The setting up of new molecular methods for Saccharomyces cerevisiae typing is valuable in enology. Actually, the ability to discriminate different strains in wine making can have a benefit both for the control of the fermentation process and for the preservation of wine typicity. This study focused on the screening of single-nucleotide polymorphisms in genes involved in wine production that could evolve rapidly considering the selective pressure of the isolation environment. Preliminary screening of 30 genes in silico was performed, followed by the selection of 10 loci belonging to 8 genes. The sequence analysis showed a low polymorphism and a degree of heterozygosity. However, a new potential molecular target was recognized in the TPS1 gene coding for the trehalose-6-phosphate synthase enzyme involved in the ethanol resistance mechanism. This gene showed a 1.42% sequence diversity with seven different nucleotide substitutions. Moreover, classic techniques were applied to a collection of 50 S. cerevisiae isolates, mostly with enologic origin. Our results confirmed that the wine making was not carried out only by the inoculated commercial starter because indigenous strains of S. cerevisiae present during fermentation were detected. In addition, a high genetic relationship among some commercial cultures was found, highlighting imprecision or fraudulent practices by starter manufacturers.

Oxygen Consumption in South African Sauvignon Blanc Wines: Role of Glutathione, Sulphur Dioxide and Certain Phenolics

The aim of this research was to investigate the interaction between sulphur dioxide, glutathione (GSH) and certain phenols in the presence of oxygen in a synthetic wine and in clarified Sauvignon blanc wine. In this study, the clarified wine, from which most of the phenols had been removed, was compared to synthetic wine solution, with both mediums being enriched with caffeic acid to investigate the effect of different levels of sulphur dioxide and GSH on oxygen consumption. Moreover, thirteen young South African Sauvignon blanc wines with different levels of sulphur dioxide were oxygenated, and the oxygen consumption and phenolic and colour changes were monitored over time. The results show that oxygen consumption was influenced greatly by the presence of sulphur dioxide and, to a lesser extent, by the presence of GSH, with both compounds decreasing during the course of the experiment. During oxidation, an increase was observed in glutathionyl caffeic acid, as well as in oxidised glutathione (GSSG); however, this did not coincide with the percentage decrease in GSH. Oxidation further led to an increase in absorbance measurements at 420 and 440 nm (yellow-orange colour), which were reduced by the presence of SO2. A large variation was also observed in the oxygen consumption of the young wines, with this rate increasing with an increase in SO2 concentration. Positive correlations were also observed between oxygen, SO2, GSH and Cu concentrations, which were again negatively correlated with absorbance at 420 and 440 nm and GSSG concentrations.