Insights in the Fruit Flesh Browning Mechanisms in Solanum melongena Genetic Lines with Opposite Postcut Behavior

Color, taste, flavor, nutritional value, and shelf life are important factors determining quality and healthiness of food and vegetables. These factors are strongly affected by browning processes, occurring after fruit or vegetable cutting. Characterization of ten eggplant genotypes for chlorogenic acid (CGA) content, total phenols (TP), polyphenoloxidase (PPO) activity, and browning tendency corroborated a lack of significant correlations between biochemical factors and fruit flesh browning. Further in-depth molecular and biochemical analyses of two divergent eggplant genetic lines, AM199 (high browning) and AM086 (low browning), within 30 min from cutting, highlighted differences in the physiological mechanisms underlying the browning process. qRT-PCR analysis revealed distinct activation mechanisms of CGA biosynthetic and PPO genes in the two genetic lines. Metabolic data on CGA, sugars, and ascorbic acid contents confirmed that their different browning tendency matched with different metabolic responses to cutting. Our findings suggest that the complex mechanism of flesh browning in the two eggplant genetic lines might be mediated by multiple specific factors.

Inhibition of ochratoxin A production in Aspergillus carbonarius by hydroxycinnamic acids from grapes

Hydroxycinnamic acids (HCAs), phenolic components of wine, are known to have antimicrobial properties. Aspergillus carbonarius is one of the most important ochratoxin A (OTA) producing fungi in wine. Strategies for the control and prevention of A. carbonarius contamination are important for the maintenance of wine safety. This study sought to determine the potential of HCAs, such as caffeic, p-coumaric and ferulic acids, as antifungal natural compounds for the control of A. carbonarius growth and OTA production. The HCAs were tested at the increasing concentrations of 0.30, 0.65 and 1.10 mg/ml in minimal medium (MM) and grape juice. Germination of conidia was not affected in neither of the two media in presence of HCAs. At all the concentrations tested, OTA biosynthesis in MM was reduced and the dose effect was more evident for p-coumaric and ferulic acids; in grape juice the reduction trend was confirmed, and ferulic acid showed the highest inhibitory effect. Moreover, the expression level of genes encoding a polyketide synthase (AcOTApks) and a nonribosomal peptide synthetase (AcOTAnrps) involved in OTA biosynthesis, was evaluated by real-time PCR in A. carbonarius grown in presence of 0.65 mg/ml of HCAs. From gene expression analysis only the AcOTApks gene showed a marked reduction of transcription level in presence of p-coumaric and ferulic acids. On the contrary, caffeic acid seemed to not influence the expression levels of the genes analysed in this study, suggesting a different mechanism of action on the regulation of OTA biosynthesis.

Chemiotropic behavior of female olive fly (Bactrocera oleae GMEL.) onOlea europaea L

An interpretation is given of a number of observations on the chemiotropic behavior ofBactrocera oleae in connection with olive maceration water and the fly's return to the olive groves after the first summer rains. To this end, the headspace of both maceration water and leaf leaching water, simulating rainfall, were examined. In both cases, the presence of ammonia, which is generally known to attract fruit flies (Diptera, Tephritidae), was detected and, for the first time, in addition to other compounds that are inert for the fly, the presence of styrene was also detected. This aromatic hydrocarbon was found to be a strong attractant. It is shown that both ammonia and styrene are products of the metabolism of microbial flora present on the olive and leaf surface.

Comparative antioxidant activity of cultivated and wild Vaccinium species investigated by EPR, human neutrophil burst and COMET assay

OBJECTIVES

The Vaccinium (V.) spp. berries are considered a source of antioxidants, mainly belonging to polyphenols, specifically flavonoids and anthocyanins. Wild genotypes generally contain more antioxidants than cultivated counterparts. So, seven different antioxidants assays on extracts from cultivated and wild Vaccinium berries were performed, to evaluate their difference in terms of bioactivity on oxidative protection and minimum dosage to have a significant action.

MATERIALS AND METHODS

Four cell-free antioxidant assays (ABTS radical scavenging and electronic paramagnetic resonance using Fremy's salt, superoxide anion and hydroxyl radical), and three assays on human cells (two luminol amplified chemiluminescence, LACL, one on DNA damage, COMET) were used to measure the effects of cultivated blueberry (V. corymbosum) and wild bilberry (V. myrtillus) on the differently induced oxidative stress. Concentrations vs activity patterns were obtained by successive dilutions of extracts in order to identify both EC50 and minimum significant activity (MSA).

RESULTS

All the assays (except for the hydroxyl radical scavenging) showed a good relationship mainly with anthocyanin and polyphenol content and the significant greater activity of wild Vaccinium extracts. In fact, LACL data gave an EC50 of 11.8 and an MSA of 5.2 g were calculated as fresh weight dosage in cultivated berries, compared with lower doses in wild berries, EC50 of 5.7 g and MSA of 3.4 g.

CONCLUSIONS

Wild Vaccinium extracts averaged 3.04 and 2.40 fold more activity than cultivated extracts by EC50 and MSA, respectively. COMET assay confirmed the stronger action on DNA protection in wild samples.

Effects of different fungicide treatments on grape, must and wine quality

The aim of this study was to evaluate the effectiveness of natural products and low-rate copper formulations against grapevine downy mildew, in order to reduce or replace copper use in organic farming, and to assess the effects on the qualitative parameters of grape, must and wine of the different treatments. The trial was carried out in an organic vineyard in accordance with the EPPO/OEPP guidelines. Plots were prepared, each containing 12 vine-plants and repeated four times in randomized blocks. At harvest, representative grape samples were picked off from the plots treated with the different products: for each treatment, a random sub-sample was kept for analyses, the remaining part was processed to produce wine. Grapes, musts and wines were characterized for their food quality indices, as well as for their nutraceutical profiles and antioxidant activity. On must and wine, sugars, acidity and pH were determined according to official methods. On grape and wine, total polyphenol, flavonoid and hydroxycinnamic acid contents were determined by spectrophotometric analysis, as well as antioxidant activity tests. Organic acids and single polyphenols were also determined by HPLC. The results of the trial, characterized by moderate infection pressure, indicate that all tested products guaranteed a satisfactory control of Plasmopara viticola although the alternatives to copper were not as effective as copper. Data evidence that grape quality and its oenological potential were not significantly influenced by applied treatments and that they did not significantly differ in comparison with the untreated control, only with an interesting significant negative correlation between proanthocyanidins level and the severity of disease on ripe berries. The uniformity of data seems to evidence a general adaptation of plants to different treatment stresses, probably due both to low input of active ingredients and to moderate downy mildew infection.

Comparison of cardioprotective abilities between the flesh and skin of grapes

Recent studies have documented that grapes and grape juices are equally cardioprotective as red wine. The existing reports implicate that the skin and seeds of the grapes containing polyphenolic antioxidants are instrumental for the cardioprotective properties of grapes. The present study examines if the flesh of grapes also possesses any cardioprotective abilities. Three groups of randomly selected rats were fed, water only (control), flesh of the grapes (2.5 mg/kg b. wt.) or the skins (2.5 mg/kg b. wt.) for 30 days. At the end of the 30 days, isolated perfused hearts were made ischemic for 30 min followed by 2 h of reperfusion in the working mode. The results demonstrated that both flesh and skin of the grapes could protect the hearts from ischemic reperfusion injury as evidenced by improved postischemic ventricular recovery and reduced myocardial infarct size. High performance liquid chromatography (HPLC) revealed that skin and flesh contained comparative amounts of glucose, fructose, tartaric acid, malic acid, shikimic acid, and trans-caftaric acid. In addition, the flesh contained reduced amounts (compared to skin) of cis-coutaric, trans-coutaric, caffeic, p-coumaric, cinnamics, and catechin/epicatechin. Total polyphenolic index was also lower in flesh compared to skin. The anthocyanins were present exclusively in the skin. Electron paramagnetic resonance (EPR) spectrometry of hydroxy radicals indicated that both flesh and skins possessed equal amount of ROS scavenging activities. Total malonaldehyde content in the heart was reduced comparatively with either flesh or skin. The results indicate for the first time that the flesh of grapes are equally cardioprotective as skin, and antioxidant potential of skin and flesh of grapes are comparable with each other despite of the fact that flesh does not possess any anthocyanin activities.

The introduction of the stilbene synthase gene enhances the natural antiradical activity of Lycopersicon esculentum mill

Tomato (Lycopersicon esculentum) is a vegetable rich in antioxidants, such as lycopene, lutein, and zeaxanthin. Their presence is responsible for the characteristic ability of this product to inhibit the formation of reactive oxygen species, including singlet oxygen. The grapes and wines derived from grapes also contain powerful antioxidants. The antioxidant effect is derived from the polyphenols such as resveratrol and proanthocyanidin. Resveratrol is phytoalexin that is synthesized via the activation of the gene, stilbene synthase (STS). We decided to determine if the introduction of this gene into Lycopersicon esculentum Mill could modify its antioxidant activity. Using Electronic Paramagnetic Resonance (EPR) spectroscopy, which permits the detection of antiradical activity, especially *OH (hydroxyl radical), we showed that the antioxidant activity of the products, into which the gene STS had been introduced, was almost double than that of natural products and that their activity was especially pronounced due to ripening. Moreover, resveratrol concentrations in modified tomatoes were much higher than that found in the individual fruit. In the isolated hearts subjected to ischemia/reperfusion, the rats fed with modified tomato exhibited better cardiac performance, reduced myocardial infarct size and decreased number of apoptotic cardiomyocytes, and reduced oxidative stress compared to unmodified tomato or resveratrol alone indicating superior cardioprotective abilities of modified tomatoes.

EPR evaluation of the antiradical activity of wines containing high concentrations of resveratrol

The ability of two samples of red wine with different resveratrol concentrations to inhibit hydroxyl radicals (*OH) produced by a Fenton-type reaction was assessed using the method of electronic paramagnetic resonance (EPR). One sample was an autochthonous wine, Uvalino, which has a very high resveratrol concentration; the second was another red wine with a much lower resveratrol concentration. The ability of the sample of Uvalino wine to obstruct hydroxyl radicals was evident, but it wasn't much better than the ability of the sample of wine with a lower resveratrol concentration. The resveratrol concentration of wine is an important factor for the inhibition of the formation of free radicals, especially hydroxyl radicals; however, it is not the only one responsible for this property of wine. Resveratrol concentration can act synergically with other factors, such as polyphenols, which are also contained in wine and have antioxidant properties.