Fresh Grape Juice Research Articles

Nonthermal inactivation effects on oxidative enzymes in grape juice influenced by moderate electric fields: Effect of constant exposure electrical treatments combined with temperature

Inactivation of polyphenol oxidase (PPO) and peroxidase (POD) enzymes in fresh grape juice was studied by subjecting the juice to moderate electric field (MEF) treatments of 82 and 87 V/cm field strengths. We used an electro-processing device that was built to minimize ohmic heating and enhance cooling during application of electric fields. Kinetic studies indicate that the MEF treatments increase the inactivation of both enzymes at 65 and 75 °C, compared to the corresponding control treatments without electric fields. The increase in the inactivation becomes statistically significant ( P ≤ 0.05) in the MEF treatment at 75 °C. Molecular motion simulations of PPO and POD enzymes correlate with the experimental results. The study results further indicate the efficacy of MEF treatments on the nonthermal inactivation of enzymes, which are held at or near their thermal inactivation threshold temperatures (≤80 °C for PPO and POD). • Moderate electric field (MEF) treatments inactivate enzymes (PPO, POD) in grapes. • The efficacy of MEFs increases with increasing field strength and temperature. • The thermal impact on grape juice can be reduced by applying MEF treatments. • Enzyme's thermal inactivation threshold temperature is useful in MEF studies. • Thermostability and electric field sensitivity of enzymes affect the inactivation.

Comparing the Effect of Grape Fermentative Product and Fresh Red Grape Juice on Antioxidant Biomarkers of Liver Mitochondria Isolated From Rats in Vitro

Background: Mitochondria are a source of reactive oxygen species (ROS), and several natural compounds are used as antioxidant agents. This study aimed to investigate and compare the effects of fresh grape juice red wine on oxidative stress biomarkers in rat liver mitochondria. Materials and Methods: In this regard, mitochondria were isolated from the liver of 27 male Wistar rats (220-250 g). The isolated mitochondria were cultured in different doses of red wine and fresh red grape juice for 24, 48, and 72 h. After treatment, total antioxidant capacity, lipid peroxidation, total thiol groups, and catalase activity were determined in the isolated mitochondria of the rat liver. Results: The results confirmed the oxidant/antioxidant effects of red wine and fresh red grape juice at different times. Conclusion: According to the results, the fresh red grape juice showed higher antioxidant properties than red wine in the liver mitochondrial samples.

Hepatoprotective Effect of Fresh Grape Juice Prepared by a Low-Speed Masticating Juicer in db/db Mice.

This study investigated the hepatoprotective effect of fresh grape juice prepared using a low-speed masticating (LSM) juicer or a high-speed centrifugal (HSC) juicer in mice. Six-week-old db/db mice were fed on an AIN-93G diet or a diet containing 1% freeze-dried LSM or HSC grape juice for 7 weeks. Treatment with LSM grape juice significantly decreased hepatic triglycerides, serum aspartate transaminase activities, and homeostasis model assessment for insulin resistance values, whereas HSC juice did not significantly influence these parameters. The LSM grape juice showed higher antioxidant and anti-inflammatory activities than HSC juice. The benefits of LSM grape juice are probably due to a much higher proanthocyanidin content than that of HSC juice. These results suggest that LSM grape juice can exert hepatoprotective effects in db/db mice, partly through improving insulin resistance and promoting antioxidant and inflammatory activities.

Investigating the oxyresveratrol β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin complexes: The effects on oxyresveratrol solution, stability, and antibrowning ability on fresh grape juice

The inclusion complexes of oxyresveratrol (Oxy) with β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) were prepared and characterized by UV–vis spectroscopy, FT-IR spectroscopy, XRD, TG-DTG and SEM. Based on the optimal formulation, 222.23 ± 1.52 μg and 232.65 ± 2.64 μg of Oxy was included in 1.00 mg of the Oxy-β-CD and Oxy-HP-β-CD dried powder with the water solubility up to 14.44 ± 0.83 mg/mL and 47.33 ± 0.78 mg/mL, yielding about 30 and 100-fold increase in Oxy solubility (about 0.47 mg/mL), respectively. The physical stability and dissolution rate study showed that the formation of inclusion complexes significant enhanced the storage stability of Oxy and its dissolution rate. These results indicated that β-CD and HP-β-CD may be suitable delivery systems of Oxy. Furthermore, as illustrated in this study, inclusion complexes exhibited strong antibrowning effects on fresh grape juice in 24 h, showing its great potential application in the food industry.

Fungal diversity in the grapes-to-wines chain with emphasis on Penicillium species

The aim of this work was the description of surface and endogenous mycobiota colonisation of grapes, fresh grape juice, grape must, and wine primarily focused to the current spectrum of the penicillium species. One sample of white grape variety Palava and one sample of blue grape variety Dornfelder were collected in Small Carpathian wine growing region of Slovakia in the year 2017. Direct plating of grapes on agar plates was used for analysis of surface mycobiota of grapes while surface sterilsed grapes were used for endogenous mycobiota analysis. Mycobiota of juice, must, and wine was analysed by plate dilution method. Overall, we isolated 148 strains belonging to 13 genera of filamentous microscopic fungi and Mycelia sterilia from grape variety Palava, while the most frequent was Alternaria. Alternaria was the most common genus in the surface and endogenous colonisation with an average relative density 50% and 73.6%, respectively. A total of 2 species of Penicillium were detected from the grapes to wine, potentially toxigenic Penicillium expansum and P. chrysogenum. A total of 39 strains belonging to 6 genera and Mycelia sterilia were identified from grape variety Dornfelder. The most abundant genus was also Alternaria (51.3%), followed by Penicillium (12.8%). Alternaria was the most common genus in the surface and endogenous colonisation and fresh grape juice with an average relative density from 20% (grape juice) to 71% (endogenous colonisation of grapes). A total of 3 species of Penicillium were detected from the grapes to wine, where Penicillium expansum were detected most commonly. In the second part of our work some selected isolates were tested to the ability to produce mycotoxins such as patulin, citrinin, and roquefortin C in in vitro condition by thin layer chromatography method. All tested strains of Penicillium species were able to produce at least one mycotoxin.

Effect of food lures for monitoring of Anastrepha fraterculus (Diptera: Tephritidae) in Acca sellowiana (Myrtaceae)

The South American fruit fly, Anastrepha fraterculus (Diptera: Tephritidae) stands out for its polyphagous habit of damaging the production of several fruits in southern Brazil. This study aimed to evaluate the capture efficiency of A. fraterculus using grape juice at different periods of decomposition and aging as well as to test the capture efficiency of the enzymatic hydrolyzed protein Cera Trap® in feijoa crops. The work was conducted in a commercial feijoa orchard in São Joaquim, SC, Brazil during the 2014 growing season. Undiluted Cera Trap®, fresh grape juice and grape juice that had aged for 7 and 14 days were evaluated. All of the treatments with grape juice were used at the recommended concentration of 25 %. McPhail traps were used with 300 mL for each lure. On a weekly basis, the number of adults and the percentage of female fruit flies captured were evaluated, using identification and counting. Cera Trap® was the lure that captured the highest number of fruit flies, with a high percentage of females and with a higher frequency of captures during the season. Cera Trap® also showed the highest number of action thresholds compared to grape juice treatments. The 25 % fresh and aged grape juice showed a low number of captures and a low number of action thresholds. We conclude that fresh and aged grape juice were not effective for capturing and monitoring A. fraterculus in feijoa orchards. The Cera Trap® lure proves to be an alternative to improve monitoring of A. fraterculus in orchards in southern Brazil.

Modification of carbon paste electrodes with recrystallized zeolite for simultaneous quantification of thiram and carbendazim in food samples and an agricultural formulation

A simple, inexpensive, highly sensitive, selective novel electrochemical method was developed for simultaneous quantification of the fungicides thiram and carbendazim in samples of honey, fresh grape juice, and an agricultural formulation using a carbon paste electrode modified with recrystallized zeolite. Zeolite was characterized by TG-DSC, XRD, FT-IR, and SEM-EDS before and after recrystallization treatment. The electrodes were electrochemically characterized using cyclic voltammetry, square-wave voltammetry, and electrochemical impedance spectroscopy. Electrode area, standard heterogeneous rate constant, and double-layer capacitance were the electrochemical variables investigated. Recrystallized zeolite had a strong influence on these variables. Development of the method for simultaneous thiram and carbendazim quantification involved optimizing instrumental parameters (frequency, amplitude, and potential step) and experimental parameters (pH, zeolite content, temperature, and recrystallization time). The oxidation peak current for thiram varied linearly in the concentration range of 0.36–4.99 × 10−7 mol L−1, with limit of detection (LD) of 6.74 × 10−9 mol L−1 and limit of quantification (LQ) of 20.17 × 10−9 mol L−1. For carbendazim, the oxidation peak current varied linearly in the concentration range of 0.10–2.35 × 10−6 mol L−1, with LD and LQ of 3.51 × 10−9 and 11.71 × 10−9 mol L−1, respectively. Thiram and carbendazim recovery experiments were performed by adding known amounts of these fungicides to samples of honey and grape juice, yielding recovery rates in the 98.85–101.15% range. In the agricultural formulation, the concentrations measured with the new method were close to those specified on the label, with deviations of below 1.1%. No thiram or carbendazim were found in the grape juice and honey samples. The results demonstrated the method's feasibility for quantifying both compounds simultaneously in these samples.

Examination of heat treatments at preservation of grape must

Heat treatment is a well-known process in food preservation. It is made to avoid and to slow down food deterioration. The process was developed by Louise Pasteur French scientist to avoid late among others wine further fermentation. The different heat treatments influence the shelf life in food production. In our article we present the process of grape must fermentation, as grape must is the base material of wine production. The treatment of harvested fresh grape juice has a big influence on end product quality. It is our experiments we examined the same grape must with four different methods in closed and in open spaces to determine CO2 concentration change. There are four different methods for treatment of grape juice: boiling, microwave treatment, treatment by water bath thermostat and a control without treatment. As a result of the comparison it can be stated that the heat treatment delays the start of fermentation, thereby increasing shelf life of grape must. However, no significant differences were found between two fermentation of heat-treated grape must by the microwave and water-bath thermostat. The different heat treatment of grape must base materials was done at the laboratory in Faculty of Mechanical Engineering of Szent István University. The origin of the table grapes used for the examination was Gödöllő-hillside.

Anti-yeast activity of natural compounds: In vitro and in vivo tests

• The anti-yeast activity of trans-2-hexanal, cinnamon, eugenol and thymol was addressed by in vitro and in vivo tests. • A Central Composite Design (CCD) was also carried out to highlight possible synergistic effects between trans-2-hexanal, cinnamon and eugenol. • Compounds were all effective against yeasts. • Their combination further reduced the active agent concentration. The anti-yeast activity of some natural compounds (trans-2-hexanal, cinnamon oil, eugenol and thymol) was addressed by in vitro and in vivo tests. First, their efficacy was tested against some yeasts. By a sensory evaluation the thymol was discarded and the other three natural preservatives were tested in grape juice inoculated with a cocktail of selected yeasts. The most effective compound was trans-2-hexanal. A Central Composite Design (CCD) was also carried out to highlight possible synergistic effects between trans-2-hexanal, cinnamon oil and eugenol. Results showed that compounds were all effective against yeasts and their combination further reduced the active agent concentration. To finally assess the activity of the six most effective combinations of the CCD, a fresh grape juice added with compounds and stored at two storage temperatures, was monitored during time. Results confirmed the effectiveness of the three natural compounds in providing an immediate and significant protection of juice to yeast proliferation.

Isolation of intact glycosidic aroma precursors from grape juice by hydrophilic interaction liquid chromatography

Background and Aims Aroma precursors in grape juice include glycosylated terpenoids or benzenoids. The separation of these polar substances has been achieved by several chromatographic techniques but often after the esterification of the sugar hydroxyls. We aimed to develop a high-performance liquid chromatography method to isolate the glycoconjugates in their natural form. Methods and Results The glycoside fraction was extracted from fresh grape juice, treated with lead (II) acetate to precipitate phenolic compounds and finally separated by hydrophilic interaction liquid chromatography. Three compounds were isolated, and their structures elucidated by means of spectroscopic data; one revealed previously unreported structural features. Conclusions Our hydrophilic interaction liquid chromatography method has been proven effective for the purification of the complex blend of many chemical compounds that contribute to grape and wine flavour. Significance of the Study The present article proposes a new, straightforward procedure for the isolation of flavour glycoconjugates.

EFFECTS OF VARIOUS CROP LOADS AND LEAF FERTILIZER ON GRAPEVINE YIELD AND QUALITY

Crop loads and leaf fertilizers are highly important for yield and quality of grapevine. This research was conducted in the Konya province of Turkey in 2008 and 2009. The effects of crop loads and leaf fertilizers were investigated on yield and quality of Vitis vinifera L. cv. ‘Gök üzüm’. The combined leaf fertilizer (TARİŞ-ZF) significantly increased quality parameters such as berry length, berry weight, maturity index, juice yield and drying index of grapevine. Increasing crop load values (16, 21, and 26 buds/vine) increased fresh grape yield and juice yield; however, maturity index and drying index decreased in comparison to the control. According to these results, it was suggested that to produce a high yield 26 buds/vine pruning and non-fertilization could be utilized or to increase quality parameters 16 buds/vine pruning, and fertilization may be applied on grapevine cultivation.

Stepwise increase of resveratrol biosynthesis in yeast Saccharomyces cerevisiae by metabolic engineering

Resveratrol is a unique, natural polyphenolic compound with diverse health benefits. In the present study, we attempted to improve resveratrol biosynthesis in yeast by different methods of metabolic engineering. We first mutated and then re-synthesized tyrosine ammonia lyase (TAL) by replacing the bacteria codons with yeast-preferred codons, which increased translation and improved p-coumaric acid and resveratrol biosynthesis drastically. We then demonstrated that low-affinity, high-capacity bacterial araE transporter could enhance resveratrol accumulation, without transporting resveratrol directly. Yeast cells carrying the araE gene produced up to 2.44-fold higher resveratrol than control cells. For commercial applications, resveratrol biosynthesis was detected in sucrose medium and fresh grape juice using our engineered yeast cells. In collaboration with the Chaumette Winery of Missouri, we were able to produce resveratrol-containing white wines, with levels comparable to the resveratrol levels found in most red wines.

From Tanning to Tannins

![Figure][1] A team member stands next to the ancient wine press. CREDIT: HANS BARNARD ![Figure][1] A clay fermentation vat. CREDIT: GREGORY ARESHIAN In the same cave complex in southern Armenia where researchers uncovered the world's oldest leather shoe last year ( Science , 18 June 2010, p. [1461][2]), archaeologists have found evidence for the world's oldest winery. University of California, Los Angeles, archaeologists Hans Barnard and Gregory Areshian, who was part of the leather shoe team, found the ancient vintner's supplies during a 2007 National Geographic Society expedition. The stash included grape seeds from Vitis vinifera (the species still used in winemaking today), desiccated grape vines, a wine press, a clay fermentation vat, and earthen drinkware. Chemical analysis of a gray rime clinging to potsherds revealed the plant pigment malvidin, which in the region is only found in grapes and pomegranates. As the site contained no pomegranate remains, the pigment pointed to grape juice. And because fresh grape juice didn't last very long before the advent of mechanical refrigeration some 5700 years later, the cave dwellers likely fermented it into wine, the researchers reported online last week in the Journal of Archaeological Science . The site dates to approximately 4100 B.C.E., making it the oldest known winemaking facility, although traces of wine itself have been found in sites 4000 years older. Little is known about who used this cave system, but its numerous gravesites indicate that the caves may have played a ceremonial funerary role. The proximity to graves fits with many traditions of imbibing wine during burial rituals, says Patrick McGovern, a biomolecular archaeologist at the University of Pennsylvania Museum of Archaeology and Anthropology who has studied ancient Egyptian beer and wine. The finding shows how advanced winemaking was in these early stages of human civilization, he says. “I just hope they took their leather shoes off before they trod on the grapes.” [1]: pending:yes [2]: http://www.sciencemag.org/content/328/5985/r-samples.full#compilation-3-1-article-title-1

Mycobiota of Czech wine grapes and occurrence of ochratoxin A and Alternaria mycotoxins in fresh grape juice, must and wine.

The aim of this study was to monitor the mycobiota of wine grapes, occurrence of ochratoxigenic microfungi in wine grapes and occurrence of ochratoxin A and Alternaria mycotoxins in fresh grape juice, must and wine from domestic crops in the year 2004. Thirteen samples of wine grapes (white /nine samples/ and red /four samples/) were collected during harvesting in the Znojmo wine region, SE Moravia. One sample of a wine grape variety was represented by three subsamples of wine grapes, which were sampled in left, middle and right part of the vineyard. Five wine grape berries per bunch were randomly selected, plated onto Dichloran Rose Bengal Chloramphenicol (DRBC) agar, and incubated for 5–7 days at 25 °C. Alternaria alternata, Cladosporium herbarum, C. cladosporioides, Penicillium expansum, P. aurantiogriseum, P. spinulosum and Rhizopus nigricans were isolated from the samples. Ochratoxigenic microfungi, e. g. Aspergillus carbonarius, and other species of section Nigri, A. ochraceus, Penicillium verrucosum and P. nordicum, were not found in the samples. The HPTLC method for quantification of ochratoxin A (OTA) and Alternaria mycotoxins (alternariol (AOH), alternariol monomethyl ether (AME), altenuene (ALT), and tenuazonic acid (TeA)) in fresh grape juice (13 samples), must (13 samples) and wine (13 samples) was used. The limit of quantification (LoQ) was 8 ng/l for OTA, 1.5 μg/l for AOH, 1.5 μg/l for AME, 1.5 μg/l for ALT and 7.5 μg/l for TeA. Occurrence of OTA and Alternaria mycotoxins in fresh grape juice, must and wine was not proved.

Polyphenoloxidase deactivation kinetics during ohmic heating of grape juice

The heating method affects the temperature distribution inside a food, and directly modifies the time–temperature relationship for enzyme deactivation. Fresh grape juice was ohmically heated at different voltage gradients (20, 30, and 40 V/cm) from 20 °C to temperatures of 60, 70, 80 or 90 °C and the change in the activity of polyphenoloxidase enzyme (PPO) was measured. The critical deactivation temperatures were found to be 60 °C or lower for 40 V/cm, and 70 °C for 20 and 30 V/cm. Various kinetic models for the deactivation of PPO by ohmic heating at 30 V/cm were fitted to the experimental data. The simplest kinetic model involving one step first-order deactivation was better than more complex models. The activation energy of the PPO deactivation for the temperature range of 70–90 °C was found to be 83.5 kJ/mol.

Stereodifferentiation of some chiral monoterpenes using multidimensional gas chromatography

Heptakis (2,3,6-tri-O-alkyl)-β-cyclodextrins are used as chiral stationary phases for the resolution of α-pinene (1), β-pinene (2), limonene (3), α-terpineol (4), linalool (5) and the furanoid cis/trans linalool oxides (6) by chirospecific CGC-analysis. The first investigations on the direct chirality evaluation of the monoterpenoid grape and wine flavour compounds 4–6 are reported using enantioselective multidimensional gas chromatography (MDGC) and chiral main columns, coated with peralkylated β-cyclodextrins. The fresh grape juice, the corresponding must, the young and the bottle maturated wine of muscat cultivars are investigated.

Ethyl Carbamate Precursors in Grape Juice and the Efficiency of Acid Urease on Their Removal

Non-fermented juices from 15 different grape varieties grown in New York were found to generate 19 to 54 µg/L of ethyl carbamate upon heating at 70°C for 48 hours in the presence of 12% added ethanol. These findings show that ethyl carbamate precursors are present already in the fresh grape juice. Incubation of grape juice with acid urease for four weeks at 37°C did not reduce the amount of ethyl carbamate formed in the presence of alcohol. Urea analyses of the various grape juice showed no detectable amount of urea. Apparently, urea is not a precursor in natural grape juice. No correlation was found between the amount of potential ethyl carbamate and the concentrations of citrulline and arginine.

Effects of grape skins and seeds on the composition and quality of muscadine wines

The contributions of grape skins and seeds to the composition and quality of muscadine wines, when these are present during a partial fermentation process, were determined. The presence of the grape components affected total and volatile acidity, total phenol and volatile ester concentrations, as well as wine color. The quality of white wine made from partially fermented must in the presence of grape skins and seeds was lower than that in which the seeds were absent during this process, as well as that which was produced from fresh grape juice. Grape seeds had no significant effect on the sensory scores for red wines.

Fate of DDT and parathion in grapes processed into arak, an alcoholic beverage.

Arak, the national alcoholic drink in Lebanon, was prepared from grapes to which either DDT or parathion had been added. Samples of the nine fractions produced from the fermentation and distillation steps were analyzed for DDT and parathion and their respective metabolites. DDT degraded to DDD during the fermentation step resulting in a sharp decrease in DDT level. The two distillation steps contributed to a further decrease in the DDT level so that the final product contained less than 2% of the amount found in the fresh grape juice. Although the concentration of DDD increased sharply during fermentation, it also decreased to a negligible level during the subsequent distillation procedure. Parathion was more stable than DDT during the fermentation and first distillation steps. However, the second distillation process caused a sharp decline in its level and the Arak contained only about 6% of the residues present in the fresh juice, paranithophenol being the only metabolite detected.

New Baits and Attractants for Slugs

The slug Deroceras reticulatum (Muller) was attracted to beer and fell into shallow vessels of the liquid and drowned. Moderately attractive baits were fresh unfermented grape juice and a fermenting sugar-yeast Drosophila bait. Commercial and laboratory-prepared metaldehyde baits on wheat bran or a plastic foam (Oasis®) were increased in effectiveness when moistened with beer but were no more effective than beer alone. Bay 37344 (4-(methylthio)-3,5-xylyl methylcarbamate) on bran and plastic foam plus beer also were highly effective. Baits containing metaldehyde on wheat bran or rice hulls were also increased in attractiveness to Vaginulus plebeius Fisher by adding beer. Observations indicate that slugs do not deliberately crawl into the liquid but tumble in from edges of the vessels.