Polyphenols are organic compounds that can be found in food, especially in fruits, vegetables, and their products. It was shown that their presence significantly affects the properties of food ...products and that the consumption of food rich in phenolic compounds has a beneficial effect on human health. The subjects of this research were polyphenols: anthocyanins, flavonols, and flavan-3-ols in the skin of grapevine variety Regent. Polyphenols from grape skins were extracted via microwave-assisted extraction (MAE) and matrix solid-phase dispersion (MSPD) as unconventional and green techniques. Therefore, the main aim of this work was to optimize the conditions for the extraction of polyphenolic compounds from grape skin using MAE and MSPD. The extracts were analyzed using high-performance liquid chromatography with a diode array detector and fluorescence detector. Analyses showed that MAE was a very effective method for extracting polyphenolic compounds from grape skin with 10 mL of 60% ethanol for 5 min at 40 °C. The best results for the MSPD extraction of polyphenolic compounds from grape skin were obtained with phenyl as an MSPD sorbent with 10 mL of acetonitrile:water 50:50 v/v as an elution solvent. This scientific research can be used for the better use of grapes as a basis for obtaining flavonoids for commercial purposes.
Varietal thiol concentration in wine is influenced by numerous factors, of which grape variety and winemaking practices are often highlighted as the most important. Therefore, the aim of this work ...was to study the effects of grape clone and yeast strain (
and non-
) on the varietal thiols concentrations and sensory characteristics of Graševina (
L.) white wines. Two grape clones were evaluated (OB-412 and OB-445) along with three different commercial yeast strains (
Lalvin Sensy and Sauvy, and
Flavia). The results showed that the concentration of varietal thiols in Graševina wines amounted up to a total of 226 ng/L. The clone OB-412 was characterized by its significantly higher concentrations, especially of 3-sulfanylhexanol (3SH) and 3-sulfanylhexyl acetate (3SHA). Moreover, alcoholic fermentation with pure
Sauvy yeasts generally resulted in higher thiol concentrations, while sequential fermentation involving
positively affected only the 4-methyl-4-sulfanyl-pentan-2-one (4MSP) concentration. Finally, sensory analysis showed that fermentation with pure
Sauvy yeast also produced more desirable wines. The results suggest that clonal, and especially yeast strain, selections are important modulators of the aroma and sensory properties of wine.
The aromatic and sensory profiles of monovarietal sparkling ciders made according to the modified Méthode Ancestrale or Pétillant Naturel (Pét-Nat) method were established. Three Croatian traditional ...apple varieties (‘Božićnica’, ‘Bobovac’, and ‘Crvenka’) were basic raw materials for Pét-Nat ciders in this study. The basic apple must and cider parameters were determined by applying OIV methods and nitrogenous compounds, total phenols, and color parameters were analyzed by spectrophotometer. Volatile compounds in final Pét-Nat ciders were determined by SPME-Arrow-GC/MS method and Odor Active Values (OAV) were calculated. The results show that variety significantly altered the pH value, color, aromatic and sensory profile of Pét-Nat ciders. The main contributors (OAV > 1) to the aroma of all Pét-Nat ciders were 1-hexanol, 1-propanol, (6Z)-nonen-1-ol, 1-dodecanol, hexanoic, octanoic and isovaleric acid, citronellol, ethyl hexanoate, ethyl butanoate, ethyl-9-decenoate and isoamyl acetate, eugenol and methionol. ‘Božićnica’ Pét-Nat was differentiated by a high concentration of 1-decanol and 4-ethylphenol, ‘Bobovac’ by 4-vinyl guaiacol and ‘Crvenka’ by 4-ethyl guaiacol. Sensory analysis showed that the highest rated overall quality was attributed to ‘Crvenka’ Pét-Nat cider, with the high-quality color, fruity odor (‘apple’,’apple juice/compote’, ‘pineapple’, and ‘buttery’) and well-balanced taste. This research demonstrates the possibilities in the production of natural sparkling cider from traditional Croatian apple varieties by analyzing the composition and quality of the final product for the first time.
The population of Croatian autochthonous cultivars has a high degree of infection with economically important viruses, so it is necessary to carry out the elimination of the viruses in some cultivars ...to obtain healthy planting material. In this research, we tested in vitro meristem culture establishment on 18 autochthonous cultivars with different viral infections and the possibility of GLRaV-3 elimination through in vitro meristem culture. Plant material was sampled in a vineyard in two phenological stages, 10 days before flowering and 10 days after flowering of the grapevine. Apical meristem explants (1 mm) were placed into the MS culture medium supplemented with 0.5 mg/L benzyl adenine (BA) and 0.05 mg/L indol-3-acetic acid (IAA), and their survival, regeneration, and rooting were monitored. The results showed that the cultivar and the growth phase have a significant impact on the success of in vitro culture. In all cultivars studied higher success of in vitro culture establishment parameters (survival, regeneration, and rooting) was obtained in the case of explants sampled after flowering, with the exception of one cultivar for explants survival. Contrary to expectations, genotypes infected with three viruses (GLRaV-1, GLRaV-3, and GFLV) showed better results than genotypes infected with one or two viruses. The results showed successful in vitro establishment of Croatian autochthonous cultivar and GRLaV-3 elimination in one cultivar. However, due to the significant effect of cultivar, for routine application of this in vitro protocol on more than 100 autochthonous cultivars in need of sanitation, further studies should be conducted.
Polyphenols are secondary plant metabolites and important organic compounds present in grapes, must and wine. The importance of polyphenolic compounds present in grapes is mainly related to the ...quality of the wine. Those compounds affect the colour, taste, astringency, bitterness, and potential of wine aging. Therefore, the aim of this research was to determine and compare quantitative and qualitative changes in low molecular weight polyphenol content of 11 red grapevine varieties during ripening. Samples were collected periodically from the beginning of verasion to the technological maturity. The polyphenolic compounds were analysed with high performance liquid chromatography (HPLC) with prior lyophilization and extraction. Based on the obtained results, changes in the composition and content of researched groups of polyphenolic compounds during maturation were determined. Keywords: grape berry, red grapevine varieties, polyphenolic compounds, liquid chromatography Polifenoli su sekundarni biljni metaboliti te vazni organski spojevi prisutni u grozdu, mostu i vinu. Vaznost polifenolnih spojeva prisutnih u grozdu uglavnom je vezana uz kakvocu vina obzirom da utjecu na boju, okus, astringenciju, gorcinu te potencijal starenja vina. Cilj ovog rada je utvrditi i usporediti kvantitativne i kvalitativne promjene sadrzaja polifenola male molekulske mase u kozici grozda 11 crnih sorata vinove loze tijekom dozrijevanja grozda. Uzorci su prikupljani periodicno od pocetka sare do tehnoloske zrelosti. Sadrzaj polifenola u kozici boba utvrden je tekucinskom kromatografijom visoke djelotvornosti (HPLC) uz prethodnu liofilizaciju i ekstrakciju. Temeljem dobivenih rezultata utvrdene su promjene sastava i sadrzaja pojedinih grupa polifenolnih spojeva tijekom dozrijevanja. Kljucne rijeci: boba grozda, crne sorte, polifenolni spojevi, tekucinska kromatografija Polyphenols are secondary plant metabolites and important organic compounds present in grapes, must and wine. The importance of polyphenolic compounds in grapes is mainly related to the quality of the wine. Those compounds affect the colour, taste, astringency, bitterness, and potential of wine aging. Recently, due to numerous research of the polyphenolic composition of grapes, their nutritional value as well as many positive effects on human health have been recognized. Their beneficial effect on the organism derives from antioxidant capabilities, chelating activity, and inactivation of certain enzymes that are attributed to antitumor, antimicrobial, antiallergic, neuroprotective, anti-inflammatory and many other properties. A large group of polyphenolic compounds such as phenolic acids (hydroxycinnamic and hydroxybenzoic acid), flavonoid stilbenes (anthocyanins, flavonols and flavan-3-ols) have been found in grape berry. The largest proportion of polyphenolic compounds in grape berries is contained in the seeds, then skin and pulp. Phenolic compounds are particularly important in red grape wine production technology, because they greatly affect the colour and the characteristic taste of wine. Therefore, the aim of this study is to determine the changes that occur in the polyphenol profile (hydroxycinnamic acids, anthocyanins, flavonols, flavan-3-ols) of 11 red grape varieties during ripening. The research was set up in a vineyard at the location of experimental station Jazbina, viticultural region Sredisnja bregovita Hrvatska, subregion Prigorje - Bilogora and vineyard area Zagreb. Samples were collected periodically, from the beginning of the verasion to technological maturity. They were adequately stored, lyophilized, and subjected to extraction. The obtained extracts were analysed with high performance liquid chromatography. Based on the obtained results, anthocyanins are the most common polyphenol compounds in the skin of the investigated varieties, followed by flavanol glycosides, flavanol-3-ols and hydroxymethyl acids. The mass fraction of anthocyanin and flavonol glycosides in berry skin increases from the beginning of the verasion to the technological maturity, while the mass fraction of flavan-3-ols, hydroxycinnamic acids and flavonol glycosides decreases by technological maturity.
In the era of sustainable grapevine production, there is a growing demand to define differences between
varieties in susceptibility to downy mildew. Croatia, as a country with a long tradition of ...grapevine cultivation, preserves a large number of native grapevine varieties. A leaf disc bioassay has been conducted on 25 of them to define their response to downy mildew, according to the International Organisation of Vine and Wine (OIV) descriptor 452-1, together with the stress response of the leaf discs using chlorophyll fluorescence and multispectral imaging with 11 parameters included. Time points of measurement were as follows: before treatment (T
), one day post-inoculation (dpi) (T
), two dpi (T
), three dpi (T
), four dpi (T
), six dpi (T
), and eight dpi (T
). Visible changes in form of developed
(
) sporulation were evaluated on the seventh day upon inoculation. Results show that methods applied here distinguish varieties of different responses to downy mildew. Based on the results obtained, a phenotyping model in the absence of the pathogen is proposed, which is required to confirm by conducting more extensive research.
The investigation of virus incidence was conducted on 14 autochthonous Croatian grapevine cultivars on vines from 51 vineyard located in the Dalmatian region. A total of 1,116 vines were tested by ...ELISA on nine viruses: Arabis mosaic virus (ArMV), Grapevine fanleaf virus (GFLV), Grapevine fleck virus (GFkV), Grapevine leafroll-associated virus 1, 2, 3 and 7 (GLRaV-1, GLRaV-2, GLRaV-3 and GLRaV-7), Grapevine virus A and B (GVA and GVB). ELISA confirmed presence of eight viruses: GLRaV-3 in 888 vines (79.6%), GVA 685 (61.4%), GLRaV-1 455 (40.8%), GFkV 223 (19.9%), GFLV 219 (19.6%), GLRaV-2 46 (4.1%), ArMV 36 (3.2%) and GVB 35 (3.1%). Altogether 93 vines (8.3%) were free of all tested viruses, 168 (15.1%) were infected with a single virus, 368 (32.9%) with two, 314 (28.1%) with three, 127 (11.4%) with four, 43 (3.9%) with five, and 3 (0.3%) vines with six viruses. Symptoms of premature leaf color change and downward curling of leaf blades were common, while abnormal branching, short internodes, double nodes and irregular ripening were detected sporadically. The investigation confirms deteriorated sanitary status of all cultivars except Grk and Plavina and indicates the necessity of intensifying grapevine clonal and sanitary selection programs.
Sulfur dioxide (SO
) is widely the most used enological additive with reductive, antiseptic and dissolving properties. According to increasing health concerns and the gradual decrease in total SO
...concentrations allowed in wine, alternative and supplementary agents for preservation are being investigated. For this reason, the current study was focused on the impact of different commercial reductive agents on white wine antioxidant activity and chemical composition. The effect of additives that combine sulfites, ascorbic acid and enological tannins were compared against standard 5% sulfurous acid (H
SO
) during the pre-fermentative treatments of Sauvignon Blanc must (
L.). The basic parameters of quality, free amino-nitrogen and total polyphenoliccompounds in must were analyzed. Gas chromatography and spectrophotometric methods were used to investigate the overall volatile composition, antioxidant and chromatic parameters in wines. The obtained results undoubtedly pointed out the positive effect of sulfuric acid on the fermentation dynamics. Furthermore, application of combined reducing additives with potassium metabisulfite, L-ascorbic acid, gallotannins and ellagitannins, resulted in a higher antioxidant capacity and increased concentration of aromatic compounds and their odor activity values in Sauvignon Blanc wine.
For the characterization of grape cultivars, the profile and content of flavonoids are important because these compounds have an impact on grape and wine quality. A new extraction method for the ...recovery of flavonoids, e.g. anthocyanins, flavonols and flavan-3-ols from grape skins was developed. The optimization of solid-liquid extraction of flavonoids was conducted, with respect to the type of the organic solvent and its percentage in the extraction solvent as well as the extraction temperature and extraction time, using response surface methodology. Optimal conditions were obtained by using extraction solvent composed from acetonitrile:water:formic acid (20:79:1; v/v/v), at an extraction temperature of 50 °C, an extraction time of 1 h in a single-step extraction and with a solid-to-solvent ratio of 1:80 g mL(-1) (125 mg of grape skin powder and 10 mL of extraction solvent). The new optimal extraction method is inexpensive, simple, fast, accurate and selective for the recovery of simple flavonoids.
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