•Leaf removal and reflective mulch impact on red wines: Merlot, Teran and Plavac mali.•Leaf removal had the strongest influence on phenolic composition of wines.•Reflective mulch treatment had the ...least effect on phenolic composition of wines.•Total phenols, anthocyanins and flavan-3-ols contents exhibited strong correlation with antioxidant activity.
Two years study was conducted to evaluate if leaf removal and red geotextile reflective mulch affect phenolic composition of wines from three red wine grape cultivars, Merlot, Teran and Plavac mali (Vitis vinifera L.). Leaf removal (LR) and reflective mulch (RM), made from weave of aluminum platelets protected by a transparent film and sewn together with red polypropylene threads, were tested separately and combined (LR+RM) on vines of Merlot, Teran and Plavac mali in 2009 and 2010 years, and compared with untreated control. All treatments were applied at veraison. LR had the strongest influence on phenolic composition of experimental wines, particularly in terms of increasing gallic acid, catechin, malvidin-3-glucoside, delphinidin-3-glucoside and peonidin-3-glucoside content. LR+RM resulted in higher gallic acid and malvidin-3-glucoside concentrations. RM treatment had the least effect on phenolic composition of wines but still affected higher epicatechin and gallic acid content. The total phenols, anthocyanins and flavan-3-ols contents in wines exhibited strong correlation with antioxidant activity.
Grapevine leaves are photosynthetically the most active green organs providing carbohydrates that are of utmost importance for the regular vine’s metabolism and growth. Moreover, leaves are the ...pioneers of fungal infections caused by B. cinerea, E. necator, and P. viticola. Plant response to these microorganisms mostly depends on the content and composition of phenolic compounds abundantly found in the leaf’s outer tissues (epidermis, cuticle, trichomes). In order to obtain a satisfactory quantity of phenolic compounds, an experiment was conducted towards optimizing a solid–liquid extraction method. Variables were as follows: the type of organic solvent, the sample weight, the extraction temperature, and the extraction time. The optimal conditions were obtained by applying the response surface methodology. Therefore, by using acetonitrile as the organic solvent, conducting a single-step extraction at the temperature of 48 °C during the time period of 2 h and 25 min with a solid-to-solvent ratio of 1:56 g mL−1 (178 mg of leaves powder and 10 mL of extraction solvent) the optimal content of phenolic compounds was obtained. This protocol is reliable, fast, and relatively easy to perform for the determination of the abovementioned compounds.
During the ripening process of grapes, the grapevine leaves are the most active green organs that are important for photosynthesis, which is closely linked to the development and metabolism of the ...plant. The detection of plant pigments and phenolic compounds in grapevine leaves can be a good indicator of the ageing process, vine vigor and the plant's ability to respond to fungal attack. In a one-year study, the development of leaf chlorophylls, carotenoids and phenolic compounds during the ripening of six indigenous Croatian grape cultivars and the international cultivars Merlot and Chardonnay was investigated. The chlorophyll a/b ratio and total chlorophyll and total carotenoid concentrations were also investigated. PCA was used to highlight relevant information from the data with the aim of distinguishing individual compounds based on the cultivar and phenological stage. The leaf total hydroxycinnamic acid and flavan-3-ol concentrations decreased slowly during grape development, with the highest concentration immediately after flowering and the lowest during grape ripening. The concentrations of β-carotene, lutein and xanthophylls tended to decrease during bunch closure or veraison, while the concentration of chlorophylls a and b peaked during veraison and then decreased during grape ripening. This research will provide an opportunity to select cultivars with the physiological adaptation to synthesize secondary metabolites that are important for managing stress conditions.
The biochemical response and gene expression in different grapevine cultivars to water deficit are still not well understood. In this study, we investigated the performance of four traditional ...Croatian Vitis vinifera L. cultivars (‘Plavac mali crni’, ‘Istrian Malvasia’, ‘Graševina’, and ‘Tribidrag’), and one wild (Vitis vinifera subsp. sylvestris) genotype exposed to water deficit (WD) for nine days under semi-controlled conditions in the greenhouse. Sampling for biochemical and gene expression analyses was performed at days six and nine from the beginning of WD treatment. The WD affected the accumulation of metabolites with a significant increase in abscisic acid (ABA), salicylic acid (SA), and proline in the leaves of the stressed genotypes when the WD continued for nine days. Lipid peroxidation (MDA) was not significantly different from that of the control plants after six days of WD, whereas it was significantly lower (297.40 nmol/g dw) in the stressed plants after nine days. The cultivar ‘Istrian Malvasia’ responded rapidly to the WD and showed the highest and earliest increase in ABA levels (1.16 ng mg−1 dw, i.e., 3.4-fold increase compared to control). ‘Graševina’ differed significantly from the other genotypes in SA content at both time points analyzed (six and nine days, 47.26 and 49.63 ng mg−1 dw, respectively). Proline level increased significantly under WD (up to 5-fold at day nine), and proline variation was not genotype driven. The expression of aquaporin genes (TIP2;1 and PIP2;1) was down-regulated in all genotypes, coinciding with the accumulation of ABA. The gene NCED1 (9-cis-epoxycarotenoid dioxygenase) related to ABA was up-regulated in all genotypes under stress conditions and served as a reliable marker of drought stress. This work suggests that the stress response in metabolite synthesis and accumulation is complex, treatment- and genotype-dependent.
Dalmatian vineyards host many autochthonous varieties. The phenolic profile, defined by the relative proportions of different phenolic compounds, is specific for each grape variety. The aim of this ...study was to determine and analyze the flavonoid compounds of twenty rare red grape varieties. Nineteen phenolic compounds, represented by anthocyanins, flavanols, and flavonols, were detected and quantified using HPLC in three consecutive vintages. The content of grape skin anthocyanins (10414.06 (Plavac mali crni)-19.58 (Trišnjavac) mg kg−1 d.w. of grape skin), flavonols (1742.08 (Pošip crni)-215.56 (Crljenak viški) mg kg−1 d.w. of grape skin), and flavan-3-ols (448.04 (Pošip crni)-87.88 (Glavinuša) mg kg−1 d.w. of grape skin) showed significant differences in investigated varieties. According to the investigated phenolic compounds, Pošip crni, Ljutun, Zadarka, Dobričić, Plavac mali crni, and Trnjak differed from other investigated varieties. These local varieties can be perceived as an alternative to widespread varieties in Dalmatia. This was shown by one of the first studies on phenolic profiles of (mostly) rare autochthonous varieties.
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.
The aim of this work was to determine the effect of different drying treatments: freeze-drying, room-drying, and oven-drying on the grape phenolic composition of the 'Regent' and 'Cabernet Sauvignon' ...varieties. After drying, the samples were grounded, submerged to ultrasound-assisted extraction, and analyzed with high-performance liquid chromatography (HPLC). This study demonstrated that the use of different drying methods significantly affects the content of polyphenols in grape skins extracts. The greatest content of anthocyanins-diglucoside was preserved using freeze-drying, i.e. 15706.86 mg/kg for 'Regent', while the content of anthocyanins-monoglucoside was best preserved by room-drying, i.e. 216778.68 and 9220.30 mg/kg for 'Regent' and 'Cabernet Sauvignon', respectively. The highest content of flavonol glycosides (2583.04 and 1429.64 mg/kg for 'Regent' and 'Cabernet Sauvignon', respectively), hydroxycinnamic acids (1303.31 and 544.88 mg/kg for 'Regent' and 'Cabernet Sauvignon', respectively), and stilbene (2321.52 and 79.36 mg/kg for 'Regent' and 'Cabernet Sauvignon', respectively) was observed in the oven-dried samples. By applying freeze-drying the most optimal content of flavan-3-ol was preserved. Contents of polyphenolic compounds in oven-dried samples after 6 months of storage were almost identical to those in the samples analyzed immediately after drying. The greatest rate of degradation was observed in the room-dried samples while it was moderate in the freeze-dried ones. The results of this experiment demonstrate that it is necessary to dry samples in different ways to obtain the highest content of a certain polyphenolic group of compounds. The application of a drying method is determined by the goal of the final dried product in terms of content and composition of different polyphenolic compounds; thus, the obtained results could have an application in scientific research and for commercial purposes as well.
Agrivoltaics and aquavoltaics combine renewable energy production with agriculture and aquaculture. Agrivoltaics involves placing solar panels on farmland, while aquavoltaics integrates photovoltaic ...systems with water bodies and aquaculture. This paper examines the benefits and challenges of agrivoltaics and aquavoltaics, focusing on their potential for Croatian agriculture and freshwater aquaculture. Benefits include dual land use, which allows farmers to produce clean energy while maintaining agricultural practices. They diversify renewable energy sources and reduce dependence on fossil fuels and greenhouse gas emissions. Solar panels in agrivoltaics provide shade, protect crops, reduce water needs, and increase yields. Challenges include high initial costs and limited accessibility, especially for small farmers. Integration with existing systems requires careful planning, considering irrigation, soil moisture, and crop or fish production. Maintenance and cleaning present additional challenges due to dust, debris, and algae. Policy and regulatory frameworks must support implementation, including incentives, grid integration, land use regulations, and conservation. The location, resources, and crops grown in Croatia present an opportunity for agrivoltaics and aquavoltaics, considering cultivation methods, species, and regulatory requirements.
The aim of this study was to assess the influence of the application of mycorrhizal fungal inoculum on “Cabernet Sauvignon” (Vitis vinifera L.) leaf gas exchange, yield parameters, as well as grape ...berry composition, especially regarding phenolic compounds. The experiment was conducted over two years under natural vineyard conditions of the Zagreb wine-growing area, the continental region of Croatia. “Cabernet Sauvignon” grapevines were grafted on SO4 rootstock, both being commonly used in all wine production areas in Croatia. Results obtained demonstrated that symbiotic grapevines, in general, expressed improved leaf gas exchange parameters and higher yield parameters, especially regarding the number of clusters per vine. It should be emphasized that mycorrhizal fungi affected higher total flavan-3-ols, total anthocyanins, and total polyphenols in berry skin in both experimental years. Despite variation in some yield parameters, generally, it is possible to obtain higher yields together with the improved phenolic composition of grapes.
The practical application of grape quality zoning and selective harvesting in small vineyards (<1 ha) has not yet gained much importance worldwide. However, winegrowers with small vineyards are ...looking for ways to improve wine quality and maximise profit. Therefore, the aim of this study was to identify the most predictive vegetation index for grape quality zoning among three vegetation indices—NDVI, NDRE, and OSAVI—at three grapevine growth stages for the efficient use in small vineyards for the selective harvesting and production of different wine types from the same vineyard. Multispectral images were used to delineate two vigour zones at three different growth stages. The target vines were sampled, and the most predictive vegetation index was determined by overlapping the quality and vigour structures for each site and year. A differential economic analysis was performed, considering only the costs and revenues associated with grape quality zoning. The results show that OSAVI is the least predictive, while NDVI and NDRE are useful for grape quality zoning and selective harvesting. Multi-year monitoring is required to determine the ideal growth stage for image acquisition. The use of grape quality zoning and selective harvesting can be economically efficient for small wineries producing two different “super-premium” wines from the same vineyard.
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