Institute of Agriculture and Tourism

Poreč, Croatia

Institute of Agriculture and Tourism

Poreč, Croatia
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Bubola M.,Institute of Agriculture and Tourism | Sivilotti P.,University of Udine | Poni S.,Catholic University of the Sacred Heart
American Journal of Enology and Viticulture | Year: 2017

This study aimed to assess the effects of early leaf removal (ELR) and cluster thinning (CT) on vegetative growth, yield components, and berry composition of Teran (Vitis vinifera L.) grown in the Istria region of Croatia. Both treatments were compared with an untreated control (UC) during the 2012 and 2013 growing seasons. ELR involved the removal of six basal leaves at the preflowering stage, while in CT, 35% of clusters were removed at the onset of veraison. Both ELR and CT resulted in lower yield per vine compared to UC (22 and 37% less, respectively), and in greater Brix at harvest (+1.3 and +1.0, respectively). The concentration of total phenolics in grapes increased by 19% in ELR and by 6% in CT compared to UC, while total anthocyanin concentrations increased only in ELR (+20% versus UC). Despite greater yield and a lower leaf area-to-yield ratio compared to CT, ELR achieved higher total anthocyanin and phenolic concentration, suggesting that ELR is more suitable than CT for the production of high-quality Teran grapes. © 2017 by the American Society for Enology and Viticulture. All rights reserved.

Lukic I.,Institute of Agriculture and Tourism | Lotti C.,Research and Innovation Center | Vrhovsek U.,Research and Innovation Center
Food Chemistry | Year: 2017

Recently, various technologies which utilise fermentation with skins have been developed for obtaining distinct white wines. This study first reports the dynamic changes of volatiles and phenols that occur during skin fermentation in white winemaking. Volatiles were analysed by solid-phase extraction (SPE), solid-phase microextraction (SPME) and gas chromatography (GC), and phenols by ultra-performance liquid chromatography (UPLC), both with mass spectrometric detection. Monoterpenols increased during the first 3 days of skin fermentation, after which certain glycosides decreased, but were higher than in control. The presence of skins reduced ho-trienol, β-damascenone, acids and esters. After a 1–3 days lag phase, skin fermentation caused a constant increase of most phenols. It was estimated that skin fermentation up to 1–3 days might be beneficial for monoterpenol varietal aroma, which should be re-evaluated through further studies. Longer durations promoted phenol extraction more strongly, which is possibly suitable for obtaining more distinct wines or blending components. © 2017 Elsevier Ltd

Bubola M.,Institute of Agriculture and Tourism | Persuric D.,Institute of Agriculture and Tourism
Journal of Food, Agriculture and Environment | Year: 2011

The effects of cluster thinning on productive characteristics and wine phenolic composition of a red grapevine variety Merlot (Vitis vinifera L.) was evaluated in this study. Cluster thinning consisted of removing upper clusters on shoots in order to remove 30% and 60% of clusters at veraison. Control treatment without cluster thinning was also applied. Two levels of cluster thinning reduced yield by 19% and 40%, respectively. Average cluster weight and leaf area/fruit weight ratio were increased and fruit maturity was advanced with cluster thinning. Wines produced from cluster thinned treatments had higher alcohol content, lower acidity, higher concentration of total phenolics, total anthocyanins and higher color intensity comparing to the control treatment. Cluster thinning affected not only the total anthocyanin concentration but also the anthocyanin profile in wines. It significantly increased the levels of delphinidin-3-monoglucoside, cyanidin-3-monoglucoside, petunidin-3-monoglucoside and peonidin-3-monoglucoside, while the concentration of the most abundant individual anthocyanin malvidin-3-monoglucoside and acylated anthocyanins did not differ considerably among treatments. The highest increase in the concentration of phenolic compounds occurred in the treatment with 60% of clusters removed. It was concluded that more than 1.5 m 2 of leaf area per kg of fruit was needed for the production of high quality Merlot wine, which is especially adequate for aging due to high concentration of phenolic compounds.

Bohinc T.,University of Ljubljana | Ban S.G.,Institute for Adriatic Crops | Ban D.,Institute of Agriculture and Tourism | Trdan S.,University of Ljubljana
Archives of Biological Sciences | Year: 2012

This review discusses the importance of glucosinolates in plant protection. The Brassicaceae, which are cultivated worldwide, use glucosinolates and their decomposition products to defend themselves against attacks by harmful organisms. The glucosinolate content varies among individual plant species, plant organs and developmental stages. The glucosinolate content in plants is also affected by biotic and abiotic factors, while the type or quantity of glucosinolate determines the susceptibility of the plants to insect pests. These facts can pose a problem when implementing this knowledge in cultivation of the Brassicaceae, especially in regions with moderate climates where Brassicaceae crops are exposed to attacks by a large number of harmful organisms. Under these circumstances, it is essential to research new, or to improve the existing environmentally acceptable methods of protecting Brassicaceae plants against economically important pests.

Lukic I.,Institute of Agriculture and Tourism | Horvat I.,Institute of Agriculture and Tourism
Food Technology and Biotechnology | Year: 2017

To diff erentiate monovarietal wines made from native and introduced varieties in Istria (Croatia), samples of Malvazija a istarska, Chardonnay and Muscat yellow from two harvest years (2013 and 2014) were subjected to headspace solid-phase microextraction and gas chromatographic/mass spectrometric analysis (HS-SPME-GC/MS) of volatile aroma compounds. Signifi cant eff ects of variety and harvest year were determined, but their interaction complicated the diff erentiation. Particular compounds were consistent as markers of variety in both years: nerol for Malvazija, ethyl cinnamate and a tentatively identifi ed isomer of dimethylbenzaldehyde for Chardonnay, and terpenes for Muscat yellow. Wines from 2013 contained higher concentrations of the majority of important volatiles. A 100 % correct diff erentiation of Malvazija istarska and Chardonnay wines according to both variety and harvest year was achieved by stepwise linear discriminant analysis.

Lukic M.,Institute of Agriculture and Tourism | Lukic I.,Institute of Agriculture and Tourism | Krapac M.,Institute of Agriculture and Tourism | Sladonja B.,Institute of Agriculture and Tourism | Pilizota V.,Josip Juraj Strossmayer University of Osijek
Food Chemistry | Year: 2013

Sterols and triterpene diols in olive oil as indicators of variety and degree of ripening derived from three olive varieties and produced at three different harvesting periods were studied. In order to test the stability of the proposed indicators, oils obtained were stored for 12 months at three different temperatures. Thirty-six samples in total were subjected to GC analysis and results were processed by multivariate chemometric methods (MANOVA, PCA, and SLDA). Campesterol, β-sitosterol, Δ7-campesterol/ Δ5,24-stigmastadienol, clerosterol, uvaol, and campestanol/Δ7-avenasterol were established as the indicators of variety of fresh oils, while when stored oils were included in the model, the final three compounds were substituted by 24-methylene-cholesterol/ stigmasterol. The most important variables for differentiating fresh oils according to degree of ripening were Δ7-campesterol/β- sitosterol, uvaol/stigmasterol, clerosterol/Δ5-avenasterol and sitostanol/uvaol, while stored oils were differentiated by campestanol/ stigmasterol, erythrodiol, stigmasterol/Δ7-campesterol, Δ5-avenasterol, 24-methylene-cholesterol/β-sitosterol and 24-methylene-cholesterol. Results demonstrated that sterols and triterpene diols can be used as indicators of variety and degree of ripening among virgin olive oils. © 2012 Elsevier Ltd. All rights reserved.

Bubola M.,Institute of Agriculture and Tourism | Persuric D.,Institute of Agriculture and Tourism
Agriculturae Conspectus Scientificus | Year: 2012

The influence of partial defoliation performed at different grapevine growth stages on yield components, vegetative growth and fruit composition of 'Istrian Malvasia' ('Malvazija istarska') vines was investigated. During two consecutive seasons partial defoliation was performed manually at three grapevine growth stages; before bloom (BB), after bloom (AB), and at the beginning of bunch closure (BC). Three to four leaves on the basal part of primary shoots were removed in order to obtain moderately open grapevine canopy with good bunch exposure to sunlight. Control treatment without partial defoliation was also included. Partial defoliation did not significantly affect any of yield components of 'Istrian Malvasia' vines. The only consistent response to partial defoliation was the regrowth of laterals if partial defoliation was done early in the season, leading to the recovering of the removed leaf area from primary shoots. Less intensive regrowth of laterals occurred on BC treatment, resulting in the smallest leaf area per vine and the lowest leaf area/yield ratio, but the differences among treatments were not significant. Basic composition of 'Istrian Malvasia' grape juice (soluble solids, titratable acidity and pH) was not significantly affected by the timing of partial defoliation, but soluble solids tended to be higher in BB treatment and lower in BC treatment. It is concluded that the removal of three to four leaves per shoot at different grapevine growth stages did not considerably affect yield components and basic fruit composition of 'Istrian Malvasia' vines.

Brkic Bubola K.,Institute of Agriculture and Tourism | Koprivnjak O.,University of Rijeka | Sladonja B.,Institute of Agriculture and Tourism
Food Chemistry | Year: 2012

The influence of filtration through a hydrophilic cotton layer on volatile compounds, sensory characteristics and colour of two monovarietal oils was investigated in this study. Volatiles were evaluated using headspace solid-phase microextraction-gas chromatography. After the filtration of Buža oils only a slight increase in total alcohols was noticed. In filtered Črna oils a significant decrease of total alcohols and slight changes in total aldehydes, total ketones and total C5 volatile compounds concentration were detected. No significant influence on the sensory scores of oils, but some slight changes in sensorial profiles were noted (slightly higher intensities of sensory characteristics apple and grass, and higher values of the lightness L in filtered samples). The results point to unequal filtration impact on different monovarietal oils and could be useful in developing targeted technologies for specific monovarietal oils quality improvement. © 2011 Elsevier Ltd. All rights reserved.

Radeka S.,Institute of Agriculture and Tourism | Lukic I.,Institute of Agriculture and Tourism | Persuric D.,Institute of Agriculture and Tourism
Food Technology and Biotechnology | Year: 2012

The influence of different grape mash maceration treatments on the varietal and secondary aroma profiles of wines produced from an aromatic red grape variety, Muškat ruža porečki, have been investigated. Two essentially different techniques were applied, fermentative maceration at room temperature and prefermentative cryomaceration, both in durations of one, three and five days. Generally, higher concentrations of free and bound varietal aroma compounds were found in wines obtained by maceration at room temperature in relation to cryomaceration. Regarding the effect of the duration of maceration, the highest concentrations were determined in wines obtained by three-day maceration treatments, in both fermentative and cryomaceration treatments. Secondary aroma compounds followed a less uniform pattern. The compounds with the highest odour unit values in all investigated wines were linalool, citronellol, geraniol, β-damascenone, β-ionone, isoamyl alcohol, 2-phenylethanol, ethyl hexanoate, ethyl octanoate, isoamyl acetate, ethyl acetate, and diethyl succinate. It has been shown that Muškat ruža porečki is an aromatic variety, producing wines with notable monoterpenol fraction, which are characterized by a typical varietal Muscat aroma with a dominant rose odour accompanied by red fruit nuances. Sensorially, longer maceration treatments improved odour and overall wine quality, together with the intensity and recognisability of varietal Muscat aroma, while short-term cryomaceration emerged as a preferable technique for the production of light rosé wines with pronounced Muscat aroma and low phenolic content. The presented maceration techniques were shown to be applicable for the production of different types of Muškat ruža porečki rosé and red wines.

Bubola K.B.,Institute of Agriculture and Tourism | Koprivnjak O.,University of Rijeka | Sladonja B.,Institute of Agriculture and Tourism | Lukic I.,Institute of Agriculture and Tourism
Food Technology and Biotechnology | Year: 2012

The volatile compounds found in virgin olive oil, mainly C6 and C5 volatile compounds biogenerated from polyunsaturated fatty acids through the lipoxygenase pathway, are responsible for their particular aroma. The composition of volatile compounds in olive oil depends on the cultivar, the ripening degree of the fruits and processing conditions. Among many different autochthonous cultivars in Istria (Croatia), some of the most prevalent are Buža, Črna and Rosinjola. The volatiles and sensory characteristics of their monovarietal virgin olive oil are little known. Therefore, fruits from these three cultivars were handpicked at the same ripening degree and processed under the same conditions. Quantitative descriptive sensory analysis of monovarietal virgin olive oil was carried out by the panel. Volatile composition was evaluated by headspace solid phase microextraction-gas chromatography, previously optimized and validated. The main parameters affecting effectiveness, time and temperature of extraction were optimized. The extraction procedure showed detection and quantification limits, as well as linear ranges adequate for the analysis of selected volatile compounds. Good precision was obtained both in terms of intraday repeatability (relative standard deviations generally lower than 7 %) and interday precision. The tested types of monovarietal olive oil showed different volatile profiles, although E-2-hexenal was the main compound in all samples. Bu'a oil was the richest in total C6 and C5 volatile compounds. The results show that the most important contributors to the olive oil aroma (odour activity value >1.0) were 1-penten-3-one, E-2-hexenal, hexanal, hexanol, Z-3-hexen-1-ol and Z-2-penten-1-ol. These chemical findings were compared with those provided by the panel test. Buža had the highest intensity of sensory characteristic 'other ripe fruits' and Rosinjola had the highest intensity of sensory characteristic 'bitter'. All results show that olive oil aroma compounds accumulate differently depending on the cultivar, indicating a close dependence on the enzymatic pool, which is genetically dependent.

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