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Pulsed electric field (PEF) processing of white grapes (cv. Garganega) after crushing was studied on pilot-plant scale, to investigate the effects of the treatment on must and wine composition, wine color and predisposition to browning, wine aroma compounds and extraction of aroma precursors from grapes. PEF pre-treatment of grapes did not change the must or wine basic composition, nor was it able to modify the evolution of alcoholic fermentation. By contrast, PEF produced an increase in total dry extract, wine color and total phenolics. Treatment corresponding to a total specific energy of 22 kJ kg-1 allowed more intense extraction of varietal aroma precursors without provoking excessive color evolution and extraction of phenolic compounds, apparently increasing the stability of wine towards oxidation. Due to the few papers available on this subject, PEF applications on white grapes should be optimized in further experiments.

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.

Muškat ruža porečki is an autochthonous red grape variety in Istria (Croatia), typically used for the production of semi-dry to sweet (rosé and red) wines with accentuated varietal (primary) aroma due to significant monoterpene content. Usual production procedure implies maceration on ambient temperature in order to extract higher amounts of varietal aroma and phenolic compounds from grape berry skins, as well as to increase colour stability and consistency. However, the influence of maceration duration and temperature on mentioned parameters is not yet established with certainty for this variety, so it is a common case that wines produced in the region are of lower quality, lacking true varietal character despite high aromatic potential. In this work, the influence of different maceration treatments at ambient temperature (1, 3 and 5 days), and cryomaceration (1, 3 and 5 days at 5°C) on standard physico-chemical parameters (OIV methods), concentration of monoterpenes (GC-MS), colour intensity and tonality, phenol contents (total phenols, total and free anthocyanins, total flavonoids, proanthocyanidins), and antioxidant activity (UV/VIS spectrophotometry) in produced wines was investigated. Sensory evaluation of wines was performed using the 100-point OIV method. Differences between wines produced by different maceration treatments were determined for the majority of investigated parameters. The highest increase in the amounts of monoterpenes and phenols was observed in wines macerated for 3 days. Sensory evaluation showed that investigated wines also differed in organoleptic attributes, especially in varietal muscat aroma and color intensities.

During a two-year study, the effect of different grape mash maceration treatments (skin contact at 20 °C for 10, 20 and 30 h) and cryomaceration (skin contact at 7 °C for 10, 20 and 30 h) on the concentration of free and bound monoterpenes and total phenols in Malvazija istarska wine (the most spread white wine variety in Istria) was monitored. Monoterpenic alcohols linalool, a-terpineol, citronellol, nerol and geraniol were determined by gas chromatography after isolation on octadecylsilica (C18) sorbent and elution with pentane/dichlorometane ratio of 2:1, while total phenols were determined spectrophotometrically with Folin-Ciocalteau reagent. Sensory evaluation of wines was performed using the Buxbaum method. The obtained results show that linalool and geraniol are the most abundant monoterpenes in Malvazija istarska, and that grape mash maceration treatments cause significant increase of free and bound monoterpene concentrations compared to those in control treatment wine obtained without maceration. The content of phenols, which are subject to oxidation, was found to be significantly lower in wines produced by cryomaceration treatments, while in those produced by maceration at 20 °C the concentration of total phenols increased proportionally with the duration of maceration, negatively influencing wine quality by causing higher colour intensity and bitter taste., Tijekom dvogodišnjeg istraživanja praćen je utjecaj različitih postupaka klasične maceracije masulja pri 20 °C (10, 20 i 30 sati) i hladne maceracije pri 7 °C (10, 20 i 30 sati) na koncentraciju slobodnih i vezanih monoterpena, te ukupnih fenola u vinima istarske Malvazije. Monoterpenski alkoholi linalol, α-terpineol, citronelol, nerol i geraniol određeni su metodom plinske kromatografije prethodnom ekstrakcijom na sorbensu oktadecilsilicijevom dioksidu (C18) uporabom otapala pentan:diklormetan (2:1), a ukupni fenoli spektrofotometrijski s Folin–Ciocalteu reagensom. Analizirana su vina senzorski ocijenjena Buxbaum metodom. Iz dobivenih se rezultata vidi da je najviše linalola i geraniola u vinu istarske Malvazije (najraširenije bijele vinske sorte u Istri), a postupcima maceracije masulja značajno se povećava koncentracija slobodnih i vezanih monoterpena u usporedbi s kontrolnim uzorkom vina dobivenog bez maceracije. Koncentracija oksidaciji podložnih fenola kudikamo je manja u vinima proizvedenim hladnom maceracijom, dok u postupcima maceracije na 20 °C proporcionalno raste koncentracija ukupnih fenola koji negativno utječu na kakvoću vina, uzrokujući jači intezitet boje i gorčinu okusa.

In order to determine the differences in composition and sensory quality between Malvazija istarska wines obtained by standard and cryomaceration technologies, produced wines were subjected to the analysis of standard physico-chemical parameters, varietal aroma compounds and phenols. Wines were subjected to sensory evaluation by the OIV 100-point method. Malvazija istarska wines produced by cryomaceration contained higher dry extract content, higher amounts of free and bound varietal aroma compounds, and were evaluated with higher sensory evaluation scores. These wines were distinguished by the stronger body, and more complex and persistent aroma with accentuated varietal character, even after a certain period of aging.

Malvazija istarska is the most spread wine grape variety on Istrian peninsola, and the second most spread wine grape variety in Croatia. It is cultivated on more than 61 % of total Istrian vine growing area. From the grapes of this variety, dry wines with fruity and flowery aroma nuances are produced, obtained by fast grape processing and low temperature must fermentation. By cryo-maceration of grape mash it is possible to significantly increase the amount of varietal aroma compounds (predominantly contained in grape berry skins) in obtained must and, therefore, directly influence the characteristics of produced wine. On the basis of results obtained in our previous research on cryo-maceration, several Istrian wine producers applied this procedure in production of Malvazija istarska wine during harvests of 2005 and 2006. In produced wines, standard physico-chemical parameters, free and bound varietal aroma compound concentrations, flavan-3-ols concentrations and total phenols content were determined. Wines were subjected to sensory evaluation and assessed by the O.I.V. 100-point method. It was concluded that results of this investigation could be used for defining the physico-chemical and sensorial characteristics of Malvazija istarska wines produced by cryo maceration as a new brand.

During harvest 2006, the influence of grape mash pressing on aroma and phenolic composition of Malvazija istarska and Chardonnay grape musts, both originating from the western vine growing areas of Istrain peninsola, was studied. Pressing was performed using a pneumatic press of 500 L capacity. The samples of must fractions were collected at pressures of 0.5, 1.0 and 1.5 bar, while free-run must was used as a control. In all obtained musts following physico-chemical parameters were determined: sugars, pH, total acidity, varietal aroma compound concentrations, hydroxycinnamic and hydroxybenzoic acid, and flavan-3-ols concentrations, total phenols content, and antioxidant activity. On the basis of the results obtained, it was concluded that pressing significantly influence the chemical composition of analyzed musts.