| Abstract | Proizvodnja bijelih vina uglavnom se odvija standardnom tehnologijom prerade grožđa koja ne obuhvaća maceraciju masulja, a tako proizvedena bijela vina prepoznatljivih su senzornih svojstava. Nedostatak ovakvog načina proizvodnje očituje se manjkom biološki aktivnih spojeva vina, kao i ostalih spojeva uglavnom sadržanih u čvrstim dijelovima bobice grožđa. Umjerena konzumacija vina bogatih biološki aktivnim spojevima potencijalno može povoljno utjecati na zdravlje potrošača. Primjenom maceracije masulja u proizvodnji bijelih vina moguće je utjecati na sastav i koncentraciju spojeva koji određuju konačnu kvalitetu vina i njegov bioaktivni potencijal. Glavni cilj ovog istraživanja bio je utvrditi utjecaj primjene pretfermentacijske maceracije, fermentacijskih i produljenih poslijefermentacijskih maceracija masulja autohtone hrvatske sorte 'Malvazija istarska' (Vitis vinifera L.) na osnovni fizikalno-kemijski sastav, koncentraciju aromatskih i fenolnih spojeva, vitamina, makroelemenata i mikroelemenata, antioksidacijski potencijal te senzorna svojstva proizvedenih vina. Istraživanje je obuhvaćalo sljedeće tretmane: brza prerada grožđa bez maceracije masulja (kontrolni tretman, K), dvodnevna pretfermentacijska maceracija masulja na temperaturi od 8 °C (CRIO), sedmodnevna maceracija masulja na temperaturi od 16 °C (M7), 14-dnevna maceracija masulja na temperaturi od 16 °C (M14), 21-dnevna produljena poslijefermentacijska maceracija masulja na temperaturi od 16 °C (M21) te 42-dnevna produljena poslijefermentacijska maceracija masulja na temperaturi od 16 °C (M42). Osnovni fizikalno-kemijski sastav vina određen je standardnim metodama prema Međunarodnoj organizaciji za vinovu lozu i vino (OIV). Pojedinačni fenolni spojevi analizirani su primjenom tekućinske kromatografije visoke djelotvornosti (HPLC) dok je koncentracija ukupnih fenola određena UV-Vis spektrofotometrom. Primjenom UV-Vis spektrofotometrije analizirana je i antioksidacijska aktivnost vina metodama FRAP i ORAC. Tekućinskom kromatografijom visoke djelotvornosti određene su koncentracije vitamina C te vitamina B skupine dok je za analizu makroelemenata i mikroelemenata korištena multielementarna metoda određivanja elemenata (ICP-OES). Ekstrakcija hlapljivih spojeva arome vina provedena je tehnikom mikroekstrakcije na čvrstoj fazi (SPME), a identifikacija i kvantifikacija spojeva provedena je pomoću vezanog sustava plinski kromatograf – spektrometar masa (GC-MS). Vina su senzorno ocijenjena metodom kvantitativne deskriptivne senzorne analize i O.I.V. metodom 100 bodova. Dobiveni rezultati razjasnili su utjecaj pretfermentacijske, fermentacijske i produljene poslijefermentacijske maceracije na kemijski sastav te bioaktivna i senzorna svojstva vina sorte 'Malvazija istarska'. Više koncentracije fenolnih spojeva, makroelemenata i mikroelemenata te vitamina B skupine utjecale su na porast antioksidacijske aktivnosti vina, a samim time i na njegova bioaktivna svojstva u tretmanima fermentacijske i produljene poslijefermentacijske maceracije. S obzirom na proporcionalan porast navedenih spojeva s duljinom trajanja maceracije, najviše se istaknuo tretman produljene poslijefermentacijske maceracije u trajanju od 42 dana. Suprotno, niže koncentracije fenolnih spojeva u tretmanu pretfermentacijske maceracije rezultirale su slabijom antioksidacijskom aktivnosti vina ali i manje izraženim osjetima gorčine i astringencije od ostalih tretmana maceracije, dok su za izraženiju voćnost pretfermentacijskog tretmana zaslužne više koncentracije etilnih estera. Primjena postupka maceracije tijekom i/ili nakon završene fermentacije, također je pozitivno utjecala na senzorni profil vina kojim su dominirali mirisi suhog/prosušenog i orašastog voća, bilja i začinskog bilja te dojam punog tijela i aftertaste-a. Neovisno o duljini maceracije, sva vina zadržala su karakteristike sorte te ostavila snažniji ukupni dojam od vina kontrolnog tretmana. Dobiveni rezultati omogućili su identifikaciju spojeva odgovornih za promjene u bioaktivnim i senzornim svojstvima vina te su pružili uvid u dinamiku njihovog oslobađanja i međusobne interakcije. Značaj dobivenih rezultata proizlazi iz mogućnosti odabira odgovarajuće tehnologije s ciljem proizvodnje visokokvalitetnih vina specifičnih bioaktivnih i senzornih svojstava, uz maksimalno iskorištavanje potencijala sorte 'Malvazija istarska'. |
| Abstract (english) | White wine production is mainly carried out by standard grape processing technology, without the mash maceration process. White wines produced using such technology exhibit recognisable sensory characteristics and are acceptable among consumers. However, the drawback of this production approach manifests in a deficiency of wine bioactive compounds, and other compounds predominantly located in the solid parts of the grape berry. The maceration process plays a crucial role in shaping the character of white wines, contributing positively to their biochemical composition and distinctive sensory properties. While maceration is more commonly associated with red winemaking, it has found a valuable place in the production of certain white wines. During maceration, the grape solids are in contact with the juice, allowing the extraction of aromatic compounds, nutrients, and bioactive compounds such as phenolic compounds, vitamins and minerals. This extended contact not only enhances the wine's antioxidant potential but also imparts a depth of flavour and a nuanced aromatic profile. Maceration can bring forth floral, fruity, but also herbal notes that contribute to the overall complexity of the wine. As a result, white wines that undergo maceration exhibit a unique combination of bioactive compounds and sensory characteristics, offering consumers a more enriched product. In addition, moderate consumption of wines rich in bioactive compounds potentially has a favourable effect on consumer health. Therefore, the main goal of this research was to determine the influence of pre-fermentative, fermentative, and prolonged post-fermentative mash macerations of autochthonous Croatian variety Malvazija istarska (Vitis vinifera L.) on the basic physicochemical composition, aromatic and phenolic compounds concentration, vitamins, macroelements and microelements, antioxidant activity and sensory properties of the produced wines. The experiment was performed during vintages 2019 and 2020, using a white grape variety Malvazija istarska (Vitis vinifera L.), the second most widespread autochthonous variety in Croatia. Six different vinification treatments were carried out: fast grape processing without maceration (control treatment, K), pre-fermentative two-day maceration at 8 °C (CRIO), seven-day maceration at 16 °C (M7), 14-day maceration at 16 °C (M14), prolonged post-fermentative 21-day maceration at 16 °C (M21), and prolonged post-fermentative 42-day maceration at 16 °C (M42). The basic physicochemical composition of the wines was determined by standard methods according to the International Organization of Vine and Wine (OIV). Individual phenolic compounds were analysed using high-performance liquid chromatography (HPLC), while total phenolic content was determined using a UV-Vis spectrophotometer. The antioxidant activity of the wines was assessed spectrophotometrically using the FRAP and ORAC methods. Concentrations of vitamin C and B-group vitamins were determined by HPLC, and a multi-element method using inductively coupled plasma optical emission spectrometry (ICP-OES) was employed for the analysis of macroelements and microelements. The extraction of volatile aroma compounds in the wines was conducted using a solid-phase microextraction (SPME) technique, and compound identification and quantification were performed using a gas chromatograph-mass spectrometer (GC-MS) system. The wines were subjected to sensory evaluation using quantitative descriptive sensory analysis (QDA) and the O.I.V. 100-point evaluation method. Statistic data elaboration was performed using a one-way analysis of variance (ANOVA) and Fischer’s least significant difference test (LSD) to compare the mean values (n = 3) at the level of significance p ˂ 0,05. Multivariate data analysis was performed by principal component analysis (PCA) to obtain an overview of the natural data grouping and Pearson’s correlation was used to investigate the relationship between certain variables. The results indicate that the application of maceration in the production of Malvazija Istarska wines resulted in significant changes in the physicochemical composition of the wine, concentration of aromatic and phenolic compounds, vitamins, as well as macroelements and microelements compared to the control treatment, without maceration. The maceration process significantly influenced the increase in total phenolic content and the majority of individual phenolic compounds compared to the control treatment, where prolonged post-fermentation maceration for 42 days (M42) stood out the most, especially regarding hydroxybenzoic acid and flavan-3-ol concentrations. Regardless of the maceration duration, a positive effect was noted on the increase in macroelements and microelements in wines compared to the control treatment. B-group vitamin content increased as the maceration duration progressed, and the highest concentrations of total B vitamins were achieved in the M42 treatment. It was also observed that the antioxidant activity of the wines, due to higher concentrations of bioactive compounds, increased proportionally with maceration duration, with the M42 treatment being particularly prominent. Maceration also influenced the volatile aroma compounds by increasing monoterpenes, alcohols, and certain esters, especially in those treatments where prolonged post-fermentation maceration was applied (M21 and M42). In one experimental year, an increase in total C13-norisoprenoids was observed in all maceration treatments. However, maceration also led to a decrease in fatty acids, ethyl and acetate esters. Except for fruity and floral characteristics, which were also noted in the control treatment, sensory characteristics of wines produced with maceration were best described by the scents of dried and nutty fruits, as well as herbal and spicy aromas. Such aromas were most prominent in the fermentation and prolonged post-fermentation maceration treatments (M14, M21, and M42). Maceration led to a stronger perception of bitterness and astringency in wines but did not negatively impact the impression of tannin quality and presence in these wines. Maceration during fermentation and prolonged post-fermentation maceration also stood out in terms of the intensity and quality of aftertaste, as well as wine body/fullness perception. Wines produced by the two-day pre-fermentation maceration treatment at 8°C (CRIO) displayed less pronounced bitterness and astringency but a more accentuated floral character. This pre-fermentation procedure also influenced a lesser reduction in concentrations of fatty acids, as well as ethyl and acetate esters due to maceration compared to the other maceration treatments, in comparison to the control treatment where the highest concentrations of these compound groups were recorded. Regardless of the differences in individual taste and aroma properties, wines produced from maceration treatments generally retained the varietal characteristics and were sensory rated higher than wines from the control treatment, where maceration was not performed. The results facilitated the identification of compounds most responsible for changes in the bioactive and sensory properties of wines, providing insight into the dynamics of their release and their interactions depending on the applied maceration procedure. The significance of the obtained results lies in the selection of appropriate technology to produce high-quality wines with specific bioactive and sensory properties, while maximizing the potential of Malvazija istarska variety. |
