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Postfermentation wine yeast lees show antioxidant properties based on their ability to consume dissolved oxygen. The oxygen consumption capacity of suspended yeast lees obtained after fermentations with six commercial active dry yeast strains was investigated in model, white and red wines using fluorescence-based oxygen sensors operating in a nondestructive way. In model solution, the oxygen consumption rate of yeast lees was shown to depend on their amount, yeast strain, sulfur dioxide and temperature. It is slightly lower in red than in white wines. It is strongly decreased by current levels of free sulfur dioxide, thus excluding the complementary use of both as antioxidants in wine. However, in 25 randomly sampled white wines produced under commercial conditions, the rate and extent of oxygen consumption during the first six months of postfermentation had no significant correlation with any of these interacting factors, making it difficult to predict the actual antioxidant effect of yeast lees. In these wines, yeast lees consumed 0 to 47 % of the dissolved oxygen. Although total oxygen consumption capacity of yeast lees is not a limiting factor under commercial winemaking conditions, their oxygen consumption proceeds at a limited rate that reduces but cannot totally prevent concomitant chemical oxidation of the wine., Antioksidacijska svojstva kvasaca zaostalih u talogu nakon fermentacije ovise o njihovoj potrošnji otopljenog kisika. U radu je ispitan kapacitet potrošnje kisika suspendiranih stanica šest komercijalnih sojeva kvasca neinvazivnom metodom pomoću fluorescentnog senzora u vinskom talogu dobivenom nakon fermentacije modelne alkoholne otopine, bijelih i crnih vina. U modelnoj je otopini potrošnja kisika ovisila o soju i količini kvasaca, koncentraciji sumporovog dioksida i temperaturi. U crnim je vinima potrošnja kisika bila nešto manja nego u bijelim. Povećanjem koncentracije slobodnog sumporovog dioksida potrošnja se kisika smanjila, pa je zaključeno da se vinski talog i sumporov dioksid ne mogu istodobno koristiti kao antioksidansi u vinu. Međutim, utvrđeno je da potrošnja kisika u 25 slučajno odabranih uzoraka bijelog vina proizvedenih u komercijalnim uvjetima prvih šest mjeseci nakon fermentacije nije bitno ovisila o soju i količini kvasaca, koncentraciji sumporovog dioksida ili temperaturi, pa je u tim vinima bilo teško predvidjeti stvarni antioksidacijski učinak kvasaca. Kvasci iz taloga bijelih vina potrošili su od 0 do 47 % otopljenog kisika. Iako ukupan kapacitet potrošnje kisika nije ograničio uporabu kvasaca u komercijalnoj proizvodnji vina, s vremenom se potrošnja kisika smanjila i djelomično, ali ne u potpunosti, zaustavila kemijsku oksidaciju vina.

U ovom je radu ispitan utjecaj nekih fizikalno-kemijskih značajka, kao što su hlapljiva kiselost, titracijska kiselost, pH-vrijednost, udjel slobodnog SO2 i alkohola na akumulaciju hlapljivih spojeva u vinima odležalim u hrastovim bačvama. Pokušala se razriješiti kontradiktornost dobivenih rezultata u usporedbi s rezultatima drugih autora. Upotrijebljene su tri različite sorte vina, što su odležale 12 mjeseci u bačvama sličnih osobina (iz iste bačvarije, od istoga drveta, jednako tostirane, tj. paljene i istoga volumena), a pokus je ponovljen tijekom dvije uzastopne godine. Rezultati pokazuju da su volumni udjel alkohola u vinu i njegova titracijska kiselost u pozitivnoj korelaciji s konačnom koncentracijom vanilina i gvajacilnih spojeva u dozrelim vinima, a u negativnoj korelaciji sa cis- i trans-β-metil-γ-oktalaktonom. Stoga se pri ispitivanju utjecaja osobina hrastovih bačava (porijeklo i sezona rasta hrasta, veličina bačve, učestalost korištenja itd.) na koncentraciju hlapljivih spojeva u vinu također trebaju uzeti u obzir fizikalno-kemijske značajke vina, osobito titracijska kiselost i volumni udjel alkohola, jer konačna aroma vina ovisi i o tim značajkama., This paper focuses on the effect of some of the physicochemical characteristics of wines such as volatile acidity, titratable acidity, pH, free SO2 and alcohol content on the accumulation of oak-related volatile compounds in barrel-aged wines, in order to give more light on the contradictory results found by other authors in this respect. For this, three different single variety wines were aged for twelve months in barrels with the same characteristics (same cooperage, wood origin, toasting level and volume), repeating the experiment in two consecutive years. Our results show that the percentage of wine alcohol and its titratable acidity positively correlated with the final concentration of vanillin and guaiacyl compounds in the oak-matured wines and negatively with the cis- and trans-β-methyl-γ-octalactone concentration. Therefore, when studying the effect of oak barrel variables (oak origin and seasoning, size of the barrel, number of uses, etc.) on the concentration of oak-related volatile compounds in wine, the effect of the physicochemical variables of the wine, especially titratable acidity and alcohol content, should also be taken into account since the final wine aroma composition will also depend on these characteristics.

Trans-resveratrol (3,5,4’-trihydroxy-trans-stilbene) is naturally present in the skin of grapes and therefore is expected to occur in grape products. Recently, there has been a renewal of interest in wine as medical treatment for various disorders. In this study, berry skins of five red grape varieties were analysed at weekly intervals for trans-resveratrol production, during 2012 and 2013 harvest. The obtained wines were also evaluated. Quantification of trans resveratrol in grape skin extracts and wines was carried out by high-performance liquid chromatography. Favourable viticultural climate during harvest in 2012 resulted in a higher content of trans-resveratrol. The highest trans-resveratrol content was in Pinot Noir and Feteasca Neagra grape varieties, both in berry skins and wines, while the lowest amounts were identified in Cabernet Sauvignon variety. We can conclude that there was a significant correlation between the content of trans-resveratrol in grape skins and that in the respective wine., Trans-resveratrol (3,5,4'-trihidroksi-trans-stilben) je prirodni fenol, koji se nalazi u pokožici grožđa i iz nje dospijeva u proizvode od grožđa. U novije se vrijeme ponovno javlja interes za primjenu vina u liječenju različitih zdravstvenih poremećaja. U ovom je radu tjedno praćen udjel trans-resveratrola u pokožici pet sorata crnog grožđa tijekom uzgoja 2012. i 2013. godine. Nakon toga su analizirana i vina proizvedena iz tih sorata. Za određivanje količine trans-resveratrola u ekstraktu pokožice i vinu upotrijebljena je viskodjelotvorna tekućinska kromatografija. Veći je udjel trans-resveratrola pronađen u grožđu i vinu iz 2012. godine, i to zbog povoljnijih klimatskih uvjeta. Najviše je trans-resveratrola bilo u grožđu i vinu sorata Pinot Noir i Feteasca Neagra, a najmanje u onima sorte Cabernet Sauvignon. Zaključeno je da postoji značajna korelacija između količine trans-resveratrola u pokožici grožđa i u vinu, i to kod svih sorata.

Utvrđivanje autentičnosti vina ima sve veći značaj u vinarskoj industriji. Stoga se sve više naglašava uloga uvjeta zemljišta (terroir). U Europi, gdje se uglavnom proizvode sortna vina, utvrđivanje je autentičnosti vina od posebne važnosti. Antocijanini su glavna skupina fenolnih spojeva koji se upotrebljavaju za utvrđivanje autentičnosti vina. U ovom je radu ispitano 17 crnih sortnih vina iz područja sela Dolní Kounice (vinogradarska regija Moravia, Češka Republika). U analizu su uključene tri sorte: Blaufränkisch (Lemberger), Saint Laurent i Blauer Portugieser, te tri terroira: Karlov, Šibeniční vrch i Na Nivách. Za određivanje je antocijanina u crnim sortnim vinima upotrijebljena metoda tekućinske kromatografije velike djelotvornosti (HPLC). Sorte su grožđa određene pomoću kemometrijskih metoda, a crna su vina razvrstana prema udjelima delfinidin-3-O-glukozida (DpGl), malvidin-3-O-glukozida (MvGl) i delfinidin-3-O-acetilglukozida (DpGlAc). Razlike su u terroiru utvrđene prema udjelima sljedećih spojeva: DpGl, MvGl i delfinidin-3-O-p-kumarilglukozid (DpGlCm)., In recent years, the importance of wine authenticity specification has significantly influenced the world wine market. Nowadays, the importance of terroir is emphasised worldwide. Also in European countries, where varietal wines are produced predominantly, the wine authenticity is given an increasing attention. Anthocyanin pigments represent an important group of phenolic substances that are used for the evaluation of wine authenticity. In this study, altogether 17 varietal red wines originating from the village Dolní Kounice (wine-growing region Moravia, Czech Republic) are evaluated. The evaluation involved three varieties, viz. Blaufränkisch (Lemberger), Saint Laurent and Blauer Portugieser as well as three terroirs named Karlov, Šibeniční vrch and Na Nivách. Anthocyanin pigments in varietal red wines were estimated by means of the HPLC method. Thanks to the application of chemometric methods, it was possible to determine the grapevine variety and to classify red wines on the basis of delphinidin-3-O-glucoside (DpGl), malvidin-3-O-glucoside (MvGl) and delphinidin-3-O-acetylglucoside (DpGlAc) content. The terroir was discriminated on the basis of DpGl, MvGl and delphinidin-3-O-p-coumarylglucoside (DpGl-Cm) content.

Polifenoli su široko rasprostranjeni prirodni spojevi, koji uz farmakološko djelovanje imaju i bakteriostatski/baktericidni, antifungalni, protuupalni, kemopreventivni, citostatski, imunomodulacijski i antioksidacijski učinak. Upotrebljavaju se kao funkcionalna hrana u svakodnevnoj prehrani, a u većoj su količini prisutni u propolisu, vinu i različitom ljekovitom bilju. U ovom su radu opisani postupci kemijske analize (spektrofotometrija, visokodjelotvorna tekućinska kromatografija, visokodjelotvorna tankoslojna kromatografija, vezani sustav plinske kromatografije i spektrometrije masa, itd.) polifenola, tj. udjela flavonoida i fenolnih kiselina za određivanje autentičnosti i porijekla propolisa i vina. Navedene su analize osnova za kontrolu kvalitete propolisa, vina i ostalih prehrambenih dodataka koji pozitivno utječu na zdravlje., Polyphenols are ubiquitous natural compounds that show chemopreventive, cytostatic, immunomodulatory, bacteriostatic/bactericidal, antifungal, anti-inflammatory, antioxidant and many other pharmacological activities. Propolis, wine and many medicinal plants used in everyday life as functional food present rich sources of polyphenols. In this paper we focus on their production, chemical analysis (spectrophotometry, HPLC, HPTLC, GC/MS, etc.) of flavonoids and phenolic acids, all of which enable authentication and geographical traceability of propolis and wine. This represents the basis for quality control and regulatory framework for any dietary supplement claiming to have beneficial health effectiveness.

The aim of this study is to evaluate the influence of yeast strains on the composition and sensory quality of Gewürztraminer wine. Three different commercial yeast strains were examined on the microvinification scale. In the wines, the chemical parameters and the concentration of free volatile monoterpene alcohols were measured and a descriptive sensory analysis was performed. Significantly more geraniol and nerol were detected in the fermentation conducted with reference Saccharomyces cerevisiae strain and more citronellol was found in the fermentation conducted with a hybrid of S. cerevisiae hybrid and S. paradoxus. However, more α-terpineol and linalool were found in the wine fermented with a combination of Saccharomyces and Torulaspora delbrueckii strains. The best wine flavour of tropical fruits was obtained using a hybrid of S. cerevisiae hybrid and S. paradoxus, and the best wine quality was achieved with a combination of Saccharomyces and T. delbrueckii strains. The selection of yeast strains for the fermentation of Gewürztraminer must significantly influenced the concentration of free volatile monoterpene alcohols and the sensory quality of the wine. With the selected hybrid of S. cerevisiae hybrid and S. paradoxus or the combination of Saccharomyces and T. delbrueckii strains either a better flavour or overall wine quality than with the reference strain can be achieved., Svrha je ovoga rada bila odrediti utjecaj odabira sojeva kvasaca na sastav i senzorske značajke vina Gewürztraminer. Ispitana su tri različita soja komercijalnih kvasaca u postupku mikrovinifikacije. Određene su kemijske značajke vina te koncentracija slobodnih hlapljivih monoterpena, a provedena je i deskriptivna senzorska analiza uzoraka. Utvrđeno je da je pri vrenju mošta s referentnim sojem Saccharomyces cerevisiae dobiveno znatno više geraniola i nerola, dok je nakon vrenja mošta s hibridom kvasca Saccharomyces cerevisiae (hibrid) i soja S. paradoxus pronađen veći udjel citronelola u vinu. Međutim, u vinu fermentiranom s pomoću sojeva Saccharomyces i Torulaspora delbrueckii dobiveno je više α-terpineola i linaloola. Najbolji okus vina s izraženom aromom tropskog voća postignut je primjenom hibrida kvasca S. cerevisiae (hibrid) i soja S. paradoxus, a vino najbolje kvalitete dobiveno je kombinacijom sojeva Saccharomyces i T. delbrueckii. Odabir sojeva kvasaca bitno je utjecao na koncentraciju slobodnih hlapljivih monoterpena, te na senzorske značajke vina Gewürztraminer. Odabirom hibrida kvasca S. cerevisiae (hibrid) i soja S. paradoxus postignuti su bolji okus vina ili ukupno bolja kvaliteta vina nego pomoću referentnog soja kvasca.

Phenolic acids, represented by hydroxycinnamic and hydroxybenzoic acids and their derivatives, are the most abundant phenolic compounds in grape juice and wine of white grapevine cultivars. The effects of fruit zone leaf removal on the concentration of hydroxycinnamic, hydroxybenzoic and organic acids of cv. Istrian Malvasia grape juice and wine are investigated in this study. Fruit zone leaf removal was applied at three different phenological stages: before blooming, at berry set and at veraison. Control treatment without leaf removal was also included. At veraison two intensities of leaf removal were applied. Phenolic and organic acids were identified and quantified using high-performance liquid chromatography. Juice samples from the grapes treated at the stages before blooming and berry set had the lowest concentrations of tartaric acid and the highest concentrations of malic acid, while juices from veraison stage treatments had the lowest concentrations of malic acid and the highest concentrations of tartaric acid. Before blooming treatment significantly lowered the concentration of all hydroxycinnamic and hydroxybenzoic acids in grape juice in comparison with other investigated treatments, which did not affect the concentration of total hydroxycinnamic acids considerably. The concentration of hydroxybenzoic acids in grape juice was lower in veraison treatments in comparison with berry set and control treatments. The concentrations of hydroxycinnamic, hydroxybenzoic and organic acids in wine followed the same trends as observed in grape juice. It is concluded that the concentration of phenolic and organic acids in grape juice and wine of white grapevine cultivars can be managed with the timing of fruit zone leaf removal according to the desired wine style., Fenolne kiseline, tj. hidroksicimetne i hidroksibenzojeve kiseline te njihovi derivati, najzastupljenija su skupina fenolnih spojeva u moštu i vinu bijelih kultivara vinove loze. U ovom je radu istražen utjecaj defolijacije u zoni rasta grozda na koncentraciju hidroksicimetnih, hidroksibenzojevih i organskih kiselina u moštu i vinu Malvazije istarske. Lišće je odstranjeno u tri različite fenofaze rasta i razvoja vinove loze: prije cvatnje, u fazi zametanja bobica i u fazi šare. Kontrolna obrada kada nije bila primijenjena defolijacija također je bila sastavni dio istraživanja. U fazi šare primijenjena su dva intenziteta defolijacije. Fenolne su kiseline identificirane i kvantificirane visokodjelotvornom tekućinskom kromatografijom. Uzorci mošta pri obradi defolijacijom prije cvatnje i u fazi zametanja bobica imali su najmanju koncentraciju vinske i najveću koncentraciju jabučne kiseline, dok su oba tretmana primijenjena u fazi šare imala najmanju koncentraciju jabučne i najveću koncentraciju vinske kiseline. Obradom prije cvatnje dobiveno je kudikamo manje hidroksicimetnih i hidroksibenzojevih kiselina u moštu u usporedbi s ostalim postupcima što se međusobno nisu bitno razlikovali po koncentraciji ukupnih hidroksicimetnih kiselina. Koncentracija hidroksibenzojevih kiselina u moštu bila je manja u oba tretmana primijenjena u fazi šare u usporedbi s defolijacijom u fazi zametanja bobica i kontrolnom obradom. Koncentracije hidroksicimetnih, hidroksibenzojevih i organskih kiselina u vinu bile su iste kao i one u moštu. Izborom fenofaze u kojoj se primjenjuje defolijacija može se utjecati na koncentraciju fenolnih i organskih kiselina u moštu i vinu bijelih kultivara vinove loze.

A colorimetric method has been developed and optimized to measure L-malic acid in samples of fruit juices and wine. This method is based on oxidation of the analyte, catalyzed by malate dehydrogenase (MDH) from dry baker’s yeast, and in combination with the reduction of a tetrazolium salt (MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). In the present study, the method exhibited sensitivity in the range of 500–4000 mM of L-malic acid in the reaction cuvette, with the lower detection limit of 6.7·10^-2 g/L, the upper limit of 53.6·10^-2 g/L and a maximum standard deviation of only 2.5 % for the analyzed samples. The MDH activity from baker’s yeast was also optimized, the enzyme showed a high stability at pH=8.0–9.0 and the activity was maintained completely at temperatures up to 40 °C for 1 hour. The results show that the colorimetric method using enzymatic preparations from dry baker’s yeast is a simple and low-cost method with possibility of wide application, Razvijena je i optimirana metoda kolorimetrijskog određivanja koncentracije L-jabučne kiseline u voćnom soku i vinu. Zasniva se na oksidaciji jabučne kiseline, kataliziranoj malat dehidrogenazom iz suhoga pekarskog kvasca, te redukciji tetrazolijeve soli (MMT: 3-(4,5-dimetiltiazol-2-il)-2,5-difenil- tetrazolijev bromid). Osjetljivost metode bila je u rasponu od 500 do 4000 μM L-jabučne kiseline u reakcijskoj kiveti. Donja je granica detekcije u analiziranim uzorcima bila 6,7·10^-2 g/L, gornja granica 53,6·10^-2 g/L, a maksimalna standardna devijacija iznosila je samo 2,5 %. Optimirana je i aktivnost malat dehidrogenaze iz pekarskog kvasca, pa je enzim pokazao dobru stabilnost pri pH=8,0-9,0; a potpuno je zadržao aktivnost na temperaturama do 40 ºC tijekom jednog sata. Rezultati pokazuju da je predložena kolorimetrijska enzimska metoda jednostavna i jeftina te ima razne mogućnosti primjene.

The effect of red wine phenolic extracts on the stability of wine volatile esters and terpenes was examined. Muscat (white) and Xinomavro (red) wines were enriched with each extract at 120 or 200 mg/L, and stored in open bottles at 20 °C for 3 and 2.5 days, respectively. Moreover, a model wine medium containing isoamyl acetate, ethyl hexanoate and linalool was enriched with each extract at 100 mg/L, and stored in sealed bottles at 20 °C for 45–90 days. All samples were analysed for volatiles using SPME along with GC-MS analysis. Phenolic composition of wine extracts was determined using HPLC-DAD. No effect on the concentration of any volatiles was observed as a result of the addition of each extract in each wine or the model medium. A wine extract rich in phenolic acids and another one rich in anthocyanins and flavanols inhibited the decrease of volatile esters and terpenes in one or both wines and the model medium. Among them were several important for the aroma of wine such as ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate and linalool. The results presented here indicate that wine phenolic acids, and anthocyanins or flavanols may be taken into account as potent inhibitors of the disappearance of volatile esters and terpenes in wines., Istražen je utjecaj fenolnih ekstrakata crnog vina na stabilnost hlapljivih estera i terpena u vinu. Muškat (bijelo vino) i Xinomavro (crno vino) obogaćeni su s po 120 ili 200 mg/L ekstrakta i skladišteni u otvorenim bocama tijekom 3 odnosno 2,5 dana pri 20 °C. Pripravak sličan vinu, koji sadrži izoamilacetat, etilheksanoat i linalol, također je obogaćen s 100 mg/L fenolnog ekstrakta, te skladišten u zatvorenim bocama pri 20 °C tijekom 45-90 dana. Hlapljive komponente svih uzoraka analizirane su SPME i GC-MS analizom. Fenolni sastav vinskih ekstrakata određen je HPLC-DAD metodom. Dodatkom fenolnih ekstrakata nije zabilježena promjena koncentracije hlapljivih sastojaka u vinima i pripravku sličnom vinu. Vinski ekstrakt bogat fenolnim kiselinama i drugi bogat antocijanima i flavanolom smanjili su razgradnju hlapljivih estera i terpena u vinu i pripravku, prije svega spojeva važnih za aromu vina, kao što su etilacetat, izoamilacetat, etilheksanoat, etiloktanoat, etildekanoat i linalol. Rezultati pokazuju da bi se fenolne kiseline, antocijanini i flavanoli iz vina mogli upotrijebiti za inhibiciju razgradnje hlapljivih estera i terpena tijekom skladištenja vina.

Changes in some aroma compounds and sensory properties caused by different commercial S. cerevisiae strains and by epiphyte microorganisms in Chardonnay wines were investigated. Wines fermented with the Lalvin-71 B strain contained significantly lower concentrations of alcohol, isoamyl alcohol, isobutanol and total acidity than the wines obtained from spontaneous and other inoculated fermentations. The highest concentrations of 2-phenyl ethanol and 2-phenyl ethyl acetate were found in the spontaneously fermented wines, whereas no essential changes in these compounds were found among the wines of other treatments. Compared to the spontaneous fermentation, Lalvin-71 B strain fermented wines had somewhat higher concentrations of butyric and caproic acid and ethyl butyrate. Lalvin-71 B strain fermented wines were assessed as the best whereas the quality of the wines produced with Lalvin aromatic-2056 strain was the most inferior in quality.