Određivanje alkohola i ukupnog suhog ekstrakta u slovenskim vinima mjerenjem relativnog odnosa gustoće i refrakcije

The possibility of fast determination of alcohol and total dry extract from given relative density and refractive index in wine was examined on fifty eight samples of Slovenian white and red still wines. Calculated relation values obtained from literature were compared to values determined experimentally using official methods (pycnometry and hydrostatic balance). Determination of alcohol and total dry extract together by means of calculation was the most accurate for the group of white wines (according to the concentration of reducing sugars) with up to 5 g L–1 and the least accurate for the group of white wines with over 15 g L–1. For alcohol calculation the standard deviations and coefficients of variation for literature and our relations were different (literature relations: SD = 7.37–8.53, CV = 8.33–9.52 %, our relations: SD = 7.18–13.94, CV = 7.96–16.55 %) and they were higher for the total dry extract (literature relations: SD = 16.39 16.76, CV = 45.14–49.49 %; our relations: SD = 13.70–16.73, CV = 42.68–49.16 %). The most accurate relations for separate groups of wines (white wines with different reducing sugars content or red wines) have already been published (2–6). Our own relations for calculation of alcohol level and total dry extract were obtained by means of multiple linear regression analysis. The experiment has shown that none of the results are accurate enough to be obtained using only one relation for different wines.Ispitivana je mogućnost brzog određivanja alkohola i ukupnog suhog ekstrakta u 58 uzoraka slovenskih bijelih i crvenih nepjenušavih vina, na osnovi relativne gustoće i indeksa refrakcije. Izračunati odnosi vrijednosti, koji su dobiveni iz literature, uspoređeni su s eksperimentalno utvr|enim vrijednostima dobivenim korištenjem službenih postupaka (piknometrija i hidrostatska ravnoteža). Izračunavanje udjela alkohola zajedno s ukupnim suhim ekstraktom bilo je najtočnije za skupinu bijelih vina s koncentracijom reducirajućih šećera do 5 g/L, a manje točno za skupinu bijelih vina s udjelom preko 15 g/L. Pri izračunavanju alkohola standardna devijacija i koeficijenti varijacije razlikovali su se u literaturi i u našim podacima (literaturni podaci: SD = 7,37–8,53, CV =8,33–9,52 %; naći odnosi: SD = 7,18–13,94, CV = 7,96–16,55 %), a bili su viši za ukupni suhi ekstrakt (literaturni podaci: SD = 16,39–16,76, CV = 45,14–49,49 %; naši podaci: SD = 13,10–16,73, CV = 42,68–49,16 %). Najtočniji odnosi za pojedine skupine vina (bijela vina s različitim udjelom reducirajućih šećera ili crvenih vina) već su objavljeni u literaturi. Naši vlastiti rezultati dobiveni izračunavanjem udjela alkohola i ukupnog suhog ekstrakta za pojedine skupine vina, dobiveni su multiplom linearnom regresijskom analizom. Pokusima je potvrđeno da ni jedan od rezultata nije dovoljno točan ako se koristi samo jedan relativni odnos za različita vina

Influence of Temperature and Carbon Dioxide on Fermentation of Cabernet Sauvignon Must

In the process of wine fermentation temperature and the amount of carbon dioxide present represent parameters that can be easily monitored and controlled. The influence of variation of the process temperature and the fluxes of additional inlet gaseous carbon dioxide in Saccharomyces bayanus fermentation of Cabernet Sauvignon grape must on the accumulation of biomass and production of metabolites was studied. All experiments with temperature and redox potential control on-line were performed in a 10-litre laboratory stirred tank reactor. Metabolites of Saccharomyces bayanus fermentation comprising higher alcohols (1-propanol, 2-butanol, isoamyl alcohol), as well as reducing sugars, were measured off-line by gas and high pressure liquid chromatography

Influence of Temperature and Carbon Dioxide on Fermentation of Cabernet Sauvignon Must

In the process of wine fermentation temperature and the amount of carbon dioxide present represent parameters that can be easily monitored and controlled. The influence of variation of the process temperature and the fluxes of additional inlet gaseous carbon dioxide in Saccharomyces bayanus fermentation of Cabernet Sauvignon grape must on the accumulation of biomass and production of metabolites was studied. All experiments with temperature and redox potential control on-line were performed in a 10-litre laboratory stirred tank reactor. Metabolites of Saccharomyces bayanus fermentation comprising higher alcohols (1-propanol, 2-butanol, isoamyl alcohol), as well as reducing sugars, were measured off-line by gas and high pressure liquid chromatography

Determination of Alcohol and Total Dry Extract in Slovenian Wines by Empirical Relations

The possibility of fast determination of alcohol and total dry extract from given relative density and refractive index in wine was examined on fifty eight samples of Slovenian white and red still wines. Calculated relation values obtained from literature were compared to values determined experimentally using official methods (pycnometry and hydrostatic balance). Determination of alcohol and total dry extract together by means of calculation was the most accurate for the group of white wines (according to the concentration of reducing sugars) with up to 5 g L–1 and the least accurate for the group of white wines with over 15 g L–1. For alcohol calculation the standard deviations and coefficients of variation for literature and our relations were different (literature relations: SD = 7.37–8.53, CV = 8.33–9.52 %, our relations: SD = 7.18–13.94, CV = 7.96–16.55 %) and they were higher for the total dry extract (literature relations: SD = 16.39 16.76, CV = 45.14–49.49 %; our relations: SD = 13.70–16.73, CV = 42.68–49.16 %). The most accurate relations for separate groups of wines (white wines with different reducing sugars content or red wines) have already been published (2–6). Our own relations for calculation of alcohol level and total dry extract were obtained by means of multiple linear regression analysis. The experiment has shown that none of the results are accurate enough to be obtained using only one relation for different wines

PHENOL POTENTIAL OF SELECTED LONG MACERATED \u27REBULA\u27 CULTIVAR WINES

V diplomski nalogi smo analizirali 30 vzorcev vin sorte grozdja Vitis vinifera L. cv. \u27Rebula\u27 iz Vipavske doline in Goriških brd. Vina smo kupili na trgu, in sicer v specializiranih lokalnih prodajalnah vina, spletnih prodajalnah ali pri vinarjih. Osemindvajset (28) vzorcev vina je bilo pridelanih s postopkom podaljšane maceracije drozge grozdja. Dve vini pridelanih brez maceracije, smo dodali v nabor vzorcev zaradi primerjave fizikalno-kemijskih parametrov z ostalimi vzorci. V vinskih vzorcih smo izmerili naslednje standardne fizikalno-kemijske parametre: skupni in prosti žveplov dioksid, skupne titrabilne kisline, pH, hlapne kisline z destilacijsko metodo, izbrane organske kisline, sladkorje (glukozo + fruktozo), etanol in barvo vina s spektofotometrom - absorbanco pri 420 nm (A420) in barvne parametre v CIE Lab sistemu. Izmerili smo tudi skupne polifenole po spektrofotometrijski metodi Folin-Ciocalteu in izbrane posamezne polifenole (hidroksibenzojske kisline, nezaestrene hidroksicimetne kisline, procianidine) s tekočinsko kromatografijo visoke ločljivosti, sklopljeno z UV detetktorjem (HPLC-UV). Želeli smo določiti polifenolni potencial vin sorte \u27Rebula\u27, pridelanih s postopkom podaljšane maceracije drozge grozdja in nato določiti morebiten vpliv časa maceracije na količino polifenolov v vinu. Kemijske analize so pokazale veliko variabilnost v količini skupnih polifenolov, ki pa jih nismo uspeli povezati s časom maceracije. Pomanjkljivi podatki o času in drugih pogojih maceracije drozge grozdja nam tega niso dopuščali. Podatki nakazujejo trend večjih koncentracij skupnih polifenolov vina pri vinih, pridelanih s postopkom podaljšane maceracije drozge grozdja. V določenih vinih smo izmerili tudi preko 1000 mg/L (kot galna kislina) skupnih polifenolov. Med posameznimi polifenoli je bilo v vinih največ galne kisline (tudi do 90 mg/L), procianidina B1 (do 52 mg/L) in katehina (do 18 mg/L). Instrumentalno določena barva filtriranega vina (A420 in parametri CIE Lab) je povezana s količino skupnih polifenolov po metodi Folin-Ciocalteu. Parametri barve dolgo maceriranih vin se močno razlikujejo od vin brez maceracije oziroma od vin, pridelanih s krajšim časom maceracije, zato gre za dobre \u27markerje\u27 tovrstnih vin. Opazili smo, da kombinacija običajnega parametra barve belih vin A420 nm s parametri CIE Lab sistema omogoča podrobnejšo analizo barve vina.We analyzed 30 samples of wines of the grape variety Vitis vinifera L. cv. \u27Rebula\u27 from the Vipava Valley and the Goriška Brda. We purchased the wines on the market, either from the local wine stores and online or directly from the winemakers themselves. Twenty-eight (28) wine samples were made with prolonged maceration of the grape marc. Additional two wines made without maceration were added to the sample group to compare the physicochemical parameters with those of the other samples. The following standard physicochemical parameters were measured in the wines: total and free sulfur, total titratable acids, pH, volatile acids by the distillation method, organic acids, sugars (glucose + fructose), ethanol, and wine color measured spectrophotometrically at absorbance wavelength of 420 nm (A420) and color parameters in the CIE Lab system. We also deteremined the total phenols using the Folin−Ciocalteu method and selected individual phenols (hydroxybenzoic acids, non-esterified hydroxycinnamic acids, procyanidins) by using high performance liquid chromatography coupled with UV detector (HPLC-UV). We aimed to determine the phenolic potential of macerated wines of the \u27Rebula\u27 variety and at the same time we wanted to determine the possible influence of maceration time on the amounts of phenols in the wine. Chemical analysis showed high variability in total phenolic concentrations among samples, anyhow we were unable to correlate them statistically with maceration time due to insufficient data on the duration and other conditions of prolonged maceration of grape marc. The data suggest a tendency toward higher concentrations of wine polyphenols in wines produced by prolonged maceration of grape marc. Polyhenols contentration over 1000 mg/L (as gallic acid equivalents) was measured in some wines, namely, gallic acid (up to 90 mg/L), procyanidin B1 (up to 52 mg/L), and catechin (up to 18 mg/L) were the most abundant polyphenols in the wines. The instrumentally determined color of filtered wine is related to the amounts of total phenols determined by the Folin−Ciocalteu method. The color parameters of wines without maceration and of wines with shorter maceration time were very different from the long-macerated wine samples, which indicates them to be good \u27marker’ parameters for such wines. A combination of the common white wine color parameter A420 with the CIE Lab system allows a more detailed analysis of wine color

Volatile profile of wine Teran PTP

Teran PTP is a protected wine with a recognized traditional denomination produced from a grapevine variety ‘Refošk’ in winegrowing district Kras in Slovenia (European Union, 2009; Pravilnik, 2008). The aromatic profile of 82 Teran PTP wines produced in years 2011, 2012 and 2013 was monitored. Intotal the content of 16 volatile compounds was determined. The volatile compounds from wine were extracted following the liquid-liquid extraction and determined with a GC-MS method. The odour activity values and relative odour contributions were calculated for each volatile compound identified. Among sensorial important volatiles the highest odour activity values were determined for ethyl octanoate, ethyl hexanoate, isoamyl acetate and ethyl butyrate. Other research papers also showed, that all red wines investigated except one contained ethyl octanoate, ethyl hexanoate, isoamyl acetate and ethyl butyrate above sensory thresholds.</p