Bentonite is an important enological agent in the white wines production. The effect of three bentonite types (sodium, calcium and sodium / calcium) and two types of water (tap / hard; distilled / ...soft) was investigated on the doses of bentonite required to stabilize the protein, and consequently on the sensory properties of Istrian malvasia wine. A significant difference in doses of bentonite in terms of water hardness was determined. Minimum dose for the stabilization of proteins (100 g / hl) were recorded for the use of sodium and calcium bentonite in distilled water. Also the least impact on the sensory properties of Istrian malvasia wine has been observed in these treatments.
The evolution of free anthocyanins during the five different fermentation temperatures (control treatment at 22 °C, 5 days pre-fermentative cryomaceration at 5 °C followed by maceration at 25 °C, ...maceration at 25 °C, maceration at 30 °C and maceration at 25 °C + heated post-fermentation maceration to 35-40 °C after finished alcoholic fermentation) of Teran wine was studied. Sampling was made at day 5, 10, 15 and three months after the end of maceration during storage time. Anthocyanins were determined by high performance liquid chromatography method coupled with photodiode array detection (HPLC-PDA). The results showed that the modification of the temperature conditions during maceration increased the anthocyanin concentration for pre-fermentative cryomaceration and maceration at 25 °C, while the maceration at higher temperatures showed a decrease in the anthocyanin concentration in young Teran wine. Quantitatively, malvidin derivatives were the most abundant anthocyanin compounds in all studied wines. Malvidin-3-glucoside was the major anthocyanin in Teran wine, with concentrations up to 138.59±1.22 mg/L and 76.93±0.36 mg/L for C treatment in 2008 and 2009 vintage, respectively. Results of this study indicate that five days pre-fermentative cryomaceration at 5 °C followed by maceration at 25 °C is most appropriate in order to achieve maximum anthocyanin concentration in Teran wines.
Bentonit je nezaobilazno sredstvo u proizvodnji bijelih vina. Istraživan je utjecaj tri tipa bentonita (natrijev, kalcijev i natrij/kalcijev) i dva tipa vode (vodovodna/tvrda i destilirana /meka) na ...doze bentonita potrebnih za stabilizaciju bjelančevina, a, posljedično tome, i na senzorska svojstva vina Malvazija istarska. Utvrđena je značajna razlika u dozama bentonita s obzirom na tvrdoću vode. Najmanje doze za stabilizaciju bjelančevina (100 g/hl) zabilježene su kod primjene natrijevoga i kalcijevoga bentonita u destiliranoj vodi. Kod tih je tretmana uočen i najmanji utjecaj na senzorska svojstva vina Malvazija istarska.
Effects of maceration duration on the phenolic composition and antioxidant capacity in red grapevine variety ‘Teran’ (Vitis vinifera L.) was investigated in this study. Total phenolics, flavonoids, ...nonflavonoids, individual and total anthocyanins, vanillin index and antioxidant capacity measured by DPPH, ABST and FRAP methods were determined in ‘Teran’ wines during five different skin maceration periods (3, 7, 12, 17 and 21 days). Th e highest increase in the concentration of the most phenolic compounds and antioxidant capacity was obtained between the 3rd and 7th day of maceration. Prolonging the maceration from 7 to 21 days did not lead to significantly higher concentrations of total phenolics, flavonoids, nonflavonoids, total anthocyanins and antioxidant capacity measured with ABTS and FRAP methods. It is concluded that maceration duration of seven days is the most appropriate in order to obtain high concentrations of total phenolics and anthocyanins and high antioxidant capacity of ‘Teran’ wines.
The evolution of free anthocyanins during the five different fermentation temperatures (control treatment at 22 °C, 5 days pre-fermentative cryomaceration at 5 °C followed by maceration at 25 °C, ...maceration at 25 °C, maceration at 30 °C and maceration at 25 °C + heated post-fermentation maceration to 35-40 °C after finished alcoholic fermentation) of Teran wine was studied. Sampling was made at day 5, 10, 15 and three months after the end of maceration during storage time. Anthocyanins were determined by high performance liquid chromatography method coupled with photodiode array detection (HPLC-PDA). The results showed that the modification of the temperature conditions during maceration increased the anthocyanin concentration for pre-fermentative cryomaceration and maceration at 25 °C, while the maceration at higher temperatures showed a decrease in the anthocyanin concentration in young Teran wine. Quantitatively, malvidin derivatives were the most abundant anthocyanin compounds in all studied wines. Malvidin-3-glucoside was the major anthocyanin in Teran wine, with concentrations up to 138.59±1.22 mg/L and 76.93±0.36 mg/L for C treatment in 2008 and 2009 vintage, respectively. Results of this study indicate that five days pre-fermentative cryomaceration at 5 °C followed by maceration at 25 °C is most appropriate in order to achieve maximum anthocyanin concentration in Teran wines.
