Abstract:
To study the possibility of producing mulberry wine by using only the sugar in the fruit (no condition sugar added) and also to study the physical and chemical properties of the wine. Firstly, the optimum condition of the single ice crystal freeze concentration of ethanol-water model was determined, the ice crystal growth rate (u) and the stirring rate (Nr) for each initial ethanol concentration (5, 7.5 and 10%v/v) were investigated by calculating the effective partition constant (K value) of each experiment. The U and Nr used were 0.5, 1 and 2 cm/h, and 300, 800 and 1200 rpm respectively. Increasing of stirring rate and decreasing of ice crystal growth rate lowered the K value. The lowest K value for the initial ethanol concentration of 5%v/v was 0.23 at u = 0.5 cm/hr and Nr=1200 rpm. However, there was nosignificant difference (p > 0.05) compared to that of the condition u=1 cm/hr and Nr=1200 rpm which showed the K value of 0.25. For the initial ethanol concentrations of 7.5 and 10%v/v, u=0.5 cm/hr Nr=1200 rpm gave the lowest K values of 0.23 and 0.35 respectively (p < 0.05). Two optimum conditions (u=1 cm/hr, Nr=1200 rpm for ethanol concentration < 7.5 %v/v and u=0.5 cm/hr, Nr=1200 rpm for ethanol concentration > 7.5 %v/v) were applied in the single ice crystal freeze concentration for the no sugar added mulberry wine. The result showed that the ethanol concentration of the wine increased from 5.5%v/v to 11.2-11.4%v/v, which insignificantly different (p > 0.05) from commercial mulberry wine. The concentrations of other components in the wine such as total soluble solid (TSS), anthocyanin, reducing sugar, phenolic compound, total acid, volatile acid, methanol, ester and acetaldehyde were also increased. However, the concentration of methanol was as high as 941 mg/l which were higher than stated in Thai Industrial Standard Institute (TISI) standard value for wine (420 mg/l). So, the mulberry wine could not be produced by concentrating the wine fermented from no sugar added mulberry juice. So, the mulberry juice was concentrated first and then fermented. The vacuum evaporation method and the suspension freeze concentration method were applied in concentrating the juice to obtain the TSS of 20 ํBrix. The results showed that the mulberry wine contained 101 and 180 mg/l of methanol. The concentrations of other components were 11.0 and 10.4%v/v of ethanol, 9 and 8 ํBrix of TSS, 0.32 and 0.1 g/100ml of reducing sugar, 0.48 and 0.56 g/100ml of total acid, and 0.22 and 0.46 g/100ml of volatile acid