Gemar melacha for winemaking and the stage at when terumot and ma'aserot are taken from wine
What is the definition of gemar melacha for wine? Are white wine and red wine different in this regard? What about grape juice? At what point can vintners taste-test without taking terumot and ma'aserot? An abstract from Emunat Itecha, Tammuz 5779, issue 124.
What is considered gemar melacha, the final stage of the preparation process, in winemaking according to halacha? From which stage is it possible to separate terumot and ma'aserot from the wine? From which stage in the winemaking process is it forbidden to drink or taste the wine? Are vintners' taste tests for the purpose of taking various operative decisions vis-à-vis the winemaking process considered shetiyat aray (casual drinking) or shetiyat keva (fixed drinking)?
Conclusions:
The mainstream halachic consensus is that gemar melacha for wine takes place at the end of the fermentation process, after filtration and separation of the grape skins and pips.
For this reason, terumot and ma'aserot should be separated after the completion of the fermentation process, after the liquid is poured into the grape press. It is optimal to wait until the later stage of clarification (the process in which solids are removed from the liquid, such as dead yeast cells).
Even if the end-product is grape juice and the fermentation process is halted immediately at the beginning of production, terumot and ma'aserot are taken when the peels and pips are separated from the juice. In this case, fermentation is not part of the process and thus is not a parameter for gemar melacha. It is even permitted to separate terumot and ma'aserot from grape juice to exempt wine, since in both cases they are considered completed at this stage (following the rule of hamafrish min hagamur al hagamur).
When producing white wine, the peels and pips are separated from the liquid immediately at the start of the winemaking process (at times from as early as four hours from the grapes' arrival from the vineyard). In this case, the gemar melacha takes place only after the completion of the fermenting process, as mentioned above.
If terumot and ma'aserot are taken after the grapes are pressed—before the completion of the fermentation process and after filtration—the separation is nevertheless effective (since there are several lenient opinions).
For red wine, which is filtered upon the completion of the fermentation process, it seems that one can be lenient and taste the wine before filtration. After pouring the wine into the press, tastings should be prohibited without terumot and ma'aserot.
For the preparation of white wine, where filtration comes before the end of the fermentation process, it seems that one can be lenient and taste the wine after filtration. This is as long as the alcoholic fermentation process has not been completed to the point that the wine is considered fit for drinking.
It is possible to find solutions that facilitate separating terumot and ma'aserot in a fast and easy manner: 1) Say at the beginning of the day the text for separation ahead of time on the cups of wine that will be drunk throughout the day; 2) If this is not possible, one may separate terumot and ma'aserot before each tasting and say the shortened text.
For the full article in Hebrew, see here.