Level of Cooking to Be Considered Mevushal
15. There is a machlokes what level of cooking is required for wine to be considered mevushal and free of concern for the issur of yayin nesech. We will mention some levels mentioned by the poskim.
16. Boiling. The Rishonim mention that once wine reaches the level of boiling, it becomes mevushal. In Rishonim terminology, “boiling” [רתיחה ] refers to yad soledes bo, the same as for hilchos Shabbos (רא''ש ע''ז פ''ב סי' י''ג, רשב''א תוהב''א ב''ה ש''ג, ר''ן ע''ז דף י' ע''א בדפי הרי''ף , שו''ת אג''מ יו''ד ח''ב סוף סי' נ''ב, מנחת שלמה ח''א סי' כ''ה ).
17. Reduced amount. Some write that it must be cooked enough that the amount of wine is reduced (רמב''ן הובא שם ).
18. Change to its character. However, a more machmir opinion exists. Some say that the wine must undergo a change in flavor, aroma, or color due to cooking, as wine that is not as appealing is not cherished enough to be poured for avoda zara (מאירי ע''ז דף כ''ט ע''ב ). Some write it must be changed enough that it is not drunk as “wine” (שלטי גיבורים ע''ז י' בדפי הרי''ף בשם הריא''ז ). Others are more machmir and write it must transform from having a wine flavor to having a honey flavor (חיד''א ס' ככר לאדן הג' ירושלמי תרומות ח:ה ב ,א"ח שנה ב' בלק ז').
19. In practice. In practice, the Shulchan Aruch rules, “From when is it considered mevushal? From when it is boiled on a fire” (שו''ע סי' קכ''ג ס''ג ), i.e., yad soledes bo (above, 16). The Acharonim add that wine is only considered mevushal if the cooking reduces its amount (ש''ך סק''ז ).
20. Yad soledes bo l’chumra. There are several opinions as to the definition of yad soledes bo. In modern-day terms, it ranges between 45°C [113°F] and 71°C [159.8°F] (אג''מ ח''ד סי' ע''ד אות ג', שבות יצחק הל' בישול סוף פי''ח ). Thus, to remove concerns for the issur of yayin nesech, we must be machmir to cook the wine to higher than 71°C to create mevushal wine for these purposes.
