The laws of acceptable kiddush wines are derived from the laws governing which wines could be used on the altar in Temple times. Any wine that was deemed unacceptable because of its repulsiveness is also pasul (ritually unfit) for kiddush. For example, wine that was left exposed for several hours in a cup or an open bottle may not be used for kiddush. Similarly, wine that smells bad is unacceptable (SA 272:1; MB ad loc. 3).
However, wines acceptable only be-di’avad for use on the altar are acceptable for kiddush even le-khatĥila. For example, a very sweet wine, made from overripe grapes overexposed to sunlight, is acceptable on the altar be-di’avad but acceptable for kiddush even le-khatĥila. Similarly, using grape juice on the altar was deemed acceptable be-di’avad but may be used for kiddush le-khatĥila. Nevertheless, it is most preferable to make kiddush on good alcoholic wine that makes one glad (SA 272:2; MB ad loc. 5).
Some wines have been rendered unfit for the altar because they have been mixed with other liquids, but are still acceptable for kiddush. For example, wine mixed with water is pasul for the altar, but not for kiddush. On the contrary, it is good to dilute the wine a bit to make it tastier, and to dull its strength. Nowadays, however, wines do not need to be watered down, because they are not strong to begin with (SA and Rema 272:5).
Some maintain that if wine is so watered down that there is more water than wine, it is not considered wine, the berakha recited over it is not Ha-gafen, and it is unacceptable for kiddush. Others are more lenient and permit its use as long as it still tastes like wine. Local Israeli rabbinates make sure to only certify wines in which wine content is the majority, thus satisfying all opinions.
Wine that was cooked (“mevushal”) or had sugar or honey added to it was rendered unacceptable for Temple libations because it had been altered from its original form. Some maintain that just as these wines were unacceptable for libations, so too they are unacceptable for kiddush (Rambam). But the majority of poskim maintain that these wines are acceptable for kiddush because cooking them or adding sugar to them is meant to improve them, and this is the accepted practice. Even if one has unadulterated wine but prefers the taste of the cooked or sweetened wine, it is preferable to make kiddush over the wine he prefers (SA and Rema 272:8). Many choice sweet wines have no sugar added, but rather are sweet because of the type of grape used to make them. Everyone agrees that these wines are acceptable for kiddush use.
Some maintain that only red wine is acceptable for kiddush use, while white wine is unfit (Ramban). However, most poskim maintain that white wine may be used, and this is the position of Shulĥan Arukh (272:4). If one has two wines available to him – an inferior red and a superior white – and he wishes to conform to all the positions, he should mix the white wine with a little of the red, which will leave him with tasty red wine (it is preferable to pour the white wine into the red, as explained below, 12:10).
. There is a dispute in the Gemara about the degree to which wine could be watered down and still retain its classification as wine. Some maintain that if the wine is one quarter of the mixture, it is still considered wine. This is how Kaf Ha-ĥayim 204:31 understands SA. According to Rema, as long as the wine is more than one seventh of the mixture, it is considered wine (204:5). However, SA points out that our wines are not as strong as their wines, and thus the applicable proportions are different. Pri Megadim and other Aĥaronim explained that only if the majority of the liquid is wine is it considered wine. Sephardim and many Ashkenazim follow this opinion. Other poskim maintain that as long as the liquid tastes like wine and is more than one seventh wine, it is deemed to be wine. This was the ruling followed by the Badatz of the Eda Ĥaredit (Piskei Teshuvot 204:8), which was opposed by several leading poskim (Ĥazon Ovadia 6:2). Thus, the Israeli Chief Rabbinate gives supervision to a wine only when the majority of the liquid is wine.. According to Rambam (MT 29:14), wine that has been cooked or has had sugar or the like added to it is unfit for kiddush use. This is also the opinion of a number of the Ge’onim. But Tosafot, Rosh, Ran, Ramban, and Rashba maintain that it may be used, and SA also inclines this way. Rema and MB 272:23 state that if the cooked or sweetened wine is tastier, it is preferable to make kiddush over it. Some take the more stringent opinion into account and therefore prefer to make kiddush over wine that has not been cooked or sweetened (Kitzur SA 77:6; Kaf Ha-ĥayim 272:44).
Nowadays most wines are pasteurized, meaning they are cooked at low temperatures (80-85º C, 176-185º F) in order to get rid of bacteria. It is unclear whether pasteurization is considered cooking or not, with ramifications for two issues: 1) May one use it for kiddush even according to those who prohibit mevushal wine? 2) If an idol-worshiping non-Jew touches this wine, what is its status? If it is considered mevushal, then this touch would not prohibit it, since the prohibition of yein nesekh (wine touched by an idol-worshiping non-Jew) does not apply to mevushal wine. Igrot Moshe YD 3:31 states that such wine is considered mevushal (as does Yalkut Yosef 272:10). However, Minĥat Shlomo 1:25 states that it is considered mevushal only if its taste, smell, or appearance undergoes a change; rather, pasteurization to eliminate bacteria does not give the wine the status of mevushal. In practice, one may make kiddush over pasteurized wine even le-khatĥila. In terms of the touch of a non-Jew, be-di’avad one may be lenient, because the prohibition of drinking wine touched by a non-Jew is rabbinic, and in a case of an uncertainty regarding a rabbinic law one may be lenient. One may certainly be lenient in the case of wine touched by a Shabbat-desecrating Jew. Moreover, if such a Jew regularly makes kiddush, many of those who are stringent accede to the lenient opinion, even if the wine has not been pasteurized (see above 1:14).