Strictly speaking, according to the Shulchan Aruch (558:1), the only thing one should refrain from on motzei Tisha B’Av (as a minhag kosher) is eating meat and drinking one. The Achronim add however, one should refrain from taking a haircut, washing himself etc. Therefore, on the one hand, eating meat and drinking wine is more stringent than other things, on the other hand, the poskim bring down various leniencies for motzei Tisha B’Av, as in the end of the day the dinim of aveilus are not as strict as the dinim of aveilus during the Nine Days, which are required by the Gemara. Consequently, the Mishnah Berurah brings (s.k. 2) that by a seudas mitzvah on motzei Tisha B’Av, all the guests (even those non-related) may eat meat and drink wine, unlike the week before Tisha B’Av where we are stringent about this.
Furthermore, the Biur Halachah (d.h. shelo) writes, even though one should refrain from eating meat, one is allowed to eat a food that was cooked together with meat, even if it is not by a seudas mitzvah. From the Aruch HaShulchan (558:2) it’s also clear, that even when Tisha B’Av falls on Thursday, and we are lenient in regards to many dinim, there is no heter to be lenient with eating meat and wine, and one must wait until after midday on Friday.
What’s the din if a women cooks on motzei Tisha B’Av/erev Shabbos before midday some meaty food and she wants to taste it to know if it needs more salt? Certainly, if she is tasting food which was cooked with meat but is not actually meat itself she may taste and even eat it. The question is, what about meat itself? It would seem that even meat itself she may taste and even swallow. On erev Shabbos Chazon the poskim allow a women to taste the meaty Shabbos food, however, many poskim say she should only taste and then spit it out. However, on erev Shabbos after Tisha B’Av it would seem that she may certainly swallow it, being as that even on erev Shabbos Chazon some poskim allow swallowing (see Kovets M’Beis HaLevi, Vol. 13, pg. 49 ois 3) and certainly on erev Shabbos after Tisha B’Av, where the dinim of aveilus are much more lenient. However, she should make sure to swallow less than a kezayis.
