Q. Is it enough just to taste a tiny bit or there is a shiur required?
If only a small taste is necessary, do you make a brocho?
A. Poskim address the question of whether one recites a brocho before tasting the food.
Although Halacha normally requires reciting a brocho before partaking of even a small amount of food or drink, in this instance, where a person ingests the food only for tasting purposes, perhaps no brocho is required.
Indeed, Shulchan Aruch (O.C. 210) rules that if one tastes less than a revi'is (86 cc.) of a liquid or a k’zais (28 grams) of solid food, one does not recite a brocho. Since he ingests the liquid or food only for the purpose of tasting, he does not recite a brocho unless he consumes a significant amount.
However, given the difference of opinions that exists in this regard, Mishna Berura (ibid. 19), Igrois Moishe ((80), Hazon Ovadia (Laws of Shabbat, p. 21) and others, rule that one should preferably taste the food with the intent of eating or drinking, and not merely tasting.
Horav Shlomo Miller's Shlit'a opinion is similar.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a