In determining the appropriate blessing to recite when eating rice, the Gemara cites two contradictory baraitot. In one rice is determined to be similar to cooked dishes inasmuch as blessings are recited both before and after eating, albeit the blessings are a general “By Whose word all things came to be,” and at the end, “Who creates the many forms of life and their needs for all that You have created.” In the other baraita, rice is treated like a true grain and the blessings are more specific.
In explanation, the Gemara suggests that the second baraita should be identified with the position put forward by Rabbi Yohanan ben Nuri regarding the laws of matzah. Rabbi Yohanan ben Nuri rules that rice is also a type of grain for which one would be held liable for eating on Passover if it became hametz, and that one could fulfill the mitzvah by baking it into matzah. The accepted opinion understands that the process of mixing rice with water does not lead to himutz but to sirhon. The Jerusalem Talmud explains that establishing which types of grains are those that can become hametz and matzah was based on extensive research done by the sages, who experimented with the baking process to ascertain whether the fermentation process takes place. With regard to a small number of grain-type products, there remained differences of opinions as to whether the process that took place should be considered himutz.
Although the conclusion of the Gemara clearly rejects the opinion of Rabbi Yohanan ben Nuri, nevertheless over centuries of Jewish history traditions arose that limited the use of kitniyot on Pesach due to a concern that kernels of grain may become mixed in with them. Generally speaking, Ashkenazi communities limit their use. Among the traditions:
– Some make full use of kitniyot.
– Some forbid the use of rice, but permit other types of pulses.
– Some forbid the use of all kitniyot.
As a rule, people follow the traditions of their parents and communities.