Does a rabbi has to say something from torah to make food kosher?

Answer 1

No, a rabbi doesn't have to be involved in the preparation of kosher food whatsoever. What makes food kosher is that the ingredients are kosher and the preparation follows the rules of kashrut.

Answer 2

No. The Rabbinical certification of food to make it kosher, involves the ascertaining

that the food has no ingredients or processes forbidden by Jewish law.

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To address a few widespread misconceptions on this subject:

-- Nothing that anybody can do or say, including a rabbi, can make non-kosher food kosher.

-- An edible item or preparation is inherently, in and of itself, either kosher or not. It's

often obvious, but just as often, it's not obvious, because the laws that distinguish

one status from the other are complex. In those cases, an individual educated and

trained in the law, and familiar with it, can express an opinion. Note that his opinion

is not what makes it kosher, and it's quite common that some people accept his

opinion while others don't.

-- When the food comes from the supermarket shelf, and not straight off the farm

in full view of the consumer, there is the question of how it was prepared, and

what it came in contact with during processing, cooking, and packaging ... simply

because there were many steps in there that the consumer didn't see. That's

the reason for the organizations that monitor the process, from the farm to the

packaged product, and allow their mark or icon to be printed on the package,

certifying that the product is kosher to the level of the standards of that particular

orgaization. Again, for each organization, there are kosher consumers who accept

the standards of that particular one, and others who don't.