All fruits, grains and vegetables in their natural state are kosher and pareve.

After the ingredients are deemed kosher, the production process must be reviewed. If the plant produces kosher and non-kosher, or dairy, meat and pareve products, it is essential to identify the equipment used for producing each product. Some products cannot be certified because they are made on non-kosher equipment, unless the equipment is kosherized between uses.

(Kosherizing is the process of making vessels, utensils, fillers, etc. kosher. It requires specific cleaning procedures, which focus on temperature. This prevents cross-contamination of foods that are not allowed to be eaten together, basically dairy and meat, and it prevents contamination from previous non-kosher products.)

After the agency determines that a product can be kosher, a contract is drawn up that specifies ingredients and production process. Once the contract is signed, a trained inspector called a mashgiach must visit the plant on a regular basis to make sure that the contract is being enforced.

What types of foods are the most challenging to certify kosher and why?

Rabbi Genack: Meat and meat products are the most challenging because meat requires a special kosher slaughter. This affects not only the meat itself, but ingredients that can be produced from animal sources, such as gelatin, glycerin and other derivatives. As a result, the majority of beef gelatin on the market is not kosher, although kosher versions are available. Another example of a difficult product is wine or grape juice. Because of the sacramental nature of such products, there are extra requirements involved in its kosher production, including the need for a rabbinic team to be very involved in every aspect of production. Finally, most cheeses require a rabbinic team to be involved in production, as well. In such productions, we have rotations of rabbis who stay near the factory and are on call at all times.

Kosher cheese cannot be made with animal rennet and it must be produced with onsite rabbinical supervision.

What is the difference between kosher and kosher for Passover?

Rabbi Genack: The classical food for Passover is matzah, a flat thin cracker of unleavened bread, which is baked before the dough has a chance to rise. Why matzah? The bible relates that more than 3,000 years ago, the Jewish people were freed from slavery in Egypt through divine intervention. As they prepared to leave Egypt and travel to the desert, they baked matzah, rather than bread, because they left in great haste, and there was no time to wait for the dough to rise.

To commemorate the exodus, God instructed the Jews to eat matzah every year during the Passover holiday. In addition, the bible prohibits eating chometz, which is leavened bread made from wheat, oat, spelt, rye or barley, during Passover. Chometz is proscribed because it is the antithesis of matzah, since leavened dough rises before the baking occurs.

Through Rabbinic interpretation, the definition of chometz has been expanded to include not only bread products, but any food item, made from wheat, oat, spelt, rye or barley, that is not similar to matzah. Thus, grain-fermented vinegar, as well as many breakfast cereals, are considered chometz and may not be consumed on Passover.

Further, most non-Passover kosher certified products are not produced in the presence of a Rabbinic field representative (RFR). The RF. visits the plants at regular intervals and such spot-checking is sufficient to establish the integrity of the kosher status. In contrast, most Passover-certified products are manufactured while the RFR is in attendance. This is because the bible is far more stringent and exacting in describing Passover laws than year-round kosher requirements. If non-kosher food is bad for the soul, then chometz during the eight days of Passover is spiritual poison. In a kosher home, there are weeks of cleaning and scrubbing to prepare the kitchen for Passover. Even home shelves are lined with paper to ensure against minute amounts of chometz contaminating the food, and this is why supermarkets often line their shelves where Passover products are sold. This same caution is reflected in the full-time supervisory requirements for OU products.

What differentiates the OU’s kosher certification process from others?

Rabbi Genack: OU Kosher is the world’s oldest and largest certification. The OU is a nonprofit charitable agency and our standards for kosher certification have largely set the standard in North America.