An age-old adage declares, “The more things change, the more they stay the same.” The conventional approach to understanding the profundity of this truism is that, contrary to popular belief, life in our modern-day society resembles the life of our ancestors far more than it differs from it. Lessons gleaned from history give direction on how to proceed in the future. The Ramban called this an “inyan gadol” – a matter of paramount importance – when he commented (Bereishis 12:6): Kol ma she’ira la’avos, siman labanim, “Everything that transpired in the lives of the Patriarchs is a portent for their descendants.” The Torah is the embodiment of this reality. Its laws are as contemporary as they are timeless, and its historical accounts relating the events of thousands of years ago are ever relevant to the here and now. Times may be different, but life’s challenges and appropriate responses to those challenges, as set forth by the Torah, remain the same.

Kashrus standards are impacted by “changes to keep things the same.” In the world of kashrus the buzzword for this problem is compatibility. Compatibility poses the greatest concerns for kashrus in three areas: ingredients, equipment and packaging. This concern for compatibility as outlined in Shulchan Aruch (Yoreh Dei’a 118) is known as hachlafa: the manufacturer may substitute a compatible non-kosher ingredient or utensil to make a product that could otherwise be certified as kosher. The following is meant to serve as an overview of how this issue is resolved in Shulchan Aruch and how it is implemented practically today by reputable kashrus agencies. This information is in no way intended to present all possible scenarios, but rather to convey a sense of the general issues that come up and an approach to solutions.

Ingredient Compatibility

Let us look at one company that manufactures cookies. The company applies for kosher certification. Upon review, they are found to make both kosher and non-kosher cookies, albeit on two separate production lines. The ingredient that makes the non-kosher cookies treife is an animal shortening, while a kosher vegetable shortening is used to make the kosher cookies. Both the treife animal shortening and the kosher vegetable shortening are completely compatible and can be used interchangeably for both kosher and non-kosher products. How can we assure that the animal shortening won’t be used to make the kosher cookies?

The best solution to the above problem of ingredient compatibility is to eliminate the problem altogether. Before certifying a company, a reputable kashrus agency will isolate and remove all problematic compatible ingredients – in this case, the treife animal shortening – from the company’s premises. Hence this company will be instructed to make all their cookies using only approved kosher ingredients. To enforce this, the company will be asked to sign a contract stating that their kosher certification is contingent on their using and/or warehousing only the ingredients on an approved list. Companies found in violation can have their kosher certification revoked and/or face other punitive measures.

Another classic application of this arrangement is in the case of a company that uses shortening for both its manufacturing and distribution operations. In order to certify as kosher the manufactured products that use kosher vegetable shortening, care must be taken to ensure that all compatible non-kosher animal shortening stored in the distribution section are removed permanently from the manufacturing warehouse. Then a worker would not be able, even “accidentally,” to substitute non-kosher animal shortening for the kosher vegetable shortening needed to make the product. Non-kosher ingredients must be removed even if the company strongly contends that nothing stored in distribution is ever used for manufacturing purposes.

A third example can involve a company that manufactures both dairy muffins and pareve bagels. If the company plans to certify as kosher a chocolate-chip bagel, which must be pareve (to eliminate the problem of dairy bread), then the compatible chocolate chips used in the dairy chocolate chip muffins must also be pareve, to prevent any potential “accident” of a worker’s using dairy chocolate chips to produce the pareve bagels.

It should be pointed out that the compatibility problem is generally mitigated with hashgacha temidis – continuous Rabbinic kashrus supervision, because the mashgiach is watching to make sure that the non-Jewish manufacturer is not using any questionable ingredients or equipment. The primary concern for compatibility is when there is only yotzei venichnas – intermittent kosher supervision – when the Rabbinic kosher supervisor is not always around to watch the non-Jewish manufacturer (which is true in most cases).

What about receiving a food delivery from a non-Jew? How can one be sure that the kosher food that was ordered was not substituted with a compatible non-kosher variety? The Shulchan Aruch (Yoreh Dei’a 118:1) rules that in this situation, any meat, fish fillets or wine that are handled by non-Jews be secured with two simanim (indicators of kashrus). This halacha is very relevant for large supermarket chains whose meat and seafood departments have reputable kashrus certification. All bodes well when the mashgiach is around during the day. However, what about the meat and filleted fish that is put out in the open display after the mashgiach leaves? At this time there are only non-Jews working in the store, with no on-site hashgacha. Consumers should check that the meat and/or the filleted fish packages in the open display bear two simanim that show the appropriate hechsher. This also holds true when non-Jews from a kosher grocery or restaurant deliver the meat and/or filleted fish. Cheese requires only one siman (ibid.); kosher pizza deliveries handled by non-Jews need one authentic siman kashrus on the pizza box.

Ingredient Compatibility

In addressing the issue of equipment compatibility, the Rema in Shulchan Aruch (Yoreh Deah 98:2) advises that separate salt shakers be designated for dairy and meat. Indeed, it is sound practice for kosher households to maintain separate and distinguishable dairy, pareve and meat utensils. This will diminish the chances of accidentally using a milchig fork and knife, for example, to eat a succulent fleishig steak.

Sheet pans can be the source of serious problems. There is hardly a food-service operation that doesn’t make good use of sheet pans. Consequently, kitchens in restaurants, hotels, yeshivas, synagogues, hospitals and nursing homes, more than likely roast chickens and bake pizzas on sheet pans that look identical. It goes without saying that these pans should be properly identified and marked. Moreover, these same food services may be receiving deliveries of cakes from a kosher bakery on sheet pans that are identical to their own. The sheet pans from these institutions and the bakery’s sheet pans must not get mixed up. In general, it is a good policy to make sure that sheet pans never leave the premises.

What holds true for the kosher household is equally true for kosher-certified food manufacturers. In one common scenario, safeguards and controls must be instituted to ensure that dairy equipment is not being used to make pareve products. On a commercial level, marking and identifying the equipment as either dairy or pareve, although commendable and advisable, is not quite adequate, since, for example, without an on-site mashgiach, a non-Jewish worker can still “accidentally” use a blue-marked dairy sheet pan to bake a pareve cake. Once again, the solution is to eliminate the compatibility problem altogether. Knowledge of how equipment is used is essential for the mashgiach to determine where problems may crop up. A soup pot would not be used to bake a cake, nor would a fluted bread pan be used to bake cookies; dairy pastry single racks could not be used in a pareve double-rack oven, and vice versa. However, wherever the functionality of the equipment is compatible for both dairy and pareve operations, even the products that use only pareve ingredients would have to be certified dairy.


We must also address the prevailing practice of “rework” as it relates to compatibility. In an effort to maximize efficiency, companies try to limit the discarding of scraps from their manufactured products by recycling or reworking the scrap in making other products. This practice can be likened to taking pasta left over from one meal and using it for a tuna casserole to be served at another meal. Similarly, a company that bakes breads and pastries, for instance, will rework any scrap dough so that it not go to waste. Many times dough rework from the pareve breads and the dairy pastries are compatible enough that the company will not hesitate to use the reworked pastry dough to make the bread.

The solution in a case like this involves making the two production lines totally incompatible through a fully automated closed system. In this closed system the reworked dough is mechanically conveyed back only into the original, or “parent,” product. Routinely, the Rabbinic kashrus supervisor will watch the connections on these production lines closely during his regular yotzei venichnas visits. Factories that don’t have the capacity to use fully automated closed systems would have to settle for having their products certified as either all dairy or all pareve.

Packaging Compatibility

As many companies have multiple manufacturing plants to make their products, optimally, all the plants that make the products will become kosher-certified. This, however, is not always the case, and a single company may have only a few of its plants kosher-certified. Therefore, a reputable kashrus agency will try to ensure that the packaging of the products being made in one plant doesn’t resemble the packaging of the same products made in another, non-kosher-certified plant. This is to avoid confusion among consumers who may inadvertently purchase a product that has no kosher symbol, assuming that it has the kosher symbol they found on it in the past. The consumer will not be aware that there are identical products being made in both kosher-certified and non-kosher-certified plants. Although food packages may appear identical, consumers should always be alert to check for the kosher symbol on the package and not assume that it’s there today because it was there yesterday. If the purchase was already made, and it was subsequently discovered that the kosher symbol was missing, contact the kosher agency certifying that product to inquire about the product’s kashrus status.

There is, however, another way to understand the adage of “The more things change, the more they stay the same,” underscoring modern-day technological achievements in the ability to create near-perfect imitations. Quite often the changes effected through today’s technologies are made to create more and more things that stay the same – that look, feel, smell and behave as genuine and authentic as the real thing. And so today we are witness to cloned animals, hydroponically grown vegetables, and computers that talk like people and may soon even look like them.

Kashrus is directly affected by this upsurge in imitation technology. With the new trend in trans-fat-free diets, a process has been developed to create a trans-fat-free shortening made of lard that has zero cholesterol. This means that the benefits of vegetable shortening over animal shortening have been virtually eliminated, and companies that were completely animal-fat free in the past are considering using animal fat again. This trend is being closely monitored by reputable kashrus agencies to ensure that kashrus is not being compromised. The notion that trans-fat-free is a guarantee of kashrus is a myth. Unless the packaging bears the kosher symbol, there is no guarantee.

Certainly technologies have created challenges to kosher supervision by obscuring differences and making foods and operations look and feel more and more the same. As a result, in today’s day and age, when there is a question of whether something is real or imitation, often only a connoisseur can say for sure. Technology has certainly proven its resolve and adroitness in changing things to make them the same. Still, there is one thing that has never changed and will forever remain the same – the immutable Torah and the laws of kashrus contained therein. The Torah is the “real thing,” and for the kosher consumer, that’s a great source of comfort and stability.

OU Kosher Staff