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What is Kosher?


The Hebrew word kosher translates to mean right or proper. Kosher foods are managed under kashrut; the Jewish dietary laws. Kashrut specifies which animals are acceptable to consume and dictates how they must be slaughtered and prepared. In addition, milk and eggs are kosher only if they come from kosher animals. Furthermore, kosher forbids the mixing of milk and meat, which by extension, forbids the mixing of milk-derived ingredients and other animal-derived ingredients. Kosher foods and ingredients are therefore categorized as kosher meat (fleishig), dairy (milchig), or pareve (or parve) for neutral; neither meat nor dairy. Under Kashrut, wine also has special requirements, and by extension, any ingredient derived from the wine industry (such as acetic acid or ethanol from grapes).


With the restrictions on meat and dairy derived products, as a prerequisite for kosher food chemical manufacturing, the ingredients sourced must be from exclusively botanical or petrochemical origin. Care should be taken to understand the manufacturing method and all reagents and catalysts used. Enzymatic reactions can be particularly difficult to verify as the origin of the enzyme must be certified. Similarly, emulsifiers and anti-foaming agents should be of exclusively synthetic or plant origin.

The best way to ensure the supply chain is kosher is to purchase only kosher certified ingredients from reputable kosher certifying organizations. Certifying rabbis may not require kosher certification for all ingredients, if the materials are deemed very low risk for kosher. The certifying rabbi will indicate which materials require kosher certification and what verification activities must be implemented for kosher.


Ideally kosher products should be stored in separate facilities from non-kosher products, but this is not always possible or practical. Raw material storage where manufacturing or packaging (down-filling) takes place must be strictly controlled to meet kosher requirements, however. Controls are not only necessary to prevent cross-contact, but kosher management does not allow for both kosher and non-kosher raw materials to be stored in the same processing facility where kosher and non-kosher processing takes place. If, for example, stearic acid is used as a raw material in a facility to produce both kosher and non-kosher products, only kosher stearic acid should be stored in that facility, thus minimizing the possibility that the wrong raw material is used. Using a kosher raw material when producing non-kosher products has no impact on those products so a single, kosher raw material will meet both kosher and non-kosher needs.

If the raw material is used exclusively for manufacturing non-kosher products, it can be stored in the same facility as kosher raw materials, though proper controls to prevent cross-contamination must be in place. Where a processing plant holds both kosher and non-kosher ingredients, those ingredients require physical separation such as a wall or another significant barrier between the kosher and non-kosher ingredients. Kosher and non-kosher ingredients can be stored in the same processing facility if there is a significant dissimilarity between the ingredients such as different chemical entities. Minimal differences, such as different product codes, different purities/specifications, or different packaging is not sufficient to meet the kosher separation requirement.


Any direct contact equipment used in kosher manufacturing or processing must also meet kosher requirements. Proper cleaning and other controls to prevent cross-contamination must be used. Cleaning reagents should be evaluated to ensure they do not introduce a kosher risk. Even with proper cleaning and cross-contamination control, dedicated equipment may be necessary. Kashrut applies a principle of absorption and transference to cooking including kosher manufacturing or processing involving heating. When heating, the utensil or vessel exposed to the hot materials takes on the character of those materials (adsorption). When heated again, that character is transferred to any other heated material it contacts.

For example, if a manufacturing process involves heating a non-kosher raw material in glassware with a stir rod, the glassware and stir rod take on the non-kosher character of the raw material. Neither that glassware nor the stir rod should be used for kosher processing involving heating. If they were used in such a process, the non-kosher character would transfer to the kosher raw material causing it to lose its kosher pedigree and thus no longer be considered kosher.

Where heat is used in processing, dedicated equipment, including utensils, should be used. Where dedicated equipment is not available or not feasible, it is possible for the equipment to be kosherized through a process called kashering; the process of making utensils/equipment kosher. Kashering involves applying heat equivalent to cooking, typically steam or even a blow torch, to the equipment/utensil under the direct supervision of a rabbi. In a kosher-certified facility this will be the rabbi responsible for the kosher certification. The rabbi will oversee and confirm the equipment/utensils are treated with sufficient heat for an adequate time. In most cases only metal or glass equipment/utensils can be kosherized as polymeric or ceramic items are considered too porous or subject to absorption.


Process steam used in manufacturing can create an additional challenge. Most boiler systems use a condensate return to recycle water back to the boiler. Since steam used to heat various processes also takes on the character of the material (through adsorption), steam used for heating non-kosher processes should not be used for kosher processes. Even if the steam is not directly injected into the process, kosher supervision considers steam that directly contacts the walls of the vessel being heated are subject to absorption and subsequently transference. The same rules hold true for other thermal transfer fluids.


Kosher certification is a must have for most of the food industry. Segregation, cleaning, and cleanliness are key to meeting kosher requirements. Once concepts such as absorption and transference are understood, kosher operations can be implemented, and market needs met.

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