Kosher Laws Impacting Food Technology
JOE M. REGENSTEIN
Cornell Kosher Food Initiative
Dept. of Food Science

The kosher dietary laws determine which foods are "fit or proper" for consumption by Jewish consumers who observe these laws. The laws are Biblical in origin, coming mainly from the original five books of the Holy Scriptures. Over the years, the details have been interpreted and extended by the rabbis to protect the Jewish people from violating any of the fundamental laws and to address new issues such as biotechnology.

Why do Jews follow the kosher dietary laws? Many explanations have been given. The following by Rabbi Grunfeld is possibly the best written explanation and probably summarizes the most widely held ideas about the subject (Grunfeld, 1972). These laws are not health laws. For a more complete discussion of the kosher laws and health, please see Regenstein, 1994.

The kosher market covers almost 100,000 products in the US. In dollar value about 100 billion dollars worth of products have a kosher marking on them. The actual consumers of kosher food, i.e., those who specifically look for the kosher mark, are estimated to be about 6 to 8 million Americans and they are purchasing almost 4 billion dollars worth of kosher product. Only about 1/3 of the kosher consumers are Jewish; other consumers include Muslims, Seventh Day Adventists, vegetarians, people with various types of allergy, particularly dairy, grain, and legume, and general consumers who value the quality of kosher products: "We report to a higher authority." AdWeek Magazine has called kosher "the Good Housekeeping Seal for the 90s." By undertaking kosher certification, companies can incrementally expand their market by opening up new markets.

The kosher dietary laws predominantly deal with three issues, all in the animal kingdom:

A. Allowed Animals.
B. Prohibition of Blood.
C. Prohibition of Mixing of Milk and Meat.

However, for the week of Passover (in late March or early April) restrictions on "chometz," the prohibited grains and the rabbinical extensions of this prohibition leads to a whole new set of regulations, focused in this case on the plant kingdom.

Ruminants with split hoofs that chew their cud, the traditional domestic birds, and fish with fins and removable scales are generally permitted. Pigs, wild birds, sharks, dogfish, catfish, monkfish, and similar species along with all crustacean and molluscan shellfish are prohibited. Insects are also prohibited so that carmine and cochineal (natural red pigments) are not used in kosher products.

Furthermore, ruminants and fowl must be slaughtered according to Jewish law by a specially trained religious slaughterman. These animals are also subsequently inspected by the rabbis for various defects. The meat and poultry must be further prepared by properly removing certain veins, arteries, prohibited fats, blood, and the sciatic nerve. In practical terms this means that only the front quarter cuts of red meat are generally used. To remove the blood, red meat and poultry are soaked and salted within a specified time period. Furthermore, any materials that might be derived from animal sources are generally prohibited because of the difficulty of obtaining them from kosher animals. Thus many products that might be used in the food industry, such as emulsifiers, stabilizers, and surfactants, particularly those that are fat-derived, need careful rabbinical supervision to assure that no animal-derived ingredients are used. Almost all such materials are also available in a kosher form derived from plant oils and, possibly in the future from biotechnology.

"Thou shalt not seeth the kid in its mother's milk."

This passage appears three times in the Torah (the first five books of the Holy Scriptures) and is thus taken religiously as a very serious admonition. The meat side of the equation has been rabbinically extended to include poultry. The dairy side includes all milk derivatives.

To keep meat and milk separate requires that the processing and handling of all products that are kosher will fall into one of three categories:

A. Meat products.
B. Dairy products.
C. Pareve (Parve) or neutral products.

The latter includes all products that are not classified as meat or dairy. All plant products along with eggs, fish, honey, and lac resin (shellac) are pareve. These pareve foods can be used with either meat products or dairy products, except that fish cannot be mixed directly with meat. Once a pareve product is mixed with either meat or dairy products, they take on the status of meat or dairy, respectively. Thus, any ingredients that are made by biotechnology through expression in milk would be dairy. A serious limitation.

If one wants to make the product truly pareve, the plant can usually be made pareve by the process of equipment kosherization (see below). From a marketing point-of-view, a pareve designation is most desirable when possible.

During this holiday which occurs in the spring, all products made from the five prohibited grains: wheat, rye, oats, barley and spelt (Hebrew: chometz) cannot be used except for the specially supervised production of unleavened bread (Hebrew: "matzos"), that are prepared especially for the holiday. Special care is taken to assure that the matzos do not have any time to "rise." In addition, products derived from corn, rice, legumes, mustard seed, buckwheat, and some other plants (Hebrew: kitnyos) are prohibited. Thus, items like corn syrup, corn starch, etc. would be prohibited. Thus, some opportunities for biotechnology-derived materials may exist in this context.

There are three ways to make equipment kosher and/or to change its status. Which procedure is required depends on the equipment's prior production history. Note: After a plant (or a line) has been used to produce kosher pareve products, it can be switched to either kosher dairy or kosher meat without a special equipment kosherization step. Kosher dairy or kosher pareve production can also usually be fairly easily prepared for halal production.

The simplest equipment kosherization occurs with equipment made of materials that can be koshered that have only been handled cold. These require a good caustic/soap cleaning. However, materials such as ceramics, rubber, earthenware, and porcelain cannot be koshered. If these materials are found in a processing plant, new materials may be required for production and switching between different status conditions will be difficult.

Most food processing equipment is usually operated at cooking temperatures, generally above 120F, which is defined rabbinically as "cooking." However, the exact temperature for "cooking" depends on the rabbi, although an agreement by the major four American kosher certifying agencies has settled on 120F as the temperature at which foods are cooked. To kosher these items which have been used with cooked product, the equipment must be thoroughly cleaned with caustic/soap. The equipment must be left idle for 24 hr and then the equipment must be flooded with boiling water (defined between 190F and 212F) in the presence of a kosher supervisor.

In the case of ovens or other equipment that uses "fire," kosherization involves heating the metal until it glows. Again, the rabbi will generally be present while this process is taking place.

The procedures that must be followed for equipment kosherization can be quite extensive, so that the fewer status conversion, the better. Careful formulatiing of products and good production planning can minimize the inconvenience.

Ingredient companies should try to use a "mainstream" kosher supervision agency. To sell ingredients, including those derived from biotechnology, to most kosher food producing companies will require such supervision. The ability to sell to as many customers as possible requires a broadly acceptable standard. Unless an ingredient is acceptable to the mainstream, it is almost impossible to gain the benefit of having a kosher ingredient.

Rabbis currently accept products made by simple genetic engineering, e.g., chymosin (rennin) was accepted by the rabbis about a half year before it was accepted by the FDA! The production conditions in the fermentors must still be kosher, i.e., the ingredients and the fermentor and any subsequent processing must use kosher equipment and ingredients of the appropriate status. A kosher product produced in a dairy medium would be dairy. We believe that the rabbis may soon approve porcine lipase made through biotechnology, if all the other conditions are kosher. (Any product produced by cattle by excretion in the milk would be dairy!) The rabbis have not yet determined the status of more complex genetic manipulations.

Chaudry, M.M. and J.M. Regenstein. 1994. Implications of Biotechnology and Genetic Engineering for Kosher and Halal Foods. Trends Food Sci. Technol. 5:165-168.

Grunfeld, I. 1972. The Jewish Dietary Laws. p. 11-12. The Soncino Press. London.

Ratzersdorfer, M., J.M. Regenstein, and L.M. Letson. 1988. Appendix 5: Poultry Plant Visits, in A Shopping Guide for the Kosher Consumer, J.M. Regenstein, C.E. Regenstein, and L.M. Letson (eds.) for Governor Cuomo, Governor, State of New York.

Regenstein, J.M. 1994. Health Aspects of Kosher Foods. Activities Report and Minutes of Work Groups & Sub-Work Groups of the R & D Associates. 46(1):77-83.

Regenstein, J.M. and C.E. Regenstein. 1979. An Introduction to the Kosher (Dietary) Laws for Food Scientists and Food Processors. Food Technol. 33(1):89-99.

Regenstein, J.M. and C.E. Regenste in. 1988. The Kosher Dietary Laws and their Implementation in the Food Industry. Food Technol., 42(6):86+88-94.

Regenstein, J.M. and C.E. Regenstein. 2000. Kosher Foods and Food Processing. Encyclopdedia of Food Science 1449-1453.