Passover is when Jewish eating habits seem the most distinct from those in the rest of the world—the most restrictive, the most inexplicable. Keeping Passover means adhering to rules and traditions on top of the standard rules of kashrut, or keeping kosher, which include not eating shellfish or pork and separating anything containing milk from anything containing meat. At Passover bread and all other leavened foods are banned, and the questions of what is and isn't allowed only start there. Corn or no corn? Rice or no rice? Must staples that don't need to be marked kosher the rest of the year—milk, for instance—be marked "kosher for Passover," along with the matzoh? (As with all questions Jewish, it depends on who's answering.)
And yet Passover is the time of year when sales of kosher foods reach their peak, and when the greatest number of Jews follow some form of dietary abstention. A moment of generally happy reconnection with Jewish identity, Passover can move usually unobservant Jews to consider keeping kosher year-round. With its many preparatory kitchen-cleaning requirements, it is also the most logical time to make the switch.
The market for foods certified kosher has been steadily increasing for at least a decade. Menachem Lubinsky, a marketing consultant and the editor of Kosher Today, a trade magazine, estimates that of $500 billion in retail grocery sales last year, $185 billion was certified kosher—a rise since 1988 of about 285 percent. As of 2004 fully 85,000 products were certified kosher, compared with 18,000 in 1988. Much food—flour, rice, and other staples, and all produce—is kosher by definition, and need not bear a "hechsher," or kosher symbol, although a lot of it does. A hechsher can be as much an indication that a manufacturer thinks certification will attract customers as that it produces kosher food.
Commercial kosher certification in this country has come a long way from its beginnings, in the early 1920s, when shoppers had to look hard to see if a product was officially kosher. The inconspicuousness was intentional. With increasing waves of immigrants requesting kosher foods, established (and non-Jewish) food manufacturers recognized a new market to be tapped. But they didn't want to lose any customers. So they asked the Orthodox Union, based in New York and today the largest certifying organization in the world (it certifies food in seventy-seven countries), to devise a symbol that did not show the word "kosher" or betray its meaning to those who might prefer to avoid "Jewish food." The symbol—a U inside an O—is still in use. Today's hechshers are practically blaring by comparison, and many mainstream producers now spell out the words "pareve," meaning neither dairy nor meat, and "kosher" itself.
The labeling is useful not only to those keeping kosher but also to many others who choose or need to control their diet. Vegetarians know that a product marked "dairy" or "pareve" contains no meat, and vegans and people who are lactose-intolerant know that pareve foods contain no dairy products. Seventh-Day Adventists, who are often vegetarian, are an important part of the kosher market, as are Muslims: all forms of pork are both haram (not allowed in the Muslim diet) and non-kosher, or treif (literally "unfit"). Observant Muslims will buy kosher meat in the absence of a halal butcher.
People are turning to kosher food not just because of a revival in religious observance but because anyone buying food today is rightly concerned with safety, especially the safety of meat, and kosher certification requires careful inspection. Animals that are visibly ill before slaughter are forbidden. (This would have eliminated the "downer" cow, unable to walk, that was the one confirmed carrier of mad cow disease in the United States; other safeguards include the prohibition of stunning before slaughter, which can spread brain and spinal fluids to meat.) Some animals are further examined after slaughter. "Glatt," a word meaning "smooth," signifies that the lungs of the animal have been found free of adhesions indicating possible cancer or other systemic disease. An animal rejected as glatt can be qualified as (plain) kosher, but many slaughterhouses simply sell that meat as non-kosher, so by default all their kosher meat is glatt. Although "glatt" has no meaning outside the slaughtering process, in the 1970s it became generally used to mean "extra kosher," as Lisë Stern explains in her recently published How to Keep Kosher.
Kosher certification does not, however, offer many of the guarantees that health- and environment-conscious consumers might want. Kosher food need not be organic. There is no clear rabbinical stance on genetically modified organisms, even if in theory the manifold rules against anomalous foods would seem to forbid them. This is a natural concern for "advocates of eco-kashrut," as Stern terms them in her book. (With kashrut being adopted by many young Jews, there is of course an eco-kashrut movement; you can read about it at earthkosher.com.)
And kosher food is often produced by multinational agribusinesses whose environmental and labor practices can be questionable. Hebrew National, for instance, known for its kosher hot dogs, is owned by ConAgra, a company practically synonymous with global agribusiness. (For reasons of slaughtering and certification methods, many Orthodox rabbis recommend against Hebrew National products.) Like all other industrially raised and packaged foods, kosher food can be full of trans fats (more unhealthful than butter, though pareve) and processed sugar. Lovers of "old" Coke take note: at Passover big-name sodas are made not with the usual corn syrup—cheap and insipid and, happily, not kosher for Passover—but with the far superior cane syrup.