Most food spoilage occurs when certain types of microorganisms, such as bacteria and mold, grow in food. As they grow, these microorganisms produce various chemicals that may give an objectionable odor or flavor to the food, or may even be pathogenic. One method of preventing such spoilage is to destroy the microorganism, such as by heating or irradiating the food.
Another is to put the microorganism into a dormant state by freezing, since microorganisms, while frozen, do not produce these chemicals. A third approach, however, is to add certain chemicals to the food that tend to inhibit the growth of the offensive microorganisms. It is the Kosher status of these various agents that will be the subject of our discussion.
One of the earliest recorded methods of food preservation, ironically, was through the use of microorganisms themselves. It was noted long ago that when foods were allowed to ferment under appropriate conditions, the bacteria or mold that was part of the fermentation would do two things. First, it would often improve the flavor of the food or give it different beneficial characteristics, and second it would allow for the storage of the food without further deterioration. Milk was fermented into cheese and yogurt, fruit juice into wine, and vegetables and meat into pickled foods.
The fermentation process allows for the growth of desirable microorganisms in food, and preserves it by two mechanisms. First, certain strains of bacteria are more robust than other strains, and when both types of organisms compete for the same food source, the stronger bacteria will dominate.
In this manner, the growth of stronger, more desirable bacteria can inhibit the growth of those that would otherwise cause food to spoil. Second, the desirable bacteria produce certain chemicals that tend to inhibit other microbes from growing. For example, the fermentation of fruit juice with yeast produces alcohol, which tends to inhibit the growth of organisms that would otherwise cause the food to spoil.
The bacteria used to ferment many other products, including vegetables, dairy products, and meat produce lactic acid, which also has the propensity to inhibit undesirable bacterial growth. While the exact process by which these fermentations preserved foods was not understood until recently, people have nonetheless enjoyed the fruits of these processes for thousands of years.
Modern food technology has allowed us to isolate desirable microorganisms for use in these fermentations. These are called microbial cultures. Cultures are merely concentrations of desirable bacteria, yeasts or molds that have been isolated from natural sources or have been modified (either through genetic engineering or through a more conventional process called mutagensis.)
The Jewish law status of cultures, however, raises several interesting points. We do not live in a sterile environment, and innumerable bacteria, molds, and yeasts are found on and even in virtually every food we eat. When microscopes were perfected several hundred years ago, it was discovered that these “micro”organisms were indeed living organisms, and had shapes and behavior similar to the larger animals that are called Sheratzim (insects).
The terms Sheratzim encompasses many creatures, including small insects that are not Kosher, and the question arose that perhaps microorganisms had the same status as these prohibited creatures. Jewish law authorities were quick to note that such a comparison was clearly not tenable.
The Kosher status of microbial cultures does, however, pose a concern for the following reason. When cultures are manufactured, a single colony of bacteria, for example, is placed in a fermentor containing a food source appropriate for the growth and propagation of those bacteria. This food source is called a growth media, and as the bacteria grow and reproduce, tremendous amounts of the desired bacteria are formed that are then concentrated and sold as cultures.
Often, the media most favored by the bacteria is either dairy or not Kosher, and the Jewish law status of the culture is directly tied to the Kosher status of the media on which it is grown. Care must therefore be taken that cultures used in the production of salami or pickles are grown on Kosher media that does not contain any dairy components.
Other systems of food preservation rely on the use of various chemicals to inhibit the growth of offensive microorganisms. Salt has been used for thousands of years, since it inhibits bacterial growth and provides flavor to food.
Benzoates, nitrates and nitrite are also commonly used, and pose no Kosher concern. Lactic acid (produced through the fermentation of various types of sugar), and its salts sodium and potassium lactate, is also added to a variety of foods as a preservative.
Although there is a linguistic relationship between lactic acid and lactose (milk sugar) and lactic acid can be made from that sugar, virtually all lactic acid produced today is fermented from corn or cane sugar and is therefore Pareve (non-dairy). Vinegar has been used as a preservative for thousands of years due to the properties of the acetic acid that is its active ingredient.
Vinegar can be made from wine, and requires a reliable Kosher certification. Acetic acid can be produced from petroleum derivatives (petrochemicals) or from alcohol derived from fermentation. Some sources of such alcohol are wine and lactose, and a reliable Kosher supervision is required to ensure that the source of the acetic acid is indeed Kosher certified.
Propionic acid, and its salts sodium and calcium propionate, are also used extensively to control the growth of a particular mold (known as rope) in bread. Propionic acid is generally produced from petrochemicals and poses no Kosher certification issues. However, consumer preference for “all-natural” ingredients, a status that petrochemical propionic acid does not enjoy, does raise a Kosher certification concerns.
Natural propionates can be produced through fermentation and the classic media for this process is whey, a by-product of cheese production. While the Kosher certification issues relating to whey are not the subject of this discussion, whey does require a reliable Kosher certification. In addition, the use of any dairy ingredient in bread poses an additional Kosher certification concern.
The Rabbis’ recognized that bread was eaten with every meal, and therefore required that regular bread must always be Pareve (non-dairy). In this way, people could be assured that a loaf of bread was appropriate for use as part of either meat or dairy meals, and Jewish law states that regular bread that was baked with milk (or meat fat) is not Kosher.
What is clear, however, is that natural propionates made through the fermentation of dairy whey would pose a significant Kosher certification concern, and special Pareve fermentations using corn syrup are indeed done to produce a natural propionate appropriate for use in Kosher certified bread.
Food spoilage can also take place through oxidation, where fats and other components of a food will react with the oxygen in the air and cause the food to deteriorate. Many chemicals are added to foods to prevent these chemical reactions. BHA and BHT, chemicals derived from petroleum derivatives, have been used for years and pose no innate Kosher certification concern, although the oils into which they are mixed do require Kosher certification.
Ascorbic acid (Vitamin C) and tocopherol (Vitamin E) are classified as antioxidants. Ascorbic acid is often added to fruit products to prevent them from turning brown, and tocopherol to fat-based products to prevent them from turning rancid. Both require a Kosher certification.