The food canning industry breaks down vegetable canning into six categories: 1) Root Vegetables, 2) Leafy Vegetables, 3) String Beans, 4) Fresh Pack, 5) Dry Pack, 6) Specialty Vegetables.
Root are items such as carrots, potatoes and yams, etc. Root vegetables are seasonal. Potatoes are packed during the spring and summer, while yams are packed in summer and fall. Leafy vegetables such as spinach, kale, collard greens, and mustard greens are spring and summer varieties. String beans in their multiple forms (cut, whole, and french) comprise a canning company's string bean line. Fresh pack consists of items such as fresh corn and fresh peas.
Dry pack refers to the wide variety of dried beans, garbanzo, kidney, great northern, butter beans, and black eyed peas to name a few. Specialty vegetables are items such as mushrooms, asparagus, or rutabagas.
One of the most important rules of good canning is that a clean, healthy vegetable packs better, tastes better, preserves better and sells better. Therefore, vegetables undergo rigorous inspection, cleaning, testing and more cleaning and checking to assure that the prepared vegetable is good. Each and every lot of leafy vegetable is tested for aphids (this is unique to leafy greens). This test is known as a trap flask test. It is performed on a sample of leafy vegetables taken from each batch that has been reel washed, paddle washed, pressure washed, and blanched. The leaf vegetable that most often presents an aphid problem is spinach. Canning companies constantly combat this. Through a triple effort of control in the field, development of aphid resistant varieties of spinach, and herculean cleaning efforts, however, the normal aphid score is zero on a trap flask test. The pre-canning preparation for other vegetables does not include lab testing; however each canner employs their own unique method of ridding the raw vegetables of extraneous matter. Through dry reels and destoners, skins of root vegetables are steamed, peeled and scrubbed before dicing, slicing, and blanching; green beans are snipped, cut, sized and blanched.
At this stage, the vegetables are ready for canning and various systems begin to interact. Empty cans are pre-washed and conveyed to fill stations where vegetables and hot brine, syrups or sauces fill the cans. Simple brine consists of water and salt; sweeteners usually blend water, corn syrup and liquid sugar (see the Problem of Sucrose); sauces combine corn syrups, tomato sauces, spice blends, vinegar, and oil. However, some sauces are flavored with meat and lard. It goes without saying that those companies which use common equipment for batch cooking present real kashrut concerns.
Now the cans are ready to be sealed. Empty cans are filled, capped and conveyed to the retorts. A retort is a large pressure cooker that cooks the vegetables for a controlled length of time and pressure to create a bacteria free environment in the can (so that any microorganisms that may cause spoilage will be killed).
Retorts, like any other piece of machinery vary. The basket retort looks like a large horizontal torpedo that opens up to accept large baskets of cans in its cavity. May-lo Retorts have the cans drop into a bed of water that is released from the cavity when the cooking begins. A Stearolamatic Continuous Cooker has the cans travel along a timed chain track, while a Hydrostatic Retort is a six story building of rotating shelves that can cook over 25,000 cans at one time (when filled to capacity).
After retorting, cans are cooled, palletized and stored. Since all cans look alike in their unlabeled state, each company employs their own unique labeling system, embossing the lids with a code before capping the can.
It goes without saying that any production facility is at the manufacturing mercy of many factors, machine breakdowns, personnel problems, and quality control. Canning plants also have to contend with the fickle feelings of mother nature. Simply put, if it is rainy, you cannot can what can't be harvested. Similarly, during a non-growth season, you cannot can what does not grow.
What's a canning plant to do?
Some plants will can many different varieties of vegetables to minimize down time. For example, a facility will can yams from August through December and potatoes from May through July. However, it doesn't take much to see that there are still many dormant months to address. Some plants maintain an abbreviated production year and utilize the off-season for maintenance and repair. Other companies add a whole new dimension to their canning venue: Dry Pack.
Dry Packing beans is prudent and convenient because it is not governed by seasons or weather. It can have a production life of its own and be packed for long periods of time or be used as a fill in on rainy days during a harvest season. Dry beans are easily rehydrated after soaking for eight hours and can then be treated as a fresh vegetable. Dry pack is very versatile and in its versatility lies the major kashrut concerns of a canning company. Among the many varieties of canned dry pack beans are pork and beans and other forms of canned meat and beans.
The common practice of vegetable canneries is to put a small amount of pork in each can of pork and beans. The proportion is so low that the question, "what is the real purpose for the meat?" needs to be asked. The answer is, "For the label."
Truthfully, in order to avoid being regulated by the USDA, a canning company must keep the amount of meat per can calculatingly low. Indeed, in most cases this small meat quantity would be considered nullified (batul) by Rabbinic authorities because the meat quantity is less than 1.7% of the total volume of the can's content (which is contrary to the Torah which says that any amount of tame’ food makes any food it comes in contact with tame’). This principle holds true in the vast majority of can sizes
from the 15 oz. can on up to the 128 oz. size. The smaller sized cans, 10 oz. and down the pork may not be batul - but this matter is subject to the Rabbinic authority performing the "supervision."
Obviously, the concern is not for the product itself (pork and beans) but for the rest of the vegetables produced in the plant. Are they unkosher? Can these cans be retorted together?
Another large grey area would present itself in the private label sector. The store brand, house brand, generic label or food service label can be made in many different facilities. There is no way of knowing where the corn or string beans from these private label cans are made.
In today's canning reality, most vegetable productions, excluding dry pack, are run in a non-problematic environment. Therefore, these vegetables can be purchased without too much concern, unless there is evidence to the contrary. In specific, products should not be purchased from those companies that specialize in dry pack bean productions, where there is a great likelihood that pork and beans or other meat productions are taking place. Common canned foods
that are produced by companies that dry pack are: Canned limas, kidneys, chick peas, garbanzo, great northern, blackeyed peas, purple hull and navy to name a few. Canned tomato products should be treated in the same way as dry pack vegetables.