Low Acid Foods
There is a small dilemma when the subject of low-acid recipes comes around as there are very few recipes available for a home canner. We have written eight books on processing meats and sausages which together contain almost one thousand recipes, yet not being a processing authority, we do not write recipes for low-acid canned products. We will, however, quote a low-acid recipe that comes from a reputable source, like the USDA's canning guides and bulletins. Commercial packers have recipes that are either designed by the processing authority or the commercial plant may have a processing authority with a properly equipped lab to take care of the scheduled processes at moments notice. Needless to say, such recipes are considered the trade secrets.
From the Code of Federal Regulation:
CFR 21, 118.83 A processing authority is a qualified person having expert knowledge of thermal processing requirements for low-acid foods in hermetically sealed containers and having adequate facilities for making such determinations.
Our note: each new product (recipe) must be designed by the processing authority and the canner must submit the scheduled process to FDA (FDA Form 2541 a) for the approval before the product can be distributed. The scheduled process is established for each low-acid food in each container size.
108.35, 2 (ii) If a packer intentionally makes a change in a previously filed scheduled process by reducing the initial temperature or retort temperature, reducing the time of processing, or changing the product formulation, the container, or any other condition basic to the adequacy of scheduled process, he shall prior to using such changed process obtain substantiation by qualified scientific authority as to its adequacy. Such substantiation may be obtained by telephone, telegram, or other media, but must be promptly recorded, verified in writing by the authority, and contained in the packers files for review by the Food and Drug Administration. Any intentional change of a previously filed scheduled process or modification thereof in which the change consists solely of a higher initial temperature, a higher retort temperature, or a longer processing time, shall not be considered a change subject to this paragraph, but if that modification is thereafter to be regularly scheduled, the modified process shall be promptly filed as a scheduled process, accompanied by full information on the specified forms as provided in this paragraph.
108.35, 2 (iii) Many packers employ an "operating" process in which retort operators are instructed to use retort temperatures and/or processing times slightly in excess of those specified in the scheduled process as a safety factor to compensate for minor fluctuations in temperature or time to assure that the minimum times and temperatures in the scheduled process are always met. This would not constitute a modification of the scheduled process.
There are canning meat recipes that call for pasteurization only (212° F, 100° C or less), however, they are not included in our website as any error during processing will allow bacterial spores to survive and possibly grow. Acidified low-acid foods are usually pasteurized or processed at lower temperatures. However, the pasteurization of low-acid products should be left to commercial producers who are properly trained and equipped for this type of production. You might say that we are trying to scare you, (of course we are), that is our intention. People get sick and even die from eating canned vegetables or meats. Have you heard of anyone getting sick from eating orange marmalade? Even, if jam is covered with mold on top, most people just scoop it up (they should discard the jam) and keep on eating it. Here, we stress the point again: meats are not jams or jellies, they may be packed in the same size jars, but they conform to different processing rules.
It has been mentioned a few times already that the recipes should be designed by processing authority. Occasionally, it may be difficult to follow exactly the prescribed process schedule, for example the recipe calls for a certain size of a container but we have a different one. Well, in extreme cases some substitution may be made, but always use common sense. It will be safe to downsize the size of the container (as long as the change will not adversely affect its cold point) keeping the same critical processing points such as the initial temperature, headspace, the thermal temperature and the processing time. For example, using 307 x 409 (No. 2, 21 oz can) instead of 404 x 414 (No. 3, 35 oz can). It is, however, dangerous to use a larger container or to increase the amount of starch or fat in the recipe. Salt is added for the flavor and does not play safety role in the canning preservation method. Vegetables and meats can be canned successfully with or without salt.
Cured Meat/Poultry Products
Sodium nitrite (cure # 1, cure # 2) is the most effective agent that prevents Cl. botulinum spores from germinating. This is why it is always added to naturally smoked meats and sausages as the conditions in the smokehouse favor the growth of Cl.botulinum:
- Absence of air - we choke the air supply in order for the wood to start smoldering and smoking (having ample supply of air, the wood will burn cleanly without producing smoke).
- Moisture (meat contains 75% of water).
- Right temperature - most smoking is done between 86-140° F (30-60° C.)
Keep in mind that increasing the salt level enhances the inhibitory action of sodium nitrite. The conclusion is simple: using sodium nitrite with salt in a recipe will only increase the safety factor. This is the reason why many commercially produced canned meats are minimally heat processed.
Acidity inhibits Cl.botulinum spores from germinating. Below pH 4.6 they will not germinate and such acidified low-acid foods can be processed at much lower temperatures. The conclusion: adding any amount of lemon juice, vinegar or citric acid will increase the safety factor. If you decide to do that, remember that you are not qualified to change the recipe, so maintain the original pressure, temperature and processing time.
You will not jeopardize the safety of the recipe if you increase:
- Initial packing temperature.
- Cooking temperature.
- Cooking time. The quality and the texture of the product may be affected but the safety will only be increased.
- Cutting meat into smaller pieces and adding more liquid will result in faster heat penetration and increased safety.
Adding starch or flour will decrease the safety as they absorb water and solidify during cooking what slows down heat transfer. After opening the can you can thicken the food with starch or flour before serving.
Increasing the amount of fat or oil decreases the safety factor as fats act as heat insulators. They increase thermal resistance of bacterial spores by encapsulating them a thin layer of oil film.
If you mix vegetables and meat you must process the mixture until both the meat and vegetables are safe to eat.
You may receive a home made canned product from a friend and the recipe and processing times may be unknown to you. To be extra safe, remove meat from the container, place in pan, add water, if needed; be certain meat is covered with water and, boil for 15 minutes. This will kill any vegetative bacteria and will deactivate toxin if present.