Meats and Sausages

Principles of Canning 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 many books on processing meats and sausages, which together contain almost 2,000 recipes. However, as we are not processing authorities, we do not write recipes for low-acid canned products. We will, however, provide a low-acid recipe that comes from a reputable source, such as the USDA's canning guides and bulletins. Commercial packers have recipes that are either designed by the processing authority or, in some cases, the commercial plant may have a processing authority with a properly equipped lab to handle the scheduled processes at a moment's notice. Needless to say, such recipes are considered trade secrets.

Processing Authority

A Processing authority is a person who has expert knowledge in the field of canning and microbiology. The processing authority shall establish thermal processes for canned foods. In addition, they must possess advanced testing equipment, which will allow them to conduct heat penetration tests and /or inoculated pack studies. For example, fish can be packed in brine, sauce, or oil, and each method will affect the heating characteristics of the product. A product packed in oil needs longer processing times as bacterial spores receive extra protection from a thin film of oil that encapsulates them. A process is established for a particular food, formulation, thermal processing details, container type, and size. Any changes to the formulation, process, or container size must be evaluated and approved by a processing authority and not by the packer. Processing times used by commercial producers are much shorter to prevent overcooking and preserve the best texture and color. Many factors are involved in designing a new recipe, including the properties of raw materials, the amount of sugar, the percentage of fat, thickening agents (such as starch and flour), acidifying agents (like lactic acid, citric acid, and lemon juice), and more.

From the Code of Federal Regulation:

Meats, poultry, fish, and vegetables are classified as low-acid foods (pH>4.6) and must be processed until a condition of "commercial sterility" is achieved. Commercial sterility is defined as the condition achieved by the application of heat, alone or in combination with other treatments, to render the product free of microorganisms capable of growing in the product at normal non-refrigerated conditions. The product is safe to eat because the pathogenic microorganisms are either destroyed or inactivated to the extent that they pose no health risk. The product will remain shelf-stable as long as the container is perfectly sealed, which is what prevents the entry of any microorganisms from the outside. Since spoilage bacteria are easily killed during heat treatment, the product has an almost unlimited shelf life as long as it is stored at proper conditions. After a year, its quality, however, will start to deteriorate, but the product will remain safe to eat. There are two methods of canning employed by the industry:

• Conventional canning. Home-made canning fits into this description.
• Aseptic canning. Foods and equipment are both prepared separately in sterile conditions, then combined in a sterile room. This method cannot be employed in home conditions.

Almost all of home canning is done in glass jars, but this does not mean that jars are superior to cans. If they were, commercial manufacturers would use them instead of metal cans, wouldn't they? The cans are used everywhere: the Armed Forces, Veterans Administration, School Lunches, Needy Families Programs, Hotels, Restaurants, Colleges, Penal Institutions, Catering Services, the list is endless. The main reason why metal cans are less popular among home canners is the total lack of information on the subject. All books, manuals, and guides written after 1950 do not mention canning in metal containers as a viable option for a hobbyist at all. The original work done by the USDA and other agencies culminated in 1946 with manuals on the subject of meat canning. Both methods, glass jars and tin cans, were covered, and processing times were provided for each. However, starting with the 1988 revision, the information on canning in tin cans was omitted from all USDA editions of the 539 Bulletin, which is largely a reprint of the AWI-110 original work from 1946.

Canning in glass jars is simpler and there is less room for error, so the USDA chose the easiest path for solving safety problems: if we don't offer information, people will not use metal cans. It seems that the USDA has taken for granted that people are not capable of comprehending a few basic procedures. Many of us are willing to study the subject of canning in more detail to ensure it is safe, even at home. Our hat to the University of Alaska in Fairbanks, the first institution on the Internet that decided that canning in metal cans is a suitable method for a homeowner. Many homeowners in British Columbia and in Alaska are canning game meat and fish in tin cans today. Today, we can find any kind of food packed in metal cans: soups, stews, beans, chicken, noodles, fish, meat, fat, oysters, clams, the list is endless. Almost all fish is canned in metal containers. It is a sad fact that canning meat products in metal containers does not get any recognition from the USDA, at least for canning products at home, and hopefully, this book will help people to understand that canning in metal containers is not rocket science. It is confusing for a newcomer to select the right can. The next problem is to determine what type of sealer to buy that will seal a particular can. It is easy to end up with an expensive sealer, which might be a good choice for sealing large cans with fruit, but a poor choice for canning meats. However, there are great little sealers that have been performing wonderfully for decades, and they are a perfect choice for a homeowner. The best example is the Ives-Way can sealer, which has been made in the USA for 60 years. This sealer is the best-kept secret on the Internet, as the company has no presence online, yet its sealer is known to everyone in the industry. It costs as little as any kitchen appliance, and can seal a great variety of cans by switching inexpensive chuck adapters and spacers. The setup and adjustments are very easy, and the telephone support is excellent.

There are canned meat recipes that call for pasteurization only (212°F, 100°C or less); however, they are not included on 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 the jam is covered with mold on top, most people scoop it up (they should discard it) and continue 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.

The main steps in canning are:

1. Filling the product into the container.
2. Hermetically sealing the container.
3. Thermally processing the product and the container together.
4. Cooling.

Filling Containers

Commercial packers use containers of all shapes, sizes, and materials. Glass, steel, aluminium, plastic, cardboard, aluminium combinations, plastic containers, and all types of closures. Such containers are processed by specialized equipment that is not available to a hobbyist. A homeowner can process his products in glass jars or in metal cans; both types of containers are described in detail in the Equipment section of the book. How the product is prepared and packed will influence the heat penetration of the container and will be taken into consideration by the processing authority when evaluating the process schedule of a new recipe.

Meat Preparation

Meat intended for canning should not be permitted to freeze. If it does freeze, keep it frozen until canning time because thawed meat spoils very quickly. Wash meat, if necessary, but do not soak it in water. To do so dissolves meat juices and renders the meat stringy. Wiping off with a damp cloth is usually sufficient. Cut meat into convenient pieces for packing in jars. Small bones may be left in. They seem to enhance the flavor and facilitate heat penetration.

Precooking Meat

Meat precooked in water is more like boiled meat in texture and flavor, while meat precooked in the oven resembles roasted meat. Precooking in water may be referred to as parboiling, as the fastest way to precook a large quantity of meat and is often used with chicken. Frying makes the meat harder and gives it a less desirable flavor. Pan broiling gives good results.

Glass jars - meats should be precooked in water or in the oven before being packed.

• Metal cans - meats may be:
• precooked in water or in the oven and packed hot OR packed raw and precooked in the cans while they are being exhausted before being sealed. This method gives a better-flavored product as it saves the meat juice in the can, but it requires more time and space.

Recipe Modifications

It has been mentioned a few times already that the recipes should be designed by the processing authority. Occasionally, it may not be easy 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 flavor and does not play a 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 for the wood to start smoldering and smoking (having an 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.