Chickens, as you know, are counted in the fall – but in this golden season, zealous housewives have a lot of other concerns. For instance, home canning… Those of you who will be interested in this article have probably already got your hands on the canning of tomatoes, cucumbers and other preparations. However, a few helpful tips can make this process even more hassle-free, enjoyable and rewarding.
- Moisture creates an excellent breeding ground for unwanted microorganisms – bacteria, mold, fungi;
- It promotes the activity of enzymes contained in foods;
- The oxidation reaction due to exposure to oxygen also leads to food spoilage;
- Finally, the inevitable and uncontrolled loss of liquid by products has a detrimental effect on their quality.
In this way, canning in a general sense is reduced to the following actions: preventing the activity of microorganisms, destroying enzymes, and creating a vacuum in the jar – when oxygen does not get inside, but liquid outside. It’s simple.
Safety first
We will dwell on bacteria – or rather, on the most dangerous of them, Clostridium botulinum – in a little more detail. This botulism bacteria, occurs in the form of spores or in a vegetative form, and can live in soil and water for years, and when conditions are favorable for itself, it begins to actively multiply, producing a deadly toxin in 3-4 days. These conditions include:
- Wet environment of low acidity;
- Temperature within 28-35 degrees Celsius;
- Low oxygen content (no more than 2 percent).
Although spores of this bacterium are found on the surface of most foods, they begin to multiply only under anaerobic conditions, that is, in the absence of oxygen, so fresh or air-dried vegetables and fruits are against botulism are safe.
Removing bacteria, fungus and mold from food is not an easy task. Washing, even the most thorough one, helps, but not much. Peeling (for example, from root vegetables, or removing the skin of tomatoes) and blanching are much better in this regard, and the best way to fight microorganisms is the correct heat treatment.
So, the bacterium that causes botulism dies when heated to 80 degrees for 30 minutes, boiled for 5 minutes, and industrial heating to 121 degrees for 3 minutes.
Acid is our best friend
Regardless of the method of canning, acidity is one of the main factors ensuring the long-term preservation and safety of the product. It can be both natural, as in the case of most fruits, and artificial, when the food is kept in a marinade. Foods that are low in acidity cannot inhibit bacteria, but acid levels can be increased by adding lemon juice, citric acid, or vinegar. The acidity level is measured using a pH value – the lower the pH, the higher the acid content.
Maximum pH value for safe canning is 4,6… Foods with low acidity have a pH higher than this value – these include meat and seafood, milk, and all vegetables with the exception of most tomatoes. Products of high acidity include fruits and their derivatives (preserves, jams), as well as pickles, sauerkraut, etc.
While the acidity of tomatoes is generally sufficient for safe canning, some fruits have a slightly higher acidity of 4,6, so it is advisable to add vinegar or lemon juice when canning. By the way, the heat treatment during canning also directly depends on the acidity level. As you can see, this is a very important parameter, so if possible, you should get an acidity indicator for measuring pH.