Food Safety for Food Preserving by Toby Amidor in Food Safety, July 26, 2010
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Food preserving is the hottest trend, especially with many more folks growing their own fruits and veggies at home and preserving the extras. But with home preserving comes possible food poisoning — something everyone should be cautious about. Here’s how to can your own food, safely.
One of the biggest issues when it comes to preserving is the bacteria Clostridium botulinum, which causes botulism. Clostridium botulinum survives in foods preserved without oxygen, like in improperly canned or jarred foods. The bacteria love low-acid food (most veggies) and temperatures between 40 to 120 degrees Fahrenheit.
It’s important not to taste jarred on canned food that shows signs of spoilage. The toxin produced from Clostridium botulinum is so toxic that even a drop on your tongue can cause death. Mold is another issue—which can also be potentially toxic. But before you swear off canning, there are simple signs to check if a product is spoiled:
- Check for swollen lids and broken seals.
- Examine lids for tightness and vacuum. Lids with concave centers have good seals.
- Examine the outside of the jar for streaks of dried food originating from the top.
- Look at the contents of the jar for rising air bubbles and unnatural color.
- Upon opening the jar, smell for unusual odors and look for foamy liquid and cotton-like mold (could be white, black, blue or green) on the top of the food surface and underneath the lid.
The good news: a few easy steps that can prevent the growth of Clostridium botulinum. Choosing an appropriate recipe from a reputable source is a good first step. Recipes (like those from canning guru Sherri Brooks Vinton) are based on type of food, size of jars and how it’s packed into jars. It’s important to follow the instructions (especially the cooking times) exactly how they’re written.
Most beginners use the boiling water method to can food. This method should be used with more acidic foods like chutneys, jams, pickles and tomatoes. The acidity makes it tough for the bacteria to survive. Adding lemon juice, citric acid or vinegar also helps increase the acidity level.
If you find a spoiled product, you want to handle it as if it contains botulism (even though it may not). If the jar is still sealed, then place it in a trash bag or dispose in a nearby landfill. If the jar is open, the contents must be detoxified by boiling all contents for 30 minutes and then disposing in the garbage or nearby landfill.
Toby Amidor, MS, RD, CDN, is a registered dietitian and consultant who specializes in food safety and culinary nutrition. See Toby’s full bio »