Homemade preserves, such as tomato sauce, pickles and foods stored in oil, can pose a risk to health because they may be contaminated with the bacterium Clostridium botulinum, more commonly known as botulism. This bacterium can produce toxins which, if ingested, can cause severe food poisoning. The most serious forms of botulism can lead to respiratory arrest.
To find out how to prepare and consume homemade preserves to avoid botulism infections and other food risks, watch this video produced by the Istitituto Zooprofilattico Sperimentale delle Venezie (IZSVe), an Italian health authority and research organization in the fields of animal health and food safety and zoonoses.