New conservation methods increase risk of food poisoning

In response to consumer demand for more natural food, the food industry has reduced the amount of preservatives in food over recent years. A common preservative is acetic acid, which is used to stop bacterial growth in dressings, sauces, cheese and pickles. However, new research shows that a small amount of acetic acid does not have the intended effect, but rather the opposite - it increases the amount of toxin from the harmful bacteria in the food. "In my studies I saw that a small amount of acetic acid caused the bacteria to become stressed, which meant they reacted by producing more toxin. However, if a large amount of acetic acid is added, as was done in the past, the acidity is greatly increased and the bacteria do not survive", explains Nina Wallin Carlquist, Doctor of Philosophy in Engineering at the Division of Applied Microbiology, Lund University. She recently defended a thesis on the subject, in which she studied two of the most common food poisoning bacteria, Staphylococcus aureus and Campylobacter jejuni. The Staphylococcus were used in the acetic acid study.