There are a lot of methods to preserve food, the use of extra virgin olive oil and olive oil is an ancient and effective system for its natural storage capacity, thanks to its slightly antiseptic power and with the function of isolating food from ambient air, limiting the contamination of volatile bacteria, and reducing the availability of oxygen and, therefore, of aerobic bacteria.

For anaerobic bacteria, that is those that do not need oxygen to live and reproduce, we will not suffer any effect for hygienic and organoleptic purposes, if before or after immersion in oil we do not make the product undergo a proper heat treatment, in order to avoid contaminations especially by moulds and Clostridium Botulinum, the notorious bacterium that causes “Botulism”, the most widely known food contamination disease, which can also have fateful consequences. Botulinus spores are very resistant to heat and heat treatment should be conducted at 121°C for at least 3 minutes. These temperatures can only be reached through the use of autoclaves at an industrial level and not with home treatments.

In addition to the microbiological one, there is also the taste aspect that can be altered because of products preserved in oil resulting from the process of cooking. There are, indeed, other, mostly harmless, alterations, that arise from the cellular enzymatic action. The toxins that we can find are the result of the exploitation of the nutrients that food microorganisms produce. It is a natural process of degradation and it can be avoided by cooking food before storing it in oil. There is also another element that alters both taste and goodness of food and those are oxidation and/or peroxidation. It is a spontaneous process that is independent both of microbes and food enzymes, and it is due to the presence of oxygen, light and the right temperature. For this reason, especially for extra virgin olive oil, the state and method of preservation are fundamental. Therefore, great care must be taken when we use it to preserve other foods, even if the extra virgin olive oil has important properties that make it suitable for the preservation of foods, for example, the presence of antioxidants such as tocopherols (vitamin E) and polyphenols. The techniques used for storage after covering the product are pasteurization and sterilization that cause a reduction of the antioxidants of extra virgin olive oil, which, however, is also characterized by the excellent thermal stability that guarantees the integrity of the product. This is the reason why it is particularly suitable for the preservation of pasteurized foods. Moreover, extra virgin olive oil is characterized by a low amount of polyunsaturated fatty acids, compared to monounsaturated ones, and has a greater oxidative and thermal stability, while, for example, seed oils, being much richer in polyunsaturated fatty acids are much more exposed to oxidation.

The local tradition of preparing food in oil at home is very widespread but you have to pay close attention in the preservation process. It would be better to refer to certified and guaranteed companies that have technologies and continuous controls and ensure the integrity of their products in order to protect taste and, above all, our health.