by Giuseppe Scarlata, Antonino Napoleone, Maria Chiara Rosace | December 11, 2020.

Food is an essential part of our daily lives, an essential ally that helps us to protect and preserve our physical and mental health. Unfortunately, recent restrictions applied following the increase in Covid-19 infections have significantly altered common eating habits. A study on “How did Italians’ eating habits and lifestyle changed during the pandemic?” highlighted the way most time was spent during last spring’s quarantine: in front of the cookers. Behind the preparation and storage of home-made food lies a microcosm completely invisible to the naked eye, consisting of a large number of pathogenic microorganisms that are not always tasty and easy to digest. The subject becomes even more relevant when dealing with the infamous ‘Made in Italy’ parcels containing home-made preserves and food of all kinds. In fact, these pathogenic microorganisms find their favourite habitat in food that has not been properly preserved, to the point of altering its condition and even causing serious health consequences once ingested. The microorganisms responsible are usually bacteria or toxins produced by bacteria or viruses and can cause illnesses or disorders known as food-borne diseases.

What are food-borne diseases?

The safety of a food product derives mainly from the hygienic factors adopted during preparation and/or storage. Failure to comply with certain hygiene rules may represent a risk to the health of the consumer, who may find himself in unpleasant situations, up to the onset of real pathologies known as food-borne diseases. These are infections caused by pathogenic microorganisms that colonise intestinal mucous membranes, or by toxic elements that they can produce (toxins) in contaminated food and that can persist even when the micro-organism in question has been eliminated. The latter occurs, for example, when appropriate storage methods, temperatures or cooking times are not applied, as some toxins may be more resistant than the microorganisms producing them. However, toxins of microbial origin are not the only ones that can contaminate food; there are also toxins derived from chemical substances such as pesticides used in agriculture (see our clear article “Protect our soil to preserve food safety“), toxins found in poisonous mushrooms, or toxins produced by certain plants or fish species (e.g. pufferfish). The most common symptoms are nausea, diarrhoea, abdominal cramps and vomiting, which can occur within a few hours after eating contaminated food. Except in more serious situations (perhaps due to other co-existing intolerances or allergies), these resolve spontaneously and are short-lived. Food poisoning, on the other hand, is a genuine pathological process that can last for several days and can lead to outbreaks, especially in family or public environments (schools, restaurants, etc.); in 2018 only, 5146 outbreaks of food poisoning epidemics occurred in Europe, an increase compared to 2017, both in terms of the number of people involved and of hospitalisations and deaths. Crucially, 13% of these outbreaks occurred in the family context, where it is most common to share food or make home-made preserves.

Where does contamination occur?
  • At the slaughter stage: contact with meat from animals previously infected with microorganisms that are then transmitted to direct consumers (e.g. Mycobacterium bovis responsible for tuberculosis in wild boar);
  • Washing: fruit and vegetables can be contaminated if they are washed or irrigated with contaminated water from aquifers near sewage drains containing pathogens derived from animal or human faeces (e.g. Escherichia coli);
  • At the cooking or preparation stage: irregular and incomplete cooking of the food, inappropriate cooking temperature, storage for a long time at room temperature, as well as poor hygiene conditions of those handling the food or the cooking utensils (e.g. Salmonella spp.);
  • In the distribution phase: products that are handled a lot, or cooked in conditions of poor personal hygiene and then served with long waiting times, perhaps without a cover or not refrigerated, conditions to which canteens and restaurants may be exposed (e.g. Staphylococcus aureus);
  • During storage: the most commonly affected are home-made preserves, especially vegetables in oil, but also fish and preserved meat preparations. One example is food preparations packaged in hermetically sealed containers that undergo inadequate or poorly executed heat treatments that do not guarantee proper preservation (e.g. Clostridium botulinum).
The ScienceRely survey

Following an initiative launched by ScienceRely in the previous weeks, a survey was carried out involving a heterogeneous sample of 83 participants belonging to the following categories:

  • 72.3% of the respondents belonged to an age group between 18 and 35 years;
  • 15.7% between 51 and 65 years old;
  • 9.6% between 36 and 50 years old;
  • 2.4% over 66 years old.

The highest percentage of participants (42.2%) said they lived in regions of Southern Italy, 34.9% in Northern Italy, 18.1% in Central Italy and 4.8% in a foreign city. 26.5% of these declared that they had never prepared home-made preserves compared to 36.1% of those who had at least once prepared preserves; 19.3% declared that they prepared them rarely and 18.1% frequently. From the data in Table 1, boiling is the most widely used preservation method (73.5%). From Figure 1 along with vacuum-sealing, it is considered optimal and the longest lasting method by most of the respondents.

Table 1: Known and most used conservation methods by ScienceRely survey participants.

From Figure 1, boiling along with vacuum-sealing, it is considered the optimal and the longest lasting method by most of the respondents.

Figure 1: Methods for preserving home-made preparations according to the survey participants

The survey participants declared that they were sufficiently informed on the subject as shown in Figure 2, given that Salmonella spp. and Clostridium botulinum are mainly associated with pathogenic microorganisms responsible for food poisoning.

Figure 2: Microorganisms associated to poor food storage according to the survey participants

Going back to the topic of the famous “Made in Italy food package”, 42.2% of participants have sent or received a package containing preserves or other home-made food, and the majority of responses indicated that it takes between three and five days to ship. This is an important information since long shipping times may contribute to shelf-life problems for some food products. Survey respondents indicated that the most received and/or shipped food products are jams, tomato sauce, vacuum-packed meats and cheeses, sun-dried tomatoes and aubergines in oil, tuna in oil, pesto and legumes.

A final question posed to respondents concerned the preferred ways of providing information and the level of availability for such topics. The general trend shows a lack of information in the main information channels available, with advice from friends and/or relatives prevailing (Figure 3). Moreover, the 30.9% expressed a particular preference for reading informative articles, 28.6% prefer to follow interviews with experts in the field, 23.6% rely on explanatory videos and the remaining 16.8% prefer to receive concise information accompanied by explanatory images.

Figure 3: Main source of information on food safety and food-borne diseases according to the survey participants
What to do then?

The real goal is therefore to block the activity of pathogenic microorganisms and/or the production of toxins, due to which our food deteriorates over a certain period of time, especially if badly stored. The stabilization processes are in fact adopted for this purpose and are mainly two:

  • Sterilization: consists of treating a hermetically packaged food at temperatures higher than the boiling point of water, destroying all pathogenic and non-pathogenic microbial forms;
  • Pasteurization: it is a rapid heat treatment mainly practised at an industrial level that is carried out at a temperature lower than or equal to the boiling point of the water, eliminating a large part of microorganisms and preserving the organoleptic properties of food; in fact, this treatment can be followed by other acidification (in vinegar) or vacuum-packaging of the food or the simpler storage for a certain period in the refrigerator.
In conclusion

Food is defined as healthy when it can be intended for human consumption without the risk of damaging the health of the consumer. We must pay attention because home-made food is certainly a pleasure for the palate but if not well preserved and processed can be harmful. Adjusting the cooking methods according to the food and the desired storage times avoids the establishment of infections by various microorganisms such as bacteria, viruses or parasites. Today more than ever, it is essential to get the information correctly and carefully choose the communication channels, and in this, the medical sciences rather than the media are always there to remind it, since even in the kitchen you can make the difference.


  4. The European Union One Health 2018 Zoonoses Report European Food Safety Authority and European Centre for Disease Prevention and Control (EFSA and ECDC)
  5. Linee guida per la corretta preparazione delle conserve alimentari in ambito domestico, 2014 – Istituto Superiore di Sanità, Roma.
  6. Naranjo V. et al., Vet Microbiol 2008 doi 10.1016/j.vetmic.2007.10.002.
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