Expensive but clean and with the same vitamins as fresh: our analyzes on ready-made salads

For Italians it is always time for salads. Whether it’s the loose ones or those washed, cut and packaged (the so-called IV range), in our country the salad accompanies many meals. And it is good, of course, given the caloric poverty of these foods and the presence of fibers of which our diet is extremely poor.
The differences between the two forms of salad are quite evident: the one already cut is definitely more expensive (329% more according to the latest Ismea report) but it is also more convenient for those who don’t have time. Perhaps also for this reason for the first time during these years in the months of the pandemic it has suffered a drop in sales, in favor of the cheaper loose salad. Beyond the numbers and preferences, however, there remain the doubts of those who wonder if the salad in the bag is really ready for consumption or does not have a hygienic state that requires careful washing before ending up on the plate. And if it is no longer poor in vitamins, as an old Italian study also hypothesized that claimed that the cutting operation favored oxidation and therefore the loss of nutrients.

Ready-to-eat salads against clumped leaves

To answer these questions, we asked the Maurizi group laboratories to carry out a lifejacket test useful for evaluating the differences, from a nutritional and microbiological point of view, between three samples of salad sold as is and three fourth range packs. The analysis ended up with organic lettuce purchased in a neighborhood market and similar leaves in bags purchased at the supermarket.
From a microbiological point of view, there are many food poisoning associated with products of plant origin, because vegetables can be contaminated with pathogens such as Salmonella, Listeria monocytogenes, Escherichia coli, Enterobacteria. Exactly the microorganisms that have been quantified in the laboratory, together with a parameter such as the total bacterial count, able to give the picture of the degree of general hygiene of the leaves. The samples used for the microbiological tests were suitably homogenized to obtain a representative sample and enriched with special broths indicated by the reference standard for each test microorganism. For the organic lettuce, the most external parts were also taken, therefore potentially more exposed to contamination because they are more in contact with the ground.

Cleanliness respected


From a microbiological point of view, the salad in a bag, as expected, reported better results than the one as it is. The pathogenic microorganisms Listeria monocytogenes and Salmonella spp were not detected in both samples. The bacterial load, enterobacteria and E.coli were detected in concentrations of about 2 orders of measure higher in the whole salad.
It can therefore be deduced that ready-to-eat vegetables in bags have a lower incidence of contamination by bacteria and potentially pathogenic microorganisms compared to fresh vegetables, which are not subjected to any washing and treatment before sale and that industrial washing systems guarantee effective reduction of the microbial load making the salad in a “cleaner” bag.

The nutritional differences


In the study, chemical analyzes were also carried out for the evaluation of nutritional values ​​and content of vitamins and mineral salts.
The samples used for the chemical analyzes were triturated and then processed directly for the nutritional values, and extracted with a solvent for the determination of vitamins and mineral salts.
Lettuce in general, regardless of the variety, is a light but beneficial food, especially if it is inserted regularly in our diet, as it provides very few kilocalories and has a high water content. And it is also rich in mineral salts. In particular, the mineral content is indicative of the properties of the soil in which it was grown and of the water used.
The nutritional values ​​of the two samples are almost equivalent. Even the values ​​of vitamins are equivalent, however among the mineral salts the sodium value is much higher for the lettuce in the bag.
The different distribution of mineral salts between the two samples may depend on the different type of fertilizers, on the cultivation soil or on the water used for irrigation.
However, we find both vitamins and all minerals in both types of lettuce and this indicates that from this point of view organic lettuce and packaged lettuce are equivalent and therefore there do not seem to be strong losses due to cutting the leaves, at least if this operation is immediately followed by wrapping, perhaps in a conditioned atmosphere.