One of the recent conservation techniques is “sous vide”. It offers particular advantages because of its principle of implementation. However, this means of preservation is not conducive to all foods. This is the case of raw fish that should not be kept under vacuum. One can, therefore, wonder what are the reasons for this restriction. We give you more clarification below.
The Conditions Of Conservation Related To The Temperature
In U.S. regulations relating to food, hygiene is the Decree of 21 December 2009. This decree retraces the health rules applicable to the retail trade. It is therefore aimed at establishments that carry out a direct delivery of foodstuffs to the final consumer. As for the rules, they relate in particular to the temperatures to be observed for the conservation of the different foodstuffs, whether they be fresh, frozen products or hot dishes.
In short, it is recommended the observation of the lowest temperature. Fresh produce should be kept at a temperature between 0 and 2 ° C. Indeed, the lower the temperature, the longer the shelf life. This is confirmed by the work of Australian researchers Olley and Ratkowsky on the relationship between the shelf life and rate of weathering of seafood at different temperatures.
Reasons For The Restriction On Vacuum Storage Of Raw Fish
Let’s start with the principle of vacuum storage. It consists of an extraction of air between the product and the packaging. However, it should be noted that in practice, the removal of air is never performed at a rate of 100%, so select the best vacuum sealing machine as your requirement. There is always a tiny amount of air in the package. This air is enough for the microbes present in the food or on the packaging to use it as fuel to proliferate. This proliferation is only very limited until the total disappearance of the air contained in the packaging.
Now that there is no air, the problem is still not solved. Indeed, even in the absence of air and therefore of oxygen, there exist germs that are able to develop. They are said to be anaerobic. In addition to the relatively average temperature of raw fish, these microbes use the amino acid named histidine to grow. However, it turns out that raw fish contain histidine in large quantities. This being the case, once the raw fish are evacuated, the anaerobic bacteria draw on the histidine they contain to multiply easily, allied with the temperature of the fish. At the same time, this multiplication leads to the formation of the chemical reaction of histamine, a molecule which at high doses is extremely toxic to humans.
In fact, histamine is a source of allergies in many people. While some will suffer only simple redness, others may experience anaphylactic shock after ingestion of histamine.
This is the main reason for prohibiting the emptying of raw fish. However, it can be easily preserved and without any danger when automatically followed by the vacuuming of a freezing. The product can then be kept for ten days or more, depending on the type of fish.