Differences between sterilization and pasteurization
In general terms, we can say that both pasteurization and sterilization are conservation techniques that are based on the eradication of microorganisms and enzymes by applying heat for a certain time to foods placed in hermetic containers.
Its main difference lies in the fact that sterilization seeks to eliminate all microorganisms and spores, while in pasteurization, the most resistant forms and some spores remain present.
Therefore, sterilized foods are kept at room temperature for long periods of time, while pasteurized foods, in contrast, require refrigerated preservation to delay the proliferation of possible microorganisms or spores present in the food.
Canned food at room temperature or refrigerated?
This is the key decision. What do you want to elaborate? Can you keep them refrigerated or can they be kept at room temperature?
Pasteurized preserves have a much shorter shelf life and require trucks and refrigerated display cases for their distribution and sale. Unlike traditional preserves, which can be kept in perfect condition for much longer at room temperature and are easier to market.
Now, it depends on the product you want to make, cold storage can be an advantage and be more valued by your customers. Think about it before choosing one or the other option.
And what does the pH of food have to do with it?
Very easy. The pH of the food determines the time and temperature to which we must submit the food to eliminate microbial and enzymatic activity, ensuring the stability of the product. A lower temperature and a longer time will kill the same number of microorganisms as a high temperature and a short time.
The food pH indicates its degree of concentration of hydrogen ions, that is, the level of acidity. The vast majority of foods are on a pH scale of 3 to 7 (except egg whites, which are above 7). So you can understand it better, the more acidic a food is, the lower its pH value.
Sterilization of canned food
The sterilization of foods with a neutral pH (>4.5) consists of subjecting a food to temperatures above 100ºC for a certain time to destroy all microorganisms, pathogens or not, and possible spores.
Foods with an acidic pH (<4.5) can be sterilized at temperatures below 100ºC.
What foods can we sterilize?
We can sterilize all kinds of meat, fish, vegetables and fruits. In jams, syrups, pickles, creams, soups, sauces and stews among others.
Pros of sterilization
The shelf life of sterilized products can be more than four months and, in addition, unlike pasteurized products, they do not require cold storage.
In fact, the food will remain sterile until the package is opened or damaged. Once opened, it should be consumed shortly.
Cons of sterilization
The use of high temperatures in sterilization can affect the quality reducing the nutritional value of the food by destroying some vitamins and aromas. It can also produce some organoleptic changes such as color changes and the appearance of overcooked flavors.
Pasteurization of canned foods
Pasteurization, unlike sterilization, cannot eliminate all microorganisms and spores. It consists of heating a food to less than 100ºC for a few minutes or even seconds, and then cooling it immediately. The time and temperature of cold will vary according to the product, format or type of container.
In acid foods (pH <4.5), pasteurization can be so effective that it is actually sterilization, since it manages to eradicate all living forms, microorganisms and spores.
What foods can we pasteurize?
Above all, milk and its derivatives, flavored juices and beers, but also prepared dishes and sauces are pasteurized.
Pros of pasteurization
The low temperatures allow the aromas not to volatilize too much and the flavor and nutritional properties remain unaltered.
Cons of pasteurization
The shelf life of the food can be two to three weeks and they need to be kept refrigerated between 3ºC and 6ºC. Once opened, they should be eaten shortly, like sterilized food.
Unlike sterilization, pasteurization does not remove spores. So the physical and chemical modifications continue to occur.
Differences: sterilization vs pasteurization
If this were a wrestling match and sterilization and pasteurization would compete for the title of the best food preservation technique, the truth is that both would be tied. And, the two are equally optimal. Everything depends on:
The characteristics of the food
Each product has different characteristics that will determine the type of sterilization technique to be used and the combinations of temperature and time to try to preserve the maximum properties and minimize the nutritional changes of the packaged food.
One of these properties is the acidity level of the food (pH). Foods with a higher pH need high temperatures, such as vegetables, meat or fish.
Juices, for example, have an acidic pH, which conditions the growth of different types of pathogens, especially sporulated microorganisms, the most resistant to high temperatures. This means that milder temperatures can be applied and therefore they can be pasteurized.
On the other hand, the physical shape of the food also determines the technique to be applied, since, for example, the spherical shape requires more temperature.
The type of container used can also determine whether a canned food will need to be sterilized or pasteurized. You can see the different types of containers suitable for pasteurization or sterilization in an autoclave on our Blog.
Food shelf life
As we have already mentioned, in sterilization, the product can be kept in perfect condition for more than four months and in pasteurization, from two to three weeks and always kept cold.
Difference: thermal values Fo and Po
The sterilization value is the combination of time with temperature, and is represented by “Fo” when a temperature higher than 100 ° C is used, that is, when it refers to sterilization. And with “Po” when the temperature is below 100ºC, that is, in pasteurization.
In our Blog you can download a Guide with all the Fo and Po values to pasteurize and sterilize any type of canned food.
TERRA Food-Tech® autoclaves for pasteurizing or sterilizing packaged foods
With the TERRA Food-Tech ®compact autoclaves for packaged foods developed by RAYPA, finding out the precise temperature and time to cook, sterilize and pasteurize any type of food is much easier. Thanks to the temperature probe placed in a product sample. This allows perfect control of the process while preserving the organoleptic properties, minimizing possible changes in the nutritional characteristics of the packaged product and complying with all the requirements and standards of the food industry.
For more information, contact our sales team .