Gourmet canned foods or ready-made meals based on fish must undergo a thermal process in order to be marketed.

Next, we will delve into the how, when and why of sterilization and/or pasteurization of any gourmet canned food or ready-made meal that contains fish.

Fish, an important source of minerals, proteins and omega-3 fatty acids

Fish provides proteins of high biological value, since it contains the 9 essential amino acids for our organism. It has the same amount of protein as meat or eggs. In addition, it is rich in:

Minerals

Such as zinc, iodine, potassium, iron, calcium or phosphorus.

Vitamins

A, B9 which is folic acid and B12 related to the proper functioning of the brain and circulatory system.

Fatty acids

Such as omega-3, which boosts the immune system and helps overcome fatigue, inflammation and skin rashes.

Fish is also a very digestive and tender food because, unlike meat, it has low-fiber proteins and low collagen.

Fish consumption

According to the Food and Agriculture Organization of the United Nations (FAO), since 1961, world fish consumption has grown annually by 3.2%, surpassing both population growth and meat consumption of land animals, with the exception of poultry.

Per capita fish consumption increased from 9.0 kg in 1961 to 20.2 kg in 2015. In 2016, out of 170.9 million tons produced by fisheries and aquaculture, 151.2 million were destined for human consumption, and this figure is expected to reach 201 million tons by 2030.

The export of fish and fishery products for human consumption has increased from 11% in 1976 to 27% in 2016. The main ways of consuming fish are fresh or refrigerated (45% in 2016), frozen (31%), prepared and preserved (12%) and cured (12%). Out of all fish processed for consumption, 56% is frozen.

The Spanish Agency for Food Safety and Nutrition (AESAN, by its acronym in Spanish) suggests consuming 3 to 4 servings of fish per week, alternating between white and oily fish.

Types of fish

The differentiation of the different types of fish is made according to the proportion of fat in their flesh. Based on this information, we can find:

Fatty or oily fish

The oily fish owes its name to the bluish tonality of its skin, influenced by living in cold and shallow waters.

These fish are fatter than white fish due to their activity and prolonged migrations, which leads them to accumulate fat.

They are rich in polyunsaturated fats, especially omega 3, which benefit “good” cholesterol (HDL) and decrease “bad” cholesterol (LDL). They also provide fat-soluble vitamins D, E and A, and minerals such as calcium, potassium, sodium and phosphorus.

White fish

White fish species live close to the seabed and move slightly due to the proximity of their food.

Unlike oily fish, they do not have arrow-shaped fins and their tails have straight or rounded edges at the top.

Their meat is white and has very little fat, less than 2% of its weight, which is concentrated in the liver. This type of fish is low in calories and fat, but rich in B vitamins, mineral salts and gelatins.

Semi-oily fish

Semi-oily (or semi-fatty) fish is the one that varies in fat percentage depending on the time of year, diet, size and age. This fat percentage ranges from 2.5% to 6%.

Important advice: To avoid higher mercury content, smaller species are recommended. The more fat, the higher the levels of mercury and other contaminants.

Canned foods and ready-made meals with fish

There is a wide variety of gourmet canned fish available on the market, including tuna, sardines, skipjack tuna and mackerel.

In addition, other preparations are marketed, such as fish pates and fresh or precooked dishes, such as salmon, red scorpion fish and gilthead bream pie with potato.

How to produce canned foods with fish

Fish preserves maintain the natural flavor and characteristics of the product without the use of artificial preservatives.

Principally, there are two types of canned fish:

Raw canned food

The fish is cleaned and cooked inside the container using steam or brine. In this method, common in the food industry, cooking times and salt content are continuously monitored to ensure that the product has the desired texture and flavor properties. Sterilization and cooking can be done simultaneously in an autoclave.

Cooked preserves or ready-made meals

The fish is cooked in fillets before packaging, after removal of skin, entrails and other parts. Depending on the desired shelf life, the product is pasteurized or sterilized after cooking. Using a blast chiller, the temperature is rapidly reduced to prevent the multiplication of microorganisms.

The thermal process performed by an autoclave, in addition to sterilizing, can produce a cooking effect on the canned food. Therefore, in the case of already cooked canned foods, it is recommended not to cook the product completely so that the autoclave can finish the process.

Pasteurized fish products must be kept refrigerated to avoid the proliferation of microorganisms and therefore have a shorter shelf life.

Recommendation:

To avoid altering the organoleptic characteristics of products, it is recommended to acidify them and then apply mild heat treatments, at lower temperatures and for a shorter time.

Sterilization of canned fish

In general, both gourmet canned products and ready-made meals based on fish are usually sterilized, since this procedure guarantees the total elimination of microorganisms without excessively altering their organoleptic properties and nutrients.

On the other hand, precooked foods based on fish tend to be pasteurized and should be refrigerated at all times, both during transport and storage.

Depending on the treatment the product has received, it will have a different expiration date.

Ready-to-eat pasteurized products should be kept refrigerated for up to 3 months at a temperature of 2-4ºC. On the other hand, sterilized canned foods are microbiologically safe and have a best-before date.

pH of canned fish

When preserving any food, including fish, it is essential to take into account its acidity level.

Depending on the sauce or liquid complement added, the pH will vary, affecting the time and temperature to which the food must be exposed in order to eradicate possible microorganisms and extend its shelf life.

pH < 4.5	pH 4.5 – 5.5	pH 5.5 – 7
Tuna in pickled sauce	Natural tuna	Sardines in oil
Sardines in pickled sauce	Sardines in tomato sauce	Tuna in oil
		Mackerels in oil

F₀-P₀ values for fish sterilization

The thermal values F₀ and P₀ determine the necessary time and temperature to sterilize or pasteurize a food, seeking to preserve its organoleptic properties and the nutritional values of canned foods and/or ready-made meals.

As mentioned above, gourmet preserves made of fish are usually sterilized. Therefore, the F₀ variable set in the range of 6-8 is used to carry out a correct heat treatment.

On the other hand, pasteurized products, usually ready-made meals, use the P₀ variable. This implies the mandatory use of subsequent refrigeration to prevent spore germination.

Fun fact

Have you noticed that many people prefer canned tuna instead of fresh tuna? This is because canned tuna does not have the usual fishy taste, since it is already cooked. The fact is that tuna reacts positively to the use of temperature and this allows canneries to apply very high F₀.

Common problems in fish sterilization

The biggest obstacle when preparing any fish product is microorganisms, which can come from:

Common bacteria such as Aeromonas hydrophyla, Clostridium bolutinum, among others, and non-indigenous pathogenic bacteria such as Salmonella and Escherichia coli can be found in fish.

In addition, the Anisakis parasite, which is found in fish such as cod, sardines and salmon, can cause gastroenteritis.

An appropriate heat treatment is absolutely essential to eliminate these microorganisms and parasites.

Recommended containers for canned fish sterilization

The most recommended containers for canned fish sterilization are the rigid ones, e.g., those made of metal (cans) and glass.

As for ready-made meals based on fish, they are usually packaged in trays, which facilitates their consumption by the end consumer.

Fish sterilization with TERRA Food-Tech^® autoclaves

The various features of TERRA Food-Tech^® autoclaves for fish sterilization turn a small piece of equipment into a great production partner that is cost-efficient, fast and versatile.

Adjustable F₀ - P₀

Accurately pasteurizes or sterilizes using F₀ and P₀ values

Rapid cooling

Rapid cooling through water shower to avoid product overcooking

Adjustable back pressure

Programmable back pressure value according to container type

Traceability for auditing

Manage and record the process from start to finish with our software

Accurate control

Continuous monitoring of processes thanks to the heart probe

Protection

Excellent security measures for users and their products

Success stories of canned foods and ready-made meals prepared with fish

On the market there are a large number of gourmet canned foods and ready-made meals based on fish. We invite you to explore our success stories section, where you can discover some examples.

Pibernat

Preparation of preserves made from meat, fish, sauces and sauteed foods

EatNow Food

Artisan preserves

Virtute Naturae

Making of preserves (black olives and stuffed cherry peppers)

Hundebar

Canned food for cats and dogs

Bottega da Re

Preparation of preserves and ready meals

Looking to learn more about TERRA Food-Tech^® autoclaves for sterilizing gourmet fish preserves? Contact our experts today

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