In this article, we will explain how to sterilize gourmet canned vegetables and ready-made meals based on vegetable, but first we will detail the benefits of eating vegetables and the types that can be found in markets.

We will also give you tips about sterilization and share interesting ideas and information that will be interesting for you.

Vegetables, rich in vitamins, minerals and fiber

Vegetables are essential in the world’s cuisine because of their diversity and health benefits. The consumption of vegetables is essential to maintain a healthy and balanced diet because:

They provide potassium that helps prevent and eliminate fluid retention.

They are low in fat and calories and are used to treat obesity and potential cardiovascular pathologies.

They are rich in minerals such as iron, zinc, phosphorus, potassium, calcium, magnesium and copper.

They contain vitamins A, C and group B, which are beneficial to maintain strong defenses against infections and strengthen our nervous system.

They provide prebiotic soluble fibers and insoluble fibers suitable for regulating intestinal transit.

They have antioxidants, which are very useful against aging and can also prevent certain types of tumors.

Vegetable consumption

According to data collected by the Food and Agriculture Organization of the United Nations (FAO), global consumption of fruits and vegetables increased from 306 grams per person per day in 2000 to 390 grams in 2017, but the figure includes peels and other parts that end up in the trash.

In absolute terms, the production in 2018 was 1.089 million tons of vegetables and, although its international trade represents just 8% of the global supply, its value is among the highest among commodities, according to FAO.

And in 2021, with the intention of vindicating the contribution of vegetables to health and nutrition, the United Nations General Assembly declared 2021 as the International Year of Fruits and Vegetables, coinciding with the coronavirus crisis.

To reduce the risk of developing non-communicable diseases, the WHO recommends eating at least 400 g of fruits and vegetables per day, i.e. 5 servings of fruits or more than two servings of vegetables per day (150-200 g per serving), except potatoes, sweet potatoes, cassava and other starchy tubers.

It is also recommended that at least one serving be eaten raw in order to take better advantage of its nutrients.

Types of vegetables

There are about 400,000 plant species in the world, of which about 300,000 are edible. And of these edible plants, we only consume about 200, or 0.06%.

Vegetables can be classified according to the part of the plant from which they are extracted:

Fruits: eggplant, chili, sweet corn, sweet pepper, hot pepper, etc.
Bulbs: garlic, onion, leek, French onion, shallot, etc.
Cabbages: kale, broccoli, sprouts, Brussels sprouts, cauliflower, savoy cabbage, red cabbage, white cabbage, etc.
Leaves and tender stems: sorrel, chard, cress, borage, cardoon, endive, ruff, spinach, turnip greens, lettuce, watercress, etc.
Inflorescence: artichoke.
Green legumes: peas, broad beans, green beans, snow peas, etc.
Peponide: zucchini, squash, pumpkin, cider pumpkin, butternut squash and cucumber.
Roots: chicory, celery, swede, kohlrabi, parsnip, scorzonera (black salsify), turnip, radish, red beet, salsify, carrot, etc.
Young stems: celery, white asparagus and wild asparagus.

They can also be classified according to their origin and treatment or conservation method applied:

First range: fresh vegetables and other products preserved by traditional methods such as dehydration, salting and fermentation.
These are unprocessed foods that have not undergone any disinfection treatment. Therefore, in general, these are high-risk, highly perishable foods that in most cases require refrigeration. This group includes dried vegetables (dried peppers), dehydrated vegetables and the popular pickles (gherkins, spring onions, peppers, etc).
Second range: which includes preserves and semi-preserves. Vegetables that have been exposed to a heat treatment in order to be preserved.
These products are usually sterilized and packaged in hermetically sealed containers, such as cans or glass jars.
Third range: vegetables preserved by freezing or deep-freezing. Vegetables undergo a freezing process when they are raw, so they need to be thawed for cooking and then consumed.
Fourth range: vegetables that are washed, peeled, cut and packaged under special conditions (under cold chain) and ready to be consumed as raw vegetables during a shelf life of 7 to 10 days.
Nowadays, there is a wide variety of products, lettuce leaves, single or multi-class, salads, etc.
Fifth range: The vegetables have received two different modes of technological handling, i.e. heat treatment and packaging, in addition to refrigeration, if necessary.
These are cooked products (vegetable sauces, stir-fries) or dishes prepared with vegetables.

Canned foods and ready-made meals with vegetables

The most common canned vegetables that we can find in markets are:

Canned vegetables provide virtually the same nutrients and minerals as fresh foods because they are processed immediately after harvesting, minimizing the initial loss of nutrients.

However, in order to comply with current health and hygiene regulations, all products made from vegetables must undergo a thermal process in a food autoclave before being sold, such as pasteurization or sterilization.

How to produce canned foods with vegetables

Deciding which heat treatment you must apply to your gourmet canned vegetables or ready-made meals based on vegetables will depend on the food to be packaged and what you want to achieve as a final product.

If we are looking for a product that does not require refrigeration and has a long shelf life, sterilization is the best option.

On the other hand, if the type of vegetable food to be preserved requires a less abrasive treatment, then pasteurization is the best option, although if it is not sufficiently acidic, it will require refrigeration at all times and will have a shorter shelf life.

The objective of both heat treatments is to eliminate, either partially or totally, those microorganisms that may alter the food or that may pose a risk to the consumer’s health.

Sterilization of canned vegetables

If your objective is to market gourmet canned vegetables or ready-made meals based on vegetables, you must apply them heat treatment using professional equipment in order to be able to sell them to others. This process is necessary in order to extend its shelf life with total safety, to eliminate all or almost all microorganisms, spores and enzymes.

Especially considering that canned vegetables and ready-made meals usually have a pH higher than 4.5, a factor that favors the multiplication of microorganisms.

Therefore, once packaged and coated with the covering liquid proper to canned vegetables, you should always carry out a pasteurization or sterilization process on your canned vegetables before marketing them. Remember that pasteurized products should always be kept refrigerated after heat treatment and the sterilized products may have a longer shelf life without refrigeration.

The covering liquid or governing liquid is the fluid that is added in the canning process in order to transfer heat to the solid product and thus ensure the displacement of air to the top of the jar or container used. This makes it possible to achieve vacuum sealing to guarantee the effective conservation of the product, since the absence of oxygen will make the product more durable.

In addition, it can also be an ingredient to enhance or add more flavor to foods, whether it is sweet, by adding spices, by balancing the pH, etc. This liquid also allows the ingredients to be evenly distributed in the container and also helps to preserve or enhance the natural color of products.

pH of canned vegetables

The pH of a food determines what type of microorganisms can grow in it. If the pH value is lower, there will be more acidity and fewer microorganisms, and vice versa.

As we mentioned before, regardless of the pH of your gourmet canned vegetables or ready-made vegetable dish, you will need to apply a heat treatment to them. The difference will lie in the temperature and time, since the type of pathogens that grow in a food, according to its pH, will determine the minutes and degrees to which we must expose our preserves in order to sterilize/pasteurize them correctly.

As you can see in the following list, the vast majority of vegetables are low-acid foods, i.e., their pH is greater than 4.5. This means that, in general, in vegetables their pH does not work as a preservation method by itself.

It is essential to keep in mind that most microorganisms grow at a rather neutral pH, between 5 and 8, and especially between 6.5 and 7.5.

pH < 4.5	pH 4.5 – 5.5	pH 5.5 – 7
Acidified artichokes	Artichokes in their natural state	Peas
Acidified celery	Celery in their natural state	Broad beans
Acidified eggplants	Zucchini	Corn
Acidified mushrooms	Mushrooms	Leeks
Pickles	Asparagus	Artichokes in oil
Acidified peppers	Spinach
Acidified beets	Green beans
Tomato	Peppers in their natural state
	Beet
	Potatoes in brine

Remember

It is essential to correctly calculate the pH of your canned foods or ready-made meals in order to determine the heat treatment to be applied. For this purpose, the pH must be measured after the product has been prepared and packaged, since, depending on its cooking and the combination of ingredients, the pH of the final product will vary.

F₀-P₀ values for vegetable sterilization

The thermal values F₀ and P₀ indicate the time and temperature required to eliminate pathogenic microorganisms in food.

The F₀ value is used for sterilization, at temperatures above 100°C, while P₀ value is applied in pasteurization, at temperatures below 100°C.

Although the F₀ or P₀ values will depend on the type of product, its ingredients and how it has been previously prepared, we provide some average values as a guideline.

Above all, we advise studying each product individually by correctly measuring its pH and performing subsequent controls to evaluate the entire process in order to select the most appropriate F₀-P₀ values for a product.

Generally, for canned vegetables we apply an F₀ of 7-8, although F₀= 7 is commonly used. For those products in which the pH is less than 4.5, the P₀ value may be used, and this will range from 0.5 to 40 depending on the pH of the final product.

Common problems in vegetable sterilization

As a starting point when treating any type of vegetable, whether for fresh consumption, drying or dehydrating, freezing or for the production of by-products and preserves, they must meet the following conditions:

They must be freshly harvested or in perfect preservation conditions, free of abnormal external humidity and without strange smell or taste.
They must be free of arthropods, worms, mollusks and parts or excrement of any of them.
They must be free of cryptogamic diseases.
They must be free of wilted parts and strange matter adhered to their surface.
They must be free of pathogenic microbial agents.
They must not contain pesticide impurities in a proportion higher than the tolerance limits established by the regulations.

In addition, it is essential to ensure that the preparation of a product is carried out under adequate hygienic conditions to minimize the microbial load in that product, thus ensuring that it is as low as possible.

Common bacteria in vegetables, such as Salmonella, Escherichia coli, Clostridium botulinum, Listeria monocytogenes and Shigella, are transmitted through irrigation water, fertilizers or pests.

In order to guarantee the total elimination of these microorganisms, the best option is to pasteurize or sterilize canned foods. This is the only way to ensure that your products are safe for consumption.

Although sterilization is effective in eliminating microorganisms, it can affect the organoleptic characteristics of the food, such as changes in smell, flavor, color and texture.

To reduce as much as possible these possible changes in the organoleptic aspects of your product, before applying any heat treatment, you can always blanch the vegetables in order to soften the ingredients to obtain a better filling of the packages, inactivate enzymes that cause bad odors and flavors and color changes in the food.

Recommended containers for canned vegetables sterilization

The most common and recommended containers for sterilizing canned vegetables are glass jars and cans. You can also find creams, sauces or vegetable sauces in pouches and also some vacuum-packed products.

Remember that in glass containers with twist-off or screw-on lids, you must always leave a head space or empty space to ensure hermetic sealing and allow the ingredients to expand when heated.

Sterilization of vegetables with TERRA Food-Tech^® autoclaves

The various features of TERRA Food-Tech^® autoclaves for vegetable sterilization turn a small piece of equipment into a great production partner that is cost-effective, 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 with vegetables

The production of gourmet canned vegetables is a great business opportunity for both the agri-food and catering sectors. Behind each one of these products there is a story, a manufacturing process and a period of trial and error. In our success stories we give you the opportunity to know these experiences personally.

CUICK

Preparation of ready to use stir-fries and minced food products

Virtute Naturae

Making of preserves (black olives and stuffed cherry peppers)

Aixada Conservas

Elaboration of artisan preserves

Tarro Verde

Preparation of canned vegetables, ready meals and vegetable spreads

Foz-Clua Asparagus

White asparagus canning

Espigoladors Foundation

Preparation of creams, jams, spreads, patés and sauces

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

"*" indicates required fields

Name*

Surname*

Company*

Country*

Email*

Telephone*

Message*

5+4?*

This field is for validation purposes and should be left unchanged.