How to pasteurize or Sterilize bulk substrate? (Methods)

Sterilization, or disinfection, is a very broad term. Its essence boils down to the fact that in the prepared product it is necessary to kill everything living and hostile: both adult fungi, molds, bacteria, and other microorganisms, as well as their spores, and other resting structures, which, as a rule, are more stable than their “parents” and, having survived their death, they can give rise to a new generation.

how to pasteurize or sterilize bulk substrate

What is pasteurization in mushroom?

In this sense, the sterilization process is pasteurization, and tyndalization, and ultra-pasteurization, and sterilization itself in the narrow sense, and in general, any operation that leads to the complete or maximum death of harmful microorganisms inhabiting products. Those. if you and I knew how to crush microbes by hand, this would also be one of the types of sterilization.

What is Sterilization in mushroom?

Sterilization, as you well understand, is used to disinfect food products, not because of hatred of microorganisms, but to extend the shelf life of products that are often liquid or contain a significant amount of liquid. If the product is not a good substrate for the development of molds and bacteria, or the conditions in which it is stored do not contribute to this, then there is no need for sterilization itself. For example, dried mushrooms contain so little moisture that microorganisms cannot develop on them. On mushrooms lying in the freezer at a temperature of -18 ° C, nothing will grow either.

After sterilization, you can not leave the product as it is, otherwise, it will immediately be “sown” with aggressive microflora, and all efforts will be in vain. It is for this purpose that the rolling (or any other hermetic sealing) of sterilized blanks was invented. Moreover, the container in which the processed product is placed must also be sterilized. A kind of analogue of sealing is the filling of a hot billet with hot fat (melted animal fat or butter). This creates a protective layer on top of the workpiece that is impermeable and unsuitable for microbial nutrition, like a seaming lid. Such canned food can be covered simply with parchment, without fear of spoilage.

Sterilize mushroom Substrate with Autoclave or Pressure cooker.

how to pasteurize or Sterilize bulk substrate with simple method?

Instead of lengthy processes of pasteurization and sterilization of mushrooms and mixtures with mushrooms, many housewives use the hot filling (hot pouring) method. 

Hot filling does not provide such a high degree of disinfection as pasteurization (and, moreover, sterilization), but it is quite reliable and not labor-intensive. Hot filling is far from suitable for all types of canned food, however, everything that is poured with boiling brine (pickling, salted-boiled mushrooms), or can be poured into a jar hot and immediately rolled up (mushroom hodgepodges, preparations for soups, long-term storage caviar, etc.) p.) is quite suitable for him.

During hot pouring, salted-boiled mushrooms, in which the brine for pouring is prepared separately or brought to mind after removing the mushrooms boiled in it, as well as mushrooms marinated according to the “cooking separately from the marinade” method, are laid out in a jar into which it was previously poured and boiling water is immediately poured out, or which has just been held over the steam, or taken out of the oven calcined, i.e. hot. After that, ideally, the jar should be covered with a lid, covered with a towel, and left for 10-15 minutes. But you may not do this. Boiling brine or marinade should be poured into a jar filled with mushrooms so that it slightly overflows – this will help sterilize the neck of the jar. After that, you need to immediately roll up the jar with a sterilized lid, turn it upside down and check the tightness of the closure,

Pickled mushrooms that are boiled in a marinade, salted-boiled mushrooms that go into a jar along with brine, mushroom caviar, preparations for soups, mushroom-vegetable mixtures containing a lot of liquid, are poured into hot sterile jars immediately, whole, boiling, and then immediately capped.

Read Chemical Sterilization of Mushroom Substrate.

how to pasteurize or Sterilize bulk substrate with different expert methods?

Dishes for blanks (we are talking about jars and bottles, as well as lids and corks for them), need either a good wash followed by drying or sterilization. In principle, washing with drying is enough. The fact is that during pasteurization and sterilization, jars with lids are sterilized together with the workpiece, and there is no great need for their separate additional sterilization. Sterilization (boiling) is necessary only for lids (and gaskets) if the jar with the workpiece is not rolled up before heat treatment, but only covered with them. In case of leaky closure (salted and pickled mushrooms), sterilization of the jars is also unnecessary, since the blanks themselves are not sterile.

Jars are usually washed with warm soapy water or a solution of mustard or baking soda (1 tsp per 1 liter of water). After that, the jars are rinsed with running water and dried, putting them upside down on a towel. If you are a fan of cleanliness, washed jars can be dried in the oven at a temperature of 120-180 ° C for 5-15 minutes. This is sterilization. In this case, the jars should be cooled without removing them from the oven. When canning by hot filling (when a hot preparation is placed or poured into a jar – for example, mushrooms along with boiling marinade), for additional disinfection, a cleanly washed jar can be rinsed well and held over steam (boiling kettle).

Jars can be sterilized in a slow cooker. To do this, the washed jars are placed in a double boiler container with the bottoms up and processed in the “Steaming” mode for 30 minutes. A microwave oven is also suitable for these purposes. When sterilizing in the microwave, pour 2 tbsp into each jar. l. water, place them on a special plate and put in the microwave for 2-3 minutes. The water in the jars will boil and sterilize them with steam. Cans processed in this way can be immediately filled with ready-made canned food.

Lids and O-rings should be washed in a weak solution of baking soda or soapy water and rinsed under running water. Then the lids should be boiled over low heat for 10-15 minutes. This should be done no earlier than 2 hours before the start of rolling cans. Lids made of polyethylene must also be pre-washed in a soda solution and doused with boiling water or heated in water at a temperature of 80-85 ° C. Bottle caps must be boiled for 5-10 minutes to give them elasticity. Lids and stoppers can also be dried in the oven.

old Mehtod of food sterilization

Now let’s figure out what types of food sterilization are, and then see what you can do with it at home.

The oldest method of food sterilization is called pasteurization named after the French microbiologist Louis Pasteur. The technology was proposed by him in the middle of the 19th century, it consisted in one-time heating of products or substances to 60 ° C for 60 minutes or at a temperature of 70-80 ° C for 30 minutes. At the same time, due to heating, excess air comes out of the product, and the remaining air is also sterilized. With such processing, all vegetative (“adult”) forms of microorganisms die in the products, they, like us, consist of protein, and the protein, no matter how heat-resistant, inevitably folds at this temperature, and the microorganism dies. However, mold and bacteria spores, protected by a thick impenetrable shell, remain in a viable state, and when favorable conditions arise, they begin to develop intensively. Therefore, pasteurized products are stored at low temperatures, and for a limited period of time. It is believed that the nutritional value of products during pasteurization practically does not change, since taste qualities and valuable components (vitamins, enzymes) are preserved.

New method of pasteurization

Currently, pasteurization modes have changed somewhat. In the food industry, depending on the type and properties of food raw materials,

  • long-term pasteurization is used (at a temperature of 63-65 ° C for 30-40 minutes),
  • short (at a temperature of 85-90 ° C for 0.5-1 minute) and
  • instant pasteurization (at 98°C for a few seconds).

Pasteurization is the main type of heat sterilizing treatment that can be applied at home, since it is quite problematic to get temperatures over 100 ° C at home without an autoclave.

Traditionally, pasteurization is carried out in a water bath (when jars of blanks are placed in a pot of boiling water). At the same time, a temperature of 70-95 ° C is reached inside the billet, which fully meets the technological requirements.

At the same time, you need to understand very well that, according to the rules, pasteurization cannot be used when preserving products, i.e., when sealing them., since a hermetically sealed container is a favorable environment for the germination of spores of anaerobic (developing in the absence of oxygen) microflora, including botulinum bacteria. That is why salted and pickled mushrooms are not rolled up, but simply not sealed tightly with plastic or screw caps. Again. At temperatures below 100 ° C, spores of anaerobic bacteria survive, which, after sealing (rolling), will germinate and poison your workpiece with toxins. If the jar is not tightly closed, this, on the one hand, will become a source for aerobic bacteria and molds (but they are much less dangerous compared to anaerobic ones), but it will let oxygen into the workpiece, which will create unfavorable conditions for anaerobic bacteria and prevent them from developing.

However, with the help of pasteurization, it is possible to achieve complete sterilization of the workpiece. For the purpose of long-term preservation of products, especially those initially contaminated with earth (the earth is the main source of botulinum clostridia), primarily mushrooms, fractional pasteurization is used tyndalization.


Tyndallization was a sterilization method proposed at the end of the 19th century by the English physicist John Tyndall. 

  • It consists in fractional heating of liquids (usually within 1 hour) from two to five times at intervals of 1-2 days. 
  • During this time, bacterial spores that survived when heated to 100 °C germinate, and the vegetative bacterial cells that emerged from them die during subsequent heating. There is a little trick to this. 
  • After the first pasteurization, the workpiece should not be removed in the refrigerator, but left at room temperature. Thus, by providing bacterial spores and molds with optimal temperature conditions, we lure them out and make them germinate. 
  • Of course, there will be incomparably fewer microbes than before the first pasteurization, because most of the spores will die during the first treatment. Mold and bacteria from spores will take 1-2 days to develop. 
  • After that, re-pasteurization is carried out to kill the “surprises”. 

Theoretically, they can have time to leave new spores that will survive in a very meager amount, and then especially suspicious housewives, having kept the workpiece at room temperature for another day or two, can carry out the third pasteurization. Basically, it’s better to be overdressed than underdressed. 

Some industry standards call for five times pasteurization (albeit for pharmaceutical purposes). 

Tyndallization is a very reliable method for canning (seaming), it is used by many housewives, especially when preparing mushroom jam and mushroom-vegetable mixtures. after keeping the jar at room temperature for another day or two, they can carry out the third pasteurization. 

If you roll up the jar before the start of conventional or fractional pasteurization, it must be checked for leaks. 

To do this, it is best to put the rolled up jars in a large saucepan and fill with water so that it closes the container along with the lids. If the jars are not rolled up properly, air bubbles will begin to rise to the surface of the water. In this case, the jars should be rolled up again and checked for tightness again.

Another way to check the tightness is to roll the sealed jars on the table several times and set upside down: near the place where air enters, foam or bubbles usually appear in the jar. In this case, you should roll the lid a little more with a seamer. If the jars are not pre-rolled, they should simply be covered with lids, after which you can proceed to traditional home pasteurization – in a water bath. 

The jars filled and closed with lids are placed in a deep saucepan filled with warm or hot water, on the bottom of which a wooden grate or cloth folded in several layers is placed (so that the jars do not burst from uneven heating). 

Sealing lids for jars should be boiled for 10–15 minutes together with rubber gaskets and immediately cover the jars placed in the boiling container with them. Then the pan is put on fire and the water is heated to the desired temperature. 

The jar should not touch the walls of the tank (pot) and each other, otherwise they may crack. Do not forget that only jars of the same volume can be sterilized at one time. Processing is carried out at a low boil of water. Pasteurize blanks from 10-15 minutes to 1 hour or more, depending on the volume of cans. Usually, jars with a capacity of up to 0.5 liters are heated for 10-15 minutes, up to 1 liter – 20-30 minutes, up to 3 liters – 30-40 minutes. The countdown starts from the moment the desired temperature is reached. When re-pasteurizing, the heat treatment time is usually reduced by half of the original.

After sterilization, the jar is removed from the water with special tongs, without moving or lifting the lid, then the lid is rolled up or tightly closed. If the jar is rolled up before pasteurization, the water level in the pot during boiling should be 1.5-2 cm below the level of the lids (i.e., correspond to the level of the product in the jar). Pasteurization time also depends on the consistency of the product. For example, liquid mushroom preparations (sauces, extracts), as well as finely chopped or soft mushrooms, warm up less than preparations made from coarsely chopped or whole mushrooms, or mushrooms with dense pulp.

Ultra-high-temperature processing

UHT is designed for liquid products. This treatment is usually applied to raw milk and fruit juices. The liquid is heated for 2-3 seconds to a temperature of 135-150 °C and immediately cooled to 4-5 °C. In this case, pathogens and microorganisms are destroyed. Milk, for example, after such treatment is suitable for consumption for 6 weeks or longer. Theoretically, UHT would be very suitable for sterilizing mushroom extracts and sauces, but it is not achievable at home. And it does not matter, because, unlike pasteurization, vitamins (for example, folic acid, vitamins B 12 , C and B 1 ) are already beginning to partially break down in products that have undergone ultra-pasteurization.

For traditional (leaky) canned storage of salted and pickled mushrooms, pasteurization (and even more so sterilization) is not needed. You can sterilize the jars in which they are laid out, but in principle this is not necessary. Salt and vinegar contained in salted and pickled mushrooms are reliable preservatives in themselves and allow the preparations to be stored for a long time. Sugar plays the same role in mushroom (and any other) jam. Meanwhile, any mushrooms can be sterilized – salted, pickled, pickled, fried, stewed, etc., as long as the technology is observed. In an acidic environment, microorganisms die faster and at a lower temperature, so pickled mushrooms do not need to be heated to 100 ° C, 80-85 ° is enough. There are types of blanks for which sterilization (pasteurization, tyndalization or actual sterilization) is a prerequisite. First of all, these are mushroom caviar, mushroom-vegetable mixtures, sauces and extracts, as well as mushrooms harvested without preservatives (salt, vinegar) – natural, in their own juice, etc.

Sterilization in the narrow sense takes place at a temperature of 100 ° C and above. With this method of heat treatment, all biochemical processes in products are completely stopped and all microorganisms and their spores die, and the longest and most reliable storage is ensured. The mode of sterilization of canned food depends on the capacity of the container, the consistency of the workpiece and the level of its acidity. The sterilization time for jars with a capacity of 0.5 l in a water bath at a temperature of 105 ° C is 90 minutes, but at 120 ° C 30 minutes is already quite enough. In normal household conditions, sterilization is difficult to achieve, because. boiling water at temperatures above 100 ° C can only be achieved in an autoclave or a special sterilizer.

However, there are a number of ways to get a high temperature in a conventional kitchen and carry out a full sterilization.

The simplest of them, perhaps, is to increase the boiling point of water by adding table salt to it. According to the laws of physics, the higher the concentration of salt in a solution, the higher its boiling point. To raise the boiling point of water to 101 ° C, you need to add 66 g of salt per 1 liter, to 105 ° C – 255 g, to 110 ° C – 478 g. The method has no disadvantages besides the colossal salt consumption.

There is another way to sterilize – in the oven. It is used only for heat treatment of jars sealed with glass lids with metal clips. To sterilize filled jars in the oven, a deep baking tray is filled with 2 cm of water and jars are placed on it with lids fastened with clamps. The baking sheet is placed in a heated oven and the jars are sterilized at a temperature of 140-180 ° C.

A microwave oven can also cope with the sterilization of not only empty jars, but also filled with liquid blanks. But a pressure cooker and a slow cooker will cope much better with the sterilization of any (not only liquid) blanks.

The pressure cooker is pressurized to allow true sterilization at 120°C, just like in an industrial setting. As a result, the processing time is reduced by 2-4 times compared to conventional sterilization in a saucepan standing on the stove. To sterilize jars with blanks in a pressure cooker, well-washed and dried jars (3-4 jars with a capacity of 0.5 l are included in a regular pressure cooker) must be filled with harvested mushrooms, covered with sterilized lids and put on a stand installed in a pressure cooker. After that, pour 0.5 liters of hot water into the pressure cooker (slightly below the level of the stand), close it with a lid and set the valve regulator to 120 ° C. After heating over high heat (when steam does not start to hiss out from under the valve), it should be reduced and sterilized sauces and extracts for 5-10 minutes, vegetables stuffed with mushrooms and mushroom-vegetable mixtures – 20 minutes, mushroom caviar – 25 minutes, salted , pickled, stewed, fried and other mushrooms – 30 minutes. Sterilized jars should be immediately rolled up and turned upside down. You can sterilize the jars already closed, but then their contents must be laid in such a way that the top layer of the workpiece does not reach the top of the jar by 1.5 cm, otherwise the lid may break off during the sterilization process or the jar itself may burst. Sterilized jars should be immediately rolled up and turned upside down. You can sterilize the jars already closed, but then their contents must be laid in such a way that the top layer of the workpiece does not reach the top of the jar by 1.5 cm, otherwise the lid may break off during the sterilization process or the jar itself may burst. Sterilized jars should be immediately rolled up and turned upside down. You can sterilize the jars already closed, but then their contents must be laid in such a way that the top layer of the workpiece does not reach the top of the jar by 1.5 cm, otherwise the lid may break off during the sterilization process or the jar itself may burst.

Similarly, you can sterilize blanks in a slow cooker. To do this, you need to place the jars filled with blanks and covered with lids in the multicooker bowl (do not forget to line the bottom with a small kitchen towel) and pour just enough water into it so that the jars are up to their shoulders in it. For sterilization, use the “multi-cook” or “oven” programs with a temperature of 100 ° C. For cans with a volume of 0.5 liters, 15 minutes from the moment of boiling will be enough. A standard multicooker holds 3 half-liter jars. At the end of the operation of the device, roll up the cans, turn them over and leave in this position until they cool completely.

According to most recipes, rolled jars are left to cool upside down (this additionally sterilizes the place where the lid fits on the jar) at room temperature until they cool completely, or even slow down this process by wrapping the jars in a blanket for additional self-sterilization. But some types of sterilized canned mushrooms are desirable to be cooled quickly in order to preserve the consistency and natural color. In this case, it is better to put the rolled cans on the balcony (in the courtyard) or put them in a cellar or a cold pantry. If the recipe requires rapid cooling, immediately after capping (unless the jars were sterilized sealed), the jars should be placed in a pot of hot water, to which cold water should be gradually added. This must be done fairly quickly, but carefully. When the water becomes warm (35-40 ° C),