What is dry sourdough. Dry sourdough production technology

HELLO! here I am! :) With my story about how I learned how to restore sourdough in record time. I've resurrected my sourdough starter from a dry state, but the exact same method works for those rebuilding from cold dough when the sourdough has been refrigerated for weeks or months. In both cases, very few living microorganisms remain in the sourdough, and they must be handled in a special way so as not to inadvertently suffocate them during feeding.

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Before I learned how to breed starters at home, I bought them dry from Ed Wood. He has wonderful starters, all different, from different regions of the world, and restoring the starters according to Wood's recipe takes about 5 days.

Then I learned how to breed starter cultures at home, including the super-fast Calvel method, in two days, stopped buying starter cultures and decided that I would never dry my starter cultures. Why, if recovery from a dry state takes 2 times more time than removal from scratch?

But in August last year, I first hatched a sourdough recipe that takes almost 2 weeks to hatch. This is my most favorite and valuable sourdough - San Francisco lactobacillus sourdough. It produces a bread whose taste and aroma I especially appreciate, a sourdough without which I would not be able to bake the rye bread that I like - sour, substantial, exceptionally pleasant to the bite and taste.

Such a starter cannot be hatched in 2 days, and even if it takes 5 days to recover from the dried state, then it is less than 2 weeks of hatching from scratch, right?

So I decided to dry the ripe san francisco sourdough using the instructions in Nancy Silverton's book: Spread the dough thinly and let it dry. Then, when necessary, soak and feed for 5 days in the same way as when removing the starter (3r per day, approximately 1:1, 6h.6h.12h). Instructions from Nancy Silverton's book:

This is how the sourdough spread on a silicone mat (can be spread on polyethylene) looks like during the drying process at room temperature (22C)

Dried (my layer was thinly smeared and dried in a day)

You can save the starter in the form of such flakes. Or you can grind it in a blender into powder with a teaspoon of flour to store it in powder form. I dried 2 bags - one kept in flakes and the other in powder form.

In dry form, starter cultures have a limited shelf life. Compare this to store-bought dry yeast. Over time, dry yeast also expires. Dried cells are not eternal, they continue to slowly die. Therefore, it is believed that dry starters, at least dried in such a primitive way as shown above, and which are simply stored in a jar or bag, are best stored dry for no longer than a year. Commercial dry starters like SAF Levain are usually hermetically sealed (vacuum-packed, i.e. without air) and have a shelf life of up to 3 months at 4C and up to a year if stored at 20C.

My starter was stored in a plastic bag at 12C for 6 months (dried out on September 1st). And I wanted to restore it "according to science", that is, faster than in 5 days, taking into account what I know about starters and bacteria. And I managed to restore the starter from a dry state to a working one in 24 hours! Hooray!

The steps are

(1) First leaven should be soak. Those. restore the cells of microorganisms from dried and fragile to a living "wet" state with elastic cell membranes. The package says that 150 ml of liquid sourdough was taken and dried into a powder. it turned out about 50 ml of powder (3 tablespoons)

Those. to restore, soak it, you need to add water to a volume of 150 ml. So I added water (filtered, boiled and cooled to 22C water), mixed in another 1/2 tsp. sugar (2-3g), to feed microbes and a slight osmotic pressure on the cells, and left for 1 hour at 22C, so that it all swelled and got wet.

(2) now microbes need to be activated and allowed to multiply. Activation is when bacteria recover from their lethargic state and produce again maximum the amount of acid (per hour of time), and when the yeast produces maximum the amount of gas foaming the dough (also per unit time).

As you remember, the sourdough was dried with singing, those. optimally acidic and already depleted of nutrients, so in this powder almost no food left for bacteria - sugar, vitamins, etc. But, as you remember, many bacteria died in dried sourdough (as in dried yeast): some during drying, some during storage. That is, you need to feed very carefully and gradually, white flour.

White flour has very few of its own wild micro-organisms compared to black flour, so white flour will not contaminate the reconstituted sourdough with putrefactive micro-organisms. And when a tiny amount of unleavened dough or unleavened flour is mixed in, the reconstituted starter retains the "sour" acidity needed for optimal functioning of the starter microbes.

Most starter recovery methods for 5 days take so long because a dry starter with a small number of living cells is fed too much fresh test. In unleavened dough, processes of putrefactive fermentation take place, which inhibit still weak microbes from dried sourdough. Those. the recovery process is as long as the process of removing the starter from scratch!

So I added 1 tbsp to the liquid in the glass. white flour and left to ferment for 12 hours at 22C. In the process of fermentation-activation and reproduction - I stirred the slurry with a fork from time to time. And she wandered off! Sourdough after 12 hours

(3) At this point, the starter has already begun to foam, but it has more yeast than lactic acid bacteria. This is due to the fact that different microorganisms tolerate drying and storage at different temperatures in different ways. You need to continue to refresh the starter in order to restore the correct proportions of MKB to yeast. So that it contains 40-100 times more LSD cells than yeast cells. I added another 1 tbsp to 150 ml of sourdough in a glass. white flour and 50 ml of water. Mixed and left for 4 hours at 22C.

The sourdough fermented vigorously and completely restored its appearance. It looks exactly the same as a perfectly working and ripe sourdough san francisco, with exactly the same aroma before drying.

(4) preparation of a batch of working starter San Francisco. Working sourdough san francisco is obtained after 8-12 hours of fermentation after feeding the sourdough approximately 1:1. The time was late, almost midnight, so I took 200g of sourdough, mixed in the prescribed 90g of white flour and 110g of water and left it to ferment overnight. In the morning, there was a perfectly perfect sourdough san francisco in the mug. It has grown in volume by one and a half times (this is the maximum for liquid starter cultures) and has become exceptionally frothy and deliciously sour.

In 24 hours the san francisco sourdough recovered from being dry to a fragrant and delicious sourdough with just the right acidity. URRRAAAA!!!

Starter early in the morning 8 hours after refreshment. Ideally, the pH of the starter should be in the range of 3.9-4.5 pH units. 3.9 for black, rye or wheat flour starters and 4.4-4.6 for white wheat flour starters (see page 90, Calvel, 2001, The Taste of Bread)

12 hours after refreshment - perfectly sour, boisterously fluffy, and optimally rich in microorganisms needed for dough fermentation.

Probably I will give her another day of feeding at room T (1:1, 6h6h12h at 22C), I will bud rye from her and transfer it to standard storage in a regular refrigerator at 3-6C with refreshment once a week or more often, as it is used.

And I will probably try this method of restoring starters on other starters that I have in dry form - commercial starter cultures from different companies. After all, their shelf life in dry form is not eternal, so they need to be restored and then dried again 1-2 times a year in order to keep reserves of unique regional starter cultures at home, at hand.

And how are you doing? tell! I miss you terribly and want to know everything.

How much does dry sourdough cost (average price for 1 pack)?

Moscow and Moscow region

Such a product as dry sourdough can be called auxiliary, since by itself it is not used in food, but is only used in baking in the production of bread and bakery products from wound flour. The thing is that the properties of rye flour are significantly inferior, for example, to the wheat type of the product, so it is simply impossible to make tasty and airy rye bread without sourdough.

Since baking bread becomes almost impossible due to the specificity of rye flour, bakers use dry sourdough. However, rye bread sourdough was known to people thousands of years ago. The history of bread sourdough began in ancient Egypt, where bread was first baked using natural sourdough. It is worth noting that the Egyptians used the remains of rye dough, which were previously used for baking bread, as a bread sourdough.

For the preparation of fresh sourdough, a sufficiently long period of time is required, during which it is necessary to constantly monitor the condition of the product. Just one mistake and the sourdough starter will be hopelessly damaged, and the baker will have to start the whole process again, which takes about 10 days on average. To save time, as well as raw materials, in modern baking business, as a rule, dry sourdough is used.

However, dry starters are used not only in industrial production. Modern housewives often purchase household bread machines and are happy to make bread and various bakery products at home. In the process of baking rye bread with a bread machine, dry sourdough will become an indispensable auxiliary product that will help give the dough the right consistency.

It is worth noting that dry sourdough affects not only the appearance of the finished bakery product, but also its taste and aroma. When dry sourdough is added to the dough, the final bakery product will have a characteristic taste and aroma. At home, it is really easier, faster and more convenient to use dry sourdough, which is a powdery substance, for baking bread.

Depending on the desired result, a certain type of dry sourdough is chosen. Moreover, the type of this or that dry sourdough will differ primarily in the chemical composition, which may contain both fermented malt or rye flour, and a mixture of acids, such as citric, lactic and ascorbic. As a rule, the composition of dry starter cultures includes exclusively natural ingredients, which, in addition to taste and aroma, saturate the finished bakery products with a number of compounds useful for the human body.

Caloric content of dry sourdough 330 kcal

The energy value of dry sourdough (The ratio of proteins, fats, carbohydrates - bzhu):

: 11 g. (~44 kcal)
: 2 g. (~18 kcal)
: 67 g. (~268 kcal)

Energy ratio (b|g|y): 13%|5%|81%

Greetings to all readers of the site! Dairy products are famous for their benefits to the human body. A particularly tasty representative among the sour-milk team is yogurt. Natural yogurt restores the composition of the intestinal flora, localizes dysbacteriosis, and is effective in the treatment of allergies. And yes, it's incredibly delicious! We offer to prepare such a healthy and tasty product that all children and adults love, together with our blog culinary specialist Alena. We have already told you how to cook homemade yogurt in a slow cooker, today we will make dry sourdough yogurt. Also check out this easy recipe.

Ingredients:

• Milk 6% UHT - 1 l
• Ferment "Vivo yogurt" - 1 bottle

How to make homemade yogurt:

To prepare natural yogurt, we need only 2 ingredients. One of the conditions for the preparation of a quality product is sterility, so that unnecessary bacteria do not develop in the dairy environment. Therefore, jars for yogurt must be sterilized in any way convenient for you. I pour 50 ml of water into jars and put in the microwave at full power for 5 minutes. Then I drain the water from the jars.

If using UHT milk, simply heat it in a clean saucepan to 40 degrees. If the milk is pasteurized, then boil it, strain from the foam and cool to 40 degrees.

Add the starter to the milk, mix thoroughly with a clean, dry spoon. The most popular and affordable dry sourdoughs are "Vivo" and "Evitalia".

Pour the prepared mixture into sterile jars, do not twist the lids. Put the jars in the yogurt maker, close it and turn it on for 8 hours.

Put the finished yogurt in the refrigerator for three hours, twisting the lids on the jars. For medicinal purposes, it is recommended to use a jar of yogurt 20 minutes before meals 2-3 times a day.

Yogurt is tasty and in its original form, but if you wish, you can add jam, berries, honey to it.

Bon appetit!

For viewing, I offer another interesting recipe from our cooking site.

Very beneficial for our health. A person who monitors his health tries to use them daily. However, the quality of modern products often leaves much to be desired. Therefore, many today prefer to cook them on their own. For this, two components are needed: milk and sourdough. There are many offers on the market today, but not all of them are able to provide a good quality of the final product.

Today we are interested in Vivo sourdough. Reviews say that many parents today trust only her. This is a well-known brand that invites you to cook delicious, natural and healthy products at home. Their shelf life is very short, only 1-2 days, but this guarantees the complete absence of preservatives and other chemicals in the composition.

Benefits for the body

Of course, unlike store-bought products, homemade sour milk has one drawback - it takes time to cook. This is more than offset by the fact that you will have a real live product. A particularly good result is obtained if Vivo starter is used. Reviews emphasize that it is very easy to use them, the final product ripens quickly, and the taste pleases the whole family.

Scientists' opinion

Numerous studies also confirm that kefir or yogurt prepared in this way contains lactic acid and bifidobacteria, which are very necessary for our body. Compare for yourself: what is better - store-bought yogurt with a shelf life of several months, in which only gelatin, dyes and preservatives remain, or live biomass with bacteria that inhibits the development of pathogenic microbes, neutralizes toxins and protects our intestines?

Peculiarities

To date, in pharmacies and stores you can find different starter cultures that allow you to cook a fermented milk product at home. How is Vivo's starter different from them? Feedback from regular consumers suggests that she was primarily interested in ease of use. You do not have to perform a complex process and observe technological subtleties. Just 10-15 minutes, and on the table - a delicious drink with live microorganisms. This is just the second reason why consumers decide to make kefir at home themselves.

We will analyze nutritionists a little lower) - these are, first of all, living, human-friendly bacteria that are used to ferment milk. They perfectly help to strengthen the immune system, help babies up to 6 months to adapt to the first complementary foods. It is an ideal product for the growth and development of children, it is necessary for pregnant and lactating women, the elderly and athletes. If you decide to lose weight, take antibiotics or want to restore the intestinal microflora, then this is your most faithful assistant.

Source of vitamins and trace elements

Dairy products are famous for enriching the body with a large number of nutrients. Unfortunately, this has nothing to do with store-bought products. So, if you want to be healthy, Vivo sourdough will be your ideal companion for many years to come. If right fermented milk products are present in your diet from childhood, this will help maintain health, prevent a number of diseases, and provide the body with a number of nutrients.

Our liver is constantly suffering from toxins that are produced by harmful microbes. Homemade sour milk will help you keep their number under control. In turn, this significantly reduces the burden on the kidneys and liver, and therefore prolongs your life.

For all organs and systems

Vivo sourdough is not only a product necessary for restoring normal intestinal microflora. Effectively helping with dysbacteriosis, homemade fermented milk products also improve metabolism, reduce the risk of infectious diseases and SARS, and eliminate functional disorders in the gastrointestinal tract. With regular eating, problems such as constipation, bloating and diarrhea almost completely go away.

home abundance

If you think that you can only cook kefir, then you are greatly mistaken. The manufacturer offers us a range of dry starters to choose from, with which you can get fermented baked milk and sour cream, cottage cheese and yogurt. That is, you will need a lot of desire and whole milk. In the summer, the second case will not. Adherents of a healthy lifestyle can use a fat-free product, at their discretion.

I would also like to note that Vivo bacterial starter cultures have been repeatedly tested at various institutes of microbiology and virology. The samples were examined for the composition of bacteria in the dry product and in the finished product, when fermenting one serving per liter or three liters of milk. The results of the researchers were completely satisfactory. Vivo dry starters turned out to be very good, of high quality, and the number of beneficial microorganisms in them is much higher than in store products. Moreover, even when fermenting one portion of 3 liters, they turned out to be 100 times more than the required minimum. Two cultures are easily recognized in the finished product - this is thermophilic streptococcus.

Starter culture for kefir production

This product is a natural probiotic, but what is sold today in stores is no longer even a semblance of it. Therefore, more and more people are switching to home cooking a healthy product at home. Dry kefir sourdough is produced by gentle drying, and therefore all microorganisms do not die, but go into a special form of suspended animation. After getting into a warm environment, they are activated and begin to feed intensively. As a result, the process of souring milk and turning it into a healthy drink takes place.

How is Vivo starter activated? The instruction says that this is a unique symbiosis of yeast, lacto- and bifidobacteria, which are created by nature itself in order to protect the gastrointestinal tract from various diseases. To prepare homemade kefir, you will need to prepare the dishes. Cleanliness is a guarantee that you will have a quality drink at the exit. Now it's up to the milk. It must be boiled and cooled to room temperature (about +20 degrees). It remains to dissolve the dry starter of one sachet in a small amount of liquid and add it to the milk.

Your task is completed. Now it remains only to close the lid and put it in a warm place for 4-6 hours. After that, the container is placed in the refrigerator for cooling. The drink is ready, you can treat your relatives.

homemade acidolact

Vivo fermented milk starters allow you to enjoy a range of fermented milk products that are loved by children. or "Narine" is a product of health and longevity. The probiotic microorganisms found in sourdough are very beneficial for our health. As a result of regular use of acidolact, you can notice a significant improvement in health. Among the useful properties are:

• Anti-inflammatory action.
• The ability to neutralize toxins in the body, side effects of drugs.
• Stimulation of body cleansing processes.

At home, you can prepare acidolact from a special starter culture. For one liter of milk (boiled and cooled to 37 degrees), you need to add 1 bottle of starter culture. Mix well and put in a thermos for at least 8 hours. It is very convenient to do at night. Then in the morning you will have a delicious and healthy breakfast.

Live Vivo starter cultures can also be consumed in a concentrated form. To do this, add a tablespoon of boiled water to the bottle, stir and drink before meals. Children can take one a day, and adults - 2-3 bottles a day.

Vivo Yogurt Starter

This gentle bright product with various fruit additives is most of all loved by the smallest. And for good reason. Regular consumption of yogurt stimulates the immune system and significantly reduces the risk of intestinal infections. Yogurt has a high concentration of amino acids, minerals and vitamins. This sourdough contains live cultures that have a number of useful properties.

Now let's look at how you can cook this most useful product at home. Vivo's live sourdough starters will allow you to do this quickly and without unnecessary difficulties. You will need a liter of boiled milk. To speed up the process, you can take pasteurized, and heat up to 25 degrees. Add the yeast to it and stir until completely dissolved. The mixture is left in a warm place. The ripening time of yogurt directly depends on the ambient temperature. If it is not higher than 30 degrees, then you will have to wait 14-18 hours. And by raising the temperature to 45 degrees, you will reduce the cooking time to 5 hours. At the end of the time, you need to remove the yogurt in the refrigerator for at least 2 hours. Now it remains to add muesli or berries, any jam to it.

Different options for your table

Vivo Yogurt Starter is a great everyday option for all your family members. Products differ from each other in composition, so everyone can find what suits him. Lactulose sourdough is very popular today. It is a probiotic fortified with a prebiotic. Lactulose acts as it, which in itself is neutral, but is a nutrient medium for the growth of beneficial bacteria. Regular use of this product helps to increase the acidity of the intestinal environment, which means that pathogenic microorganisms will be destroyed by themselves.

Fit yogurt is a great option for active people, the composition is ideal for those who want to be in good, athletic shape. The basis of the sourdough is specially selected strains of probiotic microorganisms, which are able to activate and accelerate the metabolic processes in the body.

DEVELOPMENT OF TECHNOLOGY FOR OBTAINING DRY FORMS OF PROBIOTIC PREPARATIONS

See also:

In the context of the increasing intensification of the technogenic impact of civilization, significant microecological disturbances occur in the human body, which have serious consequences for both individuals and society as a whole. The solution to this issue goes towards the widespread consumption of dietary supplements - nutracetics. Prebiotics - have nutritional value and are inherently natural food ingredients (vitamins and their precursors), polyunsaturated fatty acids, individual minerals and trace elements (calcium, selenium, zinc, iodine, fluorine), essential amino acids, some mono- and disaccharides, dietary fiber (cellulose, pectin, hemicellulose, etc.).

Along with prebiotics, widespread use "probiotic products"- live microorganisms or products fermented by them, which have a beneficial effect on human health, due to the normalization of its microbial ecosystem.

The industrial form of production of prebiotics and probiotics are:

• pharmaceutical preparations;
• biologically active additives (BAA);
• sourdough.

In recent years, much attention of researchers has been attracted by propionic acid bacteria (PAB), a distinctive feature of which is a wide synthesis of vitamin B12 and high immunogenic and antimutagenic properties. In this regard, it is relevant to create preparations - probiotics and prebiotics based on PCB and its symbioses with different types of lactic acid bacteria (LAB) in order to identify their ability to accumulate biomass of bacteria and vitamin B12.

These drugs are promising, their production is relevant. Therefore, below we present a small study on the development of experience in obtaining these drugs.

The aim of the project is:

1. Development of technology and conditions for the cultivation of PCB with the accumulation of the maximum amount of bacterial biomass and vitamin B12;

2. Development of technology and instrumentation for the dehydration of the resulting living form and obtaining it in a dry form, by spray drying.

To achieve the goal, the following tasks were set:

• optimize the composition of the nutrient medium and cultivation conditions for the accumulation of biomass and vitamin B12 by probiotic bacteria;
• the use of various types of symbiosis of PCB with LAB, to identify their ability to accumulate biomass and vitamin B12;
• to study the organoleptic and physico-chemical indicators of liquid sourdough;
• conduct a comparative analysis of the product obtained by different methods of dehydration;
• to study the conditions for dehydration of starter cultures by spray drying;
• select protective media for starter cultures under spray drying conditions;
• to consider the influence of the conditions for the introduction of protective environments on the quality of the resulting dry sourdough;
• obtaining probiotic products, in particular fermented milk products, based on the obtained starter cultures and analyzing their quality.

The work carried out approaches one of the directions of the development of science and technology. Priority direction index: 4 - Technology of living systems.Critical Technology Index: 4.5 Chemical and biological synthesis of medicinal and food products.

In accordance with the tasks set, a work plan was drawn up:

• search for the optimal nutrient medium, with the determination of the component composition;
• working out the conditions for the cultivation process, in order to maximize the accumulation of bacterial biomass and vitamin B12;
• study of the effect of supplements that intensify the development and accumulation of vitamin B12.

The advantage of dry preparations should be considered:

• increase in storage time;
• increased storage stability;
• less sensitive to temperature changes.

To disadvantages dry preparations applies to:

• decrease in the viability of microorganisms;
• the use of expensive protective media for dehydration;
• use of additional equipment for the dehydration process.

FREEZING DRYING (about it at the end of the page). In industry, the prevailing distribution for the production of dry starter cultures and dietary supplements has receivedfreeze dryers .During freeze drying, dehydration of the product occurs in the process of freezing in a rarefied atmosphere. In this case, the removal of moisture from the frozen product occurs at low temperatures.

This method of dehydration has several advantages:

• drying of thermolabile preparations;
• formation of a developed surface of a dry product;

and some disadvantages:

• the cost of a significant amount of heat;
• high cost per unit of product;
• possible damage to the product during thawing;
• expensive process equipment.

SPRAY DRYING. An alternative dehydration method is spray drying, carried out in a stream of hot drying agent, as a result of fine dispersion, a developed contact surface is formed, which contributes to a short-term stay of the product in contact with hot air.Spray drying is not used as a method of dehydrating substances containing live microorganisms.

Advantages of spray drying:

• the possibility of drying directly from the solution;
• developed droplet dispersion surface;
• intense heat and mass transfer;
• short duration of drying in a swirling heat agent flow;
• the maximum particle temperature in the high temperature zone does not exceed the wet bulb temperature;
• the possibility of drying heat-labile products.

Disadvantages of spray drying:

• decrease in the viability of bacteria;
• high specific consumption of the drying agent.

COMMERCIALIZATION. The main objective of the commercialization of this project is the creation of dry probiotic starter cultures and dietary supplements based on PKB and its symbioses with MKB.

The main objects of commercialization are:

- multivitamin complexes;
− dietary supplement;
− dry starter cultures enriched with vitamin B12.

Sourdough and dietary supplements have a number of advantages,which condition competitive advantages of this development:

• the raw material is whey, which is a by-product of production in the dairy industry, which has a low cost;
• the basis of the nutrient medium is whey containing the necessary set of nutrients, in this regard, the amount of added growth components is minimized;
• the composition of the starter cultures includes a high content of vitamin B12, as well as other vitamins;
• dry sourdough contains a large number of viable microorganisms.

The planned practical purpose of probiotic starter cultures enriched with vitamin B12 and dietary supplements includes:

− production of fermented milk products;
− production of beverages for functional purposes;
− application in the production of bakery products;
− use as direct application preparations;
- making cheese.

STUDY. At the first stage of the work, the composition of the growth components of the nutrient medium for the cultivation of Propionibacterium freudenreichii was optimized.It has been established that propionic acid bacteria and bifidobacteria belong to the actinomycete group of microorganisms. So for the quantitative accounting of these bacteria, identical media are used, as a result of which, for the accumulation of the biomass of propionic acid bacteria, a background medium based on whey was taken with the addition of growth components of yeast autolysate and hydrolyzed milk, followed by optimization.

Propionic acid bacteria are active producers of vitamin B12. It should be noted that the synthesis of the vitamin depends on the cultivation conditions. It is known that for the best synthesis of vitamin B12, the presence of Co 2+ ions in the nutrient medium is. Also, in some literary sources it is indicated that Co 2+ ions can be precursors of vitamin B12. However, in natural nutrient media, the cobalt content is minimal, so we also added Co 2+ ions to the background nutrient medium, which affect the biomass yield and the synthesis of vitamin B12.

Figure 1 shows that the optimal background nutrient medium at this stage for the accumulation of biomass Pr. freudenreichii is a medium of the following chemical composition: TS + 5% yeast autolysate + 5% hydrolyzed milk + CoCl2 (20 mg/l), since it allows bacteria to accumulate a significant amount of vitamin B12, in the amount of 15.4 µg/ml.

The amount of vitamin B12 was determined by the spectrophotometric method, and the biomass by weighing. Since temperature is an important factor for the cultivation of bacteria, therefore, at the next stage, we considered the effect of temperatures in the range from 27 to 31 °C on the studied bacteria Propionibacterium freudenreichii.

Figure 2 shows that the best cultivation temperature for Propionibacterium freudenreichii is 30°C, at which there is a significant accumulation of vitamin B12 - 22.911 µg/ml.

Drying modes were tested on a control medium. The background medium with the maximum accumulation of vitamin B12 and biomass was taken as a control.

Dehydration was carried out by spray drying. The data obtained are presented in table 1.

Table 1 - Indicators of dry and liquid starter cultures

Comparative analysis showed that dry sourdough is slightly inferior to liquid sourdough in terms of the presence of vitamin B12 and there was a slight decrease in CFU / CM 3

ON A NOTE

FREEZING (LYOPHILE) DRYING

In the example above, the so-called. spray drying. But it should be noted that freeze drying is widely used in practice. Various food products are perfectly preserved in this way: fruits, vegetables, dairy products, meat, fish, soups and cereals, mushrooms, seasonings. Sublimated products have the widest possibilities for use, both as ready-made instant products and as semi-finished products for further industrial processing (confectionery, food concentrate, meat and dairy, perfumery and other industries).

Concerning sublimation drying bacterial preparations, then in medicine and biotechnology they are often called preparations (sourdoughs, dietary supplements, bioconcentrates) lyophilic drying, i.e. lyophilized, because as a result, lyophilic (easily soluble) substances are obtained.

PHYSICAL FOUNDATIONS OF THE PROCESS

The process of freeze drying by its nature is the dehydration of a frozen material as a result of the transition of a substance (ice) from a solid to a gaseous state, bypassing the liquid phase. The term "freeze drying" is most often used in domestic literature and practice, however, it is not the only one. This process is also referred to as "molecular drying", based on the nature of the movement of steam in the pores of the product and in the drying chamber. In medicine and biotechnology, as noted above, it is called "lyophilization". In the foreign food industry, the term freeze-drying is often used.

The physical basis of the freeze drying process is clearly illustrated phase balance diagram for water in coordinates vapor pressure - temperature. On the state diagram, at the intersection of the boundary curves, there is a triple point at which water can exist simultaneously in all three phases: ice - water - steam. If heat is supplied to the frozen material at a pressure below the pressure of the triple point of water (4.58 mmHg or 611.73 Pa), a sublimation (sublimation) process will take place.

ABOUT THE DRYER

Vacuum drying takes place in a hermetically sealed apparatus, and heat transfer by convection is low. Therefore, in order to maintain a significant drying rate in vacuum, the heat required to evaporate the liquid is supplied to the material to be dried by conduction from a heated surface (contact drying) or by radiation from heated screens (infrared drying). Thus, vacuum drying according to the method of supplying heat to the material is contact drying or drying with infrared rays under vacuum.

WHAT IT IS FREEZING FOR

Freezing ensures the fixation of the most important properties of the product, and the subsequent sublimation of ice creates a porous structure. At the same time, sublimation dehydration involves mild heat treatment in vacuum and makes it possible to obtain a final moisture content of several percent. As a result, the quality of freeze-dried products is very high, they are easily rehydrated before further use.

However, despite the high quality of the resulting dry starters and the increase in their shelf life, they still lose a little in relation to their analogues obtained (canned) in liquid form.For example, take a look at figure 4 (the figure is taken from the description of the invention to the patent of the Russian Federation No. 2309982), which shows the change in the number of propionic acid bacteria cells in liquid, frozen and freeze-drying starter (CFU / cm3 fell from 12 orders to 10).

Fig.1. Change in the number of cells during freeze drying

Production of biomass in industrial conditions

The process of obtaining dry, liquid and frozen bacterial concentrates (starter cultures) is carried out in several stages using appropriate equipment: fermenters, separators, freezers and dryers.

1. Cultivation

Cultivation (growing) of microorganisms is carried out on a fermenter (Fig. 2)

Rice. 2. Fermenter "Bior-01", 100 l

fermenters or bioreactors, are chambers in which microorganisms are grown in a liquid or solid medium. The process that takes place in a fermenter is called fermentation.

2. Separation

The culture liquid obtained during fermentation is separated on a separator (Fig. 3).

Rice. 3. Separator

Separation(lat. separatio - separation) - these are various processes for separating mixed volumes of dissimilar particles, mixtures, liquids of different densities, emulsions, solid materials, suspensions, solid particles or droplets in a gas.

culture liquid is a liquid in which a culture of microorganisms is grown. In the culture fluid, the biomass can be in a heterogeneous form - biomass cells can form agglomerates.

At the first stage of the processing of the cultural liquid, the mass of the producer is separated from the liquid phase - separation. The liquid is also further processed if it contains metabolites of practical value.

The technological methods used to separate cells from the medium depend on the nature of the producer. For example, saccharomycetes (baker's yeast) have relatively large cells and are able to float, therefore, after thickening the biomass by flotation, they are separated on conventional drum vacuum filters. Subsequently, the biomass removed from the filter is subjected to pressing and a product with a high content of living cells with a high baking activity is obtained.

In practice, in the production of bacterial (probiotic) starters, the biomass is separated by centrifugation. The sedimentation of suspended particles occurs under the action of centrifugal force. After separation, 2 fractions are formed: biomass (solid) and culture liquid.

3. Preparation of biomass for drying (freezing)

Next, the biomass is mixed with a cryoprotective medium (cryoprotectors). Cryoprotectants protect viable microorganisms from the negative impact of the phase transition of water into ice during freezing.

Note: Cryopreservation is one of the most reliable methods for long-term preservation of microorganisms in an active form. With a general decrease in the temperature of the system (cryoanabiosis), the activity of enzymes is suppressed, metabolism, development, growth slows down, and the sensitivity of cells to a lack of nutrients is weakened. The inhibition of vital activity during the freezing of living organisms is caused by the partial transformation of water into ice.

Ice formation is associated with the extraction of water from the protoplasm of cells, as well as a decrease in the content of free water in the system. The freezing process negatively affects the structural components of cells, which can lead to their death. Therefore, a mandatory requirement in the implementation of this process is the presence of cryoprotective substances - cryoprotectors. They contribute to a decrease in the osmotic pressure inside the cells and thereby prevent the rupture of cell membranes during thawing and freezing.