Acidity as an indicator of the quality of dough and finished bread

[ACIDITY as an indicator of quality 1/3]

ACIDITY as an indicator of quality 1/3

Just about acidity. In our favorite bakery, the ingredients, the process of baking and the final result, i.e. the finished bread, have their own acidity. If we know what it should be in each specific case, we can judge the quality of the ingredients, how this or that process proceeded, and even accurately establish the readiness of the leaven, dough or the same dough.
Acidity is not only the most objective indicator of readiness, but also quality, because the composition and amount of acids affects the course of the most important processes occurring in raw materials or bread mass, and therefore also affects the taste of finished products.
Acidity is distinguished into true (or active) and total (or titrated).
The question of what more characterizes the sour taste of bread, the concentration of hydrogen ions, i.e., the true acid, or the acid determined by titration, remains unresolved. W. Ostwald proved how confused the relationship between the definition of sour taste and the definition of acidity in such a food product as bread. In addition, true and total acidity should not at all be in direct connection with each other.

True acidity. This is the concentration of hydrogen ions in the medium, characterized by the pH value ("pH" or "PIH"). Measured on a scale from 1 to 14. If the pH is less than 7 - the reaction of the medium is acidic, more than 7 - the medium is alkaline.
To express the concentration, its negative logarithm is conventionally used, which is denoted by pH. By the way, the term pH was first introduced by the founder of modern pH metering, the Danish chemist Søren Peder Lauritz Sørensen. PH determination is best done with a potentiometer. The device is based on measuring the electromotive force, which depends on the concentration of hydrogen ions at an electrode immersed in a test solution.
Due to the presence of a large amount of so-called buffer substances in flour, i.e., compounds or elements that contribute to maintaining an optimal acid-base balance, previously, when monitoring the entire bread technological process, pH values ​​were not assigned and not monitored. Now is not the case. All technologists believe that this indicator is closely related to the quality of the bread, that it helps to confidently control and even manage the fermentation of the dough.
Dorner H., Stephan H. went further, including:
- established the relationship between the pH of the dough and the elasticity of the crumb of bread;
- noted that in wheat dough the pH is higher than in ready-made bread, which is not observed in rye dough and bread, since the pH changes insignificantly during the preparation of sour dough and baking bread from it;
- determined that in the process of staling of wheat and rye bread, the pH of the crumb and crust gradually decreases (“Uber pH-Untersuchungen an Teigen und Broten” in “Brot u Gebäck” nº 8, 1956).
Total acidity. It is characterized by the total content of acids and acid-reacting substances. It is expressed in various units, including degrees of acidity and percentage of lactic acid.
When determining acid in bread by titration, only bread crumb is “tortured”. However, its even stirring is difficult: it takes too long for the added caustic soda solution to penetrate the crumb mixed in water. Therefore, a small amount of acid-free acetone is added to the test substance (bread or sourdough).
If earlier, earlier, it was technically much easier to determine the total acidity than the true one and did it in laboratory conditions, now the opposite is true. With the help of not ?! an expensive pH meter, any baker, and what a baker, anyone in their kitchen can easily and in just 20-30 seconds set the pH of the flour, water, yeast, any pre-ferment or ready-made bread at hand
In Soviet times, they wrote and were right that the most promising method for determining acidity is the method of measuring the pH value. An instruction was approved for determining the relationship between titratable and active acidity, a brief description of the pH meter, a method for determining active acidity on the device and, which is especially attractive, a table of the relationship between the values ​​of titratable and active acidity. They say that such a table was first made as an attachment to a pH meter produced by the Gomel Plant of Measuring Instruments. The determination of the titratable acidity of the test samples was carried out according to the nomograms as follows - if the active acidity was determined, for example, "Baton sliced" from wheat flour of the 1st grade weighing 0.4 kg, the value of which was 5.63 units. pH, then according to the table attached to the instructions, the titratable acidity was 2.8º.

At one time, I so wanted to find this table! Judge for yourself - having a pH toy on my hands and knowing the correct titrated acidity at all stages of making bread in accordance with GOST, I could easily, and playfully, convert the true acidity values ​​into total and vice versa, and so control the entire baking process that even it was breathtaking.
Material taken from the site 🔗, for which I express my gratitude to the Author.

[Flour]

Flour... The acidity of flour is due to the presence in it of organic acids, protein substances, acid phosphates, etc. During its storage such biochemical processes take place as a result of which the acidity of flour slightly increases compared to the acidity of grain, and occurs due to the formation of free fatty acids and acid salts. This joyous increase influences the gluten of wheat flour so that the latter becomes stronger, its elasticity increases, and its elasticity decreases. Such changes are especially noticeable when storing weak flour, which acquires the properties of medium flour in strength. In flour of high yields, the increase in acidity is more noticeable than in flour of low yields, however, in general, the acidity increases insignificantly over 15-25 days of storage, more precisely by fractions of a degree.

Do not forget that under unfavorable storage conditions, flour acquires an unpleasant, bitter-pungent taste and acidity has nothing to do with it.

According to titratable acidity, good flour in Soviet sources is divided into two categories. The first includes flour, the acidity of which for the premium grade is no more than 3º, the 1st grade - no more than 3.5º, and the 2nd grade - no more than 4.5º and rye wallpaper flour 5º. If flour has a higher acidity, it is classified in the second category. Have you noticed that the acidity of flour is to some extent related to its yield, that is, the greater the yield of flour, the higher its acidity?
In terms of active acidity, good quality flour has a pH ranging from 6 to 6.3, and the pH of healthy flour should be at least 5.95.
It is clear that a test of flour for acidity is like a test of its quality factor.
But why can acidity be overestimated or underestimated?
The acidity is too high. I will give two reasons:
- if the flour is wetter than usual (recall that for normal wheat this figure ranges between 14.5 and 15%);
- if undesirable work of unwanted microorganisms, mainly molds, is noticed in flour with high humidity.

To be fair, I will clarify that an increase in the acidity of flour is not always accompanied by a deterioration in its baking ability.

Acidity is underestimated.If the pH value of flour falls below 6, then this may indicate that the flour is spoiled or that the flour contains chemicals from the category of strong oxidants, which are usually used for the so-called bleaching of flour. These substances are added in pursuit of two goals - to bleach flour and improve its baking, or rather plastic, qualities.
On the one hand, when the flour is bleached, the pigments turn into colorless substances and it seems that the flour has increased its grade. Bleaches work in such a way that they paralyze the enzymes. As a result, the bread looks very white, as if it were baked from other flour of higher quality.
On the other hand, bleaching modifies the gluten structure and thus improves the plasticity of the flour. In both cases, we are dealing with phenomena associated with oxidation, very similar to what happens to flour during its aging. But let's not forget that artificial bleaching of flour is a process that can lead to certain toxic consequences. For example, as an unwanted bonus, a baker may develop eczema on his hands, and the nutritional properties of bread may change, and not for the better. And this list, of course, can be continued. Nevertheless, in order to improve the plastic qualities of flour, the right bakers recommend using ascorbic acid as an improver.
Flour bleaching has been practiced for a long time. Already in 1833, in order to control the quality of the flour produced, Similamètr de LEGRIP had to allow the names of those manufacturers who allowed themselves to engage in such fraud to be made public. But, in spite of everything, in the north of France, in Belgium and especially in England, they continued their dirty work of bleaching, especially if the grain harvest was bad or spoiled. Alum, sulphates of aluminum, potassium, copper and other chemical excesses were used. M. Vidal in his book "Tratado practico de Panadería, Pastelería y Confitería" published by him in 1952 in Argentina also mentions zinc sulfate, magnesium carbonate, sodium borate and copper sulfate (well, where, I ask you, the potassium salt of hydrocyanic acid , so to speak ?!). Today, in many countries, including Spain, flour bleaching is prohibited. Therefore, when I find a chilling warning on the Spanish Internet spaces to categorically not use bleached flour in one or another recipe, it makes me laugh.

When baking bread, it is preferable to work not with freshly ground flour, for which the pH value should be in the region of 6-6.2, but, as a rule, stored for 30 days. The changes that take place in the flour during its aging are associated to a certain extent with the oxidation process; during the specified time, the flour seems to bleach a little and, which is especially important, makes the mass stronger when mixed.

If you are confronted with the fact of using malted flour or flour obtained during the processing of flour from frosty grains, as well as grains affected by a bug, in baking, you need to increase the acidity and achieve a pH value of 4.5-5.0.

Flour stored in a vacuum package does not undergo such oxidation processes, and it does not improve or deteriorate in quality over time.

The fact that there are different varieties of flour is understandable. But it turns out (and this is just the topic) that from different varieties of her beloved one can isolate various strains of lactic acid bacteria that have more or less acid formation energy. So in the 60s, a strain of lactic acid bacteria E-1 was isolated from the flour of the Simferopol bakery and sour ferments, which, when added, reached the required acidity in 6-8 hours, against the previous 14-18 hours. When added to the second grade wheat flour sourdough, acidity of 12-14º was reached in 7-8 hours versus 12 hours for Delbrück bacteria. When added to a rye starter, acidity at 12º-14º increased in 4-6 hours.

[Compressed yeast.]

Here are the optimal pH values ​​for some crops that can be used in one form or another in baking:



Compressed yeast. Along with oxygen, the acidity of the environment has a huge positive effect on the multiplication of yeast, more precisely on the rate of reproduction. This optimum lies in a relatively wide range of pH from 3.8 to 5.6 and it is with this indicator that their resistance in an acidic environment improves. Yeast can withstand pH 3-3.5, but the growth rate slows down. It should also be taken into account that at low pH values ​​even slight fluctuations in its value are especially dangerous, since this leads to the cessation of crop growth.
When yeast is stored at low pH, molasses pigments are assimilated, resulting in an excessively brown color of the yeast. This does not mean that the yeast has deteriorated, but they also did not add beauty to themselves.

Malt, malt extracts. Most often, these, as they are also called "natural improvers", are divided into 3 groups, each of which has its own pH. The first includes "Standard" with a pH of 5.2-6.2, the second "Rye" with a pH of 4.2 - 5.2, and the third "Dark" with a pH of 3.7-4.5.
In the process of germination and languishing (fermentation) of rye malt, a noticeable increase in the content of acids and acid-reacting substances occurs in it. It is known that high acidity has a positive effect on the formation of malt color during drying. The acidity of the malt affects the acidity index of bread only slightly.

Milk. The acidity of milk and dairy products (excluding butter) is expressed in Turner degrees. Turner's degree indicates the number of milliliters 0.1 N. sodium hydroxide solution (or potassium hydroxide) required to neutralize 100 ml or 100 g of the product. True acidity of milk pH 6.5-6.8, total acidity 15.99-20.99 ° T. If the milk falls below pH 6.5, this may indicate that the animal is infected. If it drops to pH 4.4, the animal is seriously ill.

Milk serum. The acids contained in it dissolve part of the gluten proteins of the flour and thus somewhat worsen the structural and mechanical properties of the wheat dough. Naturally, this effect is undesirable and must be avoided. Therefore, when bread is cooked with a thick sourdough, then to prevent excessive accumulation of acids in it, i.e., in the leaven, whey is added only when kneading the dough, so as not to inhibit the fermentative flora of the leaven by the whey microflora. When preparing bread with liquid leaven, whey should be added instead of water to the brew intended for feeding the leaven. The high initial brewing temperature (+65 ... 68 ° C) pasteurizes the whey and oppresses its microflora. If the liquid sourdough is prepared without the addition of tea leaves, whey is used to prepare the feed instead of part of the water. In the summertime, in order to avoid peroxidation, whey should be added not to the leaven, but to the dough.

Boda... A pH value of 7 for water is considered normal. The most "acidic" sample of water on the planet, according to the Guinness Book of Records, was taken in 1990-1991 from the Peachmond Shack on Aironmaynt (California, USA). Its pH was 3.6.
Typically, water from natural sources has a pH of 7 to 9, river or lake water - from 7.5 to 8.5, sea water - 8.3 (with minor changes) and ocean water - 8.4.

It is worth recalling that pH is calculated as the decimal logarithm of the activity of hydrogen ions taken with the opposite sign. Therefore, water, for example, with a pH of 5 is ten times "stronger" than water with a pH of 6, and water with a pH of 4 is 100 times "stronger", that is, more acidic than pH 6, etc.

[Improvers]

Improvers... Rarely, but there are situations when the baker is forced to use only water with an increased percentage of alkalinity. In this case, he has no choice but to resort to the use of pH regulators permitted by law. The first thing that comes to mind is any pre-enzyme or food acid.
Taking this opportunity, I would like to remind you of some food acids that can be discussed here:

Acetic acid. A colorless liquid with a pungent sour taste. In industry, acetic acid is obtained from ethyl alcohol during its acetic acid fermentation or in wood-chemical production during the hydrolysis of wood.

Lactic acid (food grade) is an aqueous solution of a mixture of lactic acid and its anhydrides. It dissolves well in water, alcohol and ether in any ratio. The taste is sour, odorless and colorless. It is produced in industry by fermentation of sugar by lactic acid bacteria. The raw material is sugar beet syrup or starchy products - corn, potatoes.

Wine acid should be in the form of colorless crystals or powder, taste sharply sour. The raw material for its production is wine-making waste.

Lemon acid represents solid crystals of white or colorless. The taste is purely sour, pleasant. Citric acid is obtained industrially by fermenting sugar with the Aspergillus nieger fungus. For its production, sugar beet molasses and sugar crumbs are used.

Food acids have a significant effect on the properties of the dough. In an acidic environment, proteins swell better, gluten becomes more elastic and less elastic, the activity of enzymes (amylolytic and proteolytic) decreases. Acids have a significant impact on the taste and aroma of bread, its volume and crumb texture.
The use of acids in the accelerated preparation of dough is very important. In this case, they are added in such an amount that the dough after kneading has an acidity characteristic of a ripened semi-finished product. Many of the food acids are found in the natural flavors and aromas of bread.

I will give a list of acidifiers that are allowed in Spain for use in baking bread. They are added to the mass to correct the acidity and to minimize the chances of the bacilo mesentérico microorganisms that are responsible for the development of potato bread disease. And this disease successfully proceeds primarily where it is not only warm and humid enough, but also, most importantly, not acidic enough:

I recommend that you read this material carefully again!
It is about how to increase the acidity of the dough to improve the baking properties of the ingredients and get quality bread.

[Admin]

Admin, but how to determine the acidity of the dough (dough) at home?