Density of milk, its specific heat capacity and other physical properties

Density of milk depending on temperature

The density of whole milk does not depend on the month of milking of cows and goats. During long-term storage, the density of milk changes .
It was found that after 10 weeks of storage of goat milk, its density decreased from 1032 to 1030 kg/m3, and as a result of 20 weeks of storage, the density of milk increased to 1033 kg/m3. This pattern is caused by changes in the content of solids and gases in milk during storage. Gases present in milk have a noticeable effect on the density of the milk. As the pressure on the milk decreases and the duration of its exposure decreases, the gas content in the milk decreases, therefore the density of the milk increases.

Sterilization, pasteurization and homogenization do not affect the density of milk. However, if the pressure is less than 20 atm, the density of the milk increases noticeably during homogenization.

Experimental data indicate that as the fat content of milk increases, the density of the milk decreases . A relationship has been established between the density (hydrometer degrees) of diluted milk ρр and the proportion of water added to it D:

The temperature (in Kelvin) at which diluted milk has its maximum density can be determined by the formula:

Density of milk (in kg/m3) depending on temperature (at T=274...283 K) and dry matter content (n=11.5...16%) or fat-free dry matter (TSV=8.2...10.2% ) is expressed by the following formulas:

With an increase in the content of nonfat solids (SFS) in milk, its density increases.

What happens if you add salt to milk?

1) Salt will remain dry for a long time if you put some rice grains in the salt shaker. 2) If you add a pinch of salt to milk that has burnt during boiling, its taste will noticeably improve. 3) A pinch of salt added to milk protects it from rapid souring.

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Density of milk depending on fat content

The table shows formulas for calculating the density of milk depending on the fat content at different temperatures. Milk density values ​​are indicated at temperatures from 293 to 353 K (20 to 80 °C).

The nonfat solids (SFS) content of milk has a more significant effect on milk density than the fat content. This is determined by the fact that the density of WWS (about 1600 kg/m3) differs more from the specific gravity of water than the density of fat (930 kg/m3) at T = 288 K.

The table shows formulas for determining the density of milk depending on the content of skim solids at a temperature of 20...30 °C. Milk density values ​​are indicated with a content of nonfat solids from 8.6 to 9.1% and a fat content of 3...4%. It should be noted that as the temperature of milk increases, its density decreases .

Note: Temperature in the formulas is entered in degrees Kelvin!

Is it possible to increase the indicators

They can be increased by observing the regime for keeping animals. Cows should be examined regularly by a veterinarian. It is necessary to ensure that animals do not suffer from mastitis or diseases of the gastrointestinal tract. Be sure to monitor calving cows.

Milk from sick animals is checked additionally; it is usually discarded and not sold or processed.

Pedigree livestock is capable of producing a high-quality product. Dairy animals provide an increased amount of protein and minerals in milk compared to other types of cattle. The feed requires mineral supplements and vitamins. Animals are provided with high-quality hay, vegetables, roughage to improve digestion in winter, and are grazed in summer. Careful selection of pasture affects the quality of the product.

Regular cleaning of the barn, changing bedding, treating drinking bowls and feeders prevent the development of dangerous diseases in cows.

Expert opinion

Zarechny Maxim Valerievich

Agronomist with 12 years of experience. Our best country expert.

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Important to remember! After calving, during the first days the cow produces colostrum, which is necessary for the calf, then milk with a high protein content.

The complex of these measures allows you to increase the amount of protein, mineral salts, and therefore the quality and density of the product.

It is necessary to ensure that water does not enter the product during milking and storage of products. Immediately after milking, the indicator will be higher, since milk fat is still evenly distributed in the product. After storage, when it rises to the surface, the density indicator will decrease.

Specific heat capacity of milk depending on temperature

The table shows the specific heat capacity of milk with a fat content of 3.2% (whole milk). The heat capacity values ​​of milk are located depending on the temperature in the range from 5.6 to 69.79°C. The table clearly shows that with increasing temperature, the heat capacity of milk increases .

How many grams of mayonnaise are in a tablespoon?

1 tablespoon holds 45 grams of mayonnaise (heaped)

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Table

Specific heat capacity of milk depending on fat content at different temperatures

The specific heat capacity of milk of various fat contents is presented depending on temperature. The heat capacity values ​​of milk are indicated at fat content from 2.91 to 4.3% and at temperatures from 283 to 343 K (from 10 to 70 ° C). The specific heat capacity of milk increases with increasing temperature. Data on the heat capacity of milk may vary depending on the sample, since the heat capacity may be affected by different amounts of fat in the samples studied.

Measuring tables for various products

Measuring table of bulk products

Measuring table for liquid and paste products

How many milliliters of liquid are in a spoon or glass?

• How many ml in a tablespoon? 15 ml in a tablespoon = 3 teaspoons
• How many ml in a teaspoon? 5 ml in a teaspoon
• How many ml are in a dessert spoon? In a dessert spoon 10 ml = 2 teaspoons
• How many ml are in a faceted glass? In a faceted glass 200 ml
• How many ml are in a tea (thin) glass? 250 ml in a tea glass

Measuring table of berries, fruits, dried fruits

Measuring weight table for vegetables and other products

Freezing point of milk

The table shows the effect of the degree of dilution of milk with water on the freezing point. The degree of dilution of milk with water in the table is given in the range from 0 to 25%. According to the table, it can be seen that the freezing point of milk is only 0.5 degrees lower than the freezing point of water and does not decrease significantly when milk is diluted with water.

Physical properties of natural milk

The table shows the thermal and physical properties of milk depending on temperature, in the range from 0 to 90°C. The table shows that the density, heat capacity and thermal conductivity of natural milk weakly depend on its temperature. When milk is heated, its physical properties such as kinematic viscosity and Prandtl number undergo significant changes, which decrease their values ​​several times.

physical properties of milk are given :

• milk density, kg/m3;
• specific (mass) heat capacity, kJ/(kg deg);
• thermal conductivity coefficient, W/(m deg);
• kinematic viscosity, m2/s;
• Prandtl number of milk.

Chemical and physical properties of milk at 20°C

The table shows the chemical and physical properties of milk (average value and range of fluctuations).

properties of milk are given :

• acidity;
• buffer capacity for acid and alkali;
• redox potential, V;
• milk density, kg/m3;
• dynamic viscosity, Pa sec;
• surface tension, N/m;
• osmotic pressure, MPa;
• freezing temperature, °C;
• specific electrical conductivity, S/m;
• specific (mass) heat capacity, J/(kg deg);
• thermal conductivity coefficient, W/(m deg);
• thermal diffusivity coefficient, m2/s.

Thermal conductivity of milk

The table gives the thermal conductivity values ​​of milk in the dimension W/(m deg) depending on the fat content (from 1.6 to 4%), for temperatures of 293K (20°C) and 353K (80°C).

The data on the thermal conductivity of milk in the table indicate that with a fat content of 1.6...4%, the coefficient of thermal conductivity of milk weakly depends on the fat content in it.

Sources:

1. Thermophysical characteristics of food products. Directory. Ginzburg A.S. and others. Moscow, 1980. - 288 p.
2. Chubik I. A., Maslov A. M. Handbook on the thermophysical characteristics of food products and semi-finished products. M.: Food industry, 1970 - 184 p.
3. Gorbatova K.K. Chemistry and physics of milk: Textbook for universities. - St. Petersburg: GIORD, 2004. - 288 p.
4. Tsubanov A.G. Heat transfer: method. instructions for practical classes for students. - Minsk: BGATU, 2007. - 160 p.