LT3444B - Method for the preservation of milk sample for the determination it chemical characteristics, for example, fat content - Google Patents

Abstract

This invention is for the dairy industry.Purpose: to prolong the duration time of canned milk patterns, suitable for the research of chemical indexes, and also to save material expenses, electric power and labour hours.The canning method of a milk pattern plans milk compounding with kalium bichromate respectively in a proportion of 1,000:1, it is compounded till the preservative thaws, kept in a dark place.The new feature of the canning method is that, while compounding the milk with kalium bichromate, the 0.3-0.6 parts of bluestone are added to the compound.

Description

The present invention relates to the dairy industry, namely, to the preservation of milk samples for fat determination.

There are known methods of preserving milk samples based on mercury chloride (Kvapilik B., Suchanek S. Vliv conservace vzorku mleka na vysledky rozboru. Žibočisna vyroba - 1974-19 - C. 1) and a mixture of 1 part copper sulphate and 1 part by the antimicrobial action of sodium dihydrocitrate. (DD # 209102)

Milk samples preserved in the first way are suitable for testing for 15 days or more, but mercury chloride is very contaminating the environment after use, and this method of preservation, for example in the USA, is prohibited. In addition, mercury chloride accelerates the corrosion of metal parts in devices used for the examination of preserved samples. The second of the above methods allows the preservation of milk samples up to

10-14 days.

The technical solution for the method of preserving milk samples using potassium bichromate (TOCT 13928 MOJIOKO H CJIHBKH 3aroTOBJiiieMbie. Δτδορ προδ h nojroTOBKa hx k ηοπειτηηηιο.). To 100 cm ^{3 of} milk add 1 cm ^{J of} 10% potassium bichromate (K ₂ C ₂ O ₇ ) solution or 0,1 g of crystalline solution. The milk is stirred until the preservative is dissolved and stored in the dark at 5 to 20 ° C, stirring periodically for up to 10 days.

In this way, not only a certain quantity of milk is immediately preserved. In practice, this often involves preserving the milk samples of individual suppliers, averaging a preserved milk sample over a decade. The fat content of this sample, which corresponds to the fat content of individual deliveries, is determined and reported to the suppliers.

However, this method of preservation has some disadvantages:

. K ₂ Cr ₂ O ₇ does not always preserve friable milk samples for 10 days, especially at 15-20 ° C;

. In summer, when the ambient temperature rises to 25-30 ° C and above, canned milk samples should be stored in special cooler rooms up to 20 ° C or in refrigerators. Their installation or purchase as well as electricity require additional funds.

The object of the present invention is to extend the shelf life of canned milk samples suitable for determination of chemical parameters, as well as to save material costs, electricity and working time.

The object of the present invention is that by mixing milk with potassium bichromate in a known ratio of 1000: 1, mixing until the preservative is dissolved and storing in a dark place, the present invention proposes to add 0.3-0.6 parts of copper sulfate during mixing.

The addition of 0.3 to 0.6 parts of copper sulphate (CuSO ₄ ) extends the preservation of preserved milk samples suitable for the determination of chemical parameters, namely fat content, up to (19 ± 3) days. Therefore, where the milk fat content of the individual suppliers is determined on the basis of an average milk sample, the method of the present invention allows this test to be performed 2 times per month instead of 3 times according to the prototype method. This would save on chemical reagents, electricity as well as lab work.

The addition of 0.3 to 0.6 parts of CuSO ₄ also allows the sample storage temperature to be increased to 30 ° C. This allows you to dispense with special cool rooms or refrigeration units, even in the hot season (summer), which also simplifies the way of preservation and saves material resources and electricity.

Addition of less than 0.3 parts of CuSO ₄ (1000 parts of milk and 1 part of K ₂ Cr ₂ O ₇ ), for example 0.2 parts, does not provide the preservative with the required antimicrobial activity and the milk samples to be maintained for up to {19 ± 3) days (cf. Test Act).

Adding more than 0.6 parts of CuSO ₄ , for example 0.7 parts, is not appropriate, since the addition of 0.6 parts ensures sufficient retention of the samples, while increasing the amount only adds additional reagent wastage (see test report).

Here are concrete examples of how the milk can be preserved.

Example No. 1

Into a clean container, preferably in a glass, add 1000 g of milk with a fat content of 4.10% determined by the Gerber method (LST 1275-92. Milk and milk products - Methods for the determination of fat). It contains preservatives, ie 1 g K ₂ Cr ₂ O ₇ and 0,3 g CuSO ₄ . The mixture is then stirred until the preservative has dissolved. The container is closed and placed in a dark place at 20 ° C. During storage, the milk is stirred every 2 days. The milk fat content of the milk sample is 22 days. After storage, the fat content of the canned milk sample was 4.05%. This corresponds to the fat content of fresh milk, since the difference does not exceed the accuracy of the method (± 0,05%).

Example No. 2

Add 3,83% fat milk to the clean flask. The fat content was determined with a Milko-tester. To the milk is added 1 g K ₂ Cr ₂ O ₇ and 0,6 g CuSO ₄ . After stirring to dissolve the preservative, stopper the flask and place it in the dark at 30 ° C. The milk is stirred every other day during storage. The milk retention time of a milk sample suitable for fat content is 19 days. The retained specimen had a fat content of 3.85%. The difference in fat content between fresh and canned milk did not exceed the precision of the method, ie the results did not differ by more than 0,05%.

The proposed method of preserving milk samples has the following advantages over the prototype and other analogs:

1. extends the shelf life of preserved milk samples suitable for the determination of chemical parameters, namely up to (19 ± 3) days (compared to the second analogue and prototype);

2. allows efficient preservation of milk samples at temperatures up to 30 ° C and prototype only up to 20 ° C. This eliminates the need to use chilling agents;

3. Compared with the first analogue, the proposed method is less environmentally hazardous and does not promote corrosion of metal parts of the devices used for the examination of the fat content of the preserved samples.

4. The proposed method also produces a social effect in comparison with the prototype and the second analogue in the case of the preservation of individual samples of milk delivered by individual suppliers, forming an average preserved milk sample. The proposed method allows at least 1.6 times less fat analysis compared to the prototype, and 0.9 to 1.5 times less than the second. The reduction in the number of analyzes facilitates the work of the laboratory technician, especially when using Gerber's common acidic method, where the technician is exposed to concentrated sulfuric acid.

Example No. 3

We pour 300 g of milk with a fat content of 3.80% as determined by the Gerber method into a clean glass container. 0.3 g of K ₂ Cr ₂ O ₇ and 0.06 g of CuSO _{4 are added} thereto. The amounts of milk, K ₂ Cr ₂ O ₇ and CuSO ₄ agree as 1000: 1: 0.2. Stir the milk well until the preservative has dissolved, then close the container and store in a dark place at 30 ° C. During storage, the milk sample is stirred every other day. The milk retention time of a milk sample suitable for fat content is 12 days. The sample is then acidified and its fat determination analysis becomes inaccurate. This preservation time of the preserved milk sample is not sufficient when an average preserved milk sample is prepared and its fat content is determined less frequently than in the prototype, for example, after 15 days.

Example No. 4 Add 300 g of 3.8% fat milk to a clean glass bottle and add 0.3 g K ₂ Cr ₂ O ₇ and 0.24 g CuSO ₄ . The amounts of milk, K ₂ Cr ₂ O ₇ and CuSO ₄ agree as 1000: 1: 0.8. When the preservative has dissolved, stopper the bottle and place it in a dark place at 20 ° C. The milk is stirred every other day during storage. Milk retention time until fermentation - 26 days. By heating the milk to 40 ° C prior to fat analysis, it is difficult to dissolve the settled fat layer to obtain a homogeneous sample, which results in an inaccurate determination of the fat content of the milk sample that has been stored for 24 days at only 3.73%. This is too large a difference from the original fat content because it exceeds the accuracy (± 0.05%).

method

Claims (1)

DEFINITION OF INVENTION A method of preserving a milk sample by determining its chemical characteristics, e.g. -0.6 parts copper sulphate per 1000 parts milk.