Tests of milk composition and quality

Inhibiting substance analysis

Delvotest SP-NT test is a standard wide-range diffusion test for determination of inhibiting substances in the milk. The method is based on the fact that proliferation of Geobacillus stearothermophilus var. calidolactis spores that are sensitive to antibiotics and sulphamides leads to the formation of acid that changes the colour of the medium from violet to yellow. This method allows detection of penicillin of more than 4 µg/kg and sulphamides as well as other content of antibiotics specified by the company manufacturer. Delvotest SP-NT sensitivity to antibiotics is provided by the manufacturer in Technical Bulletin issued on 26 January 2016.

Identification of antimicrobial substances

In carrying out tests of raw cow’s milk for safety and quality monitoring and control and detection of inhibiting substances through the microbiological method, Delvotest, from 02.05.2019 antimicrobial substances are identified in raw milk samples through a modified immunoenzyme analysis method by using InfiniPlex test (504MET26:2019, issue 1, approved on 02.05.2019).

Antimicrobial substances are medicinal preparations, such as antibiotics, anti-inflammatory substances, anthelmintics, toxins and other residues inhibiting the growth of micro-organisms. Immunoenzyme test with chemiluminescence by using automated biolust technology is based on the competition of antimicrobial substance with antibodies adsorbed into separate areas of biolust. The method is qualitative, test results are expressed respectively: no residues of antimicrobial substances have been detected or one or several specific antimicrobial substances have been identified. List of antimicrobial substances determined through InfiniPlex test for milk was approved by manufacturer of the test – Randox Laboratories Ltd (United Kingdom) on 17.04.2019.

Test of milk freezing point

Test of milk freezing point is carried out with Lactoscope FTIR analysers. This method for determination of milk freezing point is assigned to the sorting method and is used to select the samples with suspected presence of side water, i.e. the freezing temperature is above minus 515 moC. The exact freezing point of milk samples is determined by analysing the selected samples with thermistor cryoscope method according to LST EN ISO 5764:2009.

Milk fatty acid analysis

Milk fats are formed from two sources. Approximately 50% of bovine milk fats are synthesized from feed, so by changing feeds and creating optimal conditions for the activity of rumen microorganisms, it is possible to alter the composition of milk fats.
Results of research conducted by scientists from the Veterinary Academy of the Lithuanian University of Health Sciences, related to the impact of feeding on the composition of milk fats, showed that the milk from pasture-grazed cows was more valuable than that of cows fed solely with feed mixtures, as it contained more polyunsaturated fatty acids essential for the human body.

As doctors claim, these acids are crucial for the prevention of cardiovascular diseases, inhibit the development of atherosclerosis, suppress inflammatory processes and diabetes.

Milk fats consist of more than 400 different fatty acids. The majority is composed of saturated fatty acids (65-70%). Monounsaturated fatty acids account for 27-33%, primarily oleic acid. Polyunsaturated fatty acids make up 3.5-5%, and milk fats are relatively rich in short-chain saturated fatty acids (10%).

The laboratory identifies these important groups of fatty acids:

• Saturated Fatty Acids (SFA)
• Unsaturated Fatty Acids (UFA)
• Monounsaturated Fatty Acids (MUFA)
• Polyunsaturated Fatty Acids (PUFA)

The analysis includes categories of fatty acids: de novo, mixed origin and pre-formed acids.

You can order the analysis along with a commercial milk composition test. Just write + fatty acids (FA) on the invoice or add an additional request.
For those with a contract, the cost of the milk composition and fatty acid analysis is only €1.69 excluding VAT (€2.05 including VAT). For those without a contract, the cost is only €2.43 excluding VAT (€2.94 including VAT).