Inhibitors in Dairy Products

Incubator Application

Hettich Incubator Application

The use of HettCube incubators and cooled incubators to detect the presence of inhibitors in milk and dairy products for infants

Inhibitors prevent the growth of micro-organisms or destroy them, and are present in veterinary products and other products. Their use is subject to statutory regulation. Milk and dairy products, therefore, have to be tested for the presence of inhibitors.


The method specified under the German Lebensmittel- und futtermittelgesetz (LfGB) [food and feedstuff Act] involves a test system with the test organism Bacillus stearo-thermophilus and agar medium. This micro-organism is particularly sensitive to penicillin. Assay discs of filter paper are immersed in the sample under test and then laid on the agar. If the sample contains an inhibitor then a clear, transparent ring will form around the disc because of the inhibition of growth.


Bulk milk must be tested every two weeks under § 2 of the Milchgüte-Verordnung [Milk Quality Regulations] for the presence of inhibitors. one aim is to protect consumers, who may be allergic to certain antibiotics. furthermore, the excessive use of antibiotics may lead to an increased resistance to their action. A further important reason for testing is that the presence of inhibitors can adversely affect the production of fermented dairy products. fermentation may be stopped and complete failure of the production process may result.

Incubation conditions according to the analytical method given in § 64 LFGB *

*Amtliche Sammlung von Untersuchungsverfahren nach § 64 LfGB (vormals § 35 LMBG), Band I (L), L 01.00-6: nachweis von hemmstoffen in Milch; Agar-diffusions-Verfahren (Blättchentest).1997[official collection of test methods in accordance with § 64 of the LfGB (previously § 35 of the LMBG), Vol. I (L) L 01.00-6: demonstration of inhibitors in milk; the agar diffusion test (assay disc test). 1997]

Hettich products are designed to help you achieve optimal results for your application and are built to perform to the specifications outlined in the operators manual. For application-specific information and settings, please refer to your organization’s standard operating procedure. As always, our Hettich representatives are here to help determine which Hettich products and accessories best fit your laboratory requirements.

HettCube Incubators

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HettCube series of incubators


Dairy Inhibitors Application Note

This application note provides information on specific application methods and the use of Hettich products. (more…) read more...

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Hettich HettCube incubators product sheet

HettCube Product Sheet

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