Compact Dry – An easy test method for counting microorganisms in the production environment
Microbiological tests for cleaning and hygiene control detect general residues of foods on insufficient cleaned surfaces in the production environment. These residues of nutrients are the basis for growth of microorganisms.
Colony counting in foods or on surfaces can be done using the ready-to-use Compact Dry plates which are available for 13 different parameters of analysis. General method base of examinations with Compact Dry plates is the cultivation of microorganisms on standard nutrient media. The test principle is based on specific chromogenic substrates which are converted into colored products by the metabolism of microorganisms. Beside examination of diluted food samples, they are also suited for swab samples from surfaces or incubation of membrane filter samples from liquids.
Compact Dry is a ready-to-use test method which helps to reduce the time needed to perform microbial testing. Therefore, it allows maximum productivity by increasing efficiency. The plates can be used to test raw materials as well as finished products like food, beverages and cosmetics. In combination with a wet swab sampling system such as Promedia ST-25 (Art. No. Z0302, available from R-Biopharm), Compact Dry plates can also be used for surface monitoring especially for areas which are difficult to reach.
Compact Dry is an easy-to-read results test method. Place 1ml of sample (liquid food or homogenized/diluted solid food) onto the plate and wait until the liquid spread over the whole plate by itself. Incubate the plates at the temperature specified in the package inserts. The grown colonies are pigmented with different colors, developed by chromogenic substrates and redox indicators. The type of bacteria is identified by its color. For further investigation single colonies can be easily selected and picked from the plate surface.
Compact Dry is also an easy-to-store test method. The plates can be kept at room temperature for up to 24 months. Therefore samples can be applied to the plates directly on-side. The firmly closing lid allows the safe transport of the Compact Dry plates. The plates can be used over an incubation temperature range of 20 – 42 °C. The rigid structure of the plates enables easy, slip-proof stacking in the incubator and prevents leakage of sampling material. This saves space and keeps the incubator neatly.
Additionally membrane filters can be tested using Compact Dry plates. Pipette 1ml of sterile water (or physiological sodium chloride solution; for example RIDA® NaCl, Art. No. Z0301) into the middle of the Compact Dry plate. Filter 100 ml water or any other liquid using an ordinary sterile membrane filter (e.g. Ø 47 mm, 0.45 μm pore size) for microbiological analysis. Place the filter on the moisturized nutrient pad with trap side up. Colonies will grow on the filter.