Rapid determination of microbiological activity - by adding DMSO to the foodstuff, cosmetic or pharmaceutical sample and analysing the di:methyl:sulphide produced in the gas phase

摘要

Process comprises mixing a sample in a closed container under (an)aerobic conditions, with dimethyl sulphoxide (DMSO) and then analysing the gas phase above the sample for its dimethyl sulphide (DMS) content. 0.1-2g Homogenised foodstuff are pref. mixed in a sample container with 1ml 5% DMSO soln. in water and the container sealed and shaken and kept under aerobic conditions or evacuated twice and gassed with N2 and incubated at 30 deg.C. 0.1-1.0 (esp. 0.1-0.5) ml of the gas phase are removed from the container and analysed by gas chromatography. The samples are incubated for 1-8 (esp. 2-3) hrs. at 30 deg.C. The gas chromatography is carried out with a column at least 2m long filled with Porapak R or a 10m glass capilliary column HP-5 each contg. a flame ionisation detector. The columns are kept at 160-180 or 40 deg.C and the detector and injector at 220 or 200 deg.C. The foodstuffs are minced meat, homogenised meat prods., starch contg. foodstuffs, foodstuffs based on milk or plant prods. such as spices. USE/ADVANTAGE - The process enables the microbiological activity in foodstuffs (esp. meat and meat prods.), pharmaceuticals, cosmetics and cell-free body liqs. to be rapidly determined. Satisfactory results are obtd. after incubating the samples for 2-3 hrs. under aerobic or anaerobic conditions, although the anaerobic conditions give a 40% higher DMSO rate of reduction and thus allow for greater accuracy which is esp. important in the case of foodstuffs where germ counts must be low. Aerobic conditions are preferred in samples in which germ counts are high