ByL.-B. C r o o n , Astn'Rogstad, T L e t h andT.Kiutamo *Four quick-test methods (the Foodoil sensor, RAU-Test,Fritest' and Spot test) and two ordinary laboratory methods (the free fatty acids and GLC determination of triglycerid h e r s ) were compared to a standard method (column chromatographic determination of polar compounds). One hundred samples collected from fast food shop and restaurants were included in the investigation. The Foodoil sensor showed the highest correlation to the standardmethod(c.f.= 094).TheRAU-Test,Fritest'andSpottestwerealso wellcorrelated to thestandardmethod.1t waseasiertocompare thecolourof the reaction mixtures to the colour scale of the RAU-Test than to that of the Fritest'.The amount offreefattyacids were found tobeanunreliableindicatorofdeteriorated fryingfat.The triglyceridedimers couldnotbequantified, but assessment by visual comparison of the peak pattern in the chromatc gram corresponded well with the results of the standard method.

SUMMARYA food-poisoning outbreak caused byBacillus cereusoccurred in a Finnish industrial plant in January 1975. Eighteen of the 36 persons who ate a lunch including boiled rice, meat and vegetables became ill. The disease pattern was similar to previously reported short incubation timeB. cereusfood-poisonings associated with cooked rice. The median incubation time was two hours, the main symptoms being nausea, abdominal pain and vomiting. Rice and certain seasonings were the contaminated raw materials. Gas chromatographic fatty acid analysis of a bacterial cell was used as a diagnostic method as well as to identify a certain strain ofB. cereus.

A rapid gas chromatographic method for the determination of fatty acid compositions of Bacillus cereus and related bacteria is presented. By the use of a free fatty acid phase-coated glass capillary column, the complete separation of fatty acids, including the branched ones, was achieved. The method enables a more distinct differentiation of Bacillus species than can be obtained with packed columns.

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A method was developed for the detection of irradiation of chicken and chicken meat products. The method consists of the extraction of fat from chicken skin or a chicken meat product, separation of hydrocarbons with an alumina column and gas chromatography (GC) and GC-mass spectrometry analyses of the hydrocarbons 16 : 2, 16 : 3, 17 : 1 and 17 : 2 formed from oleic, linoleic and stearic acids during irradiation. These hydrocarbons were only detected in irradiated samples at doses of 5 and 10 kGy. The mean concentrations of the hydrocarbons were linearly related to the dose levels of irradiation in the case of chicken fat. The concentrations of two of the hydrocarbons (l6:2 and 17:l) gave the best correlation with dose. When a dose of 10 kGy was used, the concentrations of major degradation products were 15-50 mg/kg fat. The same relationship was not found in the case of chicken meat products because the amounts of hydrocarbons detected after irradiation with the same doses were similar. On the basis of this study it was clearly demonstrated that it is possible to judge analytically whether or not a chicken sample or a chicken meat product has been irradiated at doses of 5 or 10 kGy. It should also be possible to recognise samples irradiated with doses below 5 kGy.