Production in food of 1,3-pentadiene and styrene by Trichoderma species.

The ability of two strains of Trichoderma, isolated from food, to produce the Volatile Organic Compounds 1,3-pentadiene and styrene was investigated. One of the strains had been implicated in a case of food spoilage involving the production of both compounds. In vitro in potato dextrose broth, the strains produced both 1,3-pentadiene and styrene within 5 days in the presence of sorbic acid and cinnamic acid. The taints were produced only in the presence of sorbic acid and cinnamic acid and were not synthesised de novo under the test conditions. Neither the conversion of cinnamic acid to styrene, nor the conversion of sorbic acid to 1,3-pentadiene by Trichoderma strains in foods has been previously reported. The range of organisms implicated in these types of spoilage is thus extended.

Cyclic fluctuations in acetone concentrations in the blood and milk of clinically healthy dairy cows.

Milk samples were taken daily or twice weekly, and blood samples twice weekly, from six clinically healthy dairy cows. Acetone concentration was determined by a new headspace gas-chromatographic method that proved to be suitable in terms of practically, sensitivity and precision. The concentration of acetone in milk was closely correlated with that in blood (r2 = 0.967). There was no relationship between lacteal acetone concentration and either somatic cell count or bacterial infection. In both blood and milk there were fluctuations in acetone concentration that were synchronous between the six cows. The fluctuations were apparently cyclic, with a period of approximately 10 d. Such fluctuations have not previously been reported.

A gas-chromatographic headspace method for the determination of acetone in bovine milk, blood and urine.

An automated headspace gas-chromatographic method has been developed for the determination of acetone in the milk, blood and urine of dairy cows. Five ml samples were saturated with 2 g of sodium chloride and equilibrated for 30 min at 90 degrees C in a Hewlett-Packard HP 19395 A automatic headspace sampler. The headspace volatiles were transferred without splitting to a 25 m x 0.3 mm x 0.4 microns Carbowax column in a Shimadzu GC 9A gas chromatograph, operating isothermally at 50 degrees C. The coefficients of variation for the determination of acetone were 1.5-4.4% for urine, 10.0-24.9% for milk and 2.0-19.6% for blood. The detection limits were 0.0055 mg/100 ml for milk, 0.0072 mg/100 ml for blood and 0.0080 mg/100 ml for urine. The analysis time of 5 min per sample provided an adequate rate of throughput for routine monitoring.

Tax reform, population ageing and the changing labour supply behaviour of married women.

"The burden of financing retirement incomes in an ageing population is predicted to rise sharply in future decades. This paper investigates the effects of reforms to the Australian tax-benefit system involving a greater reliance on proportional taxation for raising revenue and a more targeted welfare system for cutting government expenditure, in order to reduce expected budget deficits. Estimates of changes in net incomes and hours of work suggest that reforms of this kind shift the tax burden to lower and middle income households with a second earner and that they can have counter-productive labour supply effects. The study explores the impact of projected increases in female work force participation and illustrates the importance of shifts in the labour supply of married women in predicting the fiscal effects of demographic change."

Chromatographic analysis of species specific odor profiles inMastomys natalensis andM. coucha (Rodentia: Muridae).

Whole-body volatiles from males of the cryptic multimammate mouse speciesMastomys natalensis andM. coucha were analyzed by dynamic solvent effect sampling and capillary gas chromatography. One compound, 3-nonene-2-one, was always present, sometimes as the major component, in volatiles fromM. coucha and absent, or present only at low levels, in volatiles fromM. natalensis. The mean ±SD of the 3-nonen-2-one peak area forM. coucha was 8599 ±9630 and forM. natalensis 148 ±486. Chromatographic analysis was more reliable in identifying a male's species than were a female's in a two-choice olfactorium.

Volatile components of anal gland secretion of aardwolf (Proteles cristatus).

Volatile constituents of the anal gland secretion and of scent marks of the aardwolf were identified using dynamic solvent effect sampling, capillary gas-liquid chromatography, and mass spectrometry. Both scent marks and gland contents consisted mainly of short- to medium-chain fatty acids, a complex series of medium- and long-chain esters, indole, and hexanol. There were marked individual differences in the relative concentrations of the various components.

Aggregation pheromones of the bont tick Amblyomma hebraeum: identification of candidates for bioassay.

Volatiles emitted by male Amblyomma hebraeum while feeding on a rabbit were quantitatively sampled by the dynamic solvent effect and analysed by capillary gas-liquid chromatography and mass spectrometry. Changes in emissions of 2-methyl propanoic acid, benzaldehyde and 2-nitrophenol paralleled reported increases in the attractiveness of males to conspecific ticks after 4-5 days of feeding. These compounds are therefore candidates for the bioassay of pheromonal activity.