Australian stingless bee honeys have been shown to exert antioxidant and in vitro antimicrobial properties; however their bioactive factors remained unidentified. This study investigated the antibacterial properties of phenolic extracts from Tetragonula carbonaria honeys. Honeys were harvested from beehives in three sites of South East Australia. Liquid-liquid extractions yielded the phenolic concentrates, for analyses by liquid and gas chromatography mass spectrometry. Antibacterial assays were conducted against Staphylococcus aureus and Klebsiella pneumoniae by in vitro agar diffusion and broth dilution assays. The phenolic extracts averaged to 5.87 mg/100 g of raw honeys, and constituents were 3-phenyllactic acid, lumichrome, diglycosylflavonoids, norisoprenoids. The honeys did not contain methylglyoxal, dihydroxyacetone or phenolics characteristic of Leptospermum nectars. Hydrogen peroxide content amounted up to 155.8 μM in honeys. Beside the bactericidal effects of hydrogen peroxide at 760 μM, other antibacterial factors were the phenolic extracts of "sugarbag" honeys that were active at minimum bactericidal concentrations of 1.2-1.8 mg/mL.

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Samples of manufacturing bulk milk were collected from 102 producers by the conventional procedure and were randomly coded. At least 3 h later, samples were collected by haulers from the same tanks with in-line samplers (ISOLOK MS5) mounted on the truck. Overall weighted mean fat tests for producers on nine routes were 3.669% for conventional and 3.644% for in-line samples. The overall weighted mean of load samples taken at the plants was 3.655%. Unweighted means of the producer samples taken by the conventional and in-line methods were 3.781% and 3.752%, respectively. The difference between the means, 0.029%, was highly significant (P<0.001). There was a significant difference (P<0.05) in fat content of samples taken conventionally after 5 and 8 min of agitation. Carryover of bacteria from tanks with high counts to samples with low counts was not detectable by direct microscopic counts in field studies. However, in laboratory studies with an emptied hose and a few seconds of delay before sampling small carryover occurred. Significance of the carryover effect depends on volume of milk sampled and whether bacterial content is marginal.

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