Flavonoids, phenolic acids and abscisic acid in Australian and New Zealand Leptospermum honeys

Flavonoids, phenolic acids and abscisic acid of Australian and New Zealand Leptospermum honeys were analyzed by HPLC. Fifteen flavonoids were isolated in Australian jelly bush honey (Leptospermum polygalifolium), with an average content of 2.22 mg/100 g honey. Myricetin (3,5,7,3',4',5'-hexahydroxyflavone), luteolin (5,7,3',4'-tetrahydroxyflavone) and tricetin (5,7,3',4',5'-pentahydroxyflavone) were the main flavonoids identified. The mean content of total phenolic acids in jelly bush honey was 5.14 mg/100 g honey, with gallic and coumaric acids as the potential phenolic acids. Abscisic acid was quantified as twice the amount (11.6 mg/100 g honey) of the phenolic acids in this honey. The flavonoid profile mainly consisted of quercetin (3,5,7,3',4'-pentahydroxyflavone), isorhamnetin (3,5,7,4'-tetrahydroxyflavone 3'-methyl ethyl), chrysin (5,7-dihydroxyflavone), luteolin and an unknown flavanone in New Zealand manuka (Leptospermum scoparium) honey with an average content of total flavonoids of 3.06 mg/100 g honey. The content of total phenolic acids was up to 14.0 mg/100 g honey, with gallic acid as the main component. A substantial quantity (32.8 mg/100 g honey) of abscisic acid was present in manuka honey. These results showed that flavonoids and phenolic acids could be used for authenticating honey floral origins, and abscisic acid may aid in this authentication. (C) 2002 Published by Elsevier Science Ltd.

Surface stickiness of drops of carbohydrate and organic acid solutions during convective drying: Experiments and modeling

Drying kinetics of low molecular weight sugars such as fructose, glucose, sucrose and organic acid such as citric acid and high molecular weight carbohydrate such as maltodextrin (DE 6) were determined experimentally using single drop drying experiments as well as predicted numerically by solving the mass and heat transfer equations. The predicted moisture and temperature histories agreed with the experimental ones within 6% average relative (absolute) error and average difference of +/- 1degreesC, respectively. The stickiness histories of these drops were determined experimentally and predicted numerically based on the glass transition temperature (T-g) of surface layer. The model predicted the experimental observations with good accuracy. A nonsticky regime for these materials during spray drying is proposed by simulating a drop, initially 120 mum in diameter, in a spray drying environment.

An SNP-based PCR assay to differentiate between Listeria monocytogenes lineages derived from phylogenetic analysis of the sigB gene

The alternative sigma factor sigB gene is involved in the stress response regulation of Listeria monocytogenes, and contributes towards growth and survival in adverse conditions. This gene was examined to determine if it could be a useful indicator of lineage differentiation, similar to the established method based on ribotyping. The sigB sequence was resolved in four local L. monocytogenes strains and the phylogenetic relationship among these, and a further 21 sigB gene sequences from strains of different serotype and lineage including two Listeria innocua strains, obtained from the GenBank database were determined. The sigB nucleotide sequences of these 25 Listeria strains were then examined for single nucleotide polymorphic (SNP) sites that could differentiate between the three lineages. Based on nucleotide sequences L. monocytogenes lineage F serotype 1/2b and 4b clustered together, lineage II/serotype 1/2a and 1/2c strains clustered together, lineage III/serotypes 4a and 4c strains clustered together and L. innocua strains clustered together as an outgroup. SNPs differentiating the three lineages were identified. Individual allele-specific PCR reactions based on these polymorphisms were successful in grouping known and a further 37 local L. monocytogenes isolates into the three lineages. (C) 2003 Elsevier B.V. All fights reserved.

Radical formation on gamma-radiolysis of poly [(methacrylic acid)-co-acrylonitri

The radicals formed on gamma-radiolysis of a series of copolymers of methacrylic acid and acrylonitrile have been investigated by ESR spectroscopy. This series of copolymers spanned the full composition range and the study was carried out at 77 K and ambient temperature. The radicals formed in the copolymers at 77 and 303 K were found to be similar to those found in the two homopolymers, but in the intermediate composition range the presence of acrylonitrile propagation radicals was also detected. These radicals were not observed to be formed in significant quantities on the radiolysis of polyacrylonitrile. They are believed to result from a scission of the main chain at methacrylic acid/acrylonitrile diad sequences following loss of the methacrylic acid carboxyl group. At 77 K, the copolymers with high methacrylic acid contents were found to be more sensitive to radical formation than the methacrylic acid homopolymer, but this enhanced sensitivity was not evident at ambient temperature, where the G-values for radical formation for the copolymers were slightly less than the values for the homopolymers. (C) 2003 Society of Chemical Industry.