Southwell I.A.,Phytoquest |
Russell M.F.,Wollongbar Primary Industries Institute |
Davies N.W.,University of Tasmania
Flavour and Fragrance Journal | Year: 2011
Methyl eugenol is a naturally occurring flavour and fragrance found in a variety of different food sources, including spices, herbs and fruit and also as a component of natural essential oils. Commonly used oils with more than 0.1% of methyl eugenol include calamus, rosewood, elemi, ylang ylang, cymbopogon, star anise, lovage, verbena, nutmeg, basil, pimento, bay leaf, rose and clove. In addition there are other potential sources of exposure to methyl eugenol, including agriculture, wine consumption and ambient background in air and water. Because high doses of some allyl alkoxybenzenes have induced tumours in rats and mice, use is recommended as either restricted or, in the case of safrole, prohibited. Many reviewers and researchers present clear evidence that these restrictions are excessive, especially those who accept that carcinogenesis is a threshold phenomenon. This paper describes suitable gas chromatographic methods for the determination of trace amounts of methyl eugenol in the essential oil of tea tree, Melaleuca alternifolia, terpinen-4-ol type. Published 'trace' amounts were interpreted as being as high as 0.3-0.9% by one regulator. Peak assignment by GC-MS and co-elution with a standard facilitated the GC-FID determination of 128 commercial samples. Inter-laboratory confirmation was achieved using GC-MS with selected ion monitoring. These determinations indicated that the methyl eugenol content of tea tree oil ranged from less than 0.01% to 0.06% (mean 0.02%), i.e. 20-fold lower than the regulator's interpretation and one million times lower than the logarithmic scale levels known to cause carcinomas in rats. © 2011 John Wiley & Sons, Ltd.
Scheer C.,Institute for Sustainable Resources |
Grace P.R.,Institute for Sustainable Resources |
Rowlings D.W.,Institute for Sustainable Resources |
Kimber S.,Wollongbar Primary Industries Institute |
van Zwieten L.,Wollongbar Primary Industries Institute
Plant and Soil | Year: 2011
We assessed the effect of biochar incorporation into the soil on the soil-atmosphere exchange of the greenhouse gases (GHG) from an intensive subtropical pasture. For this, we measured N 2O, CH 4 and CO 2 emissions with high temporal resolution from April to June 2009 in an existing factorial experiment where cattle feedlot biochar had been applied at 10 t ha -1 in November 2006. Over the whole measurement period, significant emissions of N 2O and CO 2 were observed, whereas a net uptake of CH 4 was measured. N 2O emissions were found to be highly episodic with one major emission pulse (up to 502 μg N 2O-N m -2 h -1) following heavy rainfall. There was no significant difference in the net flux of GHGs from the biochar amended vs. the control plots. Our results demonstrate that intensively managed subtropical pastures on ferrosols in northern New South Wales of Australia can be a significant source of GHG. Our hypothesis that the application of biochar would lead to a reduction in emissions of GHG from soils was not supported in this field assessment. Additional studies with longer observation periods are needed to clarify the long term effect of biochar amendment on soil microbial processes and the emission of GHGs under field conditions. © 2011 Springer Science+Business Media B.V.
Vancov T.,Wollongbar Primary Industries Institute |
Vancov T.,University of New England of Australia |
Mcintosh S.,Wollongbar Primary Industries Institute
Journal of Chemical Technology and Biotechnology | Year: 2011
BACKGROUND: Prehydrolysis of wheat stubble using moderate temperatures and dilute acid strength is an effective means for solubilizing hemicellulose fractions and improving cellulose hydrolysis. Variation in prehydrolysis parameters (temperature, time, and acid strength) and enzymatic saccharification conditions were examined for conversion of wheat stubble into fermentable sugars. RESULTS: Elevating temperature and acid strength maximized sugar release in prehydrolysate liquors. The optimal conditions of 2.0% H 2SO 4/60 min/121 °C effectively solubilized 79% of the available hemicellulose. Production of inhibitory hydrolysis and degradation products such as acetic acid and levulinic acid, were detected at levels of 3.4 g L -1 and 0.64 g L -1, respectively. Sugar yields in prehydrolysate and saccharified liquors were found to increase with treatment severity. Temperature had the greatest impact on sugar release, followed by acid concentration and time. Optimizing prehydrolysis conditions at 1.0% H 2SO 4/90 min/121 °C, produced a 3.2-fold improvement in cellulose hydrolysis with recoveries approaching 82%. The addition of β-glucosidase and xylanase to the cellulase preparations assisted monomeric sugar release. CONCLUSION: Although treatment conditions for hemicellulose and cellulose hydrolysis differ, the study's findings suggest a good degree of overlap and process flexibility which should permit high recovery of pentose and hexose sugars. © 2011 Society of Chemical Industry.
McIntosh S.,Wollongbar Primary Industries Institute |
Vancov T.,Wollongbar Primary Industries Institute |
Vancov T.,University of New England of Australia
Biomass and Bioenergy | Year: 2011
Physico-chemical pretreatment of lignocellulosic biomass is critical in removing substrate-specific barriers to cellulolytic enzyme attack. Alkaline pretreatment successfully delignifies biomass by disrupting the ester bonds cross-linking lignin and xylan, resulting in cellulose and hemicellulose enriched fractions. Here we report the use of dilute alkaline (NaOH) pretreatment followed by enzyme saccharifications of wheat straw to produce fermentable sugars. Specifically, we have assessed the impacts of varying pretreatment parameters (temperature, time and alkalinity) on enzymatic digestion of residual solid materials. Following pretreatment, recoverable solids and lignin contents were found to be inversely proportional to the severity of the pretreatment process. Elevating temperature and alkaline strengths maximised hemicellulose and lignin solubilisation and enhanced enzymatic saccharifications. Pretreating wheat straw with 2% NaOH for 30 min at 121 °C improved enzyme saccharification 6.3-fold when compared to control samples. Similarly, a 4.9-fold increase in total sugar yields from samples treated with 2% NaOH at 60 °C for 90min, confirmed the importance of alkali inclusion. A combination of three commercial enzyme preparations (cellulase, β-glucosidase and xylanase) was found to maximise monomeric sugar release, particularly for substrates with higher xylan contents. In essence, the combined enzyme activities increased total sugar release 1.65-fold and effectively reduced cellulase enzyme loadings 3-fold. Prehydrolysate liquors contained 4-fold more total phenolics compared to enzyme saccharification mixtures. Harsher pretreatment conditions provide saccharified hydrolysates with reduced phenolic content and greater fermentation potential. © 2011 Elsevier Ltd.
Jordan D.,Wollongbar Primary Industries Institute |
Kirkland P.,Elizabeth Macarthur Agricultural Institute |
Morris S.,Wollongbar Primary Industries Institute |
Coilparampil R.,Elizabeth Macarthur Agricultural Institute
Preventive Veterinary Medicine | Year: 2012
Results from laboratory assays for detection of animal disease are often assessed for repeatability (agreement within laboratory) and reproducibility (agreement between laboratories). This work aimed to understand the strengths and limitations of available methods for describing these quantities. Five major veterinary laboratories in Australia volunteered to participate in a designed evaluation based on repeat testing of twenty bovine sera. Sampling was stratified so that ten of the sera were negative to the virus neutralisation test (VNT) for antibody to bovine herpes virus 1 (BHV-1) and the remaining ten sera were VNT positive. Each serum was divided into 50 replicates and each laboratory assayed one replicate of each serum on a weekly basis using a commercial ELISA for BHV-1. Laboratories were blinded to the identity of sera. The data on sample to positive control ratio (S/P) for these 1000 individual assays were collated, sources of variance analysed using a random effects model, and reliability coefficients (ρ) obtained from the variance estimates as quantitative measures of within and between laboratory agreement. Coefficient of variation (CV) was calculated for combinations of sera and laboratory. CV was found to be higher for sera with the lowest mean S/P values (VNT -ve sera). For VNT -ve sera, agreement of S/P within laboratory was low to moderate (ρ: 0.01-0.27) and the agreement between all labs was low (ρ= 0.02). Reliability coefficients for VNT +ve sera were very high for agreement within laboratories (ρ: 0.63-0.92) and moderate for agreement between laboratories (ρ= 0.52). As well, simulation demonstrated that sero-prevalence has a dramatic affect on the reliability coefficient if sampling were to be irrespective of VNT status. We conclude that there are some limitations with the available approaches for assessing agreement within and between laboratories. Although reliability coefficients have some drawbacks they are an attractive way of reducing reliance on subjective assessment of agreement. © 2011.