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Cooney T.P.,Ruakura Research Center | Varelis P.,Fonterra Research and Development Center | Bendall J.G.,Fonterra Research and Development Center
Journal of Food Protection | Year: 2016

As a food defense measure against an extortion threat to poison infant formula with monofluoroacetate, a robust methodology for monofluoroacetate analysis in fluid milk and powdered dairy products was developed and optimized. Critical challenges posed by this situation required that the analytical methodology provide (i) high specificity, (ii) high throughput capable of analyzing thousands of samples of fluid milk per day, and (iii) trace-level detection of 1 ng/g or lower to achieve the maximum residue limit. Solid-phase extraction-purified acetone extracts of fluid milk were derivatized with aniline, and after ultrahigh-performance liquid chromatography using a Kinetex-C18 column packed with 1.3-lm shell particles, the resulting Nphenyl 2-fluoroacetamide could be determined by liquid chromatography-tandem mass spectrometry in a highly specific manner and with a limit of quantification of 0.5 ng/ml. By using 4-(4-chlorophenoxy)aniline as a derivatizing agent, the method could be extended to powdered dairy products with the same limit of quantification. Between January and July 2015, some 136,000 fluid milk samples were tested using this method. This analytical testing of fluid milk formed one element in a larger program of work by multiple agencies to ensure that consumers could continue to have confidence in the safety of New Zealand milk and dairy products. Copyright ©, International Association for Food Protection.


Ross J.L.,University of Aberdeen | Ivanova E.S.,RAS Severtsov Institute of Ecology | Sirgel W.F.,Stellenbosch University | Malan A.P.,Stellenbosch University | And 2 more authors.
Journal of Helminthology | Year: 2012

A survey of nematodes associated with native and introduced species of terrestrial slugs was conducted in the Western Cape Province of South Africa, in order to gather new data regarding diversity and distribution. A total of 521 terrestrial slugs were collected from 35 localities throughout the Western Cape. All slugs were dissected and examined for the presence of internal nematodes. Extracted nematodes were identified using a combination of molecular (18S rRNA gene sequencing) and morphological techniques. Nematodes were found parasitizing slugs at 14 of the 35 sites examined, amounting to 40% of sample sites. Of all slugs, 6% were infected with nematodes. A total of seven species of nematode were identified in the province, including Agfa flexilis, Angiostoma sp., Phasmarhabditis sp. SA1, Phasmarhabditis sp. SA2, Caenorhabditis elegans, Panagrolaimus sp. and Rhabditis sp. Of these species, four were thought to be parasitic to slugs (A. flexilis, Angiostoma sp., Phasmarhabditis sp. SA1 and Phasmarhabditis sp. SA2), as opposed to forming necromenic or phoretic associations. Three new species of slug-parasitic nematode were identified during this study (Angiostoma sp., Phasmarhabditis sp. SA1 and Phasmarhabditis sp. SA2). © 2011 Cambridge University Press.


Shokri A.,University of Waikato | Shokri A.,Ruakura Research Center | Bardsley W.E.,University of Waikato
Journal of Irrigation and Drainage Engineering | Year: 2015

The Hooghoudt equation is widely used as a simple means of specifying drain spacing when designing networks of parallel drains in drainage systems, based on estimating the maximum water table height between two drains. It is shown via comparison with a numerical model that the Hooghoudt equation can overestimate water table height and therefore yield drain spacings that may be too wide. This is because the Hooghoudt drain-spacing equation in fact has a concealed dependency on Van Genuchten soil-water retention curve parameters, which can bias the water table estimates unless adjustments are made explicitly. A modification of the Hooghoudt equation is presented that incorporates two new dimensionless coefficients to make allowance for this dependency. The modified expression yields improved accuracy as measured against the numerical reference model. © 2014 American Society of Civil Engineers.


Mudge P.L.,University of Waikato | Mudge P.L.,Ruakura Research Center | Wallace D.F.,University of Waikato | Wallace D.F.,Plant and Food Research | And 4 more authors.
Agriculture, Ecosystems and Environment | Year: 2011

Grazed grasslands occupy 26% of the earth's ice free land surface and are therefore an important component of the global C balance. In New Zealand, pastoral agriculture is the dominant land use and recent research has shown that soils under intensive dairy pastures have lost large amounts of carbon (~1000 kg C ha -1 y -1) during the past few decades. The objective of this research was to determine the net ecosystem carbon balance (NECB) of an intensively grazed dairy pasture in New Zealand. Net ecosystem CO 2 exchange (NEE) was measured using an eddy covariance (EC) system from 1 January 2008 to 31 December 2009. Other C imports (feed) and exports (milk, methane, leaching, and harvested biomass) were calculated from farm production data and literature values. During 2008 there was a one in 100 year drought during summer/autumn, which was followed by a very wet winter. There were no prolonged periods of above or below average rainfall or soil moisture in 2009, but temperatures were consistently lower than 2008. The severe summer/autumn drought during 2008 caused a loss of CO 2 to the atmosphere, but annual NEE remained negative (a CO 2 sink, -1610±500 kg C ha -1), because CO 2 lost during the drought was regained during the winter and spring. The site was also a net CO 2 sink during 2009 despite the colder than usual conditions (-2290±500 kg C ha -1). Including C imports and exports in addition to CO 2 exchange revealed that the site was a C sink in both years, with a NECB of 590±560 kg C ha -1 in 2008, and 900±560 kg C ha -1 in 2009. The C sequestration found in this study is in agreement with most other Northern Hemisphere EC studies of grazed pastures on mineral soils, but is not consistent with the large C losses reported for soils under dairy pastures throughout New Zealand. In the current study (like many other EC studies) the influence of climatic conditions and management practices on the annual C balance was only semi-quantitatively assessed. An extended period of EC measurements combined with modelling is required to more accurately quantify the effect of different climatic conditions on the annual C balance, and the influence of different management practices needs to be quantified using specifically designed studies (such as paired EC towers), so that practices which minimise C losses and maximise C sequestration can be identified. © 2011 Elsevier B.V.


Palmer J.,The New Zealand Institute for Plant and Food Research Ltd | Diack R.,The New Zealand Institute for Plant and Food Research Ltd | Johnston J.,Mt Albert Research Center | Boldingh H.,Ruakura Research Center
Journal of Horticultural Science and Biotechnology | Year: 2013

The supply of carbon to fruit on whole apple trees of 'Scifresh' grafted onto M.9 rootstock was altered by adjustment of the crop load [43% removal at 60 d or 90 d after full bloom (DAFB)], by three periods of 75% shading (from 60 - 90, 90 - 120, or 60 - 120 DAFB), or by a combined treatment of fruit removal at 60 DAFB and shading from 60 - 120 DAFB. Altering the timing and duration of shading, and crop load adjustment, resulted in changes in fruit dry matter concentration (DMC), with a range at harvest from 14.0 - 17.5%. Thinning to reduce the crop load enhanced fruit DMC, with greater effects on both fruit DMC and mean fruit fresh weight the earlier it was done. Shading reduced fruit DMC, with greater reductions the longer the shade was left over the trees. All treatments had greater effects on fruit DMC and fruit quality (flesh firmness and soluble solids concentration) at harvest than on mean fruit fresh weight.This trial also provided fruit samples for measurements of both the carbohydrate content and apoplastic composition of cortical tissues. Starch contents and total apoplastic sugar concentrations were increased by reductions in crop load and were decreased by shading, with starch content being the most responsive. Apoplastic sugar concentrations increased during fruit development. The relative order of abundance of sugars in the apoplast and in the symplast plus vacuole was similar, although differences in the ratios of sugars were evident, with sorbitol accounting for ≤ 10% of the total sugar content in the apoplast and ≤ 3% in the symplast plus vacuole. This work has revealed the possibility of using apoplastic sugar concentration as an indicator of the carbohydrate supply to apple fruit.

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