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Woollard D.C.,New Hill | Macfadzean C.,New Zealand Laboratory Services Ltd | Indyk H.E.,Fonterra Cooperative Group Ltd | McMahon A.,Wyeth Nutrition | Christiansen S.,Perrigo Nutritionals PBM Products
International Dairy Journal | Year: 2014

A gas chromatography-flame ionisation detection method was developed to establish the content of myo-inositol in milk powders and infant formulations subsequent to formation of the volatile trialkylsilyl derivative. Samples were prepared by acid digestion, thereby releasing inositol from its multiple bound forms. A digestion time of 4h at 114°C was sufficient to hydrolyse potentially interfering carbohydrates and quantitatively recover bound inositol from milk-based products. Single laboratory method validation showed a within-day relative standard deviation (RSDr) of 5.9% and between-day relative standard deviation (RSDiR) of 9.6%. A between-laboratory (n=7) collaborative study yielded an average reproducibility (RSDR) of 12.8%, considered fit-for-purpose as a quality control method for milk-based infant formulations. Soy-based products, containing significant inositol hexaphosphate (IP6, phytic acid), required 32h for release of all inositol. Although current regulations do not specify the inclusion of IP6 in an inositol measurement, the current method allows for its discrimination if present. © 2014 Elsevier Ltd.

Andrewes P.,Fonterra Cooperative Group Ltd | Kelly M.,North Carolina State University | Vardhanabhuti B.,University of Missouri | Foegeding E.A.,North Carolina State University
International Dairy Journal | Year: 2011

Whey proteins in acidic beverages (pH < 4.5) are astringent, producing a dry mouth-feel. Astringency is thought to be caused by interaction of food components with saliva, often leading to aggregate formation. Such interactions decrease saliva lubrication, form rough particles, and probably increase friction on oral surfaces - changing mouth-feel. Dynamic in vitro models were constructed to reproduce the likely interaction of whey proteins with saliva in the mouth during the course of beverage ingestion. Aggregate formation in the models was examined for numerous whey protein solutions under different conditions. Trends observed in the models were consistent with previous reported sensory evaluations of whey protein astringency. For example, maximum turbidity changed little in the models with increasing protein concentration, consistent with literature describing little increase in astringency with increasing protein concentration. Modelling mouth conditions, to measure protein-saliva interactions, related to astringency better than mixing saliva and protein in simple ratios. © 2011 Elsevier Ltd.

Woollard D.C.,New Hill | Bensch A.,New Zealand Laboratory Services | Indyk H.,Fonterra Cooperative Group Ltd | McMahon A.,Wyeth Nutrition
Food Chemistry | Year: 2016

An HPLC method is described using normal phase conditions with an unbonded silica column to determine concentrations of supplementary vitamin A and vitamin E esters and β-carotene in infant formulae. The method utilises selective dual-channel fluoresence for vitamins A and E and visible absorbance for β-carotene. An attribute of the method is the use of retinol propionate, α-tocopheryl propionate and all-E-β-apo-8′-carotenoic acid ethyl ester internal standards to compensate for analytical variations associated with these labile vitamins. Extraction is performed without saponification, with the aid of protease to remove vitamin encaspsulation and facilitate vitamin partition into hydrocarbon solvent. Figures of merit indicate the method is suitable for its intended purpose in the highly regulated infant formula environment, including liquid formulations. The method is extendable to whole milk powders where total vitamin A content data can be calculated by summing the innate long-chain vitamin A esters with the added esters. © 2015 Elsevier Ltd.

Woollard D.C.,Cawthron Institute | Indyk H.E.,Fonterra Cooperative Group Ltd
International Dairy Journal | Year: 2014

A manual method is described for the determination of nitrate and nitrite in milk and milk powders that is intended to provide an alternative to conventional manual methods accomplished by cadmium reduction. Reduction of nitrate is performed in solution utilising vanadium (III) and quantitation achieved by concurrent reaction with Griess reagent. Performance data are acceptable in terms of precision and accuracy, repeatability being about 6% and intermediate precision at 8% for both analytes, providing the limit of detection is not approached. Limit of quantitation is 0.1mgkg-1 for both analytes. © 2013.

Gill B.D.,Fonterra Cooperative Group Ltd | Indyk H.E.,Fonterra Cooperative Group Ltd | Blake C.J.,Nestle | Konings E.J.M.,Nestle | And 2 more authors.
Journal of AOAC International | Year: 2015

Methods under consideration as part of the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals process are to be evaluated against a set of Standard Method Performance RequirementsSM (SMPRs) via peer review by an expert review panel (ERP). A validation protocol and a checklist have been developed to assist the ERP to evaluate experimental data and to compare multiple candidate methods for each nutrient. Method performance against validation parameters mandated in the SMPRs as well as additional criteria are to be scored, with the method selected by the ERP proceeding to multilaboratory study prior to Final Action approval. These methods are intended to be used by the infant formula industry for the purposes of dispute resolution.

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