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Palmerston North, New Zealand

Abernethy G.A.,Fonterra Research and Development Center
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2015

This paper proposes a mechanism to explain the trace levels of natural semicarbazide occasionally observed in foods. The analytical derivative of semicarbazide, 2-nitrobenzaldehyde semicarbazone, is often measured as a metabolite marker to detect the widely banned antibiotic nitrofurazone. However, this marker is not specific as semicarbazide may be present in foods for several reasons other than exposure to nitrofurazone. In some cases, an entirely natural origin of semicarbazide is suspected, although up until now there was no explanation about how semicarbazide could occur naturally. In this work, semicarbazide is proposed as being generated from natural food compounds via an azine intermediate. Hydrazine, in the form of azines or hydrazones, may be generated in dilute aqueous solution from the natural food compounds ammonia, hydrogen peroxide and acetone, following known oxidation chemistry. When this mixture was prepared in the presence of ureas such as allantoin, urea, biuret or hydroxyurea, and then analysed by the standard method for the determination of semicarbazide, 2-nitrobenzaldehyde semicarbazone was detected. 2-Nitrobenzaldehyde aldazine was also found, and it may be a general marker for azines in foods. This proposal, that azine formation is central to semicarbazide development, provides a convergence of the published mechanisms for semicarbazide. The reaction starts with hydrogen peroxide, peracetic acid, atmospheric oxygen or hypochlorite; generates hydrazine either by an oxaziridine intermediate or via the chlorination of ammonia; and then either route may converge on azine formation, followed by reaction with a urea compound. Additionally, carbamate ion may speculatively generate semicarbazide by reaction with hydrazine, which might be a significant route in the case of the hypochlorite treatment of foods or food contact surfaces. Significantly, detection of 2-nitrobenzaldehyde semicarbazone may be somewhat artefactual because semicarbazide can form during the acid conditions of analysis, which can free hydrazine in the presence of urea compounds. © 2015 Taylor & Francis. Source

Holroyd S.E.,Fonterra Research and Development Center
Journal of Near Infrared Spectroscopy | Year: 2013

Milk and milk products are a widely produced and traded source of nutrition globally. Near infrared (NIR) spectroscopy is commonly applied to these products for the purposes of composition measurement and quality control. The last five years have seen a growing emphasis on areas such as applications of NIR spectroscopy to compositional parameters that were previously done by specialised assays. Studies on proof of origin and authenticity as well as more qualitative applications such as health benefits have also appeared in the NIR literature in increasing numbers. Both these areas are reviewed by reference to application to liquid milk and specific products produced from milk alongside a number of new approaches to the more traditional quantitative use of NIR to measure gross compositional parameters such as fat, protein and moisture. The importance of appropriate sample preparation for respective products is also emphasised and a summary of the relevant wavelengths important for NIR analysis of milk and milk products is presented. Source

Anema S.G.,Fonterra Research and Development Center | de Kruif C.G.K.,University Utrecht | de Kruif C.G.K.,NIZO food research
Journal of Colloid and Interface Science | Year: 2014

Hypothesis: Oppositely charged proteins should interact and form complex coacervates or precipitates at the correct mixing ratios and under defined pH conditions. Experiments: The cationic protein lactotransferrin (LF) was mixed with the anionic protein β-lactoglobulin (B-Lg) at a range of pH and mixing ratios. Complexation was monitored through turbidity and zeta potential measurements. Findings: Complexation between LF and B-Lg did occur and complex coacervates were formed. This behaviour for globular proteins is rare. The charge ratio's of LF:B-Lg varies with pH due to changing (de) protonation of the proteins. Nevertheless we found that the complexes have a constant stoichiometry LF:B-Lg=1:3 at all pH's, due to charge regularization. At the turbidity maximum the zeta potential of complexes is close to zero, indicating charge neutrality; this is required when the complexes form a new concentrated liquid phase, as this must be electrically neutral. Complexes were formed in pH region 5-7.3. On addition of salt (NaCl) complexation is diminished and disappears at a salt concentration of about 100mMol. The coacervate phase has a very viscous consistency. If we consider the proteins as colloidal particles then the formed complex coacervate phase may have a structure that resembles a molten salt comparable to, for example, AlCl3. © 2014 Elsevier Inc. Source

Cakir-Fuller E.,Fonterra Research and Development Center
Food Hydrocolloids | Year: 2015

There is a desire to incorporate increasingly high concentrations of whey proteins into nutritional beverages to improve their nutritional content and amino acid profile. However, typical thermal treatments for sterility or extended shelf life cause undesirable aggregation/gelation of the whey proteins. To address this instability issue at high protein concentration, there is a need to develop new protein ingredient technologies that can provide resistance to heat-induced aggregation. In this study, the heat stability characteristics of model food emulsions containing standard or microparticulated whey protein concentrate (WPC80) were compared. Oil-in-water emulsions [10% (wt/wt) sunflower oil] containing increasing concentrations of protein (from 2 to 12wt%) were prepared at pH 7.0. The effects of retorting at 120°C for 10min on particle size distribution, rheological properties, susceptibility to heat-induced coagulation, microstructure and surface protein concentration of the standard and microparticulated WPCs were compared. Also, various levels of NaCl were added to examine the heat stability of micro-aggregated WPC in the presence of additional salts.Microparticulated WPC emulsions showed significantly enhanced heat stability compared with standard WPC emulsions. Emulsions with up to 11wt% protein and no visible aggregation or gelation after retorting were produced using microparticulated WPC. For standard WPC emulsions under the same heating conditions, large aggregates were formed and there was a change in flow behaviour to non-Newtonian at 3wt% protein. With this specific technology, high protein whey-based nutritional beverages can be produced using conventional thermal treatments. © 2015 Elsevier Ltd. Source

Jan Mohamed H.J.,Universiti Sains Malaysia | Rowan A.,Fonterra Co operative Group Ltd | Fong B.,Fonterra Research and Development Center | Loy S.-L.,Universiti Sains Malaysia
PloS one | Year: 2014

BACKGROUND: Vitamin D deficiency has become a global health issue in pregnant women. This study aimed to assess the adequacy of maternal vitamin D status by measuring maternal serum and breast milk 25-hydroxyvitamin D [25(OH)D] levels and to determine the association between maternal serum and milk 25(OH)D levels.METHODS: Data was obtained from the Universiti Sains Malaysia Pregnancy Cohort Study. This study was conducted from April 2010 to December 2012 in the state of Kelantan, Malaysia. Blood samples from pregnant women aged 19 to 40 years were drawn in the second and third trimesters of pregnancy, while breast milk samples at delivery, 2, 6 and 12 months postpartum were collected to analyze for 25(OH)D levels. A total of 102 pregnant women were included in the analysis.RESULTS: Vitamin D deficiency [25(OH)D <50 nmol/L] was detected in 60% and 37% of women in the second and third trimesters of pregnancy, respectively. There were 6% and 23% of women who reached normal level of vitamin D status in the second trimester and the third trimester, respectively. Multivitamin intakes during pregnancy were significantly associated with higher serum 25(OH)D levels in the second trimester (β = 9.16, p = 0.005) and the third trimester (β = 13.65, p = 0.003). 25(OH)D levels in breast milk during the first year of lactation ranged from 1.01 to 1.26 nmol/L. Higher maternal serum 25(OH)D level in the second trimester of pregnancy was associated with an elevated level of 25(OH)D in breast milk at delivery (β = 0.002, p = 0.026).CONCLUSIONS: This study shows that high proportions of Malay pregnant women are at risk of vitamin D deficiency. Maternal vitamin D status in the second trimester of pregnancy was found to influence vitamin D level in breast milk at delivery. Source

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