Department of Chemistry, University of Otago, P. O. Box 56, Dunedin 9054, New Zealand.
Isotrace NZ LTD, 167 High St, Dunedin 9016, New Zealand.
Molecules. 2020 Aug 11;25(16):3658. doi: 10.3390/molecules25163658.
Dairy products occupy a special place among foods in contributing to a major part of our nutritional requirements, while also being prone to fraud. Hence, the verification of the authenticity of dairy products is of prime importance. Multiple stable isotopic studies have been undertaken that demonstrate the efficacy of this approach for the authentication of foodstuffs. However, the authentication of dairy products for geographic origin has been a challenge due to the complex interactions of geological and climatic drivers. This study applies stable isotope measurements of H, O, C and N values from casein to investigate the inherent geo-climatic variation across dairy farms from the South and North Islands of New Zealand. The stable isotopic ratios were measured for casein samples which had been separated from freeze-dried whole milk samples. As uniform feeding and fertilizer practices were applied throughout the sampling period, the subtropical (North Island) and temperate (South Island) climates were reflected in the variation of C and N. However, highly correlated H and O (r = 0.62, p = 6.64 × 10, a = 0.05) values did not differentiate climatic variation between Islands, but rather topographical locations. The highlight was the strong influence of dN towards explaining climatic variability, which could be important for further discussion.
奶制品在满足我们大部分营养需求方面占有特殊地位，同时也容易出现欺诈行为。因此，奶制品的真实性验证至关重要。多项稳定同位素研究已经证明了这种方法在食品认证方面的有效性。然而，由于地质和气候驱动因素的复杂相互作用，奶制品的地理来源认证一直是一个挑战。本研究应用乳蛋白中的 H、O、C 和 N 值的稳定同位素测量来研究来自新西兰南北岛的奶制品农场的固有地理气候变化。对从冷冻干燥全脂奶样品中分离出的乳蛋白样品进行了稳定同位素比的测量。由于在整个采样期间采用了统一的喂养和施肥方式，亚热带（北岛）和温带（南岛）气候反映在 C 和 N 的变化中。然而，高度相关的 H 和 O（r = 0.62，p = 6.64 × 10，a = 0.05）值并不能区分岛屿之间的气候变化，而是地形位置。值得注意的是，dN 对解释气候变异性的强烈影响，这可能对进一步的讨论很重要。
