Department of Food, Bioprocessing and Nutrition Sciences, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh 27695.
Department of Food, Bioprocessing and Nutrition Sciences, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh 27695.
J Dairy Sci. 2017 Nov;100(11):8754-8758. doi: 10.3168/jds.2017-13095. Epub 2017 Aug 23.
Norbixin is the water-soluble carotenoid in annatto extracts used in the cheese industry to color Cheddar cheese. The purpose of norbixin is to provide cheese color, but norbixin is also present in the whey stream and contaminates dried dairy ingredients. Regulatory restrictions dictate that norbixin cannot be present in dairy ingredients destined for infant formula or ingredients entering different international markets. Thus, there is a need for the detection and quantification of norbixin at very low levels in dried dairy ingredients to confirm its absence. A rapid method for norbixin evaluation exists, but it does not have the sensitivity required to confirm norbixin absence at very low levels in compliance with existing regulations. The current method has a limit of detection of 2.7 μg/kg and a limit of quantification of 3.5 μg/kg. The purpose of this study was to develop a method to extract and concentrate norbixin for quantification in dried dairy ingredients below 1 μg/kg (1 ppb). A reverse-phase solid-phase extraction column step was applied in the new method to concentrate and quantify norbixin from liquid and dried WPC80 (whey protein concentrate with 80% protein), WPC34 (WPC, 34% protein), permeate, and lactose. Samples were evaluated by both methods for comparison. The established method was able to quantify norbixin in whey proteins and permeates (9.39 μg/kg to 2.35 mg/kg) but was unable to detect norbixin in suspect powdered lactose samples. The newly developed method had similar performance to the established method for whey proteins and permeates but was also able to detect norbixin in powdered lactose samples. The proposed method had a >90% recovery in lactose samples and a limit of detection of 28 ppt (ng/kg) and a limit of quantification of 94 ppt (ng/kg). The developed method provides detection and quantification of norbixin for dairy ingredients that have a concentration of <1 ppb.
胭脂树橙红素是番红花提取物中的水溶性类胡萝卜素，用于奶酪工业给切达奶酪上色。胭脂树橙红素的目的是为了给奶酪上色，但它也存在于乳清流中，并污染了干燥的乳制品成分。监管限制规定，胭脂树橙红素不能存在于用于婴儿配方奶粉或进入不同国际市场的成分的乳制品成分中。因此，需要在干燥的乳制品成分中非常低的水平下检测和定量胭脂树橙红素，以确认其不存在。已经存在一种用于胭脂树橙红素评价的快速方法，但它没有在遵守现有法规的情况下在非常低的水平下确认胭脂树橙红素不存在所需的灵敏度。目前的方法检测限为 2.7μg/kg，定量限为 3.5μg/kg。本研究的目的是开发一种从干燥的乳制品成分中提取和浓缩胭脂树橙红素的方法，以在低于 1μg/kg（1ppb）的水平下进行定量。新方法应用了反相固相萃取柱步骤，从液体和干燥的 WPC80（乳清蛋白浓缩物，含 80%蛋白质）、WPC34（WPC，34%蛋白质）、渗透物和乳糖中浓缩和定量胭脂树橙红素。为了进行比较，两种方法都对样品进行了评估。所建立的方法能够定量乳清蛋白和渗透物中的胭脂树橙红素（9.39μg/kg 至 2.35mg/kg），但无法检测可疑的粉状乳糖样品中的胭脂树橙红素。新开发的方法在乳清蛋白和渗透物方面与已建立的方法具有相似的性能，但也能够检测粉状乳糖样品中的胭脂树橙红素。该方法在乳糖样品中的回收率>90%，检测限为 28ppt（ng/kg），定量限为 94ppt（ng/kg）。所开发的方法为浓度低于 1ppb 的乳制品成分提供了胭脂树橙红素的检测和定量。
