Birlouez-Aragon I, Locquet N, de St Louvent E, Bouveresse D Jouan-Rimbaud, Stahl P
INA P-G/INRA, UMR 214, Laboratoire de Chimie Analytique, 16 rue Claude Bernard, 75231 Paris cedex 05, France.
Ann N Y Acad Sci. 2005 Jun;1043:308-18. doi: 10.1196/annals.1333.038.
Foods are complex mixtures of macro- and micronutrients, which interact, leading to oxidation, glycation, and hydrolysis upon heating (e.g., sterilization, cooking) and storage. Their nutritional quality and safety are consequently affected, justifying the need for accurate monitoring of the evolution of the food composition during processing and shelf life. Classical chromatographic analysis as well as newly proposed rapid methods based on fluorescence spectrometry analyses were applied on whey powder-based models and commercial samples (in powdered form and ultrahigh temperature [UHT] sterilized), some of which had been previously submitted to protein hydrolysis. These samples were incubated for 48 h at 60 degrees C to mimic accelerated storage. Fluorescence fingerprints addressing modifications in the product composition during processing were recorded and analyzed by chemometric methods. Carboxymethyllysine (Nepsilon-[carboxymethyl]lysine; CML) was measured using an ELISA method. Fluorescence, recorded in a front-face mode on intact samples, is very sensitive to pertinent physicochemical changes induced by heat treatment, formulation (the moisture level in powders, presence of vitamin C and iron), and storage. Similar trends were observed between powders' fluorescence and CML-for example, a strong effect of protein hydrolysis and increasing water content. Addition of vitamin C was associated with an antioxidant effect despite the presence of iron. Good calibration models were obtained for predicting CML from fluorescence spectra both in food models and in commercial samples, although more work is needed to obtain accurate and robust calibration models. Results show the potential of nondestructively applied fluorescence spectrometry for measuring CML in formulas, a rapid, simple, and cost-effective method to monitor formula quality.
食物是大量营养素和微量营养素的复杂混合物，这些营养素相互作用，在加热（如杀菌、烹饪）和储存过程中会导致氧化、糖基化和水解。其营养质量和安全性因此受到影响，这就证明了在加工和保质期内准确监测食物成分变化的必要性。经典色谱分析以及新提出的基于荧光光谱分析的快速方法被应用于乳清粉模型和商业样品（粉末形式和超高温[UHT]杀菌），其中一些样品之前已经进行了蛋白质水解。将这些样品在60摄氏度下孵育48小时以模拟加速储存。通过化学计量学方法记录和分析了针对加工过程中产品成分变化的荧光指纹图谱。使用酶联免疫吸附测定（ELISA）方法测量羧甲基赖氨酸（Nε-[羧甲基]赖氨酸；CML）。在完整样品上以正面模式记录的荧光对热处理、配方（粉末中的水分含量、维生素C和铁的存在）和储存引起的相关物理化学变化非常敏感。在粉末荧光和CML之间观察到类似趋势——例如，蛋白质水解和水分含量增加的强烈影响。尽管存在铁，但添加维生素C具有抗氧化作用。尽管需要更多工作来获得准确和稳健的校准模型，但在食物模型和商业样品中都获得了从荧光光谱预测CML的良好校准模型。结果表明，无损应用荧光光谱法在测量配方奶粉中CML方面具有潜力，这是一种监测配方奶粉质量的快速、简单且经济高效的方法。
