Miquel Becker E, Christensen J, Frederiksen C S, Haugaard V K
Food Chemistry, Department of Dairy and Food Science, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
J Dairy Sci. 2003 Aug;86(8):2508-15. doi: 10.3168/jds.S0022-0302(03)73845-4.
The present study demonstrates the use of front-face fluorescence spectroscopy and chemometrics for monitoring light-induced changes in plain yogurt during storage. Fluorescence analysis is suggested as a new rapid method for measuring riboflavin content in yogurt. Fluorescence landscapes with excitation wavelengths from 270 to 550 nm and emission wavelengths in the range 310 to 590 nm were obtained from front-face fluorescence measurements directly on yogurt samples during two storage experiments over a period of 5 wk at 4 degrees C. Yogurts were stored in two different packaging materials (polylactate and polystyrene) and under fluorescent light (3500 lux) or in darkness. Principal Component Analysis of unfolded fluorescence emission spectra revealed systematic changes in fluorescence signal throughout the storage period, strongly related to the storage conditions, i.e. storage time and differences in packaging materials. Correlation between fluorescence spectra and riboflavin content determined by the standard AOAC fluorometric method was evaluated using a Partial Least Square Regression model. The regression model showed a good ability to predict riboflavin in plain yogurt with a high correlation (R = 0.99) and a prediction error of 0.092 microgram riboflavin/g. Thus, it is concluded that nondestructive fluorescence spectroscopy can be used to monitor riboflavin content in yogurt, and that the suggested rapid method has the potential to substitute the standard method for analysis of riboflavin in yogurt.
本研究展示了利用前表面荧光光谱法和化学计量学来监测原味酸奶在储存期间光诱导的变化。荧光分析被认为是一种测量酸奶中核黄素含量的新型快速方法。在4℃下为期5周的两次储存实验期间，通过直接对酸奶样品进行前表面荧光测量，获得了激发波长在270至550nm之间且发射波长在310至590nm范围内的荧光图谱。酸奶分别储存在两种不同的包装材料（聚乳酸和聚苯乙烯）中，并置于荧光灯下（3500勒克斯）或黑暗环境中。对展开的荧光发射光谱进行主成分分析，结果显示在整个储存期间荧光信号发生了系统性变化，这与储存条件密切相关，即储存时间和包装材料的差异。使用偏最小二乘回归模型评估了荧光光谱与通过标准AOAC荧光法测定的核黄素含量之间的相关性。该回归模型显示出良好的预测原味酸奶中核黄素的能力，相关性较高（R = 0.99），预测误差为0.092微克核黄素/克。因此，可以得出结论，无损荧光光谱法可用于监测酸奶中的核黄素含量，并且所建议的快速方法有潜力替代酸奶中核黄素分析的标准方法。
