Fluorescence spectroscopy and PARAFAC in the analysis of yogurt

Authors: J. Christensenaa,*, E. Miquel Beckerb, C.S. Frederiskenb
aFood Technology, Department of Food Science, The Royal Veterinary and Agricultural University, Rolighedvesj 30, DK-1958 Frederiskberg C, Denmark
bFood Chemistry, Department of Food Science, The Royal Veterinary and Agricultural University, Rolighedvesj 30, DK-1958 Frederiskberg C, Denmark
Summary

Fluorescence spectroscopy is a widely used technique for molecular environments. It has a wide range of application. In this study, analysis of yogurt is presented. Plain yogurt samples were stored in two packages of polylactate (PLA) and polystyrene (PS). Samples were stored at 4 oC for 5 weeks. Fluorescence landscapes with excitation from 270 to 550nm and emission from 310 to 590nm with a 20nm bandwidth.
Parallel factor analysis (PARAFAC) was used to analyze the data. Split half analysis of PARAFAC models was used for model validation. Since the PARAFAC model is unique, same results were obtained for both halves which showed model validity. Zeros were inserted in place of missing values. Riboflavin content of yogurt was checked by fluorometric method. The wavelength was 446/525 nm for excitation/emission. Following  figures a and b show the analysis of fresh yogurt sample and the sample stored in severe conditions.
      
Tryptophan was identified with excitation/emission values of 285/365 nm and riboflavin at 520/270,375, and 445 nm. This study shows the oxidative quality of food product. PARAFAC was used to check this quality.
Reviewer: Aamir Alaud-din
        aamiralauddin@gist.ac.kr