MODELING AND PREDICTING SECOND and THIRD-ORDER FLUORESCENCE SPECTROSCOPY DATA AS A NOVEL

S.M. AZACARATE; C. TEGLIA; M. MONTEMURRO; G. SIANO; J.M. CAMIÑA; H.C. GOICOCHEA

Barcelona

Congreso; XVI Chemometrcis in Analytical Chemistry; 2016

Universidad de Barcelona

Fluorescencespectroscopy has found in food analysis a large use due to that it is fast,gives direct measurement, is not destructive and noninvasive [1]. In this work,the potential of excitation emission fluorescence matrix (EEM) data recordedwith a front face system along with chemometric methods was investigated forthe determination of spoilage on mayonnaise and for the rapid prediction ofchanges of microbial flora (counts of bacteria). Made in home mayonnaise andcommercial mayonnaises samples were maintained at 25°C during four days, andstored at 37ºC for three days. The microbial load on mayonnaise samples wasdetermined per day. Total viable count (TVC), aerobic mesophilic bacterias,Staphylococcus aureus, Escherichia coli and Salmonella were determined onmayonnaise at each step using culture methods. In parallel, mayonnaise sampleswere analyzed by 3D front-face fluorescence spectroscopy, without priorpreparation, at 8 and 6 different times for the samples stored 25 °C, and 37°C,respectively. The data matrices were recorded varying the excitation wavelengthbetween 230 and 400 nm each 10 nm, and registering the emission spectra from300 to 600.5 nm each 0.5 nm. Thus, the EEMs were of size 18×602. PARAFACanalysis allowed capturing the changes occurring in the fluorescence spectraldata. The best PARAFAC models showed 3 components for data recorded bothtemperatures. Profiles of main compounds were extracted with this algorithmdescribing quality evolution on the time. In order to meet those compounds thattheir concentration decreases and those that are produced (specifically aminoacids) a chromatographic analysis was performed [2]. The chromatographicanalysis confirms thedecrease of tyrosine and the production of tryptophan in the time. Partialleast squared discriminant analysis (PLSDA) was applied to data set formed byconcatenating of all the fluorescence spectra at same temperature for testingthe allocation of the spectra of the individual samples within the five andfour groups corresponding to the five and four investigated storage times. Theresults showed that 100% of good classifications were obtained using 3 PLSfactors. These results allowed the classification of samples as a function ofstored time. In addition, this information can be related to the microbialcounts. In order to evaluate other quality parameters, a study with opticalfibers is being performed. EEMs were obtained through the degradation kineticsof mayonnaise produced by irradiation the samples each twominutes for a total of 20 minutes. Third order data analysis will be directedto the fat content evaluation as well as at the content of different dressingof mayonnaise for obtaining information about the quality mayonnaises.References:[1] A.Cifuentes, D. Rutledge, TrAC-Trend Anal. Chem., 52, 1 (2013)[2] J.R.Lakowicz, Principles of Fluorescence Spectroscopy, Springer, 3, 63(2006)