# Fluorescence excitation-emission measurements of fish muscle extracts

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## Introduction

The data are used to describe how fluorescence spectroscopic data can be decomposed, the underlying phenomena resolved and the data interpreted by PARAFAC modeling. This may be of industrial importance, since in order to use fluorescence spectroscopy for quality measurements, it is important to understand the underlying factors that govern the measured spectral data. Fluorescence excitation-emission matrices (EEM) of aqueous cod extracts have been measured, enabling the use of PARAFAC for data analysis. The extracts were obtained from frozen-thawed modified atmosphere packed cod fillets from the Barents Sea. The cod fillets were stored at 2°C for up to 21 days. To expand the variation in the product, different frozen storage temperatures, frozen storage periods and chill storage periods were used.

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## Reference

Andersen, C.M. and Bro, R. Practical aspects of PARAFAC modeling of fluorescence excitation-emission data. Journal of Chemometrics, 17:200-215 (2003)

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## Get the Data (Matlab)

The data are available in a zipped MATLAB format (CMA1_fluo.mat). The data file contains the fluorescence spectra in one matrix (AllSamples_X) and the design in one matrix (design). Emission and excitation axes are given by Axis1 and Axis2, respectively.

The design matrix contains:

1. column: freeze storage temperature
2. column: freeze storage time
3. column: chill storage time

If you use the data we would appreciate that you report the results to us as a courtesy of the work involved in producing and preparing the data. Also you may want to refer to the data by referring to

Andersen, C.M. and Bro, R. Practical aspects of PARAFAC modeling of fluorescence excitation-emission data. Journal of Chemometrics, 17:200-215 (2003)

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## Data Description

Fish muscle extracts: Aqueous extracts were made by homogenizing 25 g fish muscle with 75 ml water. The pH was reduced to 5.2 with 2 M HCl and the mixture was heated to 70°C, cooled to room temperature and filtered to remove precipitated proteins. The extracts were stored at -30°C.

Fluorescence spectroscopy: The fish muscle extracts were measured spectrofluorimetrically at 22°C in a 10 by 10 nm quartz cuvette on a Perkin Elmer LS50 B spectrofluorometer. For every sample, an excitation-emission matrix (EEM) was obtained by measuring the emission spectra from 270-600 nm in 2 nm intervals with excitation at every 10 nm from 250 to 370 nm.

Design: A factorial design with two frozen storage temperatures (-20°C and -30°C), four frozen storage periods (3, 6, 9 or 12 months) and five chill storage periods (0, 3, 7, 14 or 21 days at 2°C) was used. Experiments after 3 months of frozen storage at -20°C were left out for practical reasons.