Chapter 7 - Spectroscopic Technique: Fluorescence and Ultraviolet-Visible (UV-Vis) Spectroscopies

Abstract

Public interest in food quality and production has increased in recent decades, probably related to changes in eating habits, consumer behavior, and the development and increased industrialization of the food supplying chains (Karoui et al., 2010). The demand for high quality and safety in food production obviously calls for high standards for quality and process control, which in turn requires appropriate analytical tools to investigate food. Fluorescence spectroscopy is one of the analytical techniques whose theory and methodology have been extensively exploited for studies of molecular structure and function in the discipline of chemistry and biochemistry (Karoui and Blecker, 2011; Shaikh and O’Donnell, 2017). Even though fluorescence is one of the oldest analytical methods used, it has just, recently, become quite popular as a tool in biological science related to food technology. An indication for that popularity is the increasing number of research publications about fluorescence as well as the introduction of new commercially available instruments for fluorescence analysis, in particular, front-face fluorescence spectroscopy (FFFS). Indeed, traditional right-angle fluorescence spectroscopic technique cannot be applied to thick substances due to large absorbance and scattering of light. Indeed, when the absorbance of the sample exceeds 0.1, emission and excitation spectra are both decreased and excitation spectra are distorted. To avoid these problems, a dilution of samples is currently performed so that their total absorbance would be <0.1. However, the results obtained on diluted solution of food samples cannot be extrapolated to native concentrated samples since the organization of the food matrix is lost. To avoid these problems, the method of FFFS can be used.