Intrinsic Fluorescence Markers for Food Characteristics, Shelf Life, and Safety Estimation: Advanced Analytical Approach

Unveiling angular sweep total fluorescence Spectroscopy:A novel multidimensional technique for analysis of complex multi-fluorophoric systems

Analyzing multi-fluorophoric real systems without pre-processing is challenging, often addressed with unconventional fluorescence techniques and chemometrics. In this context, we introduce a novel addition - 'Angular Sweep Total Fluorescence Spectroscopy (ASTFS),' to the arsenal of multidimensional steady-state fluorescence spectroscopic techniques. ASTFS utilizes a series of variable angle synchronous fluorescence spectra, strategically covering the fluorescence region between the first and second-order Rayleigh scattering ridges. The plot features a minimal data matrix size, avoids Rayleigh scattering signals, and incurs no blind regions. The study delves into the instrumental configurations for spectral acquisition, highlights the enhanced spectral resolution due to the band-narrowing effect, and discusses other notable features of the ASTFS plot. Further, this technique is reported to be effective in analyzing analytes in complex systems with strong background fluorescence, such as milk. The antibiotic- Norfloxacin is quantified via minimal pre-processing in milk samples and yields excellent analytical figures of merit.

Light-Emitting-Diode-Induced Fluorescence from Organic Dyes for Application in Excitation-Emission Fluorescence Spectroscopy for Food System Analysis

An experimental study is presented on the possibility of using the fluorescence from organic dyes as a broadband light source together with a monochromator for applications in excitation-emission matrix (EEM) fluorescence spectroscopy. A high-power single-chip light-emitting diode (LED) was chosen as an excitation source with a central output wavelength at 365 nm to excite a fluorescent solution of Coumarin 1 dye dissolved in ethanol. Two excitation configurations were investigated: direct excitation from the LED and excitation through an optical-fiber-coupled LED. A Czerny-Turner monochromator with a diffraction grating was used for the spectral tuning of the fluorescence. A simple method was investigated for increasing the efficiency of the excitation as well as the fluorescence signal collection by using a diffuse reflector composed of barium sulfate (BaSO4) and polyvinyl alcohol (PVA). As research objects, extra-virgin olive oil (EVOO), Coumarin 6 dye, and Perylene, a polycyclic aromatic hydrocarbon (PAH), were used. The results showed that the light-emitting-diode-induced fluorescence was sufficient to cover the losses on the optical path to the monochromator output, where a detectable signal could be obtained. The obtained results reveal the practical possibility of applying the fluorescence from dyes as a light source for food system analysis by EEM fluorescence spectroscopy.

Synchronous Front-Face Fluorescence Spectra: A Review of Milk Fluorophores

Milk is subjected to different industrial processes, provoking significant physicochemical modifications that impact milk's functional properties. As a rapid and in-line method, front-face fluorescence can be used to characterize milk instead of conventional analytical tests. However, when applying fluorescence spectroscopy for any application, it is not always necessary to determine which compound is responsible for each fluorescent response. In complex matrixes such as milk where several variables are interdependent, the unique identification of compounds can be challenging. Thus, few efforts have been made on the chemical characterization of milk' fluorescent spectrum and the current information is dispersed. This review aims to organize research findings by dividing the milk spectra into areas and concatenating each area with at least one fluorophore. Designations are discussed by providing specific information on the fluorescent properties of each compound. In addition, a summary table of all fluorophores and references cited in this work by area is provided. This review provides a solid foundation for further research and could serve as a central reference.