Surface-enhanced Raman spectroscopy study of commercial fruit juices

Surface-enhanced Raman Spectroscopy (SERS) is a vibrational spectroscopy holding potentials for a rapid evaluation of quality and composition of food industry products without any need of sample preparation. Among many nanomaterials, gold nanoparticles (GNPs) and their colloidal dispersions have attracted great interest for SERS applications due to their unique properties of small size, large surface area to volume ratio, high reactivity to the living cells, stability over high temperatures. In this frame, a low-cost substrate, based on home-made 30-nm sized GNPs, has been designed and used for the investigation of commercial fruit juices and pulp. Thanks to the use of a wavelet denoising procedure and background subtraction spectra with clear features have been obtained. Their analysis has enabled to evidence the presence of components of great importance for the quality evaluation of the products, such as fructose and pectin. The overall inspection of the results has confirmed the potentialities of SERS in food industry.