Monitoring LED-induced carotenoid increase in grapes by Transmission Resonance Raman spectroscopy

► A novel application of Transmission Resonance Raman spectroscopy is reported. ► The optical method is simple, noninvasive and can be used on line. ► We show how irradiation with low-power UV-LED photons increases the fruit quality. ► Method application to grapes shows a six-fold carotenoid content increase.