Transmission Resonance Raman (TRR) spectroscopy combines increased signal-to-noise ratio with enhanced analytical sensibility. TRR was applied to directly monitor, without any sample preparation, the enhancement of beta-carotene content in table grapes when they are irradiated by low power UV-LEDs. It was shown that, with respect to control samples, the carotenoid content in the grapes increased about five-fold, using UV-LED irradiation doses being two orders of magnitude lower than the maximum limit allowed by United States Food and Drug Administration. These promising results may pave the way for the development of easy, non-invasive techniques to improve food quality. (C) 2013 Elsevier B.V. All rights reserved.