The aim of this study was to find simple objective analytical methods to assess the adulteration of orange
juice by grapefruit juice. The adulterations by addition of grapefruit juice were studied by 3D-front-face
fluorescence spectroscopy followed by Independent Components Analysis (ICA) and by classical methods
such as free radical scavenging activity and total flavonoid content. The results of this study clearly indicate
that frauds by adding grapefruit juice to orange juice can be detected at percentages as low as 1%.