Fig. 2. Demonstration of the changes in autofluorescence that occur during fluorescence quenching. The natural autofluorescence of milled white rice is the white rice line. The scan of white rice spotted with carotene was subtracted from the scan of white rice. The resulting subtraction line is the absorption spectrum of the ß-carotene in the dry endosperm matrix. The net integrated fluorescence intensity is obtained from the 505- to 565-nm region of a fluorescence spectrum.