Fluorescence Characterization of Standard, Mutant and Sweet Corn

Abstract

This work resulted in the development of a method based on fluorescence spectroscopy to differentiate between three corn varieties, standard, mutant and sweet, and to characterize the corn variety present in finished products. This was achieved by recording fluorescence emission spectra as a function of excitation wavelength. For a standard, non-transgenic and non-sweet corn, the maximum of the first peak is around 412–414 nm at the excitation wavelength equal to 280 nm and shifts to the longer emission wavelengths as the excitation wavelength increases. Also, the second peak is located at 535 nm or is slightly higher (537 to 540 nm) and does not vary for excitation wavelengths from 280 to 360 nm. For mutant corn, the position of the first peak is located at 420 nm and above for λ_ex = 280 nm, while the second peak starts at 525–530 nm (depending on the mutant) and never reaches 535 nm. Finally, for a sweet corn, the position of the first fluorescence emission peak is around 430 nm. If the sweet corn is non-hybrid, the position of the second emission peak is at 535 nm. A hybrid sweet corn has its second peak around 530 nm. Thus, fluorescence emission at 530 is characteristic of corn that has undergone natural or artificial genetic transformation. Finally, we found simple mathematical equations to calculate the percentage of amylopectin and amylose in a given corn.