Characterization of Aged Lettuce and Chard Seeds by Photothermal Techniques

In this study, photoacoustic spectroscopy (PAS) was used as an option to evaluate aging in vegetable seeds. Aged seeds were characterized by their decrease in germination and vigor, which are important quality measures to obtain healthy and uniform crops. The seed optical parameters obtained with this technique provide information about their composition and physiological quality attributes. Red lettuce and chard seeds, aged and non-aged, were used for these experiments. The thermal diffusivity (α) and optical absorption coefficient (β) were determined for a large number of aged and non-aged seeds. In the case of β, this optical parameter was obtained in the spectral range from 250 nm to 750 nm. The results show statistically significant differences in β values for both types of seeds, with higher values found for non-aged specimens. Also images of scanning electron microscopy for aged and non-aged seeds corroborate marked differences between them. This PAS approach represents a promising method to be applied in the evaluation of seed quality in the food industry.