Simple and rapid quantification of total carotenoids in lyophilized apricots by means of reflectance colorimetry and photoacoustic spectroscopy

Photoacoustic spectroscopy (PAS) and reflectance colorimetry are suggested as new tools for the analysis of total carotenoids in lyophilized apricot powders. The data obtained by these two techniques from seven apricot cultivars were compared to those acquired by spectrophotometry and high-performance liquid chromatography. Best correlations were found between the total carotenoid content (obtained by VIS spectrophotometry: 1.2-3.4 mg per 100 g of fresh mass) and colorimetric index a* (a* represents the redness of the investigated sample), as well as either argon-ion laser- or xenon-lamp-based PAS. In all three cases, linear correlations were comparable. However, according to the sensitivity and precision data, expressed via limit of detection and measurement repeatability, the Xe-lamp-based PAS is a preferred approach, followed by colorimetric index a* and Ar-ion laser PAS. The outcome of this research provides sufficient amount of evidence that, analytical methods such as reflectance colorimetry and PAS without the use of any chemicals are feasible for reliable quantification of total carotenoids in freeze-dried apricot homogenates.