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Background: Photoacoustic spectroscopy (PAS) is a tool for the rapid and non-destructive identification of materials even without contact. In recent years, there have been several works concerning the applicability of PAS in food analytical measurements. The intention of this work is to identify whether there is a correlation between total carotenoid and the β-carotene content of pumpkin and squash measured by high-performance liquid chromatography (HPLC), spectrophotometry (SP) and PAS., Methods: ‘Crown prince F1’, ‘Veenas F1’, ‘Atlas F1’ and ‘Apollo F1’ (SAKATA) were used as experimental materials. The samples were measured in a fresh state and in a lyophilised condition with HPLC, SP and PAS., Results: The results of SP show that total carotene content varies according to the species and variety. Lyophilisation resulted in lower, although varying carotene content compared to the raw form. Typical PA spectra of pumpkins were determined (300–550 nm), normalized to the carbon black powder. At 17 Hz the amplitude and carotene content shows direct proportionality in the range investigated. Photoacoustic (PA) signal and carotenoid content of pumpkin samples gave a linear correlation (R2 = 0.9821)., Conclusions: The measurement of PA spectra gives reliable information about the total carotene content of pumpkin and squash samples. These findings may allow the use of PAS as a fast tool for the carotenoid determination in squashes and give the possibility of instead for the results to be used for the evaluation of squash varieties currently used for industrial processing in functional food development.

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 (HPLC). Best correlations were found between the total carotenoid (TC) 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 (LOD) and measurement repeatability, the Xe-lamp-based PAS is a preferred approach, followed by colorimetric index a* and Ar-ion laser PAS. Both PAS methods exhibit practically the same Pearson's correlation coefficient (R=0.987 and R=0.991) values. Nevertheless, residual sum of squares (RSS) and residual standard deviation of the linear regression (sy/x) differ markedly. For Xe-lamp-based PAS these parameters were much lower than in the case of Ar-ion laser PAS. Likewise, analysis imprecision amounted to relative standard deviation (RSD) of 1-3 % for Xe-lamp PAS and 2-6 % for Ar-ion laser PAS. On the other hand, as expected, the calibration sensitivity achieved for the PAS signal induced by an Ar-ion laser at 481 run was substantially higher than that of a Xe-lamp at 470 nm. Nevertheless, according to much lower sy/x/ the corresponding LOD for Xe-lamp PAS was still two times lower than that of Ar-ion-based laser PAS (0.59 vs. 1.10 mg per 100 g). Unlike this, Ar-ion laser PAS showed more favourable instrumental precision and standard error of the weighed mean when compared to the Xe-lamp PAS (0.1-0.6 and 0.1-0.3 % vs. 0.5-8.0 and 0.4-1.7 %, respectively). As far as colorimetric indices are concerned, only a* proved to be analytically useful; excellent R but rather modest RSS and Sy/x resulted in LOD value of 0.70 mg per 100 g and acceptable analysis imprecision of up to 3 %. 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. [ABSTRACT FROM AUTHOR]