###### Abstract  
Quantitative analysis of carotenoids has been extensively reported using UV-Vis spectrophotometry and chromatography, instrumental techniques that require complex extraction protocols with organic solvents. Fourier transform infrared spectroscopy (FTIR) is a potential alternative for simplifying the analysis of food constituents. In this work, the application of FTIR with attenuated total reflectance (ATR) was evaluated for the determination of total carotenoid content (TCC) in _Cucurbita_ spp. samples. Sixty-three samples, belonging to different cultivars of butternut squash (_C. moschata_) and pumpkin (_C. maxima_), were selected and analyzed with FTIR-ATR (attenuated total reflectance). Three different preparation protocols for samples were followed: homogenization (A), freeze-drying (B), and solvent extraction (C). The recorded spectra were used to develop regression models by Partial Least Squares (PLS), using data from TCC, determined by UV-Vis spectrophotometry. The PLS regression model obtained with the FTIR data from the freeze-dried samples, using the spectral range 920-3000 cm\({}^{-1}\), had the best figures of merit (R\({}^{2}\)\({}_{\text{CAL}}\) of 0.95, R\({}^{2}\)\({}_{\text{PRED}}\) of 0.93 and RPD of 3.78), being reliable for future application in agriculture. This approach for carotenoid determination in pumpkin and squash avoids the use of organic solvents. Moreover, these results are a rationale for further exploring this technique for the assessment of specific carotenoids in food matrices.  
butternut squash; pumpkin; carotenoids; FTIR-ATR; chemometrics; PLS 2020 10 3722 2020 22 May 2020 2020 22 May 2020 22  
used techniques for the evaluation of carotenoids are UV-Vis spectrophotometry and HPLC coupled to diode array detectors (DAD) and mass spectrometers (MS) [3; 5]. These techniques demand high solvent consumption and extensive sample preparation and extraction protocols. In this context, there is an emerging interest in vibrational spectroscopy, more specifically in Fourier transform infrared spectroscopy (FTIR), as a powerful tool for fast and simple analysis of compounds in food matrices, when coupled with multivariate statistical methods [6]. The mid-infrared region (MIR) of the electromagnetic radiation, located from 4000 cm\({}^{-1}\) to 450 cm\({}^{-1}\), contains information arising from molecular vibrations, which is sensitive to the chemical and physical states of the sample. Therefore, several FTIR-based methods have been developed to discriminate and determine various properties of food matrices [7; 8; 9; 10], showcasing an important reduction of chemicals and time consumption, as the main advantage compared to conventional analytical techniques. Moreover, the use of attenuated total reflectance (ATR) devices simplifies the application of FTIR for qualitative and quantitative analysis of materials, including food matrices.  
The capability of this technique for the determination of carotenoids in food matrices has been demonstrated in tomatoes, with good performance in lycopene quantification [11]. However, there are no previous studies of either FTIR-ATR or other MIR-based techniques for the evaluation of carotenoids in pumpkin or squash pulp, two of the richest sources of these compounds among fresh produce. Therefore, the aim of this work was to develop a methodology for the simple and fast quantification of total carotenoid content in _Cucurbita_ spp. samples by FTIR-ATR spectroscopy combined with multivariate techniques.