FTIR-ATR Spectroscopy Combined with Multivariate Regression Modeling as a Preliminary Approach for Carotenoids Determination in Cucurbita spp.

Natalia Quijano-Ortega,Silvia Grassi,Carlos Alberto Fuenmayor,Carlos Zuluaga-Dominguez,Sanín Ortiz-Grisales,Consuelo Diaz-Moreno,Maribel García-Mahecha

doi:10.3390/app10113722

Natalia Quijano-Ortega, Silvia Grassi + Show 5 more

Open Access

https://doi.org/10.3390/app10113722

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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 (R2CAL of 0.95, R2PRED 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.

Highlights

Carotenoids, a complex family of isoprenoids, are relevant in plant foods and agriculture, as nutrients, antioxidants, pigments, and ripening indicators [1,2]
The use of attenuated total reflectance (ATR) devices simplifies the application of Fourier transform infrared spectroscopy (FTIR) for qualitative and quantitative analysis of materials, including food matrices
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

Summary

Introduction

Carotenoids, a complex family of isoprenoids, are relevant in plant foods and agriculture, as nutrients, antioxidants, pigments, and ripening indicators [1,2]. Sci. 2020, 10, 3722 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, 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 use of attenuated total reflectance (ATR) devices simplifies the application of FTIR for qualitative and quantitative analysis of materials, including food matrices

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