Application of infrared spectroscopy using Fourier transformation in the analysis of bioactive compounds of citrus fruits – systematic review

Iva Mračić Raič¹, Daniela Čačić Kenjerić², Nela Nedić Tiban²,Lidija Jakobek²

¹University of Dubrovnik, Department for Mediterranean Plants, Marka Marojice 4, 20000 Dubrovnik, Croatia
²Josip Juraj Strossmayer University of Osijek, Faculty of Food Technology Osijek, Franje Kuhača 18, 31000 Osijek, Croatia

ARTICLE INFO	ABSTRACT
TYPE: Review https://doi.org/10.17508/CJFST.2026.18.1.04 PDF	Citrus fruits (Citrus spp.) constitute a significant portion of global agricultural production due to their rich nutritional profile and the presence of bioactive compounds with positive health effects. Phytochemicals such as flavonoids, carotenoids, phenolic acids and terpenoids contribute to the antioxidant, anti-inflammatory and cardioprotective effects of citrus fruits and make them important and functional foodstuffs. Infrared spectroscopy coupled with Fourier transformation, or FTIR spectroscopy, is increasingly used as a rapid, non-destructive, and reliable method for analysing the chemical composition of fresh and processed citrus fruit samples, including juices, pulp, peel, and essential oils. FTIR enables the identification and quantification of bioactive substances by detecting characteristic vibrational bands. In combination with chemometric techniques such as principal component analysis (PCA) and the method of partial least squares regression (PLSR), it allows for the accurate classification and estimation of the content of bioactive compounds. The method has also proven useful for authentication, quality control, and the analysis of citrus waste and by-products. Despite its many advantages, FTIR spectroscopy has limitations in the analysis of complex mixtures and low concentrations of compounds, as well as poor selectivity compared to methods such as high-performance liquid chromatography (HPLC) or gas chromatography with mass spectrometry (GC–MS). Therefore, it is often used in combination with other techniques to increase analytical accuracy and specificity. Thanks to its simplicity, speed, and ability to analyse different matrices, FTIR spectroscopy is a valuable tool in food and agricultural science, especially in the context of quality control and valorisation of bioactive compounds in citrus fruits.
*CORRESPONDENCE Iva Mračić Raič iva.mracic@unidu.hr
ARTICLE HISTORY Received: January 7, 2026 Accepted: March 19, 2026
CITATION Mračić Raič I, Čačić Kenjerić D, Nedić Tiban N, Jakobek L. Application of infrared spectroscopy using Fourier transformation in the analysis of bioactive compounds of citrus fruits – systematic review. Croatian Journal of Food Science and Technology (2026) 18 (1) 51―69
COPYRIGHT: © 2026 by the author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).
	KEYWORDS FTIR spectroscopy; citrus fruits; bioactive substances; chemometrics; quality analysis
	KEY CONTRIBUTION An overview of the application of FTIR spectroscopy as a fast, non-destructive method for the analysis of bioactive compounds in citrus fruits and their products is shown here. It highlights the advantages of combining FTIR spectroscopy with chemometric tools (e.g. PCA, PLSR) for accurate classification, authentication, and quality assessment of samples. The paper discusses the limitations of the FTIR method in the analysis of complex matrices and compounds in low concentrations and emphasizes the need for complementary techniques such as LC–MS and GC–MS. It emphasizes the potential of FTIR spectroscopy in sustainable food systems, especially in the valorisation of citrus processing by-products.