Headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) analysis combined with 'relative odour activity value (ROAV)' was used to monitor changes in key volatile compounds in peanut oil, soybean oil, rapeseed oil, and linseed oil during ambient storage. Volatile composition and oxidation process were compared among edible oil samples. The differences in the volatile contents of edible oils led to their characteristic flavour. Aldehydes featured a relatively high content and low odour threshold and mainly contributed to the flavour of edible oils. The key flavour compounds included pentanal, hexanal, octanal, nonanal, trans-2-heptenal, and benzaldehyde, which are important oxidative degradation products of oleic acid and linoleic acid. The formation of key volatile oxidation compounds was affected by different oxidation processes during ambient storage. Certain aldehydes increased with oxidation level, whereas other aldehydes initially increased then decreased. Correlation analysis showed that the concentrations of several volatile compounds progressively increased during oxidation. The key volatile oxidation compounds formed during oil storage at ambient temperature are partly different from those generated at high temperatures. Volatile oxidation compounds can be a marker for monitoring the oxidation degree of edible oils during ambient storage.

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A rapid method is developed to facilitate the Fourier transform infrared (FTIR) spectroscopy analysis of edible oils using disposable polyethylene (PE) films as sample support for the determination of the iodine value (IV) and saponification number (SN). For direct IV analysis, quantification is achieved using the cis and trans double band region (3206–2992 cm−1) by a partial least squares calibration model, whereas, SN is directly determined using the area in carbon chain skeleton vibration absorption region (781–650 cm−1). The proposed method is applicable to various edible oils ranging in IV from 7.0 to 190.0 g 100 g−1 and SN from 162.7 to 222.0 mg g−1 with good precision and accuracy (relative standard deviations 0.39 and 0.32%, respectively) relative to the AOCS standard methods but with markedly less sample preparation and analytical effort. Practical Applications: Standard titration methods for determining the IV and SN of edible oils are labor intensive and require complex solvents and reagents. The PE‐film‐based FTIR method is more sensitive than attenuated total reflectance‐FTIR method and free from problems associated with the viscosity of oils, which is practical and easy to operate. The method can further simplify and facilitate simultaneous FTIR IV and SN analyses and is applicable to various edible oils over a wide range. A PE‐film‐based FTIR method is developed to determine the iodine value (IV) and saponification number (SN) of edible oils. The regions 3206–2992 cm−1 and 781–650 cm−1 are selected for IV and SN analysis, respectively. In the graphical abstract the IV and SN calibration and validation figures are presented.

Fats and oils are essential food components. Their quality and safety pose major concerns for consumers and food producers because of factors such as oxidation and rancidity, excessive levels of trans fatty acid (TFA), and widespread adulteration. Thus, a rapid and easy-to-use technique must be exploited for quality parameter evaluation and monitoring to ensure the edibility, safety, and quality of fats and oils. In the last decades, Fourier transform infrared (FTIR) spectroscopy has shown great potential in analyzing fats and oils given its speed and simplicity. FTIR-based analytical techniques for common intrinsic quality parameters, including peroxide value, free fatty acid, moisture, TFA, iodine value, as well as oxidation stability, adulteration, and classification of various fats and oils, are summarized in this review. The advantages and disadvantages of selected infrared spectral accessories and sample preparation and spectral processing methods are highlighted. The prospects and reformative aspects for future application of the FTIR technique in the field of fats and oils are also discussed. This review may serve as a basis for applying FTIR not only in future research but also in the fat and oil industries.

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