On-line detection of oil on steel coils and thickness measurement using hyperspectral camera
The control of thickness homogeneity is a major concern in steel industry for quality issues. In the case of oil, an inhomogeneous coating on whole strip surface can create oxidation and lubrication trouble during coiling. Nowadays, different commercial solutions exist on the market (Light induced fluorescence, infrared gauges) but mainly for punctual measurements. The ability of new devices to characterize thin oil layers have been studied in this paper. This poster is focused on the study of spatial homogeneity for oil layer detection on steel surface for potential new online solution. The results presented in this paper confirm the interest of devices working in 3–5 μm spectral range to potentially answer to industrial needs.
Preliminary studies about thermal degradation of edible oils through attenuated total reflectance mid-infrared spectrometry
Abstract Degradation of edible oils during their heating process has been evaluated through the determination of cis -unsaturation and trans -fatty acids together with free fatty acids as a function of time and temperature heating. Two types of cooking oils, sunflower and seed (mixture of different seeds non-detailed), were heated at three different temperatures (147, 171 and 189 °C) during a total time of 1920 min (32 h) shared out in four sessions of 8 h each one, and samples were studied from their spectra obtained by Fourier transform infrared spectrometry using attenuated total reflectance measurements. A critical comparison between different multivariate calibration models built based on full spectra or selected wavenumbers, using both PLS1 and PLS2 algorithms, was carried out for a preliminary evaluation of the heating conditions (temperature and time) of oil samples.
Analytical evaluation of polyunsaturated fatty acids degradation during thermal oxidation of edible oils by Fourier transform infrared spectroscopy.
Abstract The oxidative deterioration of polyunsaturated fatty acids (PUFAs) in culinary oils and fats during episodes of heating associated with normal usage (80–300°C, 20–40 min) has been monitored by Fourier transform infrared spectroscopy (FTIR). The thermal oxidation of PUFAs is a free radical chain reaction, in which hydroperoxides are generally recognized as the primary major products. Hydroperoxides of PUFAs are easily decomposed into a very complex mixture of secondary products with the decrease in unsaturation. The oxidative advance of PUFAs during heating was studied by the determination of unsaturation percentage at different temperatures and heating times. Oils frequently used in food frying such as olive oil, sunflower oil, corn oil and seeds oil (sunflower, safflower and canola seed) were studied. The results show there is a decrease in unsaturation starting at 150°C and becoming more pronounced at temperatures around 250°C. The following variations were found in the unsaturation percentage, expressed as methyl linoleate, between the original sample and the sample heated at 300°C for 40 min: olive oil (19–6%), sunflower oil (29–12%), corn oil (28–18%) and seeds oil (23–11%). This variation in unsaturation grade provides evidence of the transformation of essential PUFAs and subsequent decrease in the oils’ nutritional value. The internal standard method is suitably precise when the n-valeronitrile is used as standard as shown by the 1–2% relative standard deviation (R.S.D.) found for seven replicates.