Evaluation of the Quality Parameters for Some Laser-Irradiated Edible Oils

Abstract

This work focuses on the laser food irradiation; mainly on investigating of the influence of green laser (532nm) radiation on some physicochemical properties of sesame oil before and after storage period of 15 consecutive days, and the effect of heating and reheating on sunflower oil properties using carbon dioxide laser compared with the electrical heater was also studied. The samples of sesame oil were irradiated using diode laser beam with wavelength 532nm and 1 W output power, to duration times of 10, 20, 30, 40, 50 and 60 minutes, and kept for a storage period of 15 consecutive days along with an untreated control at ambient conditions. While two samples of sunflower oil were heated and twice heated with carbon dioxide laser beam up to 50c it takes 30 minutes; another two samples of sunflower oil were heated and twice heated up to 250c using electrical heater in two minutes, along with an unheated control sample at ambient conditions. Physicochemical properties like acid value, ester value, free fatty acids, peroxide value, density, refractive index, viscosity, and moisture of sesame oil and of sunflower oil samples were studied. Fourier transform infrared spectroscopy was used to evaluate the degree of oxidation after irradiation processes of sesame oil and sunflower to differentiate between the chemical changes in the oil samples. The properties of sesame oil were compared at the 1st and 15th day of storage. Color measurements of sunflower oil samples were studied too. Study reveals that green laser irradiation increases ester value, saponification value, acid value, free fatty acids, peroxide value, viscosity and moisture content of sesame oil; while, it slightly change refractive index and density. Study also indicates that the storage period of 15 days decreases the ester value, saponification value, and moisture content; while, it accelerate acid value, free fatty acid, peroxide value, density viscosity, and slightly increases the refractive index. Meanwhile, FTIR spectra of the stored samples revealed a notable difference due to the green laser irradiation and storage. The results also, demonstrated that when the same sunflower oil is reheated, the chemical reactions enhance foaming, darkening of oil color, increased viscosity, and off-flavor. Hence, repeated heating of the oil can lead to degradation of the cooking oil, both chemically and physically. These results suggest that exposing sesame oil to the green laser irradiation influences their oxidation stability and quality. It was also found that the long time of heating using laser rising temperature up to 50°c catalyzed chemical reactions that resulted in effects in the oil samples characteristics greater than the effects of the electrical heater in a few minutes with temperature 250°c.