Ultrasonic assessment of oil quality during frying.
In this paper, changes in ultrasonic properties during thermoxidation of virgin olive oil were studied. Samples of virgin olive oil were heated over different periods of time from 2 to 16 h at 200 degrees C. Oil degradation was characterized by means of physical and chemical changes, i.e., viscosity, color, polar compounds, polymers, and polar fatty acids. Ultrasonic measurements were carried out while the oil sample was cooled from 35 to 25 degrees C. It was found that velocity and attenuation measurements were related to viscosity measurements through a classical equation for viscous liquids. The ultrasonic measurements were also related to the percentages of polar compounds and polymers, which shows the feasibility of using ultrasonic properties to monitor oil quality. Nevertheless, as long as the ultrasonic measurements are temperature dependent, this variable must be controlled in order to obtain repetitive and reliable measurements.
Benedito
Jose
J
Food Technology Department, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022, Valencia, Spain. jjbenedi@tal.upv.es
Mulet
Antonio
A
Velasco
J
J
Dobarganes
M Carmen
MC
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003116:Color; D005227:Fatty Acids / Q000032:analysis; D005524:Food Technology; D006358:Hot Temperature; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry*; D011108:Polymers / Q000032:analysis; D011786:Quality Control; D014465:Ultrasonics; D014783:Viscosity
D005227:Fatty Acids; D000069463:Olive Oil; D010938:Plant Oils; D011108:Polymers