EFFECT OF VACUUM FRYING ON THE OXIDATIVE STABILITY OF OILS

The purpose of this study was to evaluate frying oil quality with diff erent assessment methods during vacuum frying of carrot slices. In six consecutive days, palm oil, lard, and soybean oil were fried under va cuum at 105 degrees C for 20 min each hour in an 8-h shift. Peroxide v alue, acid value, carbonyl value, total polar components, dielectric c onstant (Food Oil Sensor reading), viscosity, and fatty acid compositi on were used to evaluate the quality of these oils. Results showed tha t palm oil and lard possess greater thermal stability than soybean oil . The decrease in C-18:2/C-16:0 ratio was greater for soybean oil than the other two oils. Of the assessment methods used, peroxide value, c arbonyl value, total polar components, and dielectric constant all sho wed good correlation with frying time and between each other. Viscosit y was suitable to assess vacuum-fried lard and soybean oil, but not pa lm oil. The measurement of dielectric constant, on the other hand, app eared to be unsuitable to assess vacuum-fried soybean oil.