Changes produced in oils during vacuum and traditional frying of potato chips.

In this study the effect of vacuum frying (VF) and traditional frying (TF) on oil degradation, fatty acid composition and alpha-tocopherol content was investigated. Two different refined sunflower oils were used: sunflower oil with high oleic acid content (HOSO) and sunflower oil with synthetic antioxidant (tertiary-butylhydroquinone) (TBHQ-SO). Oil degradation was monitored by measuring the free acidity (FFA), peroxide (PV), p-anisidine (p-AV),) total polar compounds (TPC) and oxidative stability (OE). Oils samples were taken every 4h of frying during 10 consecutive days. Values of FFA, p-AV, TPC using TBHQ-SO with traditional frying were (0.201, 207.0, 25.0) significantly higher than the obtained values with vacuum frying (0.073, 25.8, 11.2). The same parameters by using HOSO were (0.327, 82.0, 21.9) with traditional frying and (0.099, 33.3, 6.4) with vacuum frying. The EO was 2.44 and 7.95 with TBHQ-SO traditional and vacuum frying respectively, and with for HOSO 0.65 and 2.67, respectively. The polyunsaturated fatty acids percentage decreased in all treatments except in TBHQ-SOv. The alpha-tocopherol content decreased in all treatments at different rates. At the end of the frying processes the percentages of alpha-tocopherol reduction were TBHQ-SOv (4.90%), TBHQ-SOt (53.62%), HOSOv (96.87%), HOSOt (99.76%).