Radical Scavenging Activity of Tertiary Butyl Hydroquinone and Assessment of Stability of Palm Oil (Elaeis guineensis) by Ultrasonic Studies

M. Banu, Siddaramaiah and N. Prasad

Abstract
The aim of the current investigation is to evaluate the efficiency of tertiary butyl hydroquinone (TBHQ) as an antioxidant in edible oil like palm oil (Elaeis guineensis) by physical, chemical and ultrasonic properties. The effects of the varying amounts of TBHQ on the oxidation stability of palm oil have been investigated. The antioxidant incorporated palm oil system and control oil were subjected to heating at 180 ± 5 °C continuously for a period of 4 h per day for 4 days consecutively. The parameters used to assess the thermal degradation and oxidation properties of the palm oil include ultrasonic velocity, viscosity and density. Adiabatic compressibility, intermolecular free length, relaxation time, and acoustic impedance have been calculated from experimental data. The effect of thermal ageing on the physical properties of the oil was confirmed by chemical analysis, which included free fatty acid, total polar compounds, and estimation of fatty acids profile by gas chromatography (GC). The chemical changes were studied by FT-IR bands. The results obtained from ultrasonic studies have shown improvement in oxidative stability and retardation in thermal degradation of the antioxidant-loaded oil in comparison with the base oil. Hence, the ultrasonic velocity and acoustical parameters used for assessment of stability of frying oil and palm oil with TBHQ can be recommended for repeated frying without adverse effects on the physical properties.

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Keywords
palm oil, TBHQ, ultrasonic velocity, acoustical parameters, FT-IR, gas chromatography