Mechanisms of deodorizing rapeseed oil with ethanol steam at a low temperature: A focus on free fatty acids, tocopherols, and phytosterols

Previous studies have demonstrated that deodorization of oil with ethanol steam at a low-temperature (L-ESD) can achieve the same effect in removing harmful substances and preserving micronutrients while better inhibiting the formation of new harmful substances compared to deodorization with water steam at a high-temperature. To elucidate the mechanism of ESD, the kinetics and thermodynamics of ethanol steam deodorized distillate were studied in comparison with those of water steam deodorized distillate. Results revealed their deodorization kinetics and thermodynamic models, and further indicated that the additional effects of ethanol steam on free fatty acids (FFAs), tocopherols and phytosterols were related to their intermolecular forces besides the higher vapor pressure of ethanol compared to water steam, and the difference of intermolecular force of ethanol on the various FFAs, tocopherols or phytosterols depended on the number of double bonds, the number, lengths of the substituents and hydrophobicity through comparing the difference of structure between substances.