Foods (Dec 2022)
Thermomechanical Autovaporization (MFA) as a Deodorization Process of Palm Oil
Abstract
Throughout the vegetable oil industry, there is a focus on eradicating the volatile molecules affecting the aroma or taste of the crude oil, whether it is natural or derived from the extraction process. Refining aims to reduce these compounds to a level acceptable to the consumer. In addition, the famous conventional operation of deodorization calls for high levels of temperature depending on the boiling point used to remove the atmospheric pressure of each molecule. The process implies a vacuum level between 10 to 80 kPa absolute pressure, a temperature generally between 190 and 240 °C, and a duration of 2 to 3 h. These conditions necessarily (inevitably) lead to a decrease in the quality of refined oil. Recently, the application of the Multi-Flash Autovaporization “MFA” operation has shown the possibility of eradicating volatile molecules while adopting relatively low temperature and time levels. Despite the high boiling temperature of the volatile organic compounds (VOC), MFA leads to good efficiency in reducing VOCs and preserving oil quality. The main odorant compounds in the crude palm oil were E-2-Hexenal, heptanal, octanal, nonanal, and decanal. Specific literature can indicate precise boiling temperatures under atmospheric pressure. In addition, many experimental studies have explained the evolution of each molecule and shown how they depend on the operating parameters (inlet oil pressure from 200 to 450 kPa and from 5 and 30 s time of each cycle, and the number of cycles up to 7), and how the empirical mathematical models describe the MFA deodorization, estimate the efficiency of the whole process, and optimize the operating parameters. In this research, the thermodynamic data of absolute pressure volatility versus temperature was used to better identify the removal rate (up to around 87%) implied by an abrupt pressure drop to a vacuum of 5 kPa for p = 450 kPa, t = 25 s/cycle, and the number of cycles (C = 6). The safeguarding of the fatty acid profile illustrated the maintenance of the oil quality.
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