Effect of minimal refining on the minor constituents and oxidation stability of sunflower seed oil

Question of thesis was "if minimal refining process should be accomplished with the minimum losses of desirable substances for production of sunflower seed oil rich with micronutrient". The overall objectives of the study were to produce oxidatively stable minimal neutralized sunflower seed oil using three chemicals (Ca(OH)2, MgO and Na2SiO3) as alternatives to strong alkali (NaOH), which is used in conventional neutralization method; to optimize minimal neutralization operations by the response surface methodology; to determine optimal process conditions for sunflower seed oil. First part of this study suggested that the minimal operation is possible to obtain sunflower seed oil having high nutrition value by altering the neutralization process. Second part indicated that sunflower seed oils obtained by minimal neutralization having lower free fatty acids (FFAs) content and better oxidative stability than oil neutralized by traditional method. Third part focused on which weak alkaline has higher oxidation stability, minimum FFA content and maximum α-tocopherol content. The estimated optimal values for minimal neutralization of sunflower seed oil were an amount of Ca(OH)2 of 0.30 %, 53.0 ºC and 19.7 minutes; an amount of MgO of 0.38 %, 57.6 ºC and 17.8 minutes; an amount of Na2SiO3 of 0.81 %, 55.7 ºC and 19.1 minutes. It was concluded that the oil neutralized by NaOH had the shortest hydroperoxide and hexanal lag phases, thus, were the least stable oil and oils neutralized by Ca(OH)2, MgO and Na2SiO3 had lower FFA and higher oxidative stability than oil neutralized by NaOH. The oil neutralized by Ca(OH)2 had the lowest FFA, anisidine value and highest total phenolics and α-tocopherol contents and had better oxidative stability than oil neutralized by NaOH. It suggests that Ca(OH)2 could be more effective in producing a high quality oil. Key Words: Sunflower Seed Oil, Minimal Refining, Antioxidant Activity, Lipid Oxidation, Tocopherol