Refining of high-frr fatty acid olive oil
2011
Abd El-Salam, A.S.M. | Doheim, M.A. | Sitohy, M.Z. | Ramadan, M.F.
The objective of the present work was to improve the quality of high-free fatty acid olive (HFFAO) oil. Normal silica gel (SG) adsorbent was used by applying filtration and stirring techniques. On the other side, chemical treatments with alkali using NaOH HFFAO oil samples were stored under accelerated conditions for 30 days. The progress of oxidation at 60°C was followed by measuring the formation of oxidative products [peroxide value (PV) and p-anisidine value (AnV)], total phenolic compounds (TPC) and recording radical scavenging activity (RSA) toward 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The results indicated that SG and alkali treatments were effective in reducing the acidity of HFFAO oil. Generally, alkali treatments reduced the acid value of HFFAO oil, while treatments with SG induced variable degrees of improvements in HFFAO oil acidity. Alkali treatments resulted in increasing the PV levels to 35 and 28 meq peroxide kg-1 oil for HFFAO treated with soda and lime, respectively. The corresponding improvement in the PV reduction (%) for HFFAO oil using SG was in the range of 10.5% to 47.3%.Treatments with SG or alkali resulted in reduction of AnV, whereas filtration with SG had a remarkable effect on AnV. Levels of TPC were reduced (ca. 70%) with alkali treatments, while treatments with SG also resulted in reduction (ca. 22-48%) in the TPC levels. Antiradical properties of HFFAO oils were compared using stable DPPH free radicals. After 60 min incubation with DPPH, 78% of DPPH radicals were quenched by control sample, while HFFAO oils treated with SG or alkali were able to quench from 48 to 56%. During autoxidation experiments the same trends of results was noted for both control and treated oils.
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