Abstract
Peanut hulls (PNH) were carbonized at different temperatures, times, and evaluated at different concentrations as an alternative to bleaching clays. Evaluation of bleached crude soybean oil with PNH was based on their delta free fatty acids, reduction in peroxide value (PV), reduction in phospholipids (PL) and bleachability. The performance of several commercially used bleaching clays was evaluated, for comparison. Mixtures were formulated including: PNH and Tonsil -N (TN), PNH and Fuller’s earth (FE) and PNH and O-passive (OP) and examined. The oxidative stability of oils was determined. Results for the investigated commercial bleaching clays revealed: TN > FE > F > TF > OP. Highest reduction in PV and PL, and highest bleachability were achieved for soybean oil bleached with 2% PNH carbonized at 500°C for 30 min (PNH”). Mixtures of PNH” with the three chosen bleaching clays indicated that 1PNH”: 2TN gave the highest bleachability. CSO was miscella bleached in hexane using PNH” and resulted in an appreciable improvement in all oil characteristics, especially in bleachability. Oxidative stability of oils was in the following order: TN > control > FE > PNH” with Induction period values of 23,1 > 6,43 > 5,73 > 2,85 h, respectively.
Highlights
Bleaching is an essential step in the process of the production of edible vegetable oils
Comparing miscella bleaching to conventional bleaching using Peanut hulls (PNH) carbonized at 500°C for 30 min, and to Tonsil -N (TN) and Fuller’s earth (FE) bleached oils it can be seen that miscella bleaching resulted in bleached oil with superior oil color compared to the other bleached oils
The percentage of ∆Free fatty acid (FFA) was slightly lower for miscella bleaching, while the reduction in PL was lower than the other bleached oils, whereas the reduction in peroxide value (PV) for miscella bleached oil was lower than that for TN and FE bleached oils, but higher than conventionally bleached oils
Summary
Bleaching is an essential step in the process of the production of edible vegetable oils. Bleaching is the process of adsorption of mainly coloring matter (pigments) and other minor constituents of the bleaching clays used. During the bleaching of vegetable oils peroxides are degraded and removed, traces of soap and a portion of Cu and Fe are removed and traces of phospholipids are adsorbed. The resistance of oil to rancidity is reduced because some of the natural antioxidants such as tocopherols are removed and partial hydrolysis of the oil takes place (Patterson, 1992; Bailey, 1996; Omar et al, 2003). Neutral or non activated bleaching clays are derived from clay mineral deposits “Bentonite”. The clays used in the edible oil industry range from natural neutral clays to heavily acid activated clays.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
