Oxidative stability, characterization and food applications of a rice bran oil-based structured lipid
Jennings, Brenda Holmes
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Rice bran oil structured lipid (RBOSL) was synthesized from rice bran oil (RBO) and caprylic acid (a medium chain fatty acid) by Lipozyme RM IM lipase-catalyzed acidolysis in a continuous packed-bed reactor. The vitamin E content of RBOSL was significantly lower than RBO while the γ-oryzanol concentration of RBOSL was not significantly different from RBO (P > 0.05). The oxidative stability of RBOSL was significantly lower than RBO (P ≤ 0.05). Natural and synthetic antioxidants were evaluated for their ability to increase the oxidative stability of RBOSL. The natural antioxidant carnosic acid from rosemary extract was as effective as the synthetic antioxidant TBHQ in increasing the oxidative stability of RBOSL. RBOSL contained 32.1 mol% caprylic acid which was primarily at the sn-1,3 positions. Saponification value, iodine value, and viscosity were significantly different for RBO and RBOSL (P > 0.05). Free fatty acid content and smoke point were not significantly different for RBO and RBOSL (P > 0.05). Melting onset temperatures were not significantly different while endpoint and melting enthalpies were significantly different (P ≤ 0.05). Sweet potato chips (SPC) were fried separately in RBO and RBOSL and energy bars (EB) were formulated with RBO or RBOSL. Triangle test (TT) results for SPC showed no significant difference in SPC fried in RBO or RBOSL and TT for EB showed a significant difference in RBO and RBOSL formulations (P ≤ 0.05). Willingness to purchase consumer panel (5 point scale) results revealed that the most frequent response was probably would buy for SPC and EB prepared with RBOSL. Shortening blends were formulated with RBO or RBOSL and palm stearin (PS). The caprylic acid content of shortening blends containing RBOSL and palm stearin ranged from 9.9-22.1 mol%. RBOSL blended with PS was comparable to RBO blended with PS in producing shortening with similar fatty acid profiles, solid fat content, melting and crystallization properties and crystal morphologies similar to commercial shortenings. RBOSL blended with PS can provide a healthier alternative to vegetable oils currently blended with PS to produce trans-free shortenings.