Physical properties and oxidation rates of unrefined menhaden oil (Brevoortia patronus).
Unrefined menhaden oil was evaluated for thermal and rheological properties and its temperature-dependent viscosity and lipid oxidation rate were determined. Peroxide value, free fatty acids, density, specific gravity, water activity, moisture content, and enthalpy of the unrefined menhaden oil were 5.70 meq/kg, 3.80%, 0.93 g/mL, 0.93%, 0.52%, 0.15%, and 20.2 kJ/kg, respectively. The melting point range of unrefined menhaden oil was found to be -69.5 to 27.21 degrees C. The menhaden oil exhibited non-Newtonian fluid behavior at lower temperatures (5 to 25 degrees C), while it behaved like a Newtonian fluid at 30 degrees C. The oil apparent viscosity at 5 degrees C (0.22 Pa.s) was significantly higher (P < 0.05) than that at 30 degrees C (0.033 Pa.s). The average magnitude of activation energy for viscosity of the unrefined menhaden oil was 50.37 kJ/mol. The predicted apparent viscosity agreed (R(2)= 0.9837) satisfactorily with the experimental apparent viscosity. The minimal lipid oxidation rate of the oil was found at 25 and 35 degrees C for 6 h, higher lipid oxidation rates were observed when the oil was heated for 6 h at 45 to 85 degrees C. The rate of lipid oxidation for unrefined menhaden oil was temperature dependent (R(2)= 0.9425). This study showed that the magnitude of the apparent viscosity and oxidation rate of the unrefined menhaden oil was greatly influenced by temperature.
Yin
Huaixia
H
Dept. of Food Science, Louisiana State Univ. Agricultural Center, Baton Rouge, LA 70803-4300, USA.
Sathivel
Subramaniam
S
D000465:Algorithms; D055598:Chemical Phenomena; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D005395:Fish Oils / Q000737:chemistry*; D006358:Hot Temperature / Q000009:adverse effects; D007700:Kinetics; D010084:Oxidation-Reduction; D010545:Peroxides / Q000032:analysis; D012212:Rheology; D013046:Specific Gravity; D013696:Temperature; D044366:Transition Temperature; D014783:Viscosity; D014867:Water / Q000032:analysis
D005230:Fatty Acids, Nonesterified; D005395:Fish Oils; D010545:Peroxides; D014867:Water; C033266:Menhaden oil