29C-27 |
Rheological properties of menhaden oil as affected by purification process |
S. SATHIVEL1, W. Prinyawiwatkul2, I. I. Negulescu3, J. M. King2, and B. F. A. Basnayake4. (1) Fishery Industrial Technology Center, Univ. of Alaska, Fairbanks, School of Fisheries & Ocean Sciences, 118 Trident Way, Kodiak, AK 99615-7401, (2) Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200, (3) School of Human Ecology, Louisiana State Univ. Agricultural Center, 125 Human Ecology Bldg., Baton Rouge, LA 70803-4200, (4) Dept. of Agricultural Engineering, Univ. of Peradeniya, Faculty of Agriculture, Peradeniya, Sri Lanka The purification process of fish oils including degumming, neutralization, bleaching, and deodorization is designed to remove impurities. Free fatty acids, protein, moisture, and pigments are removed from the oils after each purification step. Removal of impurities may alter the oil rheological properties and flow behavior. The objectives of this work were to investigate the effects of purification steps on the rheological properties of menhaden oil, and to determine the validity of different flow models for describing rheological behavior of menhaden oil. Rheological properties of crude, degummed, neutralized, bleached, and deodorized menhaden oils were determined using a rheometer at 25C. The Herschel-Bulkley, Bingham, Casson and Newtonian models were used to fit to the experimental data. Triplicate experiments were conducted. Based on the Casson model, yield stress values of oils decreased after each purification step. The viscosity of crude oil exhibited a shear-thinning dependence behavior. The highest shear rate index (0.789) was observed in the bleached oil. Removal of non-triglycerides shifted the flow behavior of oils from non-Newtonian closer to Newtonian. The Casson model was most appropriate to describe flow behavior of menhaden oils as it worked well at both lower and higher shear rates. Prediction and mathematical representation of flow behaviors of menhaden oils from each purification step is useful. The knowledge of rheological properties of menhaden oils also helps solve problems related to transfer or movement of bulk quantities of the oils and determines proper unit operations in the processing plant.
Session 29C, Food Engineering: Rheology and texture
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