30D-19 |
Melting point, specific heat capacity, and enthalpy of catfish visceral oils as affected by extraction and purification process |
S. SATHIVEL1, W. Prinyawiwatkul1, and I. I. Negulescu2. (1) Department of Food Science, Louisiana State University Agricultural Center, Baton Rouge, LA 70803-4200, (2) School of Human Ecology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803-4200 During extraction and purification processes, oil is subjected to temperature changes. Changes in the physical state of oil (e.g., melting from solid to liquid and crystallization from liquid to solid) caused by temperature are known as phase transitions. Melting point, specific heat capacity, and enthalpy of catfish visceral oils during purification process have not been reported. This study evaluated melting point, specific heat capacity (Cp), and enthalpy of catfish visceral oils collected during extraction (crude oil) and purification process (degumming, neutralization, bleaching, and deodorization). Differential Scanning Calorimetry was used to determine melting point, Cp, and enthalpy of catfish visceral oils and individual fatty acids. Duplicate experiments were conducted. The phase transition of catfish oils occurred over a wide range of temperatures. The melting points of -46 to 20.4°C for crude oil, -46 to 11.4°C for degummed oil, -44.1 to 11.3°C for neutralized oil, -48.0 to 10°C for bleached oil, and -51.4 to 7.3°C for deodorized oil were observed. Catfish oil contained over 60% unsaturated fatty acids (UFAs) that had negative melting points. The negative onset melting points of catfish oils were attributed to these UFAs. There was a decrease in the melting point up to 61.9, 80.6, and 88.6°C for addition of one, two, and three double bonds to C18:0. Similar trends were observed for enthalpy. The enthalpy was 73.9 J/g for crude oil, 73.5 for degummed oil, 74.2 for neutralized oil, 79.6 for bleached oil, and 84.7 for deodorized oil. The enthalpy increased after each purification step that removed impurities from the oils. Cp at 20°C for crude, degummed, neutralized, bleached, and deodorized oil was 1.64, 1.96, 1.97, 1.88 and 1.79 j/g.°C, respectively. Information on melting point, specific heat capacity, and enthalpy of catfish visceral oil is useful and essential for proper design and process optimization during purification process.
Session 30D, Food Engineering: Physical and chemical properties
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