The purpose of this study was to investigate the efficiency of low temperature fractional crystallization to increase polyunsaturated fatty acid (PUFA) content of fish oil. Effects of temperature, stages of crystallization, rate of cooling, agitation and addition of primary nucleus on separation efficiency were evaluated. Low temperature crystallization of triacylglycerols (TAGs) was used to increase PUFA content of fish oil (initial PUFA content ∼30 g/100 g oil).
To optimize the fractionation process, the effect of fractionation temperature (7, 5, 0 and −5°C), crystallization procedures, cooling rate, agitation and addition of primary nucleus on PUFA content was evaluated.
The best relationship between PUFA concentration (45.8 g/100 g oil) and PUFA yield (51.5 per cent) was attained by performing two-stage crystallization of TAGs at the final temperatures of 5 and 0°C under slow cooling rate (3°C h−1 for first fractionation procedure and 0.7°C h−1 for second stage, until the final fractionation temperature, 0°C, was reached) and slow agitation (3 rpm) and in the presence of primary nucleus, which resulted in 50 per cent increase in PUFA content over the original fish oil.
Determination of iodine and saponification values, refractive index, solid fat content, melting point, cholesterol content of original oil and final fractionated product with the highest PUFA ratio showed that fractionation significantly alters physical and chemical properties of the fraction.
Comparison of iodine value, saponification value, refractive index, solid fat content, melting point and cholesterol content of original oil and the final fractionated product (with the highest PUFA ratio) showed that the fractionation process significantly alters mentioned properties of the initial oil.
The authors thank the financial support of Iran National Science Foundation (INSF) and Tarbiat Modares University Research Council.
Soleimanian, Y., Sahari, M.A. and Barzegar, M. (2015), "Influence of processing parameters on physicochemical properties of fractionated fish oil at low temperature crystallization", Nutrition & Food Science, Vol. 45 No. 1, pp. 2-19. https://doi.org/10.1108/NFS-05-2014-0038
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