Pilot scale refining of mackerel oil from byproducts

Summary

Pilot scale refining experiments have been carried out on crude oil from mackerel residue based on conditions developed in lab scale which include bleaching and deodorization. Bleaching of the mackerel crude oil gave an oil of color 1.0 (Gardner), peroxide number of 0.4 and anisidine number of 4.6. Deodorization of the bleached crude oil resulted in a further reduction in color, a peroxide number of 0.0 and anisidine number of 2.6. Analysis of volatile components of bleached and deodorized crude oil showed a 98% reduction of the volatile components of the crude oil, which was dominated by secondary lipid oxidation products, and had a positive granular zone with anisidine reduction (r = 0.98, p <0.001). Sensory profiling of the refined mackerel oil was carried out in comparison with a fresh mackerel oil added to antioxidants in the form of rosemary extract, a commercial freshly refined cod liver oil and a commercial refined soybean oil. The oils in the experiment were generally described with low sensory intensities in the properties investigated. The freshly refined mackerel oil was very neutral in smell and taste, with 15 of the properties being more neutral (lower intensity) in smell and taste than the cod liver oil and 13 of the properties being more neutral than the soybean oil, but was characterized by slightly higher odor and taste of fatty fish. Estimated yield of a fully refined oil, including winterization, was only 37%. The highest loss is due to winterization of the oil and it is further recommended to optimize this refining step to increase the yield.