Ultrasound waves increase the yield and carotenoid content of lipid extracted from cephalothorax of Pacific white shrimp (Litopenaus vannamei)

Abstract

Lipids from cephalothorax of Pacific white shrimp (Litopenaus vannamei) were obtained using solvent extraction and ultrasonic assisted extraction (UAE). Among all solvents used, the mixture of hexane:isopropane (1:1) provided the highest yield (25.32% dry weight basis) and carotenoid content (1.97 mg/g lipid). When ultrasonication with different amplitudes (50-90%) was used for 25 min, the highest yield was obtained at 80% amplitude (p < 0.05). With the same ultrasonication time, UAE with continous mode rendered the higher yield than pulse mode (p < 0.05). Lipid extracted with hexane:isopropanol mixture with UAE process had the yield of 49.81%. Phospholipids were major constituents of lipids extracted by solvent extraction. However, more free fatty acids, mono and diglycerides were found in lipids extracted by UAE process, indicating increased hydrolysis. UAE process resulted in higher oxidation of lipids as evidenced by increased peroxide values (PVs) and thiobarbituric acid reactive substances (TBARS). Those alterations were more pronounced in lipids extracted using UAE with continuous mode than pulsed mode as confirmed by fourier transform infrared (FTIR) spectra. Overall, UAE process markedly increased the yield of lipids from shrimp cephalothorax, but oxidation and hydrolysis took place to some degree.

Practical applications: Cephalothorax of Pacific white shrimp contains high value products, especially lipids rich in polyunsaturated fatty acids (PUFAs) and astaxanthin. These value-added products could serve as excellent source of nutrients as well as bioactive compounds with proven health benefits. The extraction yield of lipid and carotenoid was significantly higher when UAE was implemented, compared to the conventional solvent extraction method. The lipids extracted by UAE process were found to have high free fatty acids (FFAs). The lipids rich in FFAs can be used as alternative raw material for manufacturing of biodiesel or other marketable products.

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