Effect of Precooking on the Odor of Antarctic Krills

Cooked Odor of Antarctic Krills Part V

Abstract

To keep krills in good quality is one of the important problem in utilizing them for food or food products. The effect of precooking before freezing on the cooked odor of krills were investigated. Both precooked frozen and raw frozen krills were used as materials. The cooked odor concentrates were obtained by a simultaneous distillation and extraction system. Two fractions which showed the characteristic patterns on the preparative gas chromatogram were trapped and the individual fractions were analyzed by combining gas chromatography and mass spectrometry. The compositions of the two fractions were compared between precooked sample and its control (i.e. raw sample). A large quantity of pyrazines was found in the control sample, while precooked sample contained a large quantity of the sulfur containing compounds such as thialdines and trithiolanes with a small amount of the pyrazines. It was presumed that the difference of odor compositions between the precooked sample and its control was caused by the different mechanisms of their formation which influenced by the quantities of ammonia and free amino acids.