Vibrational spectroscopic analysis of hake (Merluccius merluccius L.) lipids during frozen storage

摘要

Vibrational spectroscopy (mid FTIR and FT-Raman) was used to monitor lipids extracted from hake fillets during frozen storage. Kramer shear resistance was used as a marker of texture changes and lipid damage was also investigated by following the development of conjugated dienes and free fatty acids by spectro-photometric methods. Results show that the intensity of the free fatty acid carboxylic v(C=O) band measured by ATR-FT1R spectroscopy can be used for monitoring the development of lipid hydrolysis in hake lipids. Changes in the Raman v(C=C) stretching region (1658 cm"1 band), partially attributed to conjugated dienes development, were the only observed spectroscopic alterations related to lipid oxidation of hake lipids during frozen storage at -10℃. The high correlation of free fatty acids with instrumental texture and the disappearance of the v_as(PO_2~-) band are consistent with membrane lipid hydrolysis being one of the factors directly related with toughening of lean fish flesh.