Effect of Frozen Storage on Protein Denaturation and Fatty Acids Profile of the Red Octopus (Octopus maya)

Quality changes in Octopus maya were analyzed during the first, third and fifth month of frozen storage (−18C). The results show that essential ω-3 fatty acids were more affected than protein. The increases in formaldehyde (HCHO) and salt-soluble nitrogen (SSN) were considered to be indicators of protein denaturation; however, until the fifth month, these compounds were not detectable in the SDS-PAGE pattern. No remarkable protein denaturation was evident at the third month of frozen storage, but a significant decrease of 20% was detectable at the fifth month. Trimethylamine nitrogen (TMA-N) and total volatile base-nitrogen (TVB-N) increased during frozen storage but both parameters were within the accepted quality standards. The total content of polyunsaturated fatty acids (∑PUFAs) was the most affected fatty acid group, since ∑PUFAs decreased by 6.07% at the third month and 9.28% at the fifth month. Practical Application The fishing industry is based largely on the cold chain to ensure the commercial viability of their products. Octopus is known for its high content of important components of the human diet, such as high-quality protein, nutritional lipid-soluble vitamins and essential ω-3 polyunsaturated fatty acids that have positive roles in human health. Freezing and frozen storage ensure preservation but this is not a guarantee of absolute quality. This study introduces the changes in protein quality and essential fatty acids in the octopus (Octopus maya) during frozen storage. These results can be used by the fishing industry for the establishment of guidelines such as optimal storage time to prevent the loss of essential nutrients and to enhance quality assurance.