Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Impact of new processing technologies together with the use of 4-hexylresorcinol based mixtures on the quality of crustacean

The first part of the study of the impact of new processing technologies using carbon dioxide in the spoilage and melanosis development of deepwater pink shrimp (Parapenaeus longirostris) concerned the comparison of the different mixtures of antimelanosic compounds when used under normal operating procedures, i.e., immersion application. A commercially available product based on sodium metabisulphite, Melaplus (MP-P) was also used also as a control. The second part of the work involved the study of the efficiency of three mixtures of 4 hexylresorcinol with acetic and ascorbic acids plus EDTA and sodium pyrophosphate when used in conjunction with three new processing techniques, (i) carbon dioxide modified refrigerated seawater, (ii) pressurized dissolved carbon dioxide and (iii) soluble gas stabilization. The results from the first phase did not showed the existence of noticeable differences between the different mixtures, both in sensory and biochemical terms. Though the results were similar to the control in what concerned the biochemical parameters, in sensory evaluation the sulphite based mixture performed better.

The study of the different processing techniques did not showed the existence of clear differences between the batches submitted to the new processing techniques. The sensory and the biochemical data of the pre-treated batches were, in general, rather similar to the data of the control batch with the respective mixture. It was also possible to verify that these results were in what concerns the sensory properties, worst than the data from the control batch with the sulfite based mixture. In conclusion and in what concerns the sensory evaluation it is evident that the use of the pretreatments with CO2 does not brings any significant advantage. Furthermore the use of CO2 has a detrimental effect on texture of the products and makes them tougher and less pleasant. Moreover, the use of 4-HR either isolated on in conjunction with new processing techniques does not bring about any advantage in what concerns the sensory properties of deepwater pink shrimp. In summary it may observed that the processing with carbon dioxide did not introduce a significant benefit in relation to the processing of the shrimps by dipping.
Furthermore, the efficiency of the mixture with 4-HR was also inferior to the one displayed by sodium metabisulphite. It is therefore necessary to continue the effort of research of new melanosis inhibitors, thus testing new formulas.

In what concerns the application of liquid ice, was studied the onboard chilling of deepwater pink shrimp with liquid ice versus the traditional chilling with flake ice. The effect on quality of this treatment was determined after catch and during five days of chilled storage, in order to simulate a characteristic fishing trips of the South of Europe. It was considered of interest to establish if the utilization of liquid ice leads to a higher degree of homogeneity of catches with different days of chilled storage and, if for the same period of storage, liquid ice improves the product quality. An experiment was also performed to study the effect of liquid ice on chilled storage of Norway lobster (Nephorps norvegicus) and red shrimp (Aristeus antennatus), having the effect on ATP and formation of derivatives also being followed.

From the microbiological and biochemical point of view chilling of shrimp on board with liquid ice showed a slight tendency to improve the quality of crustacean as compared with the traditional flake ice. A slight loss of natural coloration with a tendency to become pale was observed in crustaceans treated with sulphites, although never being rejected. Despite liquid ice is a technological process of great interest, it is possible that the implementation on board in small boats, those one day trip, will not be profitable. In this case the application of liquid ice on land will be adequate. Melanosis is not prevented by liquid ice treatment, although under some circumstances, liquid ice could delay the melanosis onset because the layer of small crystal formed could avoid the permeation of oxygen, and therefore diminish the oxidation. Since 4-hexilresorcinol is insoluble in water care should be taken when using it with liquid ice. To prepare a solution it is necessary to dissolved in a small quantity of ethanol, prior to be added to the liquid ice water. By this manner the 4-HR is effective to act in any aqueous solution, including liquid ice.

Liquid ice or binary ice is a new food chilling technique that requires less time to chill products and acts more uniformly than other types of ice. Liquid ice has the potential to be introduced as a successful method for the rapid chilling of crustacean and as a way of reducing the temperature of products below those attained with traditional ice.

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Crta Vieja Ajalvir km 2.2 Polg. Ind. La Garena, Na