Estudo de indices quimicos, sensoriais, microbiologicos e intrumentais para avaliação do frescor de lulas (Loligo plei, Blainville, 1823) armazenadas em gelo

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

Loligo plei is one of major species of squid caught in brazilian seawater. To study the efficiency of tests used like freshness indices and the shelf life of Loligo plei, squids of this species were caught by hand jiggers or purchased at a local market and stored whole in contact ice (CCG) or in non-contact ice (SCG), in polyethylene bags, during a 16 and 15 days storage time for caught and purchased squids respectively. Periodical tests of volatile basic nitrogen (VBN), ammonia, trimethylamine (TMA), non-protein nitrogen (NPN), free aminoacids (FAA), free tryptophan, urea, trimethylamine oxide (O-TMA), nucleotides (just for caught squids), moisture and pH were made to evaluate the usefulness of some of these chemical tests like freshness indicators, determining their correlation with the loss of sensory and microbiological quality. A trained panel with 14 judgements evaluated the sensory changes in squid samples by quantitative descriptive analysis (QDA) and the principal component analysis (PCA) was applied at the data. Periodical counts of psycrhotrophic bacteria (CPsy) and instrumental analysis of color in squid muscle and skin were made too. The leaching effect in CCG treatment was evaluated. The caught squids remained with CPsy smaller than 106 CFU/g during 16 days, but the purchased squids showed CPsy greater than 106 CFU/g from day 10 in both treatments. The PCA indicated that the caught and purchased squids showed good sensory quality until day 7 and 4, respectively, either in contact ice or not. The CCG treatment was more effective (p<0,05) than SCG in preserving appearance of squid muscle. The contents of O-TMA, NPN, FAA, VBN, ammonia, TMA, urea and free tryptophan/1 OOg of muscle were greater (p<0,05) in SCG than in CCG treatment at the end of storage time and except O-TMA, NPN and FAA, the others compounds progressively increased during the storage in SCG treatment, showing these chemical tests were good freshness indicators. Contents of VBN among 22-27mg/100g, for ammonia among 21-23mg/100g, for TMA smaller than 0,5mg/100g, for free Triptophan among 10-12mg/100g and for Urea among 14-19mg/100g indicated good sensory quality for L plei. In CCG treatment, nevertheless, the intense leaching caused a continuous decrease of VBN, Ammonia, O-TMA, NPN and FAA, followed by a progressive increase (p<0,05) in muscle moisture. The contents of these chemical compounds expressed in terms of muscle NPN percentage eliminated the leaching effect, showing a realist evaluation of squid spoilage, and showing those chemical tests good freshness indicators for L plei squids stored in contact ice or not. The nucleotide analysis was not suitable for squid freshness indicator. It was observed a decrease of the luminosity (L*) and an increase of chromaticity of squid skin in both treatments during storage. The increase of a* (red color intensity) and b* (yellow color intensity) in squid muscle was greater (p<0,05) in SCG treatment. The correlation study showed that the increase of TMA expressed in terms of muscle NPN percentage was strongly correlated (p<0,05) with the increase of CPsy. The color parameters and some chemical compounds showed strong linear correlation with sensory descriptors, being therefore very good freshness indicators for L. plei.

ASSUNTO(S)

molusco avaliação sensorial

ACESSO AO ARTIGO

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