The purpose of this study was to find an alternative instrumental method to sensory analysis and to further investigate the aroma properties of spoiling blue crab meat. This was accomplished by use of a Cyranose 320™ Electronic Nose, Draeger-Tubes®, and solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). These techniques were compared to the more established techniques for determining quality of blue crab meat of sensory and microbiological analysis. Three different electronic nose methods were used to evaluate five sequentially spoiled groups of crab meat. The manufacturer's recommended setup only resulted in a 30 % correct separation of the known groups, and only 10 % of the samples were correctly identified when coded unknown samples were used to validate the electronic nose training results. The compressed air method which utilized compressed tank breathing air, filtered through activated carbon and moisture traps resulted in 100 % separation of the known groups, but only correctly identified 20 % of the coded unknown samples. Draeger-Tubes® were found to be more accurate and precise compared with the electronic nose. All 5 groups of samples analyzed using Draeger-Tubes® were found to be significantly different at α = 0.05 using a Tukey-Kramer ANOVA statistical procedure. The coded unknown samples were correctly identified at a rate of 83 %. The simplicity and rapidness of this procedure allows it to possibly be an alternative for the crab industry as an alternative to sensory analysis. SPME-GC-MS found trimethylamine (TMA), ammonia, and indole to best correlate with spoilage of blue crab meat. TMA was found to be sensitive to the minor changes in the early stages (0 - 4 days of refrigerated storage) of spoilage for blue crab meat. Indole corresponded well with sensory results, which suggests that indole may be a promising indicator for detecting early, mid, and highly spoiled samples. It is feasible that these methods can be applied to other crustaceans to determine spoilage level. / Master of Science in Life Sciences

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / The mangrove crab, Ucides cordatus is one of the most shellfish produced in Brazil, but his consumption becomes scarce during closed season. This study aimed development of freezedried products of the mangrove crab stored at ambient temperature and analyze the effect of lyophilization in relation to physicalchemical, microbiological, nutritional and sensory characteristics. Two products were developed: a "freeze-dried crab meat" and "freeze-dried crab cone". The product quality was evaluated through sensory tests, microbiological, TBARS, water activity, water holding capacity, centesimal composition, nutritional value, fatty acids content, and amino acid profile of volatile compounds. The best formulation of the "freeze-dried crab cone", acceptance by the tasters, corresponded to that contained only crab meat and dehydrated condiments. The lyophilized products were stored in two different packages (laminated polyethylene terephthalate) in the period 0 to 120 days of storage at ambient temperature. Both products did not suffer microbiological and sensory changes during this period, occurring only a slight increase in water activity and moisture. As to biochemical characteristics, freeze-dried products showed all essential amino acids in quantities greater than those recommended by FAO. In the freeze-dried products was higher concentration of fatty acids when compared to the fresh beef. The volatile compounds were detected in highest concentrations after rehydration of the product in heated water ( 100  C), mainly in relation to groups of aldehydes (hexanal and pentanal) and alcohol (2-methyl-3- phenyl-propanal and 3,7-dimethyl-1,6-octadien-3-ol). In general, the total volatile compounds were lowered after 240 days of storage at ambient temperature. Therefore, with this research was observed the feasibility of developing lyophilized products ("land crab freeze-dried meat" and "freeze-dried crab cone") the basis of land crab meat can be stored at ambient temperature with sensory attributes, physicalchemical and microbiological characteristics acceptable. / O caranguejo-uÃÃ, Ucides cordatus à um dos crustÃceos mais produzido no Brasil, porÃm o seu consumo torna-se escasso no perÃodo do defeso da espÃcie. Desta forma, o objetivo deste trabalho foi o desenvolvimento de produtos liofilizados do caranguejo-uÃa armazenados à temperatura ambiente e analisar o efeito da liofilizaÃÃo em relaÃÃo Ãs caracterÃsticas fÃsicoquÃmicas, microbiolÃgicas, nutricionais e a sensoriais. Foram desenvolvidos dois produtos: a âcarne de caranguejo liofilizadaâ e âcasquinha de caranguejo liofilizadaâ. A qualidade dos produtos foi avaliada, atravÃs de anÃlises sensoriais, microbiolÃgicas, TBARS, atividade de Ãgua, capacidade de retenÃÃo de Ãgua, composiÃÃo centesimal, valor nutricional, teor de Ãcidos graxos, perfil de aminoÃcidos e dos compostos volÃteis. A formulaÃÃo da âcasquinha de caranguejo liofilizadaâ de melhor aceitaÃÃo pelos degustadores correspondeu Ãquela que continha somente carne de caranguejo e condimentos desidratados. Os produtos liofilizados foram acondicionados em dois tipos de embalagens (laminada e tereftalato de polietileno) no perÃodo de 0 a 120 dias de armazenamento à temperatura ambiente. Ambos os produtos, nÃo sofreram alteraÃÃes microbiolÃgicas e sensoriais, neste perÃodo, ocorrendo apenas um leve aumento da atividade de Ãgua e umidade. Quanto Ãs caracterÃsticas bioquÃmicas, os produtos liofilizados apresentaram todos os aminoÃcidos essenciais em quantidades superiores Ãs recomendadas pela FAO. Nos produtos liofilizados houve maior concentraÃÃo dos Ãcidos graxos quando comparados com a carne in natura. Os compostos volÃteis foram detectados em maiores concentraÃÃes apÃs a reidrataÃÃo dos produtos, em Ãgua aquecida (Â100 ÂC), principalmente, no que se refere aos grupos dos aldeÃdos (hexanal e pentanal) e alcoÃis (2- metil-3-fenil-propanal e 3,7-dimetil-1,6-octadien-3-ol). De modo geral, o total dos compostos volÃteis foi reduzido apÃs 240 dias de armazenagem à temperatura ambiente. Portanto, com essa pesquisa observou-se a viabilidade de desenvolver produtos liofilizados (âcarne de caranguejo-uÃà liofilizadaâ e uma âcasquinha de caranguejo liofilizadaâ) a base de carne de caranguejo-uÃà que podem ser estocados a em temperatura ambiente com caracterÃsticas sensÃrias, fÃsico-quimica e microbiolÃgica aceitÃveis.