Características microbiológicas, físico-químicas e sensoriais de filés de tilápias (Oreochromis niloticus) conservados em atmosferas modificadas sob refrigeração

• Ano de defesa: 2006
• Autor(a) principal: Sarmiento, Amada Maria Landa
• Orientador(a): Gomide, Lucio Alberto de Miranda
• Banca de defesa: Soares, Nilda de Fatima Ferreira , Silva, Marco Túlio Coelho
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Ciência e Tecnologia de Alimentos
• Departamento: Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos
• País: BR
• Palavras-chave em Português: Qualidade; Microbiologia; Físico-Química; Análise sensorial; Pescados; Atmosfera modificada
• Palavras-chave em Inglês: Quality; Microbiology; Physicochemistry; Sensory analysis; Fish; Modified Atmospheres
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::TECNOLOGIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/2959

The experiment evaluated the effect of different atmospheres (Vacuum, 100% CO+ Vacuum, and 1% CO + 99% CO2) on the microbial, chemical, sensory (color, odor, slime, and texture) and objective CIELab color profiles of refrigerated (2 ± 1 ºC) Tilapia filets. The results were contrasted against those of filets packaged in air (control). The microbial analyses indicated, in the filets of all treatments: absence of Salmonella in 25 g, sulfite reducing clostridium counts bellow 102 UFC.g-1 and coliform MPN equal or inferior to 23. Aerobe and anaerobe psicrotrophics predominated in every evaluated treatment. In the filets packaged on 1% CO + 99% CO2, aerobic counts of 107 UFC.g-1 were obtained after 18 days of storage and by 13 days on those of the remaining atmospheres. Anaerobic counts of 107 UFC.g-1 were obtained after 10 days of storage on air and over 13 days for the filets packaged on the remaining atmospheres. Lactic acid bacteria of modified atmosphere packaged filets showed an increase of about 4.5 log cycles, reaching 107 UFC.g-1 at about 13 days of storage. On the control atmosphere the growth of lactic acid bacteria was quite inferior, never reaching 107 UFC.g-1. TBARS, pH and NPN values of the tilapia filets were always inside the Brazilian legal limits and were not affected (P > 0.05) by the atmosphere type or storage time; they also did not differ (P > 0.05) from those of the control atmosphere. TNVB values tilapia filets, considered the best chemical index of freshness, varied (P < 0.05) with atmosphere type and storage time. For the filets packaged on the control atmosphere the 30 mg N/100 g limit was reached by 16 days of storage and on the 21st and 22nd days of storage for the filets packaged under vacuum and 100% CO + Vacuum. This limit was never reached in the filets packaged with 1%CO + 99%CO2. The type of atmosphere affected (P < 0.05) the following objective color parameters: L*, with the internal side of filets packaged in 1% CO + 99% CO2 atmosphere and the external side of filets packaged in 1% CO + 99% CO2 and 100% CO + Vácuum becoming paler; a*, with the internal side of the filets packaged in 1% CO + 99% CO2 and 100%CO + Vácuum showing redder (P < 0.05) than those of the remaining atmospheres; b*, with both sides of the filets packaged in 1% CO + 99% CO2 differing (P < 0.05) from those packaged in the remaining atmospheres; c*, with color intensity of the internal side of filets packaged in 1% CO + 99% CO2 differing (P < 0.05) from those packaged in the remaining atmospheres; and h*, with color hue of both sides of vacuum packaged filets differing (P < 0.05) from all the remaining atmospheres. During storage time it was verified (P 0.05): increase of L*int in the filets packaged in 1%CO+99%CO2 and L*ext in the filets packaged in 1% CO + 99% CO2 and 100% CO + Vácuum, yielding a paler color; increase of b*int and b*ext in the filets packaged in 1% CO + 99% CO2, turning them yellowier; increase of c*int in the filets packaged in 1% CO + 99% CO2, increasing their color intensity; decrease of h*int in the vacuum packaged filets. Color scores showed (P < 0.05) that filets packaged in CO based atmospheres (1% CO + 99% CO2 and 100% CO + Vácuum) always presented more pleasant color during storage. Slime and texture scores were affected (P < 0.05) by atmosphere type and storage time. Odor scores showed (P < 0.05) that filets odor became unpleasant (non characteristic) during storage as well as that filets packaged with air were the ones showing (P < 0.05) greater, and faster, odor deterioration. It is concluded that the use of modified atmospheres, in special those of 1% CO + 99% CO2, promote, during the evaluated storage time, better tilapia filets quality, inducing a slight reduction in microbial growth, more pleasant and stable sensory characteristics and lower alteration rate of chemical indexes, specially of TVNB.