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Efeito da embalagem em atmosfera modificada sobre a validade comercial de filé de tilápia nilótica (Oreochromis niloticus) / Effect of modified atmosphere packaging on shelf life in nilotica tilapia fillet (Oreochromis niloticus)

O objetivo deste trabalho foi determinar o efeito da Embalagem em Atmosfera Modificada (EAM) sobre a validade comercialde filé fresco de tilápia nilótica estocada sob refrigeração de 5±1°C. Ao longo de 22 dias de estocagem, realizou-se acontagem de bactérias heterotróficas aeróbias mesófilas, análise de pH e análise sensorial de filés de tilápia submetidosaos tratamentos de ar atmosférico (100%), vácuo, 50/50 CO2/N2 e 100% CO2. Os resultados foram tratados estatisticamenteatravés de análise descritiva simples. As contagens bacterianas dos tratamentos 100% ar, vácuo e 50/50 CO2/N2 chegarama níveis >log 8,0 UFC/g nos dias 6, 16 e 12, respectivamente. No tratamento com EAM 100% CO2 as contagens mantiveramseentre log 2,8-4,1 UFC/g. O pH diminuiu com o tempo de estocagem em todos os tratamentos, estando sempre dentro dospadrões permitidos (d6,5). O atributo cor foi alterado significativamente pelos tratamentos com CO2, sendo que no vácuo acor manteve-se normal por mais tempo. Pôde-se concluir que a EAM com 100%CO2 apresentou melhores resultados noaumento de validade comercial de filés de tilápia estocados a 5°C, mantendo a contagem de mesófilos e valores de pH emníveis aceitáveis durante todo o período de estocagem de 22 dias.

The aim of the present work was to determine the effect of modified atmosphere packaging on shelf life in tilapia fillet stored at 5.0±1.0°C. The methodology consisted on four treatments of tilapia fillets: atmospheric air (100%), vacuum, 50/50 CO2/N2 and 100% CO2 , stored during 22 days under refrigeration at 5°C. The analyses were: mesophilic aerobic counting, pH and sensorial analysis. Statistical analysis was made by descriptive simple method. The results were: the bacterial counting of the treatments 100% air, vacuum and 50/50 CO2/N2 had arrived the levels >log 8.0 in days 6, 16 and 12, respectively. In tilapias filets with 100% CO2 the microbiological counting had been between log 2.8-4.1 UFC/g). The four treatments presented decreased pH with the time of stockage. The values were d”6.5, that represent acceptable standard. At sensorial analysis all CO2 treatment had significantly changed the fillet tilapia color. At vacuum the color was normal for longer time. The experiment permit conclude that 100%CO2 was the best ones treatment for longer the shelf life of tilapia fillet stored at 5.0°C, with microbiological counting and pH being in acceptable levels during all 22 days of storage.

Attenuated total internal reflection infrared microscopy of multilayer plastic packaging foils.

Multilayer plastic foils are important packaging materials that are used to extend the shelf life of food products and drinks. Fourier transform infrared (FT-IR) spectroscopic imaging using attenuated total internal reflection (ATR) can be used for the identification and localization of different layers in multilayer foils. A new type of ATR crystal was used in combination with a linear array detector through which large sample areas (400 x 400 microm(2)) could be imaged with a pixel size of 1.6 microm. The method was tested on laminated plastic packing materials containing 5 to 12 layers. The results of the identification of the different materials using ATR-FT-IR were compared with differential scanning calorimetry (DSC) and the layer thickness of the individual layers measured by ATR-FT-IR was compared with polarized light microscopy (LM) and scanning electron microscopy (SEM). It has been demonstrated that individual layers with a thickness of about 3 microm could be identified in multilayer foils with a total thickness ranging from 100 to 150 microm. The results show a spatial resolution of about 4 microm (measured at wavenumbers ranging from 1000 to 1730 cm(-1)), which is about a factor of two better than can be obtained using transmission FT-IR imaging. An additional advantage of ATR is the ease of sample preparation. A good correspondence was found between visible and FT-IR images. The results of ATR-FT-IR imaging were in agreement with those obtained by LM, SEM, and DSC. ATR-FT-IR is superior to the combination of these techniques because it delivers both spatial and chemical information.

Fluoride content in bottled waters, juices and carbonated soft drinks in Mexico City, Mexico.

OBJECTIVE: The objective of this study was to analyse 283 samples of soft drinks available in the metropolitan market of Mexico City, Mexico: 105 juices, 101 nectars, 57 carbonated drinks and 20 bottled waters. MATERIALS AND METHODS: Samples of the beverages were analysed using an Orion 720A potentiometer and an Orion 9609BN F ion-specific electrode. RESULTS: Fluoride concentration in the above-mentioned products ranged from 0.07 to 1.42 p.p.m. It was found that fluoride concentrations varied according to the brand, flavour and presentation of the product. The highest mean concentration of fluoride was found in the juices and cola drinks (0.67 +/- 0.38 and 0.49 +/- 0.41 p.p.m., respectively). The mean fluoride concentration for carbonated drinks was 0.43 +/- 0.36 p.p.m. Bottled waters had a fluoride concentration of 0.21 +/- 0.08 p.p.m. CONCLUSIONS: The findings suggest that fluoride ingested through bottled drinks represents an important part of the total fluoride ingested by the population. In view of the wide variation of fluoride concentration in the tested products, it is necessary to implement regulatory guidelines for controlling its concentration in order to prevent dental fluorosis.

Botulism among Alaska natives in the Bristol Bay area of southwest Alaska: a survey of knowledge, attitudes, and practices related to fermented foods known to cause botulism.

OBJECTIVES: Botulism cases due to traditional Alaska Native fermented foods occur periodically in Southwest Alaska. In this population, we conducted a survey on knowledge, attitudes, and practices related to botulism and fermented foods. METHODS: We interviewed 140 adults randomly chosen from nine villages. Data collected included fermented food consumption frequency; knowledge about the cause and symptoms of botulism; and fermented food preparation methods. RESULTS: Most respondents (81%) had eaten Alaska Native fermented foods at least once. Over 70% identified botulism as a foodborne illness, and over 87% believed eating certain Native fermented foods could cause botulism. One-third of fermented food preparers used plastic containers for fermentation. To prevent botulism, 45% vwould consider boiling fermented foods, and 65% would not eat foods fermented in plastic or glass containers. CONCLUSIONS: Despite high awareness of botulism in this population, one-third of fermented food preparers use plastic containers, a practice which may increase the risk of botulism. Misconceptions and acceptable prevention messages about botulism, such as using traditional nonplastic fermentation methods, were identified and included in an educational video.