Rodrigues Maria

To estimate the quality of coastal waters, European Union Directive 2006/7/EC provides guidelines to assess levels of faecal bacteria, including Escherichia coli and intestinal enterococci. These microbiological criteria are based on studies that determine the risk of bathers having diseases caused by enteric bacteria, not necessarily measuring the potential danger associated with the presence of nonenteric pathogens. The association between the presence of faecal contaminant indicators and nonenteric pathogenic microorganisms has not been well defined yet. The purpose of this study is to establish a relationship between Pseudomonas aeruginosa and microbiological indicators of faecal contamination. Presence of microbiological contamination in the coastal waters near the sewage treatment plant (STP) of Peniche (Portugal) was confirmed (P. aeruginosa 135.8 Colony Forming Unit/100 mL, Escherichia coli 1100.1 Most Probable Number/100 mL, intestinal enterococci 2685.9 MPN/100 mL) with much lower levels in the areas located south of the STP, along the main water coastal current (beach 1: 0.7 CFU/100 mL, 16.5 MPN/100 mL, 100.5 MPN/100 mL; beach 2: 0.3 CFU/100 mL, 74.0 MPN/100 mL, 145.9 MPN/100 mL, respectively). Analysis of Pearson’s correlation revealed a strong positive correlation between E. coli and P. aeruginosa, suggesting E. coli as an indicator of P. aeruginosa presence.

Classical methodologies for Salmonella detection may be too long in time to assure public safety. Presently, one of the fastest assays for Salmonella detection using the mini-VIDAS^® system is the Easy Salmonella protocol. This assay, developed for food matrixes analysis, was here assessed for the applicability on the detection of these bacteria in transitional and saltwaters. The presence of Salmonella was detected in 4.2 % of the samples studied. In these transitional waters, the proposed protocol presented an efficiency of 79.1 %, due to a high false positive rate (20.8 %), and a false negative rate of 0 %—implying reducing analysis time, the use of enrichment broths, and making it more cost effective. Despite the multitude of samples nature, the method here described revealed to be an efficient and promising tool for transitional waters analysis.

Colilert® (IDEXX) was originally developed for the simultaneous enumeration of coliforms and E. coli in water samples and has been used for the quality control routine of drinking, swimming pools, fresh, coastal and waste waters (Grossi et al., 2013). The Colilert® culture medium contains the indicator nutrient 4-Methylumbelliferyl-β-D-Glucuronide (MUG). MUG acts as a substrate for the E. coli enzyme β-glucuronidase, from which a fluorescent compound is produced. A positive MUG result produces fluorescence when viewed under an ultraviolet lamp. If the test fluorescence is equal to or greater than that of the control, the presence of E. coli has been confirmed (Lopez-Roldan et al., 2013). The present work aimed to apply Colilert® to the enumeration of E. coli in different foods, through the comparison of results against the reference method (ISO 16649-2, 2001) for E. coli food analysis. The study was divided in two stages. During the first stage ten different types of foods were analyzed with Colilert®, these included pastry, raw meat, ready to eat meals, yogurt, raw seabream and salmon, and cooked shrimp. From these it were approved the following: pastry with custard; raw minced pork; soup "caldo-verde"; raw vegetable salad (lettuce and carrots) and solid yogurt. The approved foods presented a better insertion in the tray, the colour of the wells was lighter and the UV reading was easier. In the second stage the foods were artificially contaminated with 2 log/g of E. coli (ATCC 25922) and analyzed. Colilert® proved to be an accurate method and the counts were similar to the ones obtained with the reference method. In the present study, the Colilert® method did not reveal neither false-positive or false-negative results, however sometimes the results were difficult to read due to the presence of green fluorescence in some wells. Generally Colilert® was an easy and rapid method, but less objective and more expensive than the reference method.

Temperatures higher than 20ºC can boost the growth, on the salted and dried cod surface, of bacteria that present a red pigment (Rodrigues et al., 2003; Rodrigues et al., 2005). These organisms, besides the change of the food product appearance, also cause an unpleasant flavor and the product is rejected by the consumers, although does not cause any health concern. Currently, the export of salted and dried cod, to Africa, has increased and a great amount of product is rejected due to the high environmental temperature and the lack of a proper cold chain storage infrastructure. Vacuum packaging, and modified atmosphere packaging have been used for fresh and cooked seafood preservation, but, as far as the authors know, were never used to preserve salted and dried fish. In the present study it was observed the effect of vacuum packaging, packaging with 80%N2:20%CO2 and finally the addition of sodium metabisulfite on the salted and dried cod stored under temperature abuse (15ºC, 25ºC and 35ºC). Accordingly, packaging under vacum and, specially, packaging with 80%N2:20%CO2 successfuly increased the shellife of salted and dried cod . The addition of sodium metabisulfite has increased the shelflife of salted and dried cod preserved at 15ºC, but not of salted and dried cod preserved at 25ºC and 35ºC.