The objectives of this study were to ascertain the efficacies of Carnobacterium divergens V41 and its supernatant V41 as treatments to control Listeria innocua 2030c during salmon-trout (Oncorhynchus mykiss) cold-smoking processes by treating the raw fish fillets. Fillets were dip-inoculated with 2% (v/v) culture of L. innocua 2030c and/or 2% (v/v) culture of C. divergens V41 culture and 2% or 5% (v/v) of culture supernatant V41. Fillets were dry-salted for 6 h and an average salt content of 5.3% (water phase salt) was obtained. Salted fillets were cold-smoked for 5 h (3 h of drying + 2 h of smoking) and stored at 5 °C for 3 weeks in vacuum packs. The % of salt in the water phase was determined for all fillets. Sensorial analyses were performed in order to compare treated/untreated cold-smoked salmon-trout fillets to ascertain potential spoilage odours due to the treatments. All the treatments with C. divergens V41 or supernatant showed a significant inhibitory effect on L. innocua 2030c growth, but the 5% (v/v) C. divergens supernatant treatment, was by far the most effective against this species. No significant off-odours were found in the products with respect to the tested treatments.

This study was conducted to evaluate the efficacy of gaseous ozone exposure on Listeria innocua 2030c growth during cold-smoke processing of Oncorhynchus mykiss (salmon-trout). Three sets of experiments were performed: inoculation with L. innocua 2030c followed by a 20 min ozone exposure were applied to (a) fresh salmon-trout after filleting, (b) to fresh whole fish, and (c) to fresh whole fish after removal of the fish slime. In sets (a) and (b) fillets were subsequently cold-smoked but not in set (c). The ozone concentration inside the exposure chamber after 20 min reached 0.1 × 10−3 g/l. Counts of L. innocua 2030c were performed after treatment for sets (a), (b) and (c), after smoking and weekly during 21 days in vacuum packs at 5 °C, for sets (a) and (b). Sampling for total Aerobic Plate Counts (APC) of non-inoculated samples was also performed in set (a). The percentage of salt in the water phase, peroxide values and the effect of treatment on sensory properties of cold-smoked salmon-trout fillets were also determined in the first and second set. In the first set, a decrease of less than 1 log10 in L. innocua numbers occurred on ozone treated samples in all sampling occasions. APC was slightly lower on fresh fillets after treatment and on smoked fillets at 3 weeks of storage at 5 °C (less than 1 log10 CFU/g). In the second set, a reduction greater than 1 log10 L. innocua/g occurred on smoked fillets at the end of the storage period. In the third set, the slime removal resulted in a 1 log10 L. innocua/g reduction on fresh treated samples. Ozone treatment had no significant (p > 0.05) effect on L. innocua counts on samples compared to those on untreated fish. In both sets, no significant differences among ozone treated/untreated samples were noticeable by sensory evaluation (p > 0.05).

A população está cada vez mais consciente de que uma boa alimentação combinada com exercício físico regular ajuda a prevenir doenças e a melhorar tanto o bem-estar físico como o mental [1,2]. Uma dieta equilibrada, cujo modelo mais reconhecido é o da «dieta mediterrânica», permite o correto funcionamento fisiológico do organismo e ajuda a prevenir e a diminuir o risco de sofrer de certas doenças. No entanto, uma ingestão excessiva de alimentos muito energéticos, ricos em gorduras saturadas e hidratos de carbono e pobres em fibra, assim como alimentos com um elevado teor em sódio, podem aumentar a incidência de determinadas doenças, principalmente as cardiovasculares. A combinação de hábitos alimentares pouco saudáveis com um estilo de vida sedentário contribuiu para o incremento da prevalência de certas doenças crónicas e de transtornos relacionados com a alimentação (doenças cardiovasculares, hipertensão, obesidade, diabetes, osteoporose, doenças dentais e alguns tipos de tumor, entre outros) [3-6]. Normalmente, não existe uma relação direta de causa-efeito entre estas doenças e a alimentação, mas considerase um dos fatores que contribui para aumentar o risco de ocorrência e desenvolvimento das ditas doenças. Calcula-se que 80 % dos casos de doenças cardiovasculares, 90 % dos casos de diabetes tipo 2 e 33 % dos tumores poderiam ser evitados, teoricamente, se a população seguisse uma boa prática no que se refere à alimentação, à ingestão de álcool, à realização de atividade física e ao tabagismo [7]. Perante estas evidências, a Organização Mundial da Saúde (OMS) [7,8], conjuntamente com a Comissão Europeia [9] e os governos dos Estados membros da União Europeia, já assinalaram a nutrição e a promoção de bons hábitos alimentares como fatores determinantes para a prevenção e redução da incidência destas doenças.

This study was conducted to evaluate the efficacy of the mini-VIDAS Listeria monocytogenes (LMO) system (BioMe´rieux Vitek, Inc., Missouri, USA) for detection of L. monocytogenes in environmental and fish samples from three Portuguese cold-smoking plants and from their fresh fish suppliers. Mini-VIDAS-LMO is a fully automated system that uses fluorescent ELFA (Enzyme Linked Fluorescent Assay) technology for detection of Listeria monocytogenes antigens in food. It can be a rapid screening method alternative to time consuming classical isolation and identification. Two hundred and ninety five samples were tested in mini-VIDAS-LMO and in parallel by the ISO 11290-1 traditional protocol. The mini-VIDAS-LMO detected 8 of the 11 confirmed positive samples and presented 11 false positive results. The specificity of the mini-VIDASLMO found in this experiment was 0.96 and the sensitivity 0.73

Low levels of occurrence of Listeria spp. in fresh salmon (Salmo_salar ) and salmon-trout (Oncorhynchus mykiss), may be related to the selectivity of the pre-enrichment broth recommended by ISO 11290-1. The purpose of this study was to compare the abilities of Fraser base (without supplements) and 0.1% (w/v) peptone water for recovering Listeria spp. from the fresh fish samples. Fifty-six fish were swabbed and the swabs placed in Fraser base and in 0.1% (w/v) peptone water. Samples were analysed 4–6 h later following the ISO 11290-1 protocol. A total of fifteen Listeria spp. positive samples were found. Three and twelve samples were found to contain respectively, L. monocytogenes and L. innocua. The Fraser base did not detect any of the three L. monocytogenes positive samples. Only two Listeria spp. positive samples were simultaneously recovered by the two broths.

Traditional smoked and/or cured salami-like products are much appreciated by Southwest European consumers. However modern consumers require products that not only have high appealing sensory attributes but are also safe. In this work the effect of the application of two bacteriocinogenic lactic acid bacteria (LAB) Lb. plantarum ST202 and Lb. sakei ST153 for controlling Listeria monocytogenes growth in "Alheira", a traditional salami-like product, was investigated. The paste of "Alheira',' produced by an industrial meat company, was sterilized by autoclaving before inoculation and L. monocytogenes growth was evaluated during 15 days of storage. Both LAB strains showed antilisterial activity in the inoculated paste, but as in preliminary experiments with sterilized minced pork meat only strain ST153 presented activity against L. monocytogenes. it was decided, for further industrial tests, to use only this strain. Therefore, the effect of Lb. sakei ST153 against L. monocytogenes in industrially processed "Alheira", packed under vacuum or under modified atmosphere (MA) (20 % CO2 and 80 % N-2), was evaluated during 7 days storage at 4 degrees C. The effect of the inoculation of the bacteriocinogenic culture in the organoleptic properties of "Alheira" was also investigated. A quantitative descriptive sensory test was performed by a semi-trained panel after 5 days storage. No significant differences were observed in the microbiological and sensory quality of "Alheira" packed under vacuum or MA. A significant reduction in the level of L. monocytogenes was observed in the presence of Lb. sakei ST153 (2 log cycles reduction during the first 7 days). Results showed that panellists did not find significant differences between "Alheira" with Lb. sakei ST153 addition and commercial control, except for mass connection, acid taste and atypical taste. Despite that, both samples were scored above conformity limit. Thus, the application of LAB is a very promising mean of preventing L. monocytogenes growth in "Alheira".

Enhanced haemolysis agar (EHA) was compared to the two conventional Listeria isolation agars Oxford and PALCAM for its ability to detect Listeria spp. from production lines of fresh to cold-smoked fish. The ability of EHA for distinguishing L. monocytogenes colonies from other Listeria spp. was also evaluated. A total of 243 fish and environmental samples were analysed. Overall, 42 samples were found to contain Listeria spp. Only 34 samples were positive simultaneously by the three plating media. Two samples considered to be negative by the two conventional agars were found to be positive after isolation on EHA. All three selective agars were shown to be less effective in recovering Listeria spp. after primary enrichment in half-Fraser broth, compared to secondary enrichment in Fraser broth after 24 and 48 h. From 79 Listeria but presumptive negative L. monocytogenes colonies, EHA identified correctly 76 Listeria spp. and presented three false-negative results_three colonies further identified as L. monocytogenes but showing no noticeable haemolysis on EHA. Twenty-three of the thirty-three L. monocytogenes presumptive positive colonies, were confirmed positive and ten were identified as L. seeligeri. Despite its ability of distinguishing L. monocytogenes from the other Listeria spp., unless it is produced as a commercial medium, EHA cannot be an alternative to time-consuming classical identification because the preparation of this medium is both time and labour intensive.

The suitability of Listeria innocua 2030c, a tetracycline-resistant strain, to be used as an indicator for replacing Listeria monocytogenes in challenge studies with cold-smoked fish was ascertained. L. innocua 2030c was compared to serovars 4b and 1/2c of L. monocytogenes, the major types isolated from Portuguese cold-smoked fish products. Growth curves at 30°C, growth/survival patterns at 30°C under exposure to different times and concentrations of ozone and sensitivity to Carnobacterium divergens V41 and C. piscicola V1 and their bacteriocins V41 and V1, were determined. No important differences between L. innocua 2030c and L. monocytogenes 4b and 1/2c were found, therefore L. innocua 2030c can be considered a suitable indicator for replacing those L. monocytogenes strains in challenge studies. Author Keywords: Carnobacterium spp.; Listeria spp.; Ozone

Natural foods with increased nutritional content and additional biological and health benefits are appealing to modern customers. A growing interest in using natural substances to replace synthetic compounds in foods has sparked several thorough studies with plant-origin products. Maritime pine bark (Pinus pinaster subsp. atlantica) is an abundant waste from the timber industry and an important source of natural polyphenolic compounds. These compounds stand out due to their bioactive potential, especially antioxidant and antimicrobial activities, that can be used for preserving foods, increasing their shelf life, safety, nutritional value, as well as reducing food waste. The present work aims to evaluate the efficiency of pine bark extracts for reducing lipid oxidation in a ready-to-eat cured-smoked pork belly product.