High dietary salt intake is a risk factor for hypertension and a public health challenge worldwide. The aim of this study was to evaluate the effects of salt substitutes on the safety and quality of selected fish products, i.e., Matjes nordische Art and cold-smoked salmon. Sodium chloride was replaced by various salt substitutes including potassium chloride, potassium lactate, and commercial salt substitutes. Fish samples were characterized comprehensively with regard to microbiological, physico-chemical, and sensory parameters. During storage for 4 weeks at 3 °C, the commercial reference product of Matjes nordische Art (5.2 g salt/100 g) and the sodium-reduced samples (2.7–3.7 g salt/100 g) did not differ significantly (p < 0.05) with regard to aerobic and anaerobic mesophilic counts, organoleptic properties, texture, color, and the growth of Listeria monocytogenes. Moreover, 61 consumers did not discriminate in liking between the reference product and the reformulated samples. During storage for 3 weeks at 6 °C, sodium-reduced samples of cold-smoked salmon (1.4–2.3 g salt/100 g) did not differ significantly from the reference product (2.9 g salt/100 g) with respect to aerobic and anaerobic mesophilic counts, odor, and the growth of L. monocytogenes (at 7 °C). This study indicates the scientific feasibility of a product reformulation of these fish products under laboratory conditions. Before a market launch of the reformulated fish products can be considered, product development trials under real-life conditions including long-term storage trials at retail level will be necessary to meet product-specific safety and quality requirements.

Nile perch (Lates niloticus) is a popular, usually low priced food fish in many countries worldwide, and the most important export fish from Lake Victoria and its adjacent countries Uganda, Tanzania and Kenya. Despite its high import figures, the constantly increasing demand within the EU for ‘new’ fish species and the results of initial studies indicating high coliform bacterial loads, food safety aspects regarding its microbiological as well as parasitological status have been hitherto widely neglected. In the present study imported fresh fish fillets as well as superchilled fish from a German retail market and a Dutch wholesaler were examined to evaluate the current microbiological and parasitological quality. A total of 200 fresh fillets as well as 20 superchilled fish (beheaded, eviscerated, descaled) samples were screened for the presence of helminth parasites by visual inspection, candling, the UV-press method and artificial digestion method. The study includes as well a quantitative test on the recovery rate of metacercarial cysts. Microbial assessment was performed on ten fresh fillets and on the skin and tissue of 20 superchilled fish. Helminth parasites were neither detected in the edible parts nor in the skin of imported products. Results of the microbiological examination revealed low levels of bacterial contamination of superchilled fish samples, whereas high total viable counts and high levels of naturally present bacterial pathogens of the genus Aeromonas spp. and Pseudomonas spp. were identified from the fresh fillets. Our findings indicate that hygienic production conditions have improved in comparison to previous studies. As total viable counts as well as specific spoiling bacteria were high in fresh fillets, we recommend adequate heat treatment of fresh Nile perch fillets before consumption.

SummaryProximate composition, fatty acid profile, other nutritional values and spoilage indicators were examined in the muscle meat of five species: barramundi (Lates calcarifer) from various origins, tilapia (Oreochromis spp.) of different qualities, cobia (Rachycentron canadum) and leather jacket (Aluterus monoceros) from the Pacific Ocean and Patagonian grenadier (Macruronus magellanicus) from South America. Lowest lipid contents (0.4% and 0.8%) were found in leather jacket and cobia. Leather jacket fillets had lowest protein (16.2%) and highest sodium chloride content (4.9%). Concentrations of ∑EPA + DHA were 0.1 g 100 g−1 for tilapia and leather jacket, 0.2 g 100 g−1 for barramundi and cobia and 0.7 g 100 g−1 for Patagonian grenadier. Barramundi and tilapia were characterised by high taurine content (215 and 276 mg 100 g−1 ww.), and cobia had only low levels (41 mg 100 g−1 ww.). Iodine contents were low and selenium levels varied between 303 and 570 μg kg−1 ww. No sign of spoilage was detected.

Introduction: The variety of seafood on the European market has considerably increased in recent years. This study presents data to the main nutritional values and the sensory properties of two exotic fish species, mahi-mahi (Coryphaena hippurus) and emperor sea bream (Lethrinus spp.), sold on retail market in Germany. Information on the quality of frozen and glazed fillets is still missing, but is important to characterize these products. This also includes details on the substances added to increase the water-binding ability. Aims: The paper aims to assess the quality of exotic fish fillets sold on the German market, through the evaluation of physical and chemical parameters, microbiological quality and sensory attributes. Materials and methods: 10 samples of each fish species were analysed after homogenisation to determine the following parameters: pH-value (with a pH meter); water (gravimetrically); ash (in a muffle furnace at 550 °C); salt (NaCl; by auto-titration); fat (by a modified Smedes method); protein (with a LECO TruSpecN based on the principles of the Dumas combustion method); total phosphorus content (photometrically); total volatile basic nitrogen (TVB-N, using the EU reference method); total viable bacteria count (TVC) and specific fish spoiling bacteria (SSO) (by decimal dilutions method). The sensory assessments were done with cooked and fried fillets by a panel consisting of 6 specialists, using a descriptive method. Results: Lipid, ash and salt contents of mahi-mahi were comparable to the emperor sea bream values. Due to low lipid content, both species can be classified as lean species. The protein amount of emperor sea bream was significantly higher compared to mahi-mahi and many other common fish species. In mahi-mahi samples, slightly higher values of total phosphates content were found. The pH values of emperor sea bream were in a normal range for fresh fish, whereas in mahi-mahi significantly higher values were determined which was not correlated with quality deteriorations. TVB-N values in all investigated samples were low and indicate a sufficient fish freshness of the used raw material. The TVC of different mahi-mahi and emperor sea bream fillets indicated a good to sufficient microbiological status. Conclusion: Pleasant sensory properties, low microbiological charge and low fat contents of emperor sea bream and mahi-mahi lead to the conclusion that these exotic fish products are a valuable enrichment of fish products on the market.

Fish sauce, a clear brown Asian condiment with special flavour, comes increasingly in the focus of German consumers who prefer to eat Asian dishes. While Asian people use fish sauce about 20 ml once a day German consumers just use it occasionally. After opening the bottle, many oxidative reactions can occur with sensitive ingredients during storage. For clearing possible ageing 5 fish sauces were kept in a refrigerator at 4 to 8 °C for 12 months as well as subsequent for 6 months at room temperatures (18 to 22 °C) and analysed in intervals of 3 months. Sensory evaluation could not reveal statistically reliable changes (p > 0.05). However, supporting physical measurements by electronic nose could discover differences but without establishing a systematic relation to storage time. The pH values were stable in a required range during the whole storage time. Analysis of free volatile fatty acids showed only little decreases without significant difference in the mean values (p > 0.05). Moreover no changes were observed at the levels of volatile nitrogen and biogenic amines. Three fish sauces showed high amounts of histamine (up to 400 mg/kg), which must be traced back to bad manufacturing practice.

ABSTRACT The four‐plate test (FPT), Premi test and enzyme‐linked immunosorbent assay (ELISA) methods were used for screening oxytetracycline residues in fish samples. FPT is a microbiological inhibition test which uses three media seeded with Bacillus subtilis at different pH values (6, 7.2 or 8.0), and a fourth medium seeded with Micrococcus luteus. Fish fed with pellets containing antibiotics: the inhibition zones increased according to duration of feed application. Fish fed with pellets containing antibiotics: at day 1, the inhibition zone was found to be 2.5 mm wide; at day 4, the zones increased to 12.25 mm wide. The concentration of the residues accumulated and reached a plateau after 4 days. At day 15, the antibiotics were still detectable, but 5 days later (at day 20), they were no longer detectable in the fish samples. According to the Premi test, results of fish samples: fish samples of the control group were found negative, from days 1 to 20; the samples were found positive, at day 25; the samples were found negative. The results showed us that the Premi test and ELISA test were more sensitive than the European Economic Community FPT. In contrast to the FPT, 10 days after discontinuing the medicated diet, there were still residues detectable by the Premi test and ELISA test (at day 20). Data presented show the FPT, Premi test and ELISA test methods are very suitable for screening oxytetracycline residues in trout.PRACTICAL APPLICATIONSThe use of antibiotics above the maximum residue limits could result in unsafe antibiotic residues in food products. Therefore, monitoring antibiotic residues in food products are necessary to prevent unapproved uses of antibiotics. The aim of the present study was to determine the most useful method for screening oxytetracycline residues in trout.

The composition and the quality status of organically and conventionally farmed rainbow trout (Oncorhynchus mykiss) from German aquaculture and hot-smoked products thereof were investigated. The chemical composition of raw trout exhibited differences in the fat content of the edible part (1.7-4.7 %). All contaminant levels were far below national limits. Portion size samples had appreciable amounts of n-3-fatty acids EPA and DHA as well as a high vitamin D content. Differences among some fatty acids between both raising forms were nourish-physiologically insignificant. The overall quality and the microbiological status of freshly harvested rainbow trout from all selected farms were excellent. Differences in quality attributes were observed between different farms, but not between organic and conventional rearing and processing conditions.The effect of cold storage at +4 degrees C up to 24 days was studied by monitoring the microbiological, chemical, physical and sensory changes occurring in unwrapped hot-smoked rainbow trout and in vacuum-packed products. No reproducible effects of the production style on the shelf life were observed in the analyzed samples. The sensory quality decreased throughout the storage period, but none of the samples was spoiled at the end of storage.

Die Aufzucht der Forellen wurde unter standardisierten Bedingungen durchgefuhrt (Modellversuch). Futterzusammensetzung und Besatzdichte entsprachen okologischen und konventionellen Zuchtbedingungen. Es wurden verschiedene Okofutter getestet. Extrudiertes Okofutter desselben Herstellers schnitt deutlich besser ab als pelletiertes. Die Leistungsvorteile (Wachstum, Futterauswertung, Proteinausnutzung) eines hochwertigen konventionellen Futters hingen von der Pelletgrose ab. Mit 6,0 % Fett waren die geraucherten konventionellen Forellen des Modellversuches deutlicher fetter als die okologischen (4,5 %). TVB-N- Wert, Redoxpotential, Malondi-aldehyd und Glutathion sowie physikalische Methoden (Farbmessung, elektronische Nase) waren zur Verfolgung von Qualitatsveranderungen bei einer Lagerung bei 2-4 °C ungeeignet. Aufzuchtsbedingte unterschiedliche Gehalte einiger Fettsauren sind als ernahrungsphysiologisch unbedeutend einzustufen. Die mikrobiologische Qualitat war gut oder sehr gut. In konventionellen vakuumverpackten Raucherfilets wurden seltener Bakterien und niedrigere Gesamtkeimzahlen gegenuber den okologisch produzierten gefunden. Die Befunde waren aber nicht geeignet, die sensorische Qualitat zu beeinflussen. Diese nahm kontinuierlich ab, war jedoch am Ende der Lagerung noch als durchschnittlich zu bezeichnen und keinesfalls verdorben. In Ubereinstimmung mit Ergebnissen des Vorgangerprojektes „Bioforelle“ an rohen Forellen konnten auch in den Raucherforellen weder reproduzierbare Auswirkungen der Produktionsform noch qualitative Unterschiede festgestellt werden. Durch Besichtigung kleiner bis mittelstandischer Rauchereien wurden individuelle Verarbeitungsstrukturen erfasst. Die Auswirkungen der wichtigsten Arbeitsschritte (Salzen, Rauchern) auf die Qualitat wurden naher untersucht. Die Kerntemperatur von 60°C wurde in konventionellen Handelsproben nicht immer, bei der untersuchten Bioware zuverlassig erreicht. Die besuchten okologisch arbeitenden Betriebe waren modern ausgestattet unter Berucksichtigung heutiger Hygienestandards.

SummaryThe four‐plate test (FPT) method was used for the determination of sulfadiazine/trimethoprim residues in trout in the European Community (EC). This microbiological inhibition test used three media seeded with Bacillus subtilis at different pH values (6, 7.2 or 8.0) and a fourth medium seeded with Micrococcus luteus. The Premi test was also used for the determination of sulfadiazine/trimethoprim residues in trout. The effects of a trout muscle supernatant on detection limits of antibiotics with microbiological inhibition tests were measured. The supernatant was applied directly on top of the paper disks impregnated with aqueous antibiotic solutions. Inhibition zones were compared with those obtained by the same standard solution of sulfadiazine/trimethoprim without the trout supernatant. The detection limit of penicillin, sulfadimidine, streptomycin groups of antibiotics were determined for checking the test plates. For supernatant from fish fed with pellets containing antibiotics (sulfadiazine/trimethoprim), the inhibition zones increased according to the duration of the feed application. In the control group, no inhibition zones were detected. The concentration of the residues accumulated and reached a plateau after 5 days. The antibiotics were detectable in the same concentration as on day 7, but three days later (on day 10) they were no longer detectable in the fish samples. In contrast to the ‘FPT’, 3 days after discontinuing the medicated diet, there were still residues detectable by ‘Premi test’ on day 10. Data is presented that shows that the FPT and the Premi test methods are very useful for the determination of sulfadiazine/trimethoprim residues in trout.

Die Studie umfasste die Untersuchung der Aufzuchtsbedingungen sowie Futterversuche und vergleichende Untersuchungen zur Produktqualitat an Portionsforellen. Es wurden 2 okologisch zertifizierte und 3 konventionelle Forellenzuchtbetriebe verglichen. In dieser Arbeit werden nur die Ergebnisse der Qualitatsuntersuchungen wiedergegeben. Die Untersuchungen der Portionsforellen beinhalteten die Erfassung der biologischen Parameter, die mikrobiologische und sensorische Beurteilung der Ware, Farb- und Texturmessungen, die Bestimmung der chemischen Zusammensetzung einschlieslich der Ruckstande sowie bildverarbeitende Methoden und die Aufnahme des Aromaprofils. Insgesamt waren die Qualitat und der mikrobiologische Status aller untersuchten Forellen sehr gut. In ihrer chemischen Zusammensetzung unterschieden sich die Fische vor allem im Fettgehalt. Alle ermittelten Ruckstandsgehalte lagen weit unter den zulassigen Hochstwerten. Unterschiede zwischen den Aufzuchtsformen wurden nicht gefunden.

According to the guidelines of the German Food Book products of two species of the genus Helix, H. pomatia and H. aspersa, may be labelled as vineyard snail, but not the commercially important species of H. lucorum. In the present study the quality and sensory properties of H. pomatia, H. lucorum and Achatina species were compared by sensory assessment and measurement of texture and colour. DNA-analysis (PCR-RFLP) was used for differentiation of species. The sensory properties of the 3 species were found to be very similar, and not to be suited for differentiation. In contrast to this finding, the physical tests revealed some differences between species. By PCR-RFLP DNA-fragment patterns were obtained allowing unambiguous differentiation of the 3 species. Les proprietes sensorielles, la couleur, l'analyse de la texture et des methodes de biologie moleculaire (PCR-RFLP) ont ete employes pour differencier des produits prepares a partir de differentes especes d'escargots.