Invloed van het strippen op de kwaliteit van de vis en mogelijkheden ervan aan boord van de vissersvaartuigen

The influence of gutting on the quality of fish is discussed. The conclusion of this study is that the usefulness of evisceration depends upon many factors: duration of the voyage, fish species, size and quality of the catch season (influence of temperature), etc.In most cases however, gutting is to be recommended. As it is a very laborious operation especially when important quantities of fish are caught and as it should be carried out carefully in order to keep the quality of the fish at a high level, gutting machines represent a real progress, allowing better working conditions. In recent years, several interesting machines were proposed abroad. A brief description of the most important types is given in this article

De brekingsindex van het oogvocht als objektieve kwaliteitsmethode voor vis

The possibilities of the refractive index (RI ) of the eye fluid as a freshness test for fish were investigated. Procedure details were studied in order to improve the usefulness of the method. The following fishes were used : cod (Gadus morhua L), plaice (Pleuronectes platessa L), redfish (Sebastes marinus L) and blue ling (Molva byrkelange).It appears necessary to extract nearly the whole quantity of eye fluid. Checking the RI of left and right eye can be omitted. Centrifuging the eye fluid is not absolutely required but improves readability. Filtration has no practical value. Keeping the eye fluid during 24 hrs at I ° C results only in a very slight increase in RI : if necessary, determinations can be postponed without harm. The temperature of the refractometer must be maintained at 20° C ± 1,5o C. At fairly constant room temperature, no thermostat is required for routine analyses. A handrefractometer appears to be of little use.With redfish and blue ling, no satisfactory results are obtained. Spoilage curves of cod and plaice on the other hand agree fairly well with organoleptic judgment. The RI seems to be a useful freshness test with those species. Quality gradings are proposed.Advantages and limitations of the method were investigated. The RI can be determined very quickly with simple apparatus and by non specialised personnel. However, no determination is possible on beheaded of proccssed fish or on fish with very small eyes. As variations among individuals can be large, a sufficient number of fishes should always be taken for analysis

Influence of sodium tripolyphosphate and citric acid on the shelf life of thornback ray (<i>Raja clavata</i> L.)

Sodium tripolyphosphate dips (5 min in 12% solution) extended shelf life of thornback ray wings by about 2 days, improved the appearance and eliminated weight losses. With citric acid dips (5 min in 0.5% solution) a 3 day extension of storage life was obtained but the treatment had a slight bleaching effect and caused weight losses of about 5 %. Both compounds were effective in retarding the breakdown of urea with formation of ammonia in thornback ray