Influence of Gravading Process Parameters on Physicochemical Attributes of Rainbow Trout (Oncorhynchus mykiss) Gravads

Gravads are a traditional type of Scandinavian delicatessen frequently made from salmon. Developing a gravading technology by using other fish like farmed rainbow trout may make gravads more popular in countries without a tradition in this field. The aim of the present study was to investigate the influence of gravading process parameters (composition and proportion of gravading mixture, time and temperature of ripening) on the physicochemical attributes of rainbow trout gravads. The influence of gravading process parameters (time, temperature, and the amount and relative proportions of the added salt-sugar mixture) on the yield and physicochemical attributes (water activity, protein, salt, sugar and dry matter content) of rainbow trout gravads were investigated using response surface methodology. The amount of the added sugar-salt mixture and gravading time were more important factors affecting the analyzed attributes than temperature or the proportions of salt and sugar. Mathematical models were developed to estimate the quality parameters of rainbow trout gravad obtained under different process conditions. Response surfaces representing changes in gravad attributes with varying processing conditions help to make the most desirable product. The results obtained in this work may facilitate the expansion of the range of nutritionally valuable fish products available on the market.