Basis for calculating technological parameters of preparation of minced salted fish products of intermediate moisture with specified physical and chemical characteristics

The dependence of water activity on basic physical and chemical characteristics of salted fish products with intermediate moisture has been defined. During the research the product quality has been assessed by the organoleptic method; determination of the water mass fraction has been carried out by the drying method; the salt mass fraction - by the argentometric method; water activity has been measured by a cooled mirror dew-point sensor. Based on experimental data the dependence of Aw on concentration of sodium chloride in the salt semi-finished products of pollock ( Theragra chalcogramma ), Atlantic herring ( Clupea harengus ), Baltic cod ( Gadus morhua callarias ), blue whiting ( Micromesistius ), pink salmon ( Oncorhynchus gorbuscha ), horse mackerel ( Trachurus trachurus ) has been established. The empirical formula showing the correlation of the parameter ( Aw ) with mass fraction of sodium chloride and water has been derived; on its basis it is possible to calculate the parameters of semi-finished product in order to obtain a final minced salt product of intermediate moisture with desired microbial stability upon storage. The relations between the salt mass fraction and water mass fraction excluding bacterial spoilage and mold growth has been determined, they make up S ≥ 0,135 ∙ W and S ≥ 0,34 ∙ W respectively, where S - the mass fraction of salt, %, W - the mass fraction of water, %. An example of calculating the required dosage of sodium chloride in the semi-finished minced salmon has been described to produce the finished product with the exactly given values of humidity and water activity. During the process of minced salted fish products' dehydration the basic physical and chemical parameters - the mass fraction of salt and water affecting the water activity ( Aw ) - have been changing. Determination of these parameters' relationship provides the ability to predict the qualitative changes of salted fish products of intermediate moisture during storage and to calculate the necessary parameters of salted semi-finished product preparing.