Method of determining the relaxation force of fish

Abstract

There have been repeated cases of fish sales during the spawning period in the Ukrainian market, which consumer value is much lower, and fish re-freezing products. The aforementioned methods of abuse can be identified by commodity experts, while ordinary consumers, unfortunately, often cannot independently determine the quality of the fish. The basis of the vast majority of sensory checks of the elastic properties of fish is the process of compressing the product. The advantage of determining the surface relaxation rate is that it is non-destructive testing and the product appearance of the product after the examination does not change. However, this method requires some practical experience and depends essentially on the qualifications of an expert. The method and equipment for instrumental assessment of relaxation compression deformation force to define structural and mechanical properties of fish is given; it makes possible to minimize the experimenter influence on the results and obtain a quantitative value of relaxation speed at anytime in the experiment. The method of investigation of relaxation force and the rate of fish carcasses relaxation was theoretically grounded. A 3D-diagram of force that act on the indenter while pressing the surface of white cupid carcass is given. The type of dynamometer and measuring device for fixation of relaxation force dynamics is grounded. There was developed the sensor for determining the dynamics of the relaxation force with a constant depth of lowering of the indenter; scheme and photo of it is given. The mathematical models of relaxation velocity at axial deformation of compression and tension were constructed. The proposed method for quantifying the relaxation rate involves the construction of a compression deformation curve in the second of pressing a fish carcass and determining their angle of inclination. Based on the mathematical analysis of the deformation curves, it was found that for chilled meat of white cupid for 8 hours of storage, the relaxation rate at strain by 33% is greater than for the compression deformation; the primary force upon pressing on the product is 23% greater than when the specimen is subjected to a similar cross-sectional area. The developed methodology and system allows to determine the relaxation force when squeezing a fish sample just like a commodity science expert does and make quantitative assessment of its structural and mechanical properties.