Study of the rheological properties of minced fish from aquaculture objects

Abstract

The paper dwells on the prospects of using the methods of extrusion processing of products based on minced fish. It is noted that one of the promising methods is the method of cold extrusion and co-extrusion. The research aims to identify theoretical and experimental patterns of changes in the rheological characteristics of minced aquaculture fish (carp and silver carp) and analyze them in relation to extrusion processes. The dependences of the rheological characteristics of minced fish samples on the influencing parameters in a wide temperature range from –5 to +25 °C have been studied. The values of the ultimate shear stress and the penetration depth of minced fish have been determined on a conical plastometer KP-3, viscosity – on a rotational viscometer Brookfield DV–II+Pro, and adhesive ability – on a laboratory unit for determining the stickiness of the material. Based on the data of minced fish chemical composition theoretical dependences of the effective viscosity on the shear rate gradient have been obtained. Similar dependences have been obtained experimentally in a wide temperature range. The analysis of these dependencies has shown their qualitative coincidence for the usual conditions for producing minced fish, but there are quantitative differences due to the technology for preparing minced aquaculture fish. The rheological characteristics of minced fish have been analyzed for the studied temperature range. It has been determined that the temperature range from –2.5 to 0 °C is the most appropriate for cold extrusion processes. In this area the value of the effective viscosity of minced fish and its adhesive ability are minimal, which is decisive for implementing extrusion processing. The good formability of the product has also been noted under these conditions. A further research direction is to identify the influence of technological additives on the formability of minced aquaculture fish, to reduce the smell of fish, and to eliminate undesirable oxidative processes. Developing new types of fish products with innovations in form, texture, colour and composition remains relevant. The prospects of the co-extrusion method which allows creating new innovative fish products with functional properties have been confirmed.