Assessment of physical properties of pet-food based on wheat middlings and meat meal

Considering the popularity of dry pet food, its market and production are constantly increasing. The quality of the food and the source of raw materials used for its production become as important as in the production of food for human consumption. The aim of the study was to assess the basic physical characteristics of the pet food produced from wheat middlings and meat meal using the extrusion process. The composition of individual samples was as follows: sample A – meat meal 25 %, wheat meal 75 %, moisture content of 30 %; sample B – meat meal 25 %, wheat meal 75 %, moisture content of 25 %; sample C – meat meal 25 %, wheat meal 75 %, moisture content of 20 %; sample D – meat meal 50 %, wheat meal 50 %, moisture content of 30 %; sample E – meat meal 50 %, wheat meal 50 %, moisture content of 25 %; sample F – meat meal 50 %, wheat meal 50 %, moisture content of 20 %. The compounds composed in this way were subject to the extrusion process to obtain characteristic animal cookies. After the initial tests, the following extrusion process parameters were selected: first heater section: 100 ºC, second heater section: 120 ºC, head: 120 ºC, die: oval 2.5/15 mm, 37.5 mm diameter, screw: 800 mm, Ø60 mm., screw rotation: 100 rpm. Properties, such as the degree of expansion, cutting test (biting) and durability, were assessed. The moisture content of raw material before the extrusion process had the highest impact on the physical characteristics of the final product. Statistically significant differences in the cutting test were recorded, depending on the share of individual components and the moisture content.