Abstract
Extruded pet foods often contain a dietary fiber source to support gastrointestinal health. Currently there is a gap in research on how different fiber sources and processing stages impact nutrient composition and physical and organoleptic measurements of kibbles. Diets containing avocado meal (AMD), beet pulp (BPD), or cellulose (CD) were formulated to meet the 2016 AAFCO nutritional requirements for dogs and cats with similar nutrient contents and were processed to achieve similar bulk densities. Composite samples were taken at each processing stage for macronutrient analyses. Piece density, piece volume, sectional expansion index, and specific length were determined, and texture was analyzed for kibble hardness and energy to compress. Chemical compositions remained relatively unchanged during processing except for dietary fiber fractions; in general, total dietary fiber decreased in AMD and BPD vs. CD. All diets and processing stages exhibited similar piece mass and length. Piece diameter and SEI for AMD were larger and increased during drying stage, while BPD and CD were observed to decrease. Kibbles from the AMD (0.33 ± 0.07 cm3) had slightly larger piece volume vs. BPD (0.23 ± 0.05 cm3) and CD (0.21 ± 0.04 cm3) after drying vs. extrusion stage. Hardness decreased after drying for AMD (59.2 to 44.5 N) and BPD (59.9 to 27.4 N) but increased for CD (50.8 to 93.0 N), and values for all diets had noticeable standard deviation. A lower energy to compress was observed in the drier and coating stages vs. extrusion stage for all diets. This research suggests that different fiber sources in extruded high fiber pet foods have minimal effect on macronutrient composition during processing. However, some alterations on the physical attributes were observed in kibbles made with different fiber sources and at varying stages of processing. Such alterations may impact food selection and preference by pet animals.