Abstract #393

# 393
The use of varying strengths of gelatin and the effect on physical properties of extruded pet food.
Analena E. Manbeck*1, C. Greg Aldrich1, Sajid Alavi1, 1Department of Grain Science and Industry, Kansas State University, Manhattan, KS.

Previous work with low-bloom gelatin demonstrated an increase in hardness and durability when incorporated into extruded kibbles. The objective of this experiment was to determine the effect of gelatin bloom strength on extruded kibble physical properties. Four nutritionally complete diets (30% protein) were formulated with no gelatin (control) or with 10% gelatin from 50, 175 and 250 bloom strength sources (Pro-Bind 100, PigSkin 175, and PigSkin 250) exchanged with chicken by-product meal. All diets were produced on a Wenger X-20 extruder through a circle die (3mm diameter) then a triangle die (5.3mm base × 4.9mm height). Products were analyzed for bulk and piece density, throughput, cross-sectional expansion, hardness, and pellet durability index (PDI). Experimental treatments were arranged as a factorial with main effects separated using statistical software (SAS 9.4). Kibble shape had an effect on hardness, cross-sectional expansion, and piece density, but this was likely due to a slight difference in die open area. The interaction of gelatin strength and kibble shape also had effects on hardness, PDI, and density, but these can be attributed to changes in bloom strength. Relative to the control, hardness increased with 50 bloom gelatin but decreased with 175 and 250 bloom gelatin (P < 0.05; 5.93, 7.38, 4.57, 3.59kg, respectively). Relative to the control, PDI was the same for 50 bloom but decreased with both 175 and 250 bloom gelatin (88.49%, 87.57%, 64.55%, and 30.01%, respectively). The main effect means of cross-sectional expansion and specific length increased with bloom strength (3.05, 3.54, 4.29, 4.92mm2/mm2 expansion and 4.27, 4.26, 4.49, 4.74cm/g length for 0, 50, 175, 250 bloom, respectively). The main effect means for bulk and piece density became lighter with increasing bloom (0.56, 0.48, 0.39, 0.33g/cm3 piece density and 347.6, 310.7, 242.4, 212.3g/L bulk density for 0, 50, 175, 250 bloom, respectively). There were no treatment effects on throughput. Low-bloom gelatin may improve expansion while increasing product hardness and durability, making it a potential structure-enhancing ingredient.

Key Words: pet food, gelatin, extrusion