Extrusion Processing Modifications of a Dog Kibble at Large Scale Alter Levels of Starch Available to Animal Enzymatic Digestion.

Isabella Corsato Alvarenga,Christopher Waldy,Lewis C Keller,Charles G Aldrich

doi:10.3390/foods10112526

Isabella Corsato Alvarenga, Christopher Waldy + Show 2 more

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https://doi.org/10.3390/foods10112526

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Journal: Foods (Basel, Switzerland)	Publication Date: Oct 21, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: Kansas State University

Abstract

The objective of the present work was to produce dog foods from a single recipe at three levels of resistant starch (RS). The low (LS), medium (MS), and high shear (HS) foods were produced on a single-screw extruder at target screw speeds of 250, 375 and 460 rpm, respectively, and with increasing in-barrel moisture as shear decreased. Post-production, kibble measurements and starch analyses were conducted. Kibble parameters were compared by ANOVA with significance noted at p < 0.05 with a single degree of freedom orthogonal contrasts for extrusion outputs, starch analyses, and viscosity (RVA). The MS and LS kibbles exiting the extruder were denser and less expanded (p < 0.05) than the HS treatment. Resistant starch, starch cook, and raw:cooked starch RVA AUC increased linearly as shear decreased. These results confirmed that lower mechanical energy processes led to decreased starch gelatinization and greater retention of in vitro RS.

Highlights

Extrusion cooking is the most common process used to produce pet foods worldwide [1]
The high shear (HS) diet was produced with the highest extruder shaft speed (SS), while the low shear (LS) was extruded with the lowest SS, and medium shear (MS) was intermediate (Table 2)
The dry feed rate was initially set at 817 kg/h (Table 2), but production had to be stopped at the beginning of the first LS replicate due to kibble clumping

Summary

Introduction

Extrusion cooking is the most common process used to produce pet foods worldwide [1]. There is a preconditioning step before the dry mix enters the extruder barrel, where it is steam heated and further mixed to allow for hydration time. Thermal and mechanical energies are transferred to the dough, respectively, through water and steam additions and mechanical shear forces from screw components, which occur under pressure for a short time. Starches and other functional ingredients go through molecular changes that contribute to the formation of a viscoelastic material [2]. Under a moist environment and thermomechanical energy, starches gelatinize, paste, melt, and may fragment [2]

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