Pasting and Rheological Properties of Fermented and Oven-Dried Millet–Guinea Corn Ogi Fortified with Chia Seed Flour

Abstract

This study examined the pasting and rheological characteristics of fermented, oven-dried millet–guinea corn ogi formulations containing different proportions of chia seed flour. Five formulations (T1–T5) were assessed using rapid viscoanalyser and rheological measurements after reconstitution. Pasting variables included peak, trough, breakdown, final and setback viscosities, peak time and pasting temperature. Apparent viscosity, consistency index, flow behaviour index and yield stress were determined for the reconstituted samples. Across the formulations, peak viscosity declined from 1845.50 ± 12.40 RVU in T1 to 1519.60 ± 16.30 RVU in T5, whereas breakdown viscosity decreased from 747.20 ± 8.15 to 481.10 ± 6.85 RVU. Trough and final viscosities also decreased, while setback viscosity, peak time and pasting temperature increased slightly. Following reconstitution, apparent viscosity rose from 842.50 ± 12.60 to 1236.80 ± 21.30 mPa·s, the consistency index increased from 4.86 ± 0.14 to 7.24 ± 0.22 Pa·sⁿ, and yield stress rose from 3.21 ± 0.08 to 5.18 ± 0.13 Pa. The flow behaviour index declined from 0.61 ± 0.02 to 0.51 ± 0.01, indicating shear-thinning behaviour in all samples. These patterns suggest reduced viscosity development during heating alongside increased resistance to flow after reconstitution. Because cereal proportions varied with chia inclusion, the observed differences reflect formulation changes rather than the isolated effect of chia flour.