Effect of Commercial Bread Improvers on Microbial Quality, Storage Stability, and Freshness Characteristics of Wheat–Cassava Composite Bread

Composite flour made from Wheat-cassava bread offers a convenient method using locally available cassava
flour, but incorporating wheat substitution can alter dough structure and accelerate quality deterioration during
storage. This work study the effects of four commercial bread improvers such as guar gum, ascorbic acid, Panok®
and STK Royal, on the microbial quality and freshness characteristics of bread prepared from a 90:10 wheat
cassava composite flour. Each improver was incorporated at 0.5, 1.0, 2.0 and 3.0% (w/w, based on composite
flour), with bread produced without the test improver serving as the control. Total viable bacterial, coliform and
mould counts were determined by culture-based methods, while storage stability was assessed from crumb
moisture and a calculated freshness index during four days of ambient storage. Ascorbic-acid breads showed the
lowest bacterial counts (2.47 × 10² to 2.87 × 10² CFU/g). Guar-gum breads showed the lowest mould counts
(2.37 × 10² to 2.67 × 10² CFU/g), whereas the control had a mould count of 5.83 × 10³ CFU/g. No coliforms
were detected in the fresh bread samples. Freshness declined during storage in all treatments. On day 4, STK
Royal bread retained the greatest crumb moisture (11.75%) and freshness index (73.00 %), whereas the control
had the lowest values (8.51% and 60.75%). Presumptive isolates belonged to Bacillus, Micrococcus,
Staphylococcus, Aspergillus, Penicillium, Rhizopus and Mucor. The findings show that the improvers did not
provide a uniform response: ascorbic acid was associated with the lowest bacterial load, guar gum with the lowest
mould load, and STK Royal with the strongest moisture and freshness retention. These treatment-specific effects
were considered separately while formulating wheat-cassava composite bread.

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