Gluten free breads require a gluten replacement to provide structure and gas
retaining properties in the dough and mimic the viscoelastic properties of gluten.
Hydroxypropylmethylcellulose (HPMC), which forms thermoreversible gel networks on
heating had proved the most effective in structuring baked products. Response surface
methodology was used to optimize a GF bread formulation based on ingredients such as
maize starch and rice flour, which are naturally GF. (HPMC) and water (W) were the predictor
variables (factors) and loaf specific volume, crumb firmness, and overall acceptability
were the dependent variables (responses) used to assess the product quality. The optimal formulation,
determined from the data, contained 1.5 kg/100 kg HPMC and 88.7 kg/100 kg
Water, corn starch-rice flour blend basis (sfb). The developed mathematical models for the
measured responses could be successfully used for their prediction during baking. Shelf
life study of the optimized formulation revealed that bread stored under modified atmosphere
packaging (MAP) exhibited lower crumb firmness and moisture content values, thus
remained softer through storage. Scanning electron microscopy of the crumb showed continuum
matrix between starch and HPMC, in the optimized formulation, obtaining a more
aerated structure.
Response surface methodology was successfully applied to optimize HPMC and
water levels in GF bread. The two variables employed in the study had a great effect on the quality of GF bread. Up to a certain limit of HPMC addition, the specific volume increased
and crumb firmness decreased. The statistical approach allowed the achievement of the
optimized recipe which contained 1.5 kg/100 kg HPMC and 88.75 kg/100 kg water (corn
starch-rice flour blend basis) and yielded good quality bread with an overall acceptability
13% higher than that of non-HPMC GF bread. Moreover, the modeling of experimental
data allowed the generation of useful equations for general use, to predict the behavior of
the system under different factor combinations. Within the modified atmosphere package,
it appeared that the GF bread staled at a lower rate.