APPLE FIBRE AND HYDROXYPROPYLMETHYLCELLULOSE IN GLUTEN-FREE FORMULATIONS: FUNDAMENTAL RHEOLOGICAL APPROACH

ABSTRACT
Production of gluten-free bread that will match the properties of its wheat counterpart creates many challenges nowadays especially in terms of bread quality and nutritional adequacy. To address the aforementioned nutritional but also technological problems present in gluten-free bread production, dietary fibres can be applied considering their hydration and gel forming ability, textural and thickening effects. Apple fibre is an easily accessible fibre characterised by favourable soluble and insoluble fibre ratio and presence of polyphenols but is scarcely applied in gluten-free elaborations.
In the presented study a fundamental (dynamic oscillatory and creep-recovery tests) rheological approach was adopted to assess the viscoelasticity of maize-based gluten-free batters affected by different levels of apple fibre (AF) and hydroxypropylmethylcellulose (HPMC). Experiments were performed according to the Box-Behnken experimental design, with independent variables: quantity of HPMC (2, 3 and 4% on maize flour basis), quantity of AF (3, 5, and 7% on maize flour basis), and quantity of water (180, 190 and 200% on maize flour basis).
Increase in HPMC and AF content increased the values of elastic modulus inducing shifting towards solid elastic-like behaviour typical for dough. Additionally, tan δ values were higher than one in most gluten-free formulations. Significant impact on creep and recovery parameters was associated with HPMC (changes in instantaneous and retarded elastic compliance) and water content (changes in Newtonian viscosity). In applied quantities, AF does not impair any of the analysed rheological parameters and hence it could be applied in gluten-free bread production as a functional ingredient.