Effects of gluten, water and processing conditions on oat bread quality

Abstract

The aim of our work was to optimise the whole grain oat baking process both in terms of bread quality and physiological functionality of oat â-glucan in bread. The flour used in baking was whole grain oat (51%) and wheat (49%). A straight dough baking process was used. The effects of gluten, water and processing conditions (mixing time, intermediate proof, proof time, proof temperature, and baking temperature) were investigated using response surface methodology. A central composite design was constructed to study the effects of two ingredients and five processing parameters on baking performance. Response variables measured were: specific volume, instrumental crumb hardness (after 2 and 72 h storage), and sensory texture and flavour of crust and crumb. The concentration (McCleary & Codd 1991) and molecular weight distribution of â glucan (Suortti, 1993) were analysed from both flours and bread. The largest specific volume, smallest instrumental hardness of the crumb and best sensory quality was attained by adding 42% water and 7% gluten to the dough and mixing it for 4 min. The intermediate proof of 5 min resulted in the softest bread crumb, but 20 gave enhanced specific volume, crust properties and flavour. Optimal proofing conditions were 40 °C and 75 min. The optimal baking temperature was 210 °C. After optimisation, the specific volume of oat bread was 3.7 cm3/g, hardness after 2 h was 0.14 kg, and after 72 h 0.3 kg. The sensory quality of the bread was good. The results show that bread containing 51% whole grain oat can be baked and that good taste and texture as well as long shelf life can be attained by optimizing recipe and processing parameters. In straight dough baking about 30% of the â-glucan of the flour was degraded. The possibilities to reduce the degradation of â- glucan during processing will be studied further. McCleary, B. & Codd, R. 1991. Journal of the Science of Food and Agriculture 55: 55-65; Suortti, T. 1993. Journal of Chromatography 632: 105-110.