105 Enzymes as stabilizers of bread structure.

L. FLANDER, M. Salmenkallio-Marttila, M. Tenkanen, K. Autio, and K. Poutanen. VTT Biotechnology and Food Research, P.O. Box 1500, 02044 VTT, Finland.

The aim of this project was to study the effects of enzymes (alpha-amylase, two laccases, lipase and xylanase) on the structure of mixed wheat bread (85 wheat/15 graham flour), especially when baked from prefermented frozen dough. Specific volume (ml/g) of the bread and hardness (TPA, 2 and 24 hours) and pore size of the crumb were analysed. Preparations containing bacterial alpha-amylase, two laccases, lipase, xylanase, a mixture of two enzymes (xylanase and laccase 2) or a mixture of three enzymes (alpha-amylase, lipase and xylanase) were added to the dough. The dough was divided into two parts for different baking methods: 1) immediate baking after final proofing and 2) freezing for 1 week after prefermentation. A control bread without enzyme addition was baked with both methods. Without freezing of dough, all the enzymes improved the specific volume and softness of bread significantly compared to the control bread. The specific volume of bread baked from prefermented frozen dough was increased significantly by addition of alpha-amylase, xylanase, laccase 1 or the mixtures of enzymes when compared to the control bread. The mixtures of enzymes were most effective in improving the loaf volume and retaining the softness of bread with both baking methods.