Browsing by Author "Suvanto, Sonja"

The literature review focused on the characteristics of bread-quality rye and how the composition and functional properties of rye are influenced by genotype and environment. Traditional rye sourdough baking process and main baking quality measurements were reviewed. The aim of this work was to identify baking quality of rye flour with different falling numbers. Another aim was to identify the measurement that best determines the quality of rye flour for sourdough baking and to find enzymes that can be used to improve poor-quality flour. In the experimental study, the baking quality of rye flours with different falling numbers (100, 130, 200, 300) was examined in processes for making sourdough rye loaves and serving-size flat breads. Rye flours with high falling numbers (200 and 300) were treated with commercial amylase and xylanase preparations. Falling number, amylograph and swelling curve measurements were done and results were compared to quality obtained in baking trials. Rye flour with the highest falling number (300) resulted in hard and dry dough as well as dense bread, as expected. Other rye flours (100, 130, 200) and flours treated with amylase resulted also in rather hard and dry doughs, although falling number and amylograph measurements confirmed the enzyme activity. Lower falling number and amylase treatments, however, were associated with improved sensory quality of final products. Xylanase made doughs softer and stickier, which improved both handling properties of dough and quality of bread in the loaf process. In contrast, the increased softness and stickiness made the serving-size flat-bread process more difficult. The viscosity decrease caused by xylanase addition was seen in swelling curve measurements. Adjusting the acidity of buffer solution to the pH level of rye sourdough did not improve the ability of the swelling curve to predict the baking behaviour of the flour. This study showed that falling number and amylograph cannot predict properties of rye dough. Differences between rye flours with different falling numbers were best detected in the sensory quality of the final products. The baking quality of rye flours could be modified by enzyme treatments, especially by xylanase addition, but the usefulness and desirability of the treatment depended on the type of bread-making process. The effects of added xylanase in rye dough could be predicted by swelling curve measurement. The overall results emphasized the importance of baking trials in determining the baking quality of rye flour.