Browsing by Author "Österman, Erika"

The literature review deals with baking tests and rheological measuring devices, which measure the baking quality of wheat flour. The farinograph measures, for example, the water absorption, the alveograph the gas retention capacity, the extensograph the extensibility and the amylograph the starch gelatinisation of the sample. Chopins’ Mixolab-device imitates the whole bread-baking process by measuring water absorption, mixing tolerance, gluten quality, starch gelatinisation, starch gel stability and starch retrogradation of the sample. The aim of the experimental work was to determine the applicability of the Mixolab-device to measure the baking quality of wheat flour and to find out whether the results obtained by Mixolab correlate to the results of baking tests. The repeatability of the Mixolab results was ensured by repeating measurements five times. Seven gluten preparations (2% of the wheat flour mass), three enzyme preparations (30 and 70 ppm of the flour mass) and bread improvers (0.5–2.0% of the flour mass) were analyzed in wheat flour with Mixolab to find out how they affect the baking quality of wheat flour. Two gluten preparations which differed most from each other and all enzymes with both concentrations and reference sample were test baked. According to the results obtained using Mixolab, one of the gluten preparations differed from others by making the sample softer and having bigger volume than all the other gluten preparations, which made samples harder, have a smaller volume and larger water absorption potential. The exceptional gluten preparation and one of the other gluten preparations were test baked. The results obtained using Mixolab were confirmed by baking tests: samples including the exceptional gluten preparation were softer and had a greate volume than the sample which included the other gluten preparation. One enzyme preparation softened the dough more and had a bigger volume than the others. Test baking showed that the enzyme preparation possessed proteolytic activity, and destroyed the gluten matrix of the dough. The other two enzymes were quite similar and the bigger concentration softened the dough compared to the reference sample. Mixolab showed also clear differences between the bread improvers. The results obtained using Mixolab were repeatable, differences were found between samples and the results correlated with the results of the baking tests. It was difficult to interpret the results of Mixolab and that is why test baking was compulsory. There is still a lot to learn about interpreting the results of Mixolab and test baking can’t be replaced by Mixolab, at least not yet.