Abstract
The aim of the study was to compare the physical and sensory properties of gluten-free bread with the addition of whole and ground flax seeds. The grinding process of flax seeds was carried out using a knife grinder and ball mill. After short-knife grinding (20 s) (GM-200, Retsch), the seeds were divided into whole (average particle size 0.634 mm), coarse (769 mm) and fine (0.328 mm) flour, and these flours were additionally ground with ball milling (60 s) (Pulverisette 6, Fritsh). The grinding energy of seeds was evaluated. Baking of gluten-free bread was performed with 10% addition of different forms of whole and ground flaxseeds. The colour, volume, texture and sensory parameters of bread were evaluated. In addition, the crumbling index of bread was developed and defined as the percentage share of crumbed pieces of the bread slice in relation to the mass of the entire crumb sample cut out together with crumbs. Specific grinding energy of flaxseeds during short (20 s) knife grinding was equal to 109.5 J·g−1, and additional ball milling (60 s) caused significantly (α = 0.05) more than 4 times higher energy consumption, but more reduced particles of whole (0.497 mm), coarse (0.621 mm) and fine flour (0.308 mm) were obtained. After adding ground seeds, it was necessary to add more water to the dough, which increased dough yield from 220% to 240% and even to 260% when ball milling of coarse flax flour was applied. The most significant increase in the volume of bread and the most reduced crumbling was observed for breads with addition of coarse fractions of flaxseeds ground with ball milling. In comparison with the control sample of gluten-free bread; significant improvement in bread volume, textureand sensory evaluation was observed after using both whole and ground flaxseeds. Furthermore, the crumbling index was related to an organoleptic evaluation and can be used in bread quality assessment as a complement to instrumental texture measurements.