Improving gluten-free buckwheat bread by sourdough fermentation and addition of arabinoxylan and pyranose 2-oxidase

The purpose of this research was to improve the functional properties of gluten-free (GF) wholemeal buckwheat bread by sourdough fermentation and addition of arabinoxylan (AX) and pyranose 2-oxidase (POx). AXs are able to cross-link to other AX molecules under acidic conditions, which is supported by the addition of oxidizing enzymes (e.g., POx). On a first approach, the optimal sourdough concentration (% acidification of total flour weight) was adjusted. The best results were seen at an acidification of 82% of total flour weight. The optimal dosage of 3% AX and 1 nkat POx/g flour was able to increase the specific volume from 1.80 to 1.93 cm³/g bread and reduce the firmness from 9.61 to 4.69 N compared to the control bread and presented an acceptable relative elasticity of 62.20 ± 0.96%. These effects were then compared in breads produced from wholemeal and refined buckwheat flour. Interestingly, the wholemeal buckwheat bread showed a significantly lower firmness and higher relative elasticity than the bread from refined flour, which can be mainly attributed to the higher protein and dietary fibre content of wholemeal flour. Overall, this study suggested that addition of AX and POx could positively increase the quality of GF buckwheat bread.