Functionalisation of wheat and oat bran using single-strain fermentation and its impact on techno-functional and nutritional properties of biscuits

The adequate intake of dietary fibre is linked to several health benefits, for example, reducing the risk of non-communicable diseases, such as cardiovascular disease and diabetes. However, the population's intake of dietary fibre is below the dosage recommended by the World Health Organisation. The incorporation of fibre ingredients, such as bran, in cereal based products affects the techno-functional and sensory properties, resulting in inferior product quality. To compensate quality loss, wheat bran (WB) and oat bran (OB) were fermented using the lactic acid bacterium strain Leuconostoc citreum TR116 prior to the application in a biscuit system. Two types of fermentation, one without any addition of sugars (FB) and one with the supplementation of 5% fructose and 5% sucrose to trigger the production of mannitol (FB +), were conducted and sugar and acid profiles as well as pH and total titratable acids (TTA) were evaluated. Fermented WB showed a higher TTA (+ 58%) compared to fermented OB. Furthermore, FOB + resulted in higher microbial cell count and higher residual sugars after 48 h of fermentation. The application of fermented brans in a biscuit system showed a decrease in dough stickiness (- 41.7%) and an increase in dough hardness (+ 32%). The type of bran (WB and OB) as well as the type of fermentation (FB or FB +) influenced the results of biscuit dough and biscuit quality (p < 0.005). Fermentation increased biscuit spreading, influenced biscuit snap force, enhanced crunchiness and colour formation, and lowered the predicted glycaemic index. Fermented OB (FOB +) resulted in a sensory profile comparable to the control.