Impact of peeling and rye bran fermentation on flavour and texture of high-fibre wheat breads

Consumption of whole grain foods has been shown to reduce the risk of chronic diseases. However, there is a remarkable gap between the recommendation and the current intake of whole grain foods in many European countries. Whole grain rye is an excellent source of fibre and phytochemicals. The main sensory concerns of wholegrain foods include bitter flavour (impact of polyphenols and peptides), dark colour (impact of polyphenols and carotenoids) and fibre-like texture (impact of lignocellulosic layers, large particles). These undesired taste and texture characteristics of whole grain foods are the most obvious reasons for the low intake. Thereafter, by tailoring flavour of the whole grain foods consumption could be increased. In our study pre-processed (native, peeled, native-fermented and peeled-fermented) rye bran was used as an ingredient in wheat bread baking, aiming to increase the healthiness of wheat bread without compromising in its sensory characteristics. Bran from native and peeled (11%) rye grains was fermented with Saccharomyces cerevisiae. The yeast fermentation procedure was optimised for flavour and bioactivity, and the fermentation was accomplished at 24°C for 12 h. Breads containing 20 % fermented rye bran and 80 % white flour were baked. Sensory descriptive profiles, specific volume, instrumental texture and amounts of phenolic compounds (phenolic acids, alkylresorcinols, lignans) and soluble pentosans were determined from the breads. Mechanical peeling of bran used as an ingredient in wheat bread decreased significantly the flavour and colour intensity, but concurrently some of the bioactive compounds located in bran were lost. Fermentation of bran together with peeling improved the flavour properties of the bran breads. Fermentation had also other positive effects in increasing the bioactivity of bran, and improving its technological properties (related to increased amount of soluble pentosans) in wheat bread baking.