Effects of adding cellulose on rheological characteristics of wheat flour dough and on bread quality

Abstract

Several studies have associated the consumption of dietary fibre with positive health effects and as a result a wide array of fibre ingredients has been developed to be included as part of formulation of functional food. Powdered cellulose is one type of fibre ingredient that is finding wide application in food, mainly in functional bread, either to increase level of fibre or to reduce calorific value. However, the inclusion of fibre in a formulation will inevitably bring about certain changes to the product. This current study investigated the effects of adding different levels (2, 4 and 6 %) of powdered cellulose on the rheological properties of wheat dough and bread qualities. The main dough characteristics assessed were farinograph water absorption, resistance and extensibility; while bread was evaluated for volume, weight, crumb softness and nutritional values (level of insoluble dietary fibre and calorie content). The bread qualities of cellulose-added bread were compared to those of brown bread. Findings revealed that water absorption of the dough and its stability against over-mixing increased significantly (P<0.05) with increasing level of powdered cellulose. Although the dough became more resistant, it lost extensibility; and thus bread of smaller volume was observed, with a decrease of about 200 cm3 at 6 % level cellulose, compared to plain bread. Cellulose-added bread was slightly heavier than plain bread and brown bread by about 5 – 15 grams. At 4 and 6 % level of fibre, bread had softer crumbs compared to both plain white bread and brown bread. With 6 % cellulose, the level of insoluble dietary fibre was 13.8 %, as compared to 6 % in plain bread and 13.1 % in brown bread. At 6 % cellulose there was a decrease of 77kcal and 47kcal compared to plain and brown bread respectively. Addition of cellulose at 2 and 4% gave bread with larger volume without improving the nutritional characteristics. At 6 % level of cellulose, bread had almost same level of insoluble dietary fibre than that of brown bread, but still offering better quality in terms of volume, weight, colour and texture compared to the brown bread. Therefore addition of powdered cellulose at level 6 % was found to be most appropriate for the purpose of functional bread.

Keywords: Cellulose, rheology, flour, bread, insoluble fibre, calorie