Bread crumbs extrudates: A new approach for reducing bread waste

Abstract

Processing bread wastes constitutes a major problem for most bakeries. They are generally processed into “bread crumbs” and used in breading formulations. The aim of the study was to develop a new way of reducing bread wastes by processing bread crumbs in extrusion cooking. The effects of feed moisture and exit die temperature on physical and functional properties of bread crumbs extrudates (BCEs) were investigated in comparison to wheat flour extrudates (WFEs). Feed rate, screw speed and die hole diameter were kept constant (4.0 kg/h, 200 rpm and 2.0 mm, respectively). Exit die temperature was adjusted to 120, 135 or 150 °C, while feed moisture content was 13, 15 or 17%. Especially at low feed moisture content (13%), BCEs had higher expansion index values (7.57–8.07), than WFEs (5.88–6.01). The lowest bulk density values were 0.02 and 0.06 g cm−3 for BCEs and WFEs, respectively. BCEs had significantly softer and more crispy textures than WFEs at all extrusion conditions studied. BCEs' dietary fibre contents (5.75–7.28%) were significantly higher than WFEs' (4.58–5.50%). Resistant starch contents also demonstrated a similar trend. These improved properties confirmed that, bread crumbs are promising raw material in extrusion cooking and expected to provide products with added-value from bread wastes.