Physical Properties of Flours Obtained from Wasted Bread Crusts and Crumbs

Abstract

One third of the food produced in the world is wasted. Bread is one of the most wasted foods both during the distribution process and in households. To use these breads, it is necessary to get to know the properties of the flours that can be obtained from them. The purpose of this work is to know how the type of bread and its zone (crumb or crust) influence the characteristics of the flours obtained from the wasted bread. For this, flours made from the crumbs and crusts of eight different breads have been analysed. Their hydration properties, cold and post-heating rheology and gelling properties as well as the colour of flours and gels have been studied. Bread flours present higher water-holding capacity (WHC) and water-binding capacity (WBC) values and higher elastic modulus (G’) and viscous modulus (G”) values, both in cold conditions and after heating, than wheat flours. However, they generate weaker gels. Crust flours, and the gels obtained from them, are darker than those from crumbs and their gels. In terms of hydration and rheology, pan and wholemeal bread flours are generally lower than other bread flours. These flours also generate softer gels, possibly caused by the dilution of starch with other components. It can be concluded that the properties shown by wasted bread flours allow them to be reintroduced in the food chain as an ingredient in different products.

Effects of particle size in wasted bread flour properties

“…In fact, Fernández‐Peláez et al . (2021) have already observed that bread crust flours had higher a * and b * values and lower L * values than those obtained from crumbs. In terms of particle size, there is a tendency for L* values to increase and for a decrease in a * and b * as the particle size decreases.…”

“…Fernández‐Peláez et al . (2021) have attributed these differences to the presence of such ingredients as oil and to the lower content of starch and protein responsible for water hydration. It is possible to think that in bread crusts, the gelatinised starch content is lower resulting in a lower water absorption capacity.…”

“…Wasted lean breads frequently stale before the development of microorganisms, so they are discarded with a low microbial activity and can be milled to be used in the elaboration of other products (Fernández‐Peláez et al ., 2021). The baking process promotes changes in the bread structure due to the presence of high temperatures and the moisture of the dough, which enable starch gelatinisation (Martínez et al ., 2013).…”

“…The use of bread flour in the production of snacks (Samray et al ., 2019), sourdough (Gélinas et al ., 1999), bread (Meral & Karaoğlu, 2020) and cookies (Guerra‐Oliveira et al ., 2021) has been studied. Flours obtained from bread crust or crumb of different bread types have also been characterised (Fernández‐Peláez et al ., 2021). In this study, bread flour was made using a hammer mill, using a sieve with the same mesh size in all grindings.…”

Optimization of a Simultaneous Enzymatic Hydrolysis to Obtain a High-Glucose Slurry from Bread Waste

“…According to Demirci et al [ 15 ] a high optimal LIQ temperature could be explained because this temperature makes it easier for enzymes to attack starch granules. However, we must take into consideration that we are working with bread flour when the starch is pre-gelatinized (almost) completely [ 27 , 28 , 29 ]. Moreover, this temperature may be due to the chosen enzyme, whose recommended range of action is between 80–85 °C (data provided by Novozyme).…”