Elsevier

Journal of Cereal Science

Volume 85, January 2019, Pages 130-136
Journal of Cereal Science

Bread crumbs extrudates: A new approach for reducing bread waste

https://doi.org/10.1016/j.jcs.2018.12.005Get rights and content

Highlights

  • Bread crumbs (BC) are promising raw material in extrusion cooking.

  • Production of BC extrudates seems to be an innovative way for utilizing bread waste.

  • BC extrudates had better physical/chemical properties than wheat flour extrudates.

  • Higher amount of dietary fibre has been obtained from BC extrudates.

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.

Introduction

Bread is an essential part of our daily diet and bread wastage is a common problem around the world. The estimated wastage for bakery products ranges from 7 to 10% of its total production. Taking into consideration estimated world annual bread production which was about 125 million tons in 2011, the amount of waste can reach even 12.5 million tons per year worldwide. Bread waste is also widespread in Turkey and estimated to be 1.79 billion pieces annually. It is reported that a significant part of the waste (62%) is resulted from the product defects such as deformations and under/over-baking during processing and from the unsold breads in both small scale and industrial bakeries (Turkish Grain Board; TMO, 2015). Processing this waste constitutes a major problem for most industrial bakeries.

Bread waste can be used as an ingredient in food industry. Especially the products with deformations and/or under/over-baked are generally dried, ground and sieved, and then marketed as a by-product known as “bread crumbs”. Bread crumbs are extensively used for making a crisp and crunchy coating in breading formulations for fried/baked foods.

Snack foods are among the most popular foods which are liked by a high percentage of consumers, particularly children. In this group of foods, extruded products play an important role. They are preferred due to their specific sensory attributes, such as crispness, interesting appearance and taste, small size and wide range of shapes. The final texture and other quality parameters of extruded snacks depend in a high degree on the type of raw material (ingredients and additives) used. The best ones are starchy materials, such as cereal flours/grits (Meng et al., 2010, Peksa et al., 2016).

Extrusion is a continuous cooking and shaping (forming) process at which food materials are forced to flow under a variety of conditions (high temperature, pressure, shear stress and relatively low moisture content levels) through a die at a predetermined rate to give them unique physical and chemical properties. In the extruder, the raw materials are thermo-mechanically cooked at high temperature, pressure and shear stress which are generated in the screw-barrel assembly. The cooked melt is then texturized and shaped in the die. Extrusion cooking is becoming popular over other common processing methods due to its automated control, high capacity, continuous operation, high productivity, versatility, adaptability, energy efficiency and low cost. Moreover, it also enables design and development of new food products, high product quality, unique product shapes and characteristics (i.e. crispness, crunchiness), energy savings and no effluent generation (Martínez et al., 2015, Alam et al., 2016).

Despite increased use of extrusion processing, it is still a complicated process that has yet to be mastered. Small variations in processing conditions affect process variables as well as product quality. Product quality can vary considerably depending on the extruder type, screw configuration, feed moisture, temperature profile in the barrel, screw speed, feed rate and die geometry (Ding et al., 2006).

Extrusion allows starch gelatinization, denaturation of protein, reduction of microbial load, enzyme inactivation and colour changes, the extent of which are dependent on the conditions of the extrusion. Extrusion cooking is also responsible for changing the extent of molecular associations between components, e.g. the amylose-lipid complex that can affect the in vitro starch digestibility of the flours. Besides, an increase in the resistant starch content could be obtained, which is dependent on the treatment intensity (Hagenimana et al., 2006).

The aim of this study was to produce extrudates from bread crumbs at different extrusion conditions and thus to propose an innovative way for utilizing bread waste (in the form of bread crumbs). It was also aimed to investigate the effects of feed moisture and temperature on functional and physical properties of bread crumbs extrudates (BCEs) in comparison to wheat flour extrudates (WFEs) produced at the same extrusion conditions. For this purpose, (i) WFEs were directly produced from wheat flour, (ii) breads were baked using flour from the same flour party, (iii) bread crumbs were obtained by drying, grinding and sieving of these breads, and finally (iv) BCEs were produced from bread crumbs obtained. Of course, there is no need to produce bread crumbs from flour as the starting material. Bread crumbs are produced from wasted bread and available as a relatively inexpensive raw material.

Section snippets

Materials

Wheat flour and bread crumbs were obtained from Ankara Metropolitan Municipality Bakery Plant (Ankara, Turkey) in 50 kg sacks. Bread crumbs were produced from breads (by drying, grinding and sieving) made of the same wheat flour party in the same bakery plant. A lean formula (no fat, sugar or emulsifier) was used in the production of the bread.

Extrusion process

Wheat flour and bread crumbs were extruded using a laboratory scale co-rotating twin-screw extruder (Feza Makine Ltd Co., Istanbul, Turkey) with a 25:1

Physical properties of extrudates

Pictures of extrusion products obtained using different system parameters (exit die temperatures and feed moisture contents) are shown in Fig. 1. The photographs were taken under the same conditions from the same distance and put together without any magnification. They were provided for visual comparison only.

Conclusion

Although, in the present study, the bread crumbs were produced from bread obtained from the same wheat flour for comparison, there is no need to use flour as the starting material. Bread crumbs are normally produced from unsold bread in bakeries and available as a relatively inexpensive raw material. Processing bread wastes resulting from the product defects such as deformations and under/over-baking during processing and from the unsold breads in both small scale and industrial bakeries

Conflicts of interest

The authors declare no conflicts of interest.

References (29)

  • X. Meng et al.

    Effects of extrusion conditions on system parameters and physical properties of a chickpea flour-based snack

    Food Res. Int.

    (2010)
  • A. Peksa et al.

    Sensory attributes and physicochemical features of corn snacks as affected by different flour types and extrusion conditions

    LWT - Food Sci. Technol. (Lebensmittel-Wissenschaft -Technol.)

    (2016)
  • AACCI

    Approved Methods for the American Association of Cereal Chemists

    (2000)
  • M.S. Alam et al.

    Extrusion and extruded products: changes in quality attributes as affected by extrusion process parameters: a review

    Crit. Rev. Food Sci. Nutr.

    (2016)
  • Cited by (28)

    • Trends in bread waste utilisation

      2023, Trends in Food Science and Technology
    • Microbial characterization of discarded breads

      2023, LWT
      Citation Excerpt :

      In households, stale bread is often ground and used in several culinary recipes. Considering that bread is wasted throughout the food supply chain, the industry sector has come up with several options for its reuse, such as the preparation of sourdoughs (Gélinas, McKinnon, & Pelletier, 1999), cookies (Guerra-Oliveira, Belorio, & Gómez, 2021), cakes (Guerra-Oliveira, Belorio, & Gómez, 2022), snacks (Samray, Masatcioglu, & Koksel, 2019), and beer (Brancoli, Bolton, & Eriksson, 2020). Bread is a baked product.

    • Redistribution of surplus bread particles into the food supply chain

      2023, LWT
      Citation Excerpt :

      Extruded expanded products such as breakfast cereals and puffed snack systems are clear examples. Samray, Masatcioglu, and Koksel (2019) proposed the use of breadcrumbs for making direct expanded extrusion systems from wheat, which resulted in greater expansion ratio and enhanced crunchiness. Later, Luo and Koksel (2020) proposed the use of breadcrumb together with pea flour to obtain extrudates of better nutritional quality (mostly attributed to the pea components), higher expansion ratio and crunchiness and lower hardness.

    View all citing articles on Scopus
    View full text