Waste bread recycling as a baking ingredient by tailored lactic acid fermentation

Mikko Immonen,Ndegwa H Maina,Yaqin Wang,Rossana Coda,Kati Katina

doi:10.1016/j.ijfoodmicro.2020.108652

Mikko Immonen, Ndegwa H Maina + Show 3 more

Open Access

https://doi.org/10.1016/j.ijfoodmicro.2020.108652

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Abstract

Food-grade waste and side streams should be strictly kept in food use in order to achieve sustainable food systems. At present, the baking industry creates food-grade waste as excess and deformed products that are mainly utilized for non-food uses, such as bioethanol production. The purpose of this study was therefore to explore the potential of waste wheat bread recycling for fresh wheat bread production. Waste bread recycling was assessed without further processing or after tailored fermentation with lactic acid bacteria producing either dextran or β-glucan exopolysaccharides. When non-treated waste bread slurry was added to new bread dough, bread quality (specific volume and softness) decreased with increasing content of waste bread addition. In situ EPS-production (dextran and microbial β-glucan) significantly increased waste bread slurry viscosity and yielded residual fructose or glucose that could effectively replace the sugar added for yeast leavening. Furthermore, fermentation acidified waste bread matrix, thus improving the hygienic safety of the process. Bread containing dextran synthesized in situ by Weissella confusa A16 showed good technological quality. The produced dextran compensated the adverse effect of recycled bread on new bread quality attributes by 12% increase in bread specific volume and 37% decrease in crumb hardness. In this study, a positive technological outcome of the bread containing microbial β-glucan was not detected. The waste bread fermented by W. confusa A16 containing dextran appears to enable safe bread recycling with low acidity and minimal quality loss.

Highlights

Food waste is a huge problem from a global food security and sustainability perspective (Gustavsson et al, 2011, Otles et al, 2015)
P. claussenii strains, produced higher acidification compared to W. confusa A16, with the titratable acidity (TTA) of 10.2ml NaOH and 7.8mg/g lactic acid (P. claussenii 55T EPS-pos.), and TTA of 8.8ml NaOH and 6.4mg/g lactic acid (P. claussenii 179)
The more intense acidification caused by fermentation with P. claussenii 55T and 179 strains might be due to the addition of yeast extract providing free nitrogen to support microbial metabolism

Summary

Introduction

Food waste is a huge problem from a global food security and sustainability perspective (Gustavsson et al, 2011, Otles et al, 2015). The term ‘waste’ includes all food-processing side streams that are currently disposed from manufacturing plants for non-food use. The total production volume of cereals produced in Europe is about 400 million tonnes/year off which roughly 5% is lost during processing (Gustavsson et al, 2011). Considering current global undernourishment of over 800 million people, resource efficient practices should be implemented to avoid wasting edible food materials (FAO et al, 2014). Innovative ways to exploit side streams are crucial for cost efficiency and for achieving sustainable food systems in a circular economy

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