Abstract
The amount of bread wasted daily worldwide, throughout its entire lifecycle, from production to distribution, is estimated to be hundreds of tons, therefore representing both economic and environmental issues. This work aimed at the valorization of wasted bread, setting-up a protocol for obtaining a growth medium to be used for the cultivation of food industry microbial starters. The optimization of the protocol included the set-up of parameters for the hydrolysis of the bread nutrient compounds with proteolytic and amylolytic enzymes and the supplementation with nitrogen and/or carbon sources. The suitability of the optimized medium for the growth of lactic acid bacteria, yeasts and fungi from dairy, bakery, and wine industries was assessed. Lactic acid bacteria growth was strongly affected by the quantity and quality of nitrogen sources employed, while yeasts and fungi growth exceeded that obtained with the reference media commonly employed for their cultivation. Wasted bread medium (WBM) represents a realistic option for the valorization and re-use of bread waste, responding to the modern vision of circular economy.
Highlights
Breadmaking involves industrial and artisanal bakeries all over the world, that together represent one of the largest sectors of the global food industry
The cell density of Lb. plantarum LB1 and S. cerevisiae E10, inoculated as indicator microorganisms, was measured after incubation for all the Wasted bread medium (WBM) samples obtained by varying the production protocols parameters, and compared to that obtained with media commonly used to propagate lactic acid bacteria (LAB) and yeasts (Figure 1)
The use of selected microorganisms as viable starter cultures is largely adopted in the modern food industry to address the fermentation processes toward specific sensory, nutritional and functional targets, to extend the shelf-life, and to ensure the standardization of the product quality (Leroy and De Vuyst, 2004)
Summary
Breadmaking involves industrial and artisanal bakeries all over the world, that together represent one of the largest sectors of the global food industry. Bread production is estimated to be about 100 million tons per year, 65% of which is consumed in Europe (Melikoglu and Webb, 2013). A complex physical-chemical process defined as staling occurs in bread, mainly driven by the loss of moisture and retrogradation of starch (Narvhus and Sørhaug, 2006). Bread composition makes it susceptible for microbial attack, which is why preservatives, inhibiting spore, molds and/or yeasts growth, are used to reduce spoilage and ensure safety (Suhr and Nielsen, 2004). Because of the susceptibility to staling and spoiling, a huge amount of bread is discarded by consumers or unsold from the retails causing relevant economic losses. Determining the precise amount of bread wasted during its life cycle is difficult, but it is estimated that hundreds of tons
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