Chemistry

Metallurgy

Materials science

Food waste

Engineering

Hydrolysate

Food science

Biochemistry

Organic chemistry

Enzymatic hydrolysis

2,3-Butanediol

Fermentation

Raw material

Biorefining

Yield (engineering)

Valorisation

Hydrolysis

Yeast extract

Biorefinery

Waste management

Bioresource Technology

Bread is Europe's most wasted food, and the second most wasted food after potatoes in UK. Bread waste (BW) is a clean source of high-quality fermentable sugars. In this study, the potential of Enterobacter ludwigii to accumulate 2,3-butanediol (BDO) from BW was evaluated. Initially, the optimal inoculum size and yeast extract concentration were determined, followed by extraction of sugars from BW using acid and enzymatic hydrolysis. A glucose yield of 330-530 g/kg BW was obtained, and the sugars released were utilised for BDO production by E. ludwigii. The fed-batch cultivation using pure glucose and glucose rich hydrolysates from acid and enzymatic hydrolysis resulted in BDO titres of 144.5, 135.4, and 138.8 g/L, after 96 h, with yield of 0.47, 0.42 and 0.48 g/g yield, respectively. The innovation of the work is valorisation of BW to BDO with a circular biorefining approach and thus, reducing BW disposal and associated environmental burden.

Fermentative production of 2,3-Butanediol using bread waste – A green approach for sustainable management of food waste