Enhanced succinic acid biochemical production through steam explosion of phosphoric soaked vine shoots

The circular economy has emerged as a promising strategy to address global sustainability challenges. In this context, the valorisation of agro-industrial waste, such as vine shoots, represents an opportunity to convert biomass waste into valuable products. In this study, vine shoots were processed to obtain fermentable sugars and, afterwards, succinic acid, a relevant compound to the industry. First, vine shoots were subjected to steam explosion pretreatment with dilute phosphoric acid. Response surface methodology was applied to evaluate the effects of temperature (170 °C – 200 °C) and phosphoric acid concentration (0.5 % w/v – 2.5 % w/v). Optimal conditions were identified at 190 °C and 2.5 % (w/v) phosphoric acid, achieving an efficiency of hemicellulose removal of 78.2 % and 75.9 % saccharification efficiency. Enzymatic hydrolysis of the optimally pretreated solid at 20 % (w/v) solid loading yielded glucose concentrations of up to 36.9 g/L, with reduced enzyme loadings (12 FPU/g substrate) showing no negative impact on final glucose yields. Fermentation of this hydrolysate using Actinobacillus succinogenes resulted in succinic acid production of 34.6 g/L, which represented a yield of 0.57 g/g of consumed sugars. These findings demonstrate the potential of vine shoot waste as a feedstock to produce bio-based succinic acid. • Optimal conditions for steam explosion pretreatment were 190 °C and 2.5 % H 3 PO 4 . • Steam explosion pretreatment with H 3 PO 4 solubilized 78 % of hemicellulosic sugars. • Succinic acid yield of 0.55 g/g was achieved from pretreated vine shoots. • 76 % saccharification efficiency under optimized steam explosion conditions