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- ItemDirect production of lactic acid based on simultaneous saccharification and fermentation of mixed restaurant food waste(Amsterdam : Elsevier, 2016) Pleissner, Daniel; Demichelis, Francesca; Mariano, Silvia; Fiore, Silvia; Gutiérrez, Ivette Michelle Navarro; Schneider, Roland; Venus, JoachimThis study introduces to a one-step process for the fermentative production of L(+)-lactic acid from mixed restaurant food waste. Food waste was used as carbon and nitrogen source in simultaneous saccharification and fermentation (SSF) using Lactobacillus sp. or Streptococcus sp. strains for L(+)-lactic acid production. Waste consisted of (w/w) 33.5% starch, 14.8% proteins, 12.9% fat and 8.5% free sugars. Lactobacillus sp. strains showed a productivity of 0.27–0.53 g L−1 h−1 and a yield of 0.07–0.14 g g−1 of theoretically available sugars, while Streptococcus sp. more efficiently degraded the food waste material and produced lactic acid at a maximum rate of 2.16 g L−1 h−1 and a yield of 0.81 g g−1. For SSF, no enzymes were added or other hydrolytic treatments were carried out. Outcomes revealed a linear relationship between lactic acid concentration and solid-to-liquid ratio when Streptococcus sp. was applied. Statistically, from a 20% (w/w) dry food waste blend 52.4 g L−1 lactic acid can be produced. Experimentally, 58 g L−1 was achieved in presence of 20% (w/w), which was the highest solid-to-liquid ratio that could be treated using the equipment applied. Irrespective if SSF was performed at laboratory or technical scale, or under non-sterile conditions, Streptococcus sp. efficiently liquefied food waste and converted the released nutrients directly into lactic acid without considerable production of other organic acids, such as acetic acid. Downstream processing including micro- and nanofiltration, electrodialysis, chromatography and distillation gave a pure 702 g L−1 L(+)-lactic acid formulation.
- ItemFermentative lactic acid production from coffee pulp hydrolysate using Bacillus coagulans at laboratory and pilot scales(Amsterdam : Elsevier, 2016) Pleissner, Daniel; Neu, Anna-Katrin; Mehlmann, Kerstin; Schneider, Roland; Puerta-Quintero, Gloria Inés; Venus, JoachimIn this study, the lignocellulosic residue coffee pulp was used as carbon source in fermentative l(+)-lactic acid production using Bacillus coagulans. After thermo-chemical treatment at 121 °C for 30 min in presence of 0.18 mol L−1 H2SO4 and following an enzymatic digestion using Accellerase 1500 carbon-rich hydrolysates were obtained. Two different coffee pulp materials with comparable biomass composition were used, but sugar concentrations in hydrolysates showed variations. The primary sugars were (g L−1) glucose (20–30), xylose (15–25), sucrose (5–11) and arabinose (0.7–10). Fermentations were carried out at laboratory (2 L) and pilot (50 L) scales in presence of 10 g L−1 yeast extract. At pilot scale carbon utilization and lactic acid yield per gram of sugar consumed were 94.65% and 0.78 g g−1, respectively. The productivity was 4.02 g L−1 h−1. Downstream processing resulted in a pure formulation containing 937 g L−1 l(+)-lactic acid with an optical purity of 99.7%.