Analysis Package P22 : Organic Acids and Furans

Acetone organosolv fractionation of beech and birch wood at the lab-scale results in high sugar yields from the (hemi)cellulose and the isolation of a high-purity lignin. In this study, the process is scaled up to validate the technology at the pilot scale using industrial-size beech and birch wood chips and low liquid-to-solid ratios as a next step toward commercialization. Translation of the fractionation process to the pilot-scale showed a similar performance as compared to the lab-scale processing with a good conversion of the wood polymeric pentoses to mostly monomeric sugars and a high delignification. Continuous lignin precipitation by solvent evaporation using the LigniSep process resulted in the formation of nonsticky lignin aggregates with a good filterability. The improved lignin yields and advanced process design as compared to the traditional dilutive lignin precipitation approaches are likely to translate to a better process economy. The pulp washing efficiency and the recovery of (nonprecipitable) lignin from the aqueous hemicellulose stream still need to be improved for an efficient process design. However, the fractionation performance and high product concentrations in the spent liquor provide an excellent start position for improved process design at the commercial scale.

A study was conducted to identify optimal conditions (time and temperature) for heat pre-treatment of corn whole stillage (WS). Six samples of WS from different sources were divided into 13 sub-samples to give a total of 78 sub-samples. Thirteen treatments were applied to 13 sub-samples from each source (1 sub-sample/treatment). The treatments were untreated WS, and WS that was pre-treated (70 psi) for 10, 20, or 30 min and at 100, 120, 140, or 160 C in a 3 x 4 factorial treatment arrangement. Sub-samples were subjected to in vitro digestion with porcine pepsin and pancreatin, followed by in vitro fermentation for 72 h. Accumulated gas production was recorded and modeled to estimate kinetics of gas production. Heat pretreatment of WS at >= 120 C decreased (P < 0.05) its total dietary fiber (TDF) and chemically available lysine content by approximately 10 and 19 %, respectively; and increased (P < 0.05) total furans (TF) content from 0.50 to approximately 154 mg/kg. Pretreatment time and temperature interacted on TDF and TF content in WS, such that an increase in pretreatment time had no effect on TDF and TF content in WS when pretreated at 100, 120, or 140 C, but reduced (P < 0.05) TDF content and increased (P < 0.05) TF content in WS when pretreated at 160 C. Pretreatment time and temperature interacted (P < 0.05) on chemically available lysine content of WS, such that an increase in pretreatment time unaffected chemically available lysine content when the WS was pretreated at 100 or 120 C, but reduced (P < 0.05) chemically available lysine content when the WS was pretreated at 140 or 160 C. Pre-treatment time and temperature did not interact on in vitro disappearance of dry matter (IVD-DM), and total gas production. The coefficient of IVD-DM for untreated WS was 0.734. An increase in pre-treatment temperature from 0 to 160 C resulted in linear increase (P < 0.05) in coefficient of IVD-DM by 13 %, and of total gas production by 16 %. Response surface analysis indicated that maximum coefficient of IVD-DM and total gas production resulted from longer pretreatment times (20-30 min) and highest pretreatment temperature, whereas maximum chemically available lysine content resulted from pretreatment at 100 C for 20 min. In conclusion, the optimal conditions for pretreatment of WS for production of distillers dried grains with solubles of improved digestibility and fermentability by pigs were temperature of 140-160 C, and duration of approximately 20 min.