Hemicellulosic hydrolysates detoxification

The xylitol production rate is highest at very high xylose concentrations (80 g/1) [8, 10]. However, concentrating the hemicellulose hydrolysates using vacuum evaporation to achieve high xylose concentrations also concentrates the non-volatile inhibitors [11]. At these inhibitor concentrations, volumetric productivity actually declines [12-14]. Many studies have demonstrated the inhibitory effect of these hydrolysis-derived compounds on growth and production of products, such as ethanol and xylitol [15-16]. Concentrated hydrolysate requires detoxification for optimum xylitol production. 

C5 hemicellulosic hydrolysates, produced by the NREL Clean Fractionation procedure, have been detoxified by methods related to the TVA detoxification procedure (Strickland and Beck, 1984). With the appropriate addition of an organic acid cosubstrate, levulinic acid, also produced from renewable feedstocks, we have produced P(3HB-co-3HV) copolymers possessing physical and chemical properties that are potentially useful for application as industrial bioplastics. Thermal characteristics and viscosity-derived molecular masses of a set of P(3HB-co-3HV) samples produced microbially from detoxified hemicellulosic hydrolysate and levulinic acid, are presented in Table 9.3. 

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