METHOD FOR PROCESSING VEGETAL RAW MATERIALS IN ORDER TO PRODUCE PENTOSE HYDROLYSATES ESSENTIALLY CONTAINING XYLOSE

摘要

The present invention relates to a method for producing pentose hydrolysates from pentosane-containing raw materials which have a higher purity as well as a higher xylose content. This method can be used for increasing the xylite production rate and comprises processing the hydrolysate in the following manner. This method uses as pentosane-containing raw materials the distiller's grain from the brewers' industry. During a first step, the distiller's grain having a natural humidity is submitted to a liquid-phase disintegration in a disc mill comprising a vibrator with an oscillation frequency of between 10 and 50 Hz. The disintegration can also be carried out in an ultrasonic apparatus with waves at a frequency of between 22 and 44 kHz or in a rotary-pulse apparatus having a rotor rotating at 3000 r/min., wherein the disintegration is carried out for a duration of 1 to 15 minutes and the solid phase is further separated from the liquid suspension. A second step comprises carrying out a high-temperature scrubbing during which the solid phase is mixed with water according to a ratio of 1 : 5-8. The mixture is maintained at a temperature of between 140 and 160 DEG C for 10 to 30 minutes while being periodically stirred. The solid phase is then separated and submitted to hydrolysis using a 0.5-2.5 % solution of sulphuric acid for a duration of between 2 and 4 hours and at a temperature of between 100 and 120 DEG C. This method ensures the protection of the pentosanes against the acidic decay during the refining process of the vegetal raw materials. The xylose concentration relative to the total amount of sugars in the hydrolysate increases from 57 % (when the starting mixture is distiller's grain) to 84-87 %, while the arabinose content is divided by two (from 30 to 13-17 %). This method further produces a proteinic paste containing up to 40 % of raw proteins while maintaining the nutritional values of the distiller's grain components.