In order to
increase the pool of sugars available for yeast, enzymatic hydrolysis,
followed by a thermo-chemical pre-treatment (blanching with
2% of sulphuric acid addition) was performed. The enzymatic preparations
Viscozyme and Ultraflo Max (both from Novozymes),
exhibiting cellulolytic, xylanolytic and pectinolytic activity, were
used. Enzymatic hydrolysis was carried out in an Inox steel reactor
(working capacity 2.4 m3
) for 24 h at 50 ± 1 C (location: sugar factory,
Dobrzelin). The temperature was raised to 80 C at the end of
the hydrolysis to deactivate the enzymes and to limit the growth of
undesired microflora. From a mixture of 250 kg of wet beet pulp
(approx. 50 kg of DM), 2.7 dm3 of each enzymatic preparation
and 300 dm3 of water, about 375 dm3 of filtered hydrolysate and
approx. 175 kg of wet solid residues were obtained after enzymatic
hydrolysis.