Carvalheiro Florbela, Duarte Luís C, Medeiros Raquel, Gírio Francisco M
INETI, Departamento de Biotecnologia, Estrada do Paço do Lumiar 22, 1649-038 Lisboa, Portugal.
Appl Biochem Biotechnol. 2004 Spring;113-116:1059-72. doi: 10.1385/abab:115:1-3:1059.
Dilute-acid hydrolysis of brewery's spent grain to obtain a pentose-rich fermentable hydrolysate was investigated. The influence of operational conditions on polysaccharide hydrolysis was assessed by the combined severity parameter (CS) in the range of 1.39-3.06. When the CS increased, the pentose sugars concentration increased to a maximum at a CS of 1.94, whereas the maximum glucose concentration was obtained for a CS of 2.65. The concentrations of furfural, hydroxymethylfurfural (HMF), as well as formic and levulinic acids and total phenolic compounds increased with severity. Optimum hydrolysis conditions were found at a CS of 1.94 with >95% of feedstock pentose sugars recovered in the monomeric form, together with a low content of furfural, HMF, acetic and formic acids, and total phenolic compounds. This hydrolysate containing glucose, xylose, and arabinose (ratio 10:67:32) was further supplemented with inorganic salts and vitamins and readily fermented by the yeast Debaryomyces hansenii CCMI 941 without any previous detoxification stage. The yeast was able to consume all sugars, furfural, HMF, and acetic acid with high biomass yield, 0.68 C-mol/C-mol, and productivity, 0.92 g/(L.h). Detoxification with activated charcoal resulted in a similar biomass yield and a slight increase in the volumetric productivity (11%).
研究了啤酒厂废谷物的稀酸水解以获得富含戊糖的可发酵水解产物。通过在1.39 - 3.06范围内的综合强度参数（CS）评估操作条件对多糖水解的影响。当CS增加时，戊糖浓度在CS为1.94时增加到最大值，而葡萄糖最大浓度在CS为2.65时获得。糠醛、羟甲基糠醛（HMF）以及甲酸和乙酰丙酸的浓度以及总酚类化合物的浓度随强度增加而增加。在CS为1.94时发现了最佳水解条件，原料中超过95%的戊糖以单体形式回收，同时糠醛、HMF、乙酸和甲酸以及总酚类化合物的含量较低。这种含有葡萄糖、木糖和阿拉伯糖（比例为10:67:32）的水解产物进一步补充了无机盐和维生素，并在没有任何预先解毒阶段的情况下很容易被酵母汉逊德巴利酵母CCMI 941发酵。该酵母能够消耗所有糖类、糠醛、HMF和乙酸，生物质产量高，为0.68 C-mol/C-mol，生产力为0.92 g/(L·h)。用活性炭解毒导致了相似的生物质产量和体积生产力略有增加（11%）。
