Krafft Malte Jörn, Berger Jens, Saake Bodo
Chemical Wood Technology, University of Hamburg, Barsbüttel, Germany.
Front Chem. 2021 Oct 14;9:760657. doi: 10.3389/fchem.2021.760657. eCollection 2021.
The utilization of agricultural products and residues for the production of value-added and biobased products is a highly relevant topic in present research. Due to the natural recalcitrance of lignocellulosic biomass against enzymatic degradation, pretreatments are important requirement for further processes. For the raw material in this study, corn stover (CS) as highly available agricultural residue and maize silage (MS) as model substrate for an ensiled agricultural product were pretreated by steam refining. However, after processing a liquid fraction and fibers are present. Subsequent to steaming the fiber fraction is well characterized. Nonetheless, in depth characterizations of the filtrates are also important for their subsequent utilization. Decreasing molar masses from 7,900 g/mol to 1,100 g/mol for CS filtrates and 100.000-12.900 g/mol for MS filtrates were determined with increasing severity. Due to their proven inhibitory effect on microorganisms weak acids, furans and phenolic compounds within the liquid phased were analyzed. Especially formic acid increases with increasing severity from 0.27 to 1.20% based on raw material for CS and from 0.07 to 0.23% based on raw material for MS. Further GC/MS measurements indicate, that up to 8.25% (CS filtrate) and 5.23% (MS filtrates) of the total peak area is related to inhibitory phenols. Considering the data, detoxification strategies are of non-negligible importance for filtrates after steam refining and should be considered for further research and process or parameter optimizations. An alternative may be the application of milder process conditions in order to prevent the formation of inhibitory degradation products or the dilution of the gained filtrates.
利用农产品及其残余物生产增值生物基产品是当前研究中一个高度相关的课题。由于木质纤维素生物质对酶解具有天然抗性，预处理是后续加工的重要前提。对于本研究中的原料，将极易获取的农业残余物玉米秸秆（CS）和青贮农产品的模型底物玉米青贮料（MS）进行蒸汽精制预处理。然而，处理后会出现液相部分和纤维。蒸汽处理后，纤维部分得到了很好的表征。尽管如此，对滤液进行深入表征对于其后续利用也很重要。随着处理强度增加，CS滤液的摩尔质量从7900 g/mol降至1100 g/mol，MS滤液的摩尔质量从100000 g/mol降至12900 g/mol。由于已证实弱酸、呋喃和酚类化合物对微生物有抑制作用，因此对液相中的这些物质进行了分析。特别是甲酸，随着处理强度增加，基于CS原料从0.27%增至1.20%，基于MS原料从0.07%增至0.23%。进一步的气相色谱/质谱测量表明，总峰面积中高达8.25%（CS滤液）和5.23%（MS滤液）与抑制性酚类有关。考虑到这些数据，解毒策略对于蒸汽精制后的滤液具有不可忽视的重要性，在进一步研究以及工艺或参数优化中应予以考虑。一种替代方法可能是采用较温和的工艺条件，以防止形成抑制性降解产物或稀释所得滤液。
