Ren Haiyu, Richard Tom L, Chen Zhilin, Kuo Monlin, Bian Yilin, Moore Kenneth J, Patrick Patricia
Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Biotechnol Prog. 2006 Jan-Feb;22(1):78-85. doi: 10.1021/bp050174q.
Ensilage is a truncated solid-state fermentation in which anaerobically produced organic acids accumulate to reduce pH and limit microbial activity. Ensilage can be used to both preserve and pretreat biomass feedstock for further downstream conversion into chemicals, fuels, and/or fiber products. This study examined the ensilage of enzyme-treated corn stover as a feedstock for particleboard manufacturing. Corn stover at three different particle size ranges (<100, <10, and <5 mm) was ensiled with and without a commercial enzyme mixture having a cellulase:hemicellulase ratio of 2.54:1, applied at a hemicellulase rate of 1670 IU/kg dry mass. Triplicate 20 L mini-silos were destructively sampled and analyzed on days 0, 1, 7, 21, 63, and 189. Analysis included produced organic acids and water-soluble carbohydrates, fiber fractions, pH, and microorganisms, including Lactobacillus spp. and clostridia were monitored. On days 0, 21, and 189, the triplicate samples were mixed evenly and assembled into particleboard using 10% ISU 2 resin, a soy-based adhesive. Particleboard panels were subjected to industry standard tests for modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding strength (IB), thickness swell (TS), and water absorption at 2 h boiling and 24 h soaking. Enzyme addition did improve the ensilage process, as indicated by sustained lower pH (P < 0.0001), higher water-soluble carbohydrates (P < 0.05), and increased lactic acid production (P < 0.0001). The middle particle size range (<10 mm) demonstrated the most promising results during the ensilage process. Compared with fresh stover, the ensilage process did increase IB of stover particleboard by 33% (P < 0.05) and decrease water adsorption at 2 h boiling and 24 h soaking significantly (P < 0.05). Particleboard panels produced from substrate ensiled with enzymes showed a significant reduction in water adsorption of 12% at 2 h boiling testing. On the basis of these results, ensilage can be used as a long-term feedstock preservation method for particleboard production from corn stover. Enzyme-amended ensilage not only improved stover preservation but also enhanced the properties of particleboard products.
青贮是一种截断的固态发酵过程，在此过程中厌氧产生的有机酸积累以降低pH值并限制微生物活性。青贮可用于保存和预处理生物质原料，以便进一步向下游转化为化学品、燃料和/或纤维产品。本研究考察了酶处理玉米秸秆青贮作为刨花板制造原料的情况。将三种不同粒径范围（<100、<10和<5毫米）的玉米秸秆分别在添加和不添加商业酶混合物（纤维素酶与半纤维素酶比例为2.54:1，以1670 IU/kg干质量的半纤维素酶用量添加）的情况下进行青贮。在第0、1、7、21、63和189天对一式三份的20升小型青贮窖进行破坏性采样和分析。分析内容包括产生的有机酸和水溶性碳水化合物、纤维组分、pH值以及微生物，包括对乳酸杆菌属和梭菌进行监测。在第0、21和189天，将一式三份的样品均匀混合，并使用10%的ISU 2树脂（一种大豆基胶粘剂）制成刨花板。对刨花板进行行业标准测试，测定其断裂模量（MOR）、弹性模量（MOE）、内结合强度（IB）、厚度膨胀率（TS）以及在2小时煮沸和24小时浸泡后的吸水率。添加酶确实改善了青贮过程，表现为pH值持续较低（P<0.0001）、水溶性碳水化合物含量较高（P<0.05）以及乳酸产量增加（P<0.0001）。中等粒径范围（<10毫米）在青贮过程中显示出最有前景的结果。与新鲜秸秆相比，青贮过程确实使秸秆刨花板的内结合强度提高了33%（P<0.05），并显著降低了在2小时煮沸和24小时浸泡后的吸水率（P<0.05）。用酶青贮的底物制成的刨花板在2小时煮沸测试中的吸水率显著降低了12%。基于这些结果，青贮可作为一种长期保存玉米秸秆用于刨花板生产的原料的方法。酶改良青贮不仅改善了秸秆的保存效果，还增强了刨花板产品的性能。
