蒸汽爆破技术在玉米秸秆饲料化利用中的研究进展

玉米秸秆是作物残余物中最丰富的木质纤维素生物质之一,主要由纤维素、半纤维素和木质素通过氢键及其他化学键、分子键结合而成,是具有复杂聚合结构的高分子化合物,作为动物饲料的可利用率较低。蒸汽爆破即汽爆,是应用蒸汽弹射原理实现爆炸过程中对生物质预处理的技术。将蒸汽爆破技术应用于玉米秸秆处理,可高效分离纤维素,对玉米秸秆具有明显的解聚作用,有利于提高玉米秸秆的饲料化利用程度。作者介绍了蒸汽爆破工艺原理与参数,综述了蒸汽爆破处理对玉米秸秆纤维结构、化学成分和酶解产糖的影响,以及对玉米秸秆的营养成分消化率和瘤胃微生物附着的影响。已有研究表明,蒸汽爆破可使蒸汽分子渗入植物组织,经过瞬时释放将内能转化为机械能,作用于生物质组织细胞层间,达到原料分解的目的;蒸汽爆破可改变玉米秸秆的纤维结构,降低半纤维素和木质素含量,提高纤维素含量(随着蒸汽爆破的压强和维压时间的增加,半纤维素含量显著降低,而物料含水率的增加会导致纤维素含量升高);蒸汽爆破可提高玉米秸秆体外发酵酶解产糖率,随着蒸汽爆破压强和维压时间的增加,玉米秸秆体外培养酶解还原糖产量增加;蒸汽爆破可使玉米秸秆的体外发酵产气量、产气速率、干物质和酸性洗涤纤维含量显著提高,可提高反刍动物对玉米秸秆的消化利用率,充分利用玉米秸秆的纤维素,提高玉米秸秆的营养价值;蒸汽爆破通过破坏玉米秸秆的表面结构,可促进瘤胃微生物在玉米秸秆上的附着,从而促进玉米秸秆的降解。综上,蒸汽爆破技术处理玉米秸秆可提高其作为饲料的利用率。

Research Progress on Steam Explosion Technology in Feed Utilization of Corn Straw

Corn straw is one of the most abundant lignocellulosic biomass in crop residues.It is mainly composed of cellulose, hemicellulosic and lignin through hydrogen bonds, other chemical bonds and molecular bonds to form polymer compounds with complex polymerization structure, which makes its low availability as animal feed.Steam explosion is a technology which applies steam ejection principle to pretreat biomass in explosion process.The steam explosion technology was applied to the treatment of corn straw, which could effectively separate cellulose and had obvious depolymerization effect on corn straw, which was beneficial to improve the utilization degree of corn straw as feed.In this paper, the principle and parameters of steam explosion technology were introduced, and the effects of steam explosion technology on fiber structure, chemical composition, enzymatic hydrolysis sugar production, nutrient digestibility of corn stalk and microbial attachment in rumen were reviewed.Existing studies have shown that steam explosion can make steam molecules penetrate into plant tissues, and transform internal energy into mechanical energy through instantaneous release, acting on the cell layers of biomass tissue to achieve the purpose of raw material decomposition.The content of hemicellulose and lignin can be decreased by changing the fiber structure of corn straw, and the content of cellulose can be increased.With the increase of steam blasting pressure and maintaining pressure time, the content of hemicellulose can be decreased significantly, and the increase of material moisture content will lead to the increase of cellulose content.With the increase of steam burst pressure and maintenance time, the reduction sugar yield of maize straw in vitro fermentation increased.The in vitro gas production, gas production rate, dry matter and acid detergent fibre of corn stalks were significantly increased, the digestibility and utilization rate of ruminant corn stalks were improved, the cellulose of corn stalks was fully utilized, and the nutritional value of corn stalks was improved.By destroying the surface structure of corn stalks, rumen microorganism can be attached to corn stalks, thus promoting the degradation of corn stalks.To sum up, steam explosion technology can improve the utilization rate of corn straw as feed.