Analysis of Softwood

Preheating with hot air at 85-125 C was evaluated for its effectiveness in removing terpenes and terpenoids in softwood sawdust, thereby enhancing fungal preprocessing and subsequent saccharification of softwood-based mushroom substrates. Sawdust from pine (Pinus sylvestris L.) and spruce (Picea abies (L.) H. Karst.) was preheated prior to shiitake (Lentinula edodes (Berk.) Pegler) cultivation. Preheating removed up to 96?% of terpenes in pine- based substrates and up to 50?% in spruce-based substrates. Additionally, preheating decreased total terpenoids content in spruce by up to 78?%. For the pine-based substrate, the mild heating generally led to faster colonisation and improved mushroom yield, with the fastest mycelia colonisation and highest yield observed for 105 C treatment. This temperature was associated with the lowest content of total terpenes and absence of major monoterpenes. The content of terpenes and terpenoids continued to decrease during cultivation, alongside fungal degradation of lignocellulose. As a result of more extensive lignin degradation, the enzymatic digestibility of cellulose was higher for spruce-based spent mushroom substrate than for pine-based one (up to 89?% vs. 49?% conversion). Enzymatic digestibility showed a negative correlation with the a-pinene content, and a positive correlation with increasing preheating temperatures.

Pretreatments of lignocellulosic biomass prior to fast pyrolysis need to give a better yield and quality of pyrolysis oil and be practical to implement at a commercial scale. This study demonstrated, at a large pilot scale, that thermomechanical refining can reduce the particle size, hemicellulose content, and mineral content of pine wood chips, leading to improved yields of carbohydrate-derived chemicals on fast pyrolysis. Additionally, a hemicellulose-rich byproduct can be generated during the pretreatment for separate valorization. The impact of different presteaming times, citric acid infusion, and disc refining on the yield and composition of the pyrolysis oil was studied. Presteaming of citric acid-infused wood chips at 173 C for 3 min and refining to wood fiber proved most effective in improving the yield of pyrolysis oil organics, including the valuable biochemicals levoglucosan and hydroxyacetaldehyde, while reducing the yields of low-value char and noncondensable gases.