Research paper Evaluation of the correlations between biodegradability of lignocellulosic feedstocks in anaerobic digestion process and their biochemical characteristics X. Liu, R. Bayard * , H. Benbelkacem, P. Buffi  ere, R. Gourdon Universite de Lyon, INSA-Lyon, Laboratoire DEEP, B^ at. S. Carnot, 9 rue de la Physique, F-69621 Villeurbanne, France article info Article history: Received 6 February 2015 Received in revised form 23 June 2015 Accepted 25 June 2015 Available online xxx Keywords: Anaerobic digestion Biomethane potential Lignocellulosic residues Biochemical analyses Biological oxygen demand Enzymatic hydrolysis abstract Biochemical composition and reactivity are key factors controlling the biodegradability of lignocellulosic residues. In the present study, 14 lignocellulosic substrates including 6 agricultural and 8 forest residues were analyzed for 9 biochemical characteristics, including BioMethane Potential (BMP), Biological Ox- ygen Demand (BOD), Enzymatic Cellulose Degradation tests (ECD), Van Soest and NREL fractionation methods. The data obtained were exploited by principal component analysis (PCA) and other statistical methods to investigate the possible correlations between the parameters. The study showed that the contents in particular lignin or in non-extractible residues (RES) were the characteristics which influ- enced most the anaerobic biodegradability (BMP), while the influence of the soluble fraction was quite low. BMP was well correlated with the ratio of the contents in non-lignin over lignin fractions and the cellulose to lignin ratio. Regarding agricultural residues, BMP was better correlated with lignin content than with RES content. Agricultural and forest residues exhibited distinct characteristics of aerobic and anaerobic biodegradability. Good correlation was observed between ECD and lignin content. Finally, it was also observed that Van Soest's and NREL methods did not provide the same results in terms of biochemical composition. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Energy recovery from lignocellulosic biomass is one of the major options to reduce greenhouse gases emissions and the depletion of fossil fuels without causing direct competition with food products. Several processes are possible to meet this objective. Microbial Anaerobic Digestion (AD) into methane is one of the most attractive approaches as compared to typical pathways to biodiesel or ethanol. It is known that are in AD processes biopolymers are converted into simple compounds and finally into methane and carbon dioxide through the activity of the different types of anaerobic micro-organisms. To date, AD has essentially been developed for the treatment of animal manure, municipal solid waste, sewage sludge and energy crops. Yet, large amounts of lignocellulosic biomass such as crop residues and forest residues remain available in Europe and other countries as a potential resource to increase the production of renewable fuels [1,2,3]. Due to the diversity of vegetable species and growth conditions however, the biochemical composition of biomass substrates is quite variable both qualitatively and quantitatively [4]. Lignocel- lulosic biomass is mainly composed of cellulose, hemicelluloses and lignin, with cellulose being the most abundant natural carbo- hydrate polymer. The variability in biochemical composition and structural characteristics, along with other parameters, make quite variable and not easily predictable the potential production of methane by biological anaerobic digestion of these substrates. Therefore, detailed analyses of feedstocks are required to estimate the anaerobic biodegradability of lignocellulosic biomass. Several methods of chemical characterization are available, such as elemental analysis biochemical fiber analysis, enzymatic hydroly- ses and experimental evaluations of biodegradability. Several studies have already investigated for various biomasses the re- lationships between biodegradability and some biochemical char- acteristics of the substrates, including proteins, lipids, carbohydrates and fibers contents [5e15]. Methane production from lignocellulosic biomass in AD process is however strongly affected by the structure of the lignocellulosic complex where the relatively recalcitrant lignin limits the accessibility to micro- * Corresponding author. E-mail address: remy.bayard@insa-lyon.fr (R. Bayard). Contents lists available at ScienceDirect Biomass and Bioenergy journal homepage: http://www.elsevier.com/locate/biombioe http://dx.doi.org/10.1016/j.biombioe.2015.06.021 0961-9534/© 2015 Elsevier Ltd. All rights reserved. Biomass and Bioenergy 81 (2015) 534e543