Determination of Plant Cell Wall Composition by a Physical and Chemical Approach

Abstract

Since many years lignocellulosics plants like flax or hemp have been cultivated. At first, these plants were mainly produced for their fibers. Nowadays, agricultural by-products are changed into bio-based building engineering products like particle boards and mortars. These materials allow good insulation characteristics (acoustics, thermic) and have a low environmental impact. Thus, the current research is focused on plant valorisation into bio-based building products. However, plants are a natural and variable matter which is not submitted to international standards in compared to building materials. A better understanding of plant material is required to better value these products with great characteristics. The aim of this investigation is to provide an accurate analysis of chemical composition of plant materials especially hemp shiv. A deeper understanding could be necessary to understand plant aggregate interactions with building engineering products. At first, Van Soest method (VS) was performed to quantify cell wall compounds. Non-destructive version of Van Soest method (NVS) allowed us to separate each fraction derived from this method. All these fractions have been analysed by Thermal Gravimetric Analysis (TGA) to quantify and identify molecules in crushed samples. The results obtained from these technics are analysed and compared. Analyses suggested that hemp shiv contain 49% of cellulose, 21% of hemicellulose, 21% of soluble compounds (pectins, lipids, oses, ashes, proteins…) and 9% of lignin. TGA results showed different thermal stabilities depends on considered fraction, which be link to cellulose interactions with lignin and hemicellulose. By this physical technic we provide another method to quantify cell wall molecules.