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

Abstract

For many years lignocellulosic 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 low environmental impact. Thus, the current research is focused on plant valorization into bio-based building products. However, plants are a natural and variable matter that is not submitted to international standards compared to building materials. A better understanding of plant material, which has great characteristics, is required for its valorization. This investigation aims to provide an accurate analysis of the chemical composition of plant materials, especially hemp shiv. A deeper understanding of plant aggregate interactions with building engineering products could be necessary. At first, the Van Soest method (VS) was performed to quantify cell wall compounds. A non-destructive version of the Van Soest method (NVS) allowed us to separate each fraction derived from this method. Thermal Gravimetric Analysis (TGA) has analyzed all these fractions to quantify and identify molecules in crushed samples. The results obtained from these technics are analyzed and compared. Analyses suggested that hemp shives contain 49% cellulose, 21% hemicellulose, 21% soluble compounds (pectins, lipids, oses, ashes, proteins), and 9% lignin. TGA results showed different thermal stabilities depending on the considered fraction, which we link to cellulose interactions with lignin and hemicellulose. This physical technic provides another method to quantify cell wall molecules.