Characterizing New Mexico-Grown Cannabidiol (CBD) Hemp (Cannabis sativa L.) for Sustainable Development

Hemp (Cannabis sativa L.) offers multiple products: flower, fiber, and grain. Extensive breeding efforts have led to hemp varieties with different morphologies, physiologies, and chemical compositions optimized for specific purposes. In the state of New Mexico, the focus on high-cannabinoid varieties for flower production has prompted hemp producers and processors to assess their strategies for recovering value from the fibrous residues from cannabidiol (CBD) crops. Lignocellulosic hemp biomass has potential as a source of bioenergy; a precursor for chemicals to produce paints, plastics, and sealants; a building material in bio-composites; and as a paper or pulp additive. Choosing the right product stream hinges on the physiochemical traits of the lignocellulosic hemp biomass and the available processing equipment.

Currently, the domestic focus on cannabinoids and the absence of local fiber processing infrastructure (decortication facilities) result in the underutilization of high-CBD hemp crops' stalks and stems, constituting up to 70% of the total crop dry weight. These residues are often discarded or repurposed into low-value products such as animal bedding or compost. A first step in the development of biorefinery concepts is the characterization of the available materials to enable comparison to other lignocellulosic resources.

Here, hemp biomass from pilot field trials was first milled, sieved, and then measured for moisture and ash contents. Serial Soxhlet extractions were performed, first with water to remove soluble inorganic materials such as soil residues, then with ethanol to obtain soluble organic compounds including terpenoid compounds, chlorophyll, and plant waxes. The extractives-free hemp biomass was then subjected to acid hydrolysis, autoclaving, ultraviolet-visible (UV-Vis) spectroscopy, and high-performance liquid chromatography (HPLC) to determine the lignin and lignin and structural sugars contents. The higher heating value (HHV) of the hemp biomass was determined using bomb calorimetry and was expected to range between 17.5 and 18.8 MJ/kg.