Chemical characterisation and technical assessment of agri-food residues, marine matrices, and wild grasses in the South Mediterranean area: A considerable inflow for biorefineries

The integration of easily available and under-exploited biomasses is considered a sustainable strategy in biorefining approaches. Mediterranean countries, especially Algeria, Morocco, and Tunisia, offer such under-exploited waste of different origins. This study revealed the chemical composition and phytochemical characteristics of various agri-food side-products, marine residues, and wild grasses collected in the Maghreb region. Results showed that these wastes contained variable proportions of polysaccharides, lignin, constitute molecules (proteins, lipids, and inorganic molecules) and, various secondary metabolites, mainly flavonoids and condensed tannins. Based on this, the Mediterranean waste was divided into three categories. The first category included waste with high lignin content (40 wt%). The second category contained waste with lignin content below 10 wt% and structural carbohydrate content below 50 wt%. Additionally, the waste in this category comprised noticeable amounts of flavonoids and condensed tannins, particularly from thistle, speedwell, and spurge. Finally, the third category included waste with lignin content above 15 wt% and carbohydrate content in the range of 45-55 wt%. The results also showed that the waste in the third category has a chemical composition similar to that of raw materials envisioned for use in European or North American commercial biorefineries. The findings of this study indicate that the biomass waste employed in this study can be used to develop marketable bioproducts and may be a potential raw material for a biorefinery facility.

Keywords: Agri-food residues; Biorefineries; Lignocellulosic; Marine matrices; Waste; Weeds.