Chemical Characterization of Okra Stalk (Abelmoschus esculentus) as Potential Raw Material for Biorefinery Utilization

In the present work, okra stalk (Abelmoschus esculentus) was chemically characterized to evaluate its appropriate exploitation as a biorefinery feedstock. The chemical composition of this renewable lignocellulosic material yielding maximum up to 120 tons per hectare was primarily determined by methods of wood chemical analysis. In terms of its main organic constituents, its dry matter contained 65.0% carbohydrates (cellulose, hemicelluloses and other polysaccharides), 20.5% lignin and 5.0% extractives. In addition, thermogravimetric analyses revealed that the content of proteins and inorganics was 6.6 and 3.3% of the dry matter, respectively. Among the inorganic elements determined by inductively coupled plasma atomic emission spectroscopy, calcium was shown to be the dominant one, with a concentration of 17.2 mg/g, followed by magnesium, silica and potassium. The analytical data indicated that the stalk of okra plant with a high crop yield would be a potential feedstock as such or together with other similar feedstocks for versatile biorefinery purposes, including pulping and manufacturing of chemicals.