New sustainable bioconversion concept of date by-products (Phoenix dactylifera L.) to biohydrogen, biogas and date-syrup

Abstract The dates production is usually accompanied by considerable loss of fruit byproducts. The chemical analysis showed that ‘Deglet Nour’ discarded flesh is rich in soluble sugars (79.8% ± 0.8%) and fibers (12.3% ± 0.4%). A processing approach was implemented to permit the production of biohydrogen from the flesh and biogas from the crude fiber fraction after soluble sugars extraction. This approach showed interesting results since the obtained biochemical hydrogen potential and the maximum methane yield were 292 mL H2/gVS initial and 235 mL CH4/gVS fibers respectively. Parallelly, the “hot water” soluble sugar fraction (date syrup) was of interest for agro-alimentary applications and showed a high sucrose, glucose and fructose content of 33.5%, 11.8% and 13.17% respectively. This study presents a proof of concept allowing an efficient sustainable energetic conversion of the date by-products biomass to biohydrogen via dark fermentation or to soluble sugars fraction and biogas via a biorefinery approach.