Value-added soluble metabolite production from sugarcane vinasse within the carboxylate platform: An application of the anaerobic biorefinery beyond biogas production

•Sugarcane vinasse dark fermentation targeted enhanced VFA production.•Different temperature (30–60 °C) and pH (5.0–10.0) conditions were assessed.•Lactate and ethanol were also used as carbon sources in chain elongation tests.•Alkaline (pH = 8.8–10.0) and mesophilic (40 °C) conditions maximized VFA production.•Lactate dosing was a key-factor to stimulate caproic- and valeric-type fermentation.