Detoxification of Dilute Ammonia Pretreated Energycane Enzymatic Hydrolysate by Flocculation for Syrup Production

This study investigated the detoxification of dilute ammonia pretreated energycane enzymatic hydrolysate using polyelectrolyte flocculants.  Energycane bagasse (non-commercial variety HO 02-114) was pretreated with ammonium hydroxide (28% v/v solution) and water at a ratio of 1:0.5:8 at 160 °C for 1h. Pretreated energycane bagasse was then hydrolyzed by commercially available enzymes. By-products such as formic acid, acetic acid, lactic acid, citric acid, furfural, and HMF were formed during enzymatic hydrolysis. Detoxification procedures were carried out to recover and/or remove the by-products and retain the sugars. Two types of flocculants were evaluated.  Dosage, reaction time and pH were controlled to determine the optimum condition for removing the non-sugar compounds, while retaining the fermentable sugars. Both flocculants reduced the concentrations of organic acids and furans by more than 50% without significant sugar losses. These results suggest that the use of flocculants may provide practical alternatives for the detoxification of lignocellulosic hydrolysates and their conversion into syrups.