This method is used by Mussatto et al. with a soda pulping process on BSG followed by the addition of sulfuric acid in the black liquor. Different pH conditions were experimented with the best conditions yielding 81 % of the solubilised lignin. Using a different strategy, Niemi et al. described an optimised protocol in 3 steps with first, the enzymatic degradation of carbohydrates, then the enzymatic lyse of proteins, followed by their precipitation in HCl, yielding a solution rich in lipids and lignin under the degraded form of lignan. Cassoni et al. investigated the use of DES for lignin extraction from BSG and olive tree pruning (OTP), with a higher antioxidant power reported for the latter. Good lignin yields (54.5 % for BSG and 37.8 % for OTP) were obtained with purities over 75 % and similar Mw using a lactic acid (LA) and choline chloride (CC) (5:1) mixture as DES for the delignification process. Gbenebor et al. used diethyl ether to remove extractable, before degrading carbohydrates (cellulose and hemicellulose) in strong acidic conditions (10 M of H2SO4, HCl or acetic acid) and 5M NaOH and filtration, with the highest purity (98 % purity) and yields (82.9 % of the lignin contained in BSG, representing 5.6 wt% of the original composition) obtained when using H2SO4. Characterisation of the extracted lignin showed good thermal stability with a Tg of 107 °C (H2SO4). Finally, organosolv treatment is a possible procedure to recover the degraded lignin within a black liquor. This was described by Parchami et al. after an acidic pre-treatment to eliminate the glucan-rich fraction. The organosolv process conditions were optimised using 50 % v/v ethanol to obtain precipitated lignin with a 58 % yield and a 95 % purity.