Recovery of vegetable tannins from divi‐divi pods

AbstractAn experimental survey was developed to determine optimal operational conditions when extracting tanning materials from mied divi‐divipods with a 10% (v/v) alcohol–water solution. The study included runs at both laboratory and pilot levels. The percentage of extracted tanning materials from samples was measured when varying the following variables: (1) temperature, (2) solvent to solute ratio, (3) extracting time, (4) type of solvent, (5) agitation, and (6)average particle size. The optimal values were as follows: 50°C, 120 cm3 of solvent: 1 g of divi‐divi, 20 min, 10% (v/v) ethanol–water, agitation on, and 0.087 cm average particle size. The maximum yield of extracted tanning materials was 54 by weight (dry basis) when divi‐divi pods up to 6 months old were used, but the tannic content in pods decreased by 15% and 32% after 12 and 42 months of storage respectively.