DETANNIFICATION OF OAK (QUERCUS-INCANA) LEAVES - TREATMENTS AND THEIR OPTIMIZATION

Oak leaves widely available in hilly regions of various countries can be effectively utilized as livestock feed if a simple and economically viable detannification process is developed. Treatments using various organic solvents, alkalis, oxidizing agents, a tannin complexing agent, water and an acid were optimized for maximum reduction of tannins in oak (Quercus incana) leaves. Acetone, ethanol and methanol removed tannins by about 70%. The reduction in tannins using alkalis ranged between 70 and 90%. Sodium hydroxide was most effective, followed by Na2CO3 and NaHCO3. Both KMnO4 and K2Cr2O7 decreased tannin levels by about 95%. Using water, the reduction in tannin level was only 43%. The use of H2O2, NaOCl and aqueous HCl showed no advantage over the use of water. The tannin complexing agent, FeSO4 reduced tannins by 85%. These reductions in tannin level were achieved under optimum conditions which were: shaking for 20 min at 25-degrees-C using 0.05 M NaOH or Na2CO3, 0.1 M NaHCO3, 30% acetone, 40% ethanol, 50% methanol, 0.02 M K2Cr2O7, 0.03 M KMnO4 or 0.015 M FeSO4. The use of alkalis and oxidizing agents has potential for the detannification of oak leaves at an industrial scale.