Influence of ultrasound on extraction of tannins from deoiled salseed cake

Deoiled salseed cake which contains 13–18% of tannins has extensive use in the production of poultry and cattle feed mixtures, where the tannin content is reduced to 4% or less. Studies have been carried out to remove tannins by the application of ultrasound as a function of frequency (43, 720 and 1000 kHz); intensity (2 to 9 W cm −2); time (0 to 60 min); and by using different solvents. It has been observed that the percentage of extraction is greater at lower frequencies: 78% of tannins is extracted in a 40% aqueous acetone solvent using ultrasound in only 30 min compared to 20 h with conventional techniques.