ULTRASOUND EXTRACTION OF VALONEA TANNIN PART II: EFFECTS ON TANNIN STRUCTURE AND TANNING ABILITY

Ultrasound extraction of valonea tannin and its effects on extraction yields in comparison with conventional extraction method was examined in our previous study. Since the extraction conditions are very effective on the characteristics of the tannins, in the present part of the study the tannins obtained by conventional and ultrasonic extraction methods were examined comperatively in terms of their tanning ability, filling properties and molecular structure (by MALDI-TOF). The results demonstrated that while increasing extraction temperatures were increasing filling coefficients of the tannins in conventional extraction, increasing ultrasonic power were decreasing the filling coefficients in ultrasonic extraction. The MALDI-TOF analysis results revealed that whereas in conventional extraction, high extraction temperatures (90 degrees C) caused an onset of some minor fragmentations; in ultrasonic extractions, high ultrasonic powers (100W) caused significant decompositions on valonea tannin.