Removing the bitterness of olives with a pilot-scale ultrasonic system and determining its effect on table olive quality

Abstract

The naturally black table olive processing methods produce black table olives with a popular flavor. However, this method requires more than six months. For this reason, it is thought that removing the bitterness of black olives in a short time without moving away from the traditional flavor may provide added value. Ultrasound technology has the potential to quickly remove the bitterness of olives without detracting from the natural flavor. Therefore, in this work, debittering of olives was studied by a blower and thermostat integrated pilot scale ultrasound bath. Brine (5%) and black olives were placed in this bath and operated at three different (15, 25, 35oC) temperatures. After that the olives were kept in the open air. Sensory scores, microbiological counts, color values, texture profile, pH and oleuropein, hydroxytyrosol, tyrosol, vanillic acid, titratable acid, dry matter and salt content of the fresh and processed olives were determined. Ultrasonic debittering was completed in a short time (2.8–3.9 days). At the end of this process bitterness of olives was determined in the range of 1.31–1.33 by using 1 (did not feel) to 4 (extremely felt) sensory scale form. Obtained results are promising in terms of olive debittering in a short time, with low salt content, without losing the sensory characters.