New developments in table olive debittering
Olive fruit cannot be eaten directly from the tree because of its content of the phenolic glucoside oleuropein, which is extremely bitter. Since ancient times, many methods have been developed for making olives edible. At the beginning of the 20th century, the use of NaOH to hydrolyze the bitter glucoside gave rise to the two most commercially important elaboration processes, the Spanish-style green olives and the California-style black olives. Few changes have been made in these methods except for the reuse of the alkaline solutions. Natural olives are those not treated with alkali, and they are appreciated in local markets and by organic consumers, although there is an increasing demand for this product in international markets. The bitterness in these natural olives can be eliminated by (i) washing, (ii) diffusion into the preservation brine, (iii) microbiological activity, (iv) enzymatic hydrolysis, and (v) chemical hydrolysis. This study was mainly focused on the debittering of olives by the action of the endogenous enzymes of the fruit. It has been discovered that the oleuropein content of olives put directly into brine is reduced due to the enzymatic activity of β‑glucosidase, this reaction being modulated by the chemical conditions of the brine. In addition, the enzymatic oxidation of oleuropein by polyphenoloxidase generates non-bitter metabolites, and this reaction can be useful to accelerate the debittering of olives put directly into brine. This enzymatic reaction is also involved in the debittering of some olives during the dry-salting process of black olives. Therefore, the study of the enzymatic debittering of olives will help to improve traditional elaboration processes and create new products.
Brenes, M., Ramírez, E., García, P., Medina, E., de Castro, A. and Romero, C. (2018). New developments in table olive debittering. Acta Hortic. 1199, 483-488
debittering, enzyme, hydrolysis, table olives, oleuropein