Using Resins to Debitter Olives May Be Eco-Friendly Alternative

Amberlite resins present a possible environmentally friendly solution to removing bitterness from olives, reducing wastewater and chemicals used in commercially employed methods.

Researchers have found a way to remove the bitterness from olives in a more environmentally friendly way than commercially favoured methods, reducing toxins and wastewater.

Olives contain phenolic compounds that create a bitter flavor when they are fresh, and the compounds are often neutralized with chemicals and repeated rinses, according to the paper, “Reducing phenolics related to bitterness in table olives” by researchers Rebecca L Johnson and Alyson E Mitchell from the University of California, Davis. The paper was published in the Journal of Food Quality in August 2018.

“Current commercial table olive processing methods remove many of these bitter phenolic compounds and as a result, can alter the health-promoting potential of various table olive products,” the researchers wrote. “Additionally, current commercial table olive processing methods are some of the most water-intensive methods used in commercial food processing and can require more than 7,571 litres of water per ton of olives (eg., California and Spanish methods) and generate highly toxic wastewater.”

The researchers wrote that their group experimented with four Amberlite resins and found that they not only removed the bitterness but saved the compounds for other uses rather than destroying them.

“Preliminary results demonstrate that all resins could remove oleuropein during brine treatments thereby significantly reducing olive bitterness without the need for additional processing,” Johnson and Mitchell wrote.

Oleuropeins are only one phenolic compound contained in olives, though they are the most common during harvest time, Johnson and Mitchell added.

There are three primary methods used by commercial olive processors: Greek, Spanish and California. Johnson and Mitchell noted there are less popular artesian means to debitter the olives, but added that they are not ideal for commercial use. The Greek style uses a smaller amount of water to the Spanish and California ones do, though each has its pros and cons. The California process uses the most water, according to the authors. More