Even if you love olives out of the jar, chances are you wouldn't like them straight off the tree. When freshly-picked, they contain bitter-tasting chemical compounds that have to be removed via an environmentally-iffy process. According to a new study, however, there could be a greener alternative.
In order to rid olives of phenolic compounds such as oleuropein and ligstroside, producers typically soak the fruits in a dilute lye solution, then wash them several times. Not only does this use up a lot of water, but it also results in toxic wastewater being returned to the environment.
Scientists at the University of California, Davis instead looked to four types of Amberlite-brand macroporous resins, which are non-toxic resins composed of tiny porous beads. Those beads are in turn capable of adsorbing various compounds.
After olives had been stored in vats of brine containing the different resins for 76 days, it was found that one of the resins – known as FPX66 – had reduced oleuropein to concentrations even lower than those of commercially-processed California-style black olives. Levels of ligstroside were also significantly reduced.
Fewer subsequent wash cycles of the olives were required, plus the extracted phenolics could be recovered from the resin via an ethanol-treatment process. Those compounds could then be utilized in nutritional supplements, plus the resin could be reused.
A paper on the research was recently published in the Journal of Agricultural and Food Chemistry.
In related news from a couple of years ago, scientists at France's Mulhouse Institute of Materials Science have devised a process of converting olive mill wastewater into biofuel, fertilizer and clean water.
Source: American Chemical Society