Re-use of partially purified iron color fixation solutions using electro-coagulation and ozonation in ripe table olive processing and packaging

• The results reported information about the re-use possibilities of partially purified iron solutions in ripe olive process.
• Reuse purified iron solution by electro-coagulation/ozonation does not produce changes in the flavor of ripe-olives.
• Reusing the purified solution completely in packaging eliminates this waste-water in the industry.

The present work investigates the feasibility of re-using partially purified iron fixation solutions by electro-coagulation followed by ozonation in another fixation stage of black ripe olive processing and/or as cover brines in packaging. Re-use after the addition of ferrous gluconate during the color fixation stage involves a slightly lower amount of iron penetrating into the olives than when tap water is used. As a result, the olives are slightly less dark before packing when a gluconate solution is re-used. However, it is possible to completely re-use the partially purified solution using 50% of it as a color fixing liquid and 50% to prepare the cover brine in the packaging or to fix the color using tap water to prepare the gluconate solution and 100% purified solution as cover brine, in which case this waste-water is completely eliminated from the industry. Iron concentration in the flesh and surface color are the same for these two working methods and ripe olives present the same flavor as olives produced following the traditional procedure using only tap water.