Spanish Researchers Develop Lower-Sodium, Mineral-Fortified Table Olives

Researchers at Spain’s Instituto de la Grasa de Sevilla (IG-CSIC) have developed stuffed table olives with 50 percent less sodium while increasing potassium, magnesium and calcium.

According to the researchers, the method used to produce the pimento-stuffed olives could help consumers reduce sodium intake without sacrificing the flavor or nutritional benefits of the traditional table olive.

Commercially produced Spanish table olives typically contain relatively high sodium concentrations, estimated at about 14.4 to 18.1 grams per kilogram. That is equivalent to roughly 36 to 45.5 grams of table salt. Sodium levels can be even higher in stuffed olives, depending on the filling.

The World Health Organization recommends limiting sodium intake to less than two grams per day, equivalent to about five grams of salt. Reducing sodium in commonly consumed foods is therefore considered an important public health measure.

In Spain, where about 16.5 percent of the population has hypertension and traditional salt-based preservation methods remain widespread, sodium reduction in table olives has become an area of active research.

The challenge for producers is that salt plays an important role during fermentation, helping control microbial populations and prevent spoilage. Reducing sodium too early in production can therefore compromise product stability.

The researchers took a different approach, reducing sodium after fermentation.

After fermenting the stuffed olives under conventional conditions, they desalted them until the flesh contained approximately 2.5 percent sodium chloride. They then placed the olives in brines containing different combinations of potassium chloride, calcium chloride and magnesium chloride.

With sodium chloride maintained at 2.5 percent, the containers were pasteurized and stored for two months, allowing the olives and brine to reach mineral equilibrium.

The original stuffed olives contained approximately 21.2 grams of sodium per kilogram. Desalting reduced that level by about 65 percent, but it also removed roughly 65 percent of the potassium, 61 percent of the magnesium and 45 percent of the calcium originally present in the olive flesh.

To compensate for those losses, the researchers used the new brine formulations to raise mineral concentrations to approximately 5.4 grams of potassium, 4.6 grams of calcium and 1.8 grams of magnesium per kilogram.

Based on the researchers’ calculations, the finished product would provide approximately 30 percent of the recommended daily intake of sodium, 27 percent of potassium, 58 percent of calcium and 32 percent of magnesium.

The study also found that the minerals behaved differently during processing. Sodium, potassium and magnesium remained relatively mobile between the olives and brine, while calcium and phosphorus showed a stronger association with organic components in the olive flesh.

The researchers said their analysis of mineral distribution coefficients could help explain why adding a particular mineral salt to brine does not necessarily result in a proportional increase of that mineral in the olives themselves.

The findings could have practical applications for producers seeking to develop table olives with specific nutritional profiles. Increasing magnesium in otherwise balanced formulations, for example, could help producers meet requirements for certain nutritional claims.

However, sodium reduction also presents sensory challenges. As noted in previous research, replacing sodium chloride with alternative salts such as potassium chloride can increase bitterness, potentially reducing consumer acceptance.

The authors therefore placed their method within a broader range of approaches for maintaining an appealing sensory profile, including seasoning with herbs, modified-atmosphere packaging, essential oils and other preservation technologies.