Impact of Salts Mixtures on the Physicochemical and Sensory Characteristics of Spanish-Style Manzanilla Green Table Olives during Packaging

Using response surface methodology (RSM), this study investigates the effect of NaCl substitution (50%) with KCl, CaCl2, and MgCl2 in the packaging brines (controlled variables) on the characteristics (responses) of plain green Spanish-style Manzanilla olives, maintaining the salt-mixture level of 5%. The RSM showed that the increment of CaCl2 caused a linear significant (p-value ≤ 0.05) decrease in pH and a linear increase in firmness (instrumental), hardness (panel scores), and crunchiness. The models for bitterness and fibrousness also included quadratic (CaCl2·MgCl2) and cubic (the three salt) interactions, which led to areas of minimum and maximum scores around the central points of the CaCl2-MgCl2 and KCl-MgCl2 axes, respectively. In contrast, the increase in the KCl level linearly decreased bitterness scores. Optimisation resulted in a relatively low desirability (0.57) and the selection of a combination that may necessitate further refinement, such as increasing KCl or reducing CaCl2 levels, especially for markets sensitive to bitterness. Interestingly, the overall score and buying predisposition positively correlate with salty, smell, acid, and appearance and negatively with bitterness. Furthermore, PLS-R analysis found that the pivotal attributes influencing overall appreciation were smell and crunchiness while buying predisposition was promoted by crunchiness. Conversely, bitterness had a detrimental impact on these appreciations. Cluster analysis grouped the experimental runs into four categories, with sensory profiles predominantly diverging in bitterness, salty, and kinesthetic characteristics. Ultimately, this study elucidates four distinct sensory profiles that consumers experience.