Effects of substituting sodium chloride with potassium chloride on lipid oxidation of O/W emulsions stabilized by cetyltrimethylammonium bromide (CTAB)

Substituting NaCl with KCl is an effective method to reduce sodium consumption by the public, but it is unknown how this substitution can simultaneously affect the oxidative stability of food products. Our previous results discovered that NaCl can alter the distribution of lipid hydroperoxides in O/W emulsions, and thereby influence the lipid oxidation kinetics. In this study, we continued to investigate whether substituting NaCl with KCl would also influence the lipid oxidation of CTAB-stabilized O/W emulsions through a similar mechanism. By using a drop shape analyzer, we found that the critical micelle concentration (CMC) of CTAB is increased from 73 μM to 91 μM when 1% NaCl is replaced by 1% KCl, but no significant change was observed when 1% NaCl is substituted by 171 mM KCl (same molar concentration as 1% NaCl). The amount of lipid hydroperoxides in the aqueous phase of emulsions containing 1% KCl was lower compared to 1% NaCl due to fewer surfactant micelles. Emulsions containing 1% NaCl (as control), 1% KCl, 171 mM KCl, and no salts were stored at 37°C for 7 days to monitor their oxidative stability. Compared to 1% NaCl (control), 1% KCl significantly decreased the TBARS values throughout the oxidation period (p < 0.05). A similar trend was also observed for lipid hydroperoxides value (PV). However, 171 mM KCl group, which had similar impact on the CMC and lipid hydroperoxides distribution as 1% (171 mM) NaCl did, also decreased the TBARS value as compared to 1% NaCl group on Day 3, 4 and 6 during the 7-day storage. These results show that substituting Na by K can alter emulsion oxidation through influencing surfactant micelles and the distribution of hydroperoxides, but other factors associated with the ions themselves also exist and yet to be discovered.