Electro-activation of potassium acetate, potassium citrate and calcium lactate: impact on solution acidity, Redox potential, vibrational properties of Raman spectra and antibacterial activity on E. coli O157:H7 at ambient temperature

Abstract

Aims: To study the electro-activation of potassium acetate, potassium citrate and calcium lactate aqueous solutions and to evaluate their antimicrobial effect against E. coli O157:H7 at ambient temperature. Methods and results: Potassium acetate, potassium citrate and calcium lactate aqueous solutions were electrically excited in the anodic compartment of a four sectional electro-activation reactor. Different properties of the electro-activated solutions were measured such as: solutions acidity (pH and titratable), Redox potential and vibrational properties by Raman spectroscopy. Moreover, the antimicrobial activity of these solutions was evaluated against E. coli O157:H7. The results showed a pH decrease from 7.07 ± 0.08, 7.53 ± 0.12 and 6.18 ± 0.1 down to 2.82 ± 0.1, 2.13 ± 0.09 and 2.26 ± 0.15, after 180 min of electro-activation of potassium acetate, potassium citrate and calcium lactate solution, respectively. These solutions were characterized by high oxidative ORP of +1076 ± 12, +958 ± 11 and +820 ± 14 mV, respectively. Raman scattering analysis of anolytes showed stretching vibrations of the hydrogen bonds with the major changes within the region of 3410–3430 cm−1. These solutions were used against E. coli O157:H7 and the results from antimicrobial assays showed high antibacterial effect with a population reduction of ≥6 log CFU/ml within 5 min of treatment. Conclusions: This study demonstrated the effectiveness of the electro-activation to confer to aqueous solutions of organic salts of highly reactive properties that differ them from their conjugated commercial acids. The electro-activated solutions demonstrated significant antimicrobial activity against E. coli O157:H7. Significance and impact of study: This study opens new possibilities to use electro-activated solutions of salts of weak organic acids as food preservatives to develop safe, nutritive and low heat processed foods.