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.

Viacheslav Liato,Steve Labrie,Mohammed Aïder

doi:10.1186/s40064-016-3453-1

Abstract

AimsTo 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 resultsPotassium 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.ConclusionsThis 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 studyThis 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.

Highlights

Application of organic acids as preservative agents and disinfectants is a common practice in drug, cosmetic and food industries (Rico et al 2007)
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
Potassium acetate was purchased from Fisher scientific (Ottawa, Canada) and potassium citrate was purchased from Fisher scientific (Pittsburgh, PA, USA)

Summary

Introduction

Application of organic acids as preservative agents and disinfectants is a common practice in drug, cosmetic and food industries (Rico et al 2007). The receiving industry must have special storage and adequate managing conditions for these chemicals. In this context, handling and managing of salts of organic acids is suitable and easier because of the high level of safety and facility of storage and handling (Yoo et al 2010; Luttrell 2012). The reactivity of organic acids is higher than that of the conjugated salt, it is possible to convert a salt of an organic acid to the acid form so as to obtain the desired reactivity In this context, electrochemical activation (or “electro-activation”) of salt of an organic acid allows its conversion to the acid form under safe conditions

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