Measuring pH to monitor bacterial spoilage

The research of the INRAE Oniris SECALIM joint research unit aims to better control microbial safety and spoilage risks in order to meet the societal challenges of public health and food waste reduction. The physico-chemical properties of meat products, such as water activity and pH, are very favorable to bacterial development, which can alter the sensory characteristics of these foods. Measuring the pH of meat products during storage is an effective way to monitor microbial spoilage, since pH is often related to the growth of several spoilage microorganisms under different conditions. This study, carried out within the framework of the ANR Redlosses project, coordinated by SECALIM, aimed at developing a modeling approach to describe and simulate the evolution of the pH of fresh meat products, according to the storage conditions. The pH was measured during the refrigerated storage of several batches of fresh poultry sausages, manufactured according to several lactate formulations and packed under three modified atmospheres. A hierarchical Bayesian statistical approach was developed to best fit kinetic models with a small number of measurement points. The evolution of pH followed a two-phase curve: after a gradual decrease, pH then stabilized at around day 13 of storage, under all lactate and atmosphere conditions considered. The effects of lactate and conditioning atmosphere observed previously on pH were confirmed here: (i) the addition of lactate significantly slows down the acidification, whatever the type of conditioning, while (ii) the 50%CO2-50%N2 atmosphere accelerates the acidification phase. The process and the R script used for the Bayesian modeling of the pH kinetics could be adapted to other situations, such as other food products, or in order to evaluate the influence of other preservation strategies on the pH.

Associated publication:

Luong, N. M., L. Coroller, M. Zagorec, N. Moriceau, V. Anthoine, S. Guillou and J. M. Membre 2022. A bayesian approach to describe and simulate the ph evolution of fresh meat products depending on the preservation conditions. Foods 11(8). https://doi.org/10.3390/foods11081114.

Funding and partners:

This study was carried out by the UMR INRAE Oniris SECALIM and financed in the framework of the ANR Redlosses (ANR-16-CE21-0006) coordinated by SECALIM, in partnership with the Redlosses consortium.