Plant antimicrobial polyphenols as potential natural food preservatives

The growing demand for natural food preservatives in the last decade has promoted investigations on their application for preserving perishable foods. In this context, the present review is focused on discussing the prospective application of plant extracts containing phenolics or isolated plant phenolics as natural antimicrobials in foods. Plant essential oils are outside the scope of this review since utilization of their antimicrobial activity for food preservation has been extensively reviewed

Effect of interactions of plant phenolics with bovine meat proteins on their antibacterial activity

The activity of 5 phenolics totally inhibiting the growth of Staphylococcus aureus CNRZ3 at a 1 g L−1 concentration in Mueller-Hinton broth for 24 h incubation at 37 °C was reevaluated at 37 °C for 24 h, 15 °C for 6 days, or 6 °C for 8 days in the presence of up to 20% (w/w) bovine meat proteins to mimic the temperature of refrigerated storage of bovine meat and its protein content, respectively. These changes affected in a different way the antibacterial activity of the 5 phenolics. Isobutyl-4-hydroxybenzoate kept its bactericidal activity, while naphthazarin was bactericidal at 6 °C and 15 °C but not at 37 °C in the presence of bovine meat proteins. Gallocyanin was bactericidal at 37 °C up to a 5% (w/w) protein content in the medium but not at 15 °C or 6 °C. Resveratrol and chrysin always lost their bacteriostatic activity when bovine meat proteins were added. The partition coefficient at 6 °C of each phenolic between a 20% (w/w) bovine meat extract suspension with and without proteins was determined. The antibacterial activity reduction of phenolics in the presence of bovine meat proteins was correlated with their affinity for bovine meat protein

Antibacterial Properties of Polyphenols: Characterization and QSAR (Quantitative Structure–Activity Relationship) Models

Besides their established antioxidant activity, many phenolic compounds may exhibit significant antibacterial activity. Here, the effect of a large dataset of 35 polyphenols on the growth of 6 foodborne pathogenic or food-spoiling bacterial strains, three Gram-positive ones (Staphylococcus aureus, Bacillus subtilis, and Listeria monocytogenes) and three Gram-negative ones (Escherichia coli, Pseudomonas aeruginosa, and Salmonella Enteritidis), have been characterized. As expected, the effects of phenolic compounds were highly heterogeneous ranging from bacterial growth stimulation to antibacterial activity and depended on bacterial strains. The effect on bacterial growth of each of the polyphenols was expressed as relative Bacterial Load Difference (BLD) between a culture with and without (control) polyphenols at a 1 g L−1 concentration after 24 h incubation at 37°C. Reliable Quantitative Structure-Activity Relationship (QSAR) models were developed (regardless of polyphenol class or the mechanism of action involved) to predict BLD for E. coli, S. Enteritidis, S. aureus, and B. subtilis, unlike for L. monocytogenes and P. aeruginosa. L. monocytogenes was generally sensitive to polyphenols whereas P. aeruginosa was not. No satisfactory models predicting the BLD of P. aeruginosa and L. monocytogenes were obtained due to their specific and quite constant behavior toward polyphenols. The main descriptors involved in reliable QSAR models were the lipophilicity and the electronic and charge properties of the polyphenols. The models developed for the two Gram-negative bacteria (E. coli, S. Enteritidis) were comparable suggesting similar mechanisms of toxic action. This was not clearly observed for the two Gram-positive bacteria (S. aureus and B. subtilis). Interestingly, a preliminary evaluation by Microbial Adhesion To Solvents (MATS) measurements of surface properties of the two Gram-negative bacteria for which QSAR models were based on similar physico-chemical descriptors, revealed that MATS results were also quite similar. Moreover, the MATS results of the two Gram-positive bacterial strains S. aureus and B. subtilis for which QSARs were not based on similar physico-chemical descriptors also strongly differed. These observations suggest that the antibacterial activity of most of polyphenols likely depends on interactions between polyphenols and bacterial cells surface, although the surface properties of the bacterial strains should be further investigated with other techniques than MATS

Effect of interaction with food constituents on plant extracts antibacterial activity

International audienc

Preservation of fresh ground beef patties using plant extracts combined with a modified atmosphere packaging

International audienc

Enrobages comestibles et emballages actifs pour la conservation d’aliments périssables présentation et premiers résultats du projet de coopération Franco-Thaïlandaise ActiFoodCoat

International audienceLes différentes étapes pour la préparation de films à base de biopolymères contenant des biomolécules antimicrobiennes et/ou antioxydantes applicables pour la conservation d’aliments périssables sont illustrées par les études réalisées par 4 équipes de recherche associées à un programme de coopération Franco-Thaïlandaise. Ces grandes étapes sont : (i) le choix de la formulation des ingrédients entrant dans la composition du film, (ii) les paramètres associés aux procédés d’élaboration des films, (iii) la caractérisation des propriétés physico-chimiques des films et l’évaluation in vitro de leur activité antimicrobienne ou antioxydante et (iv) leur application in situ à des aliments périssables pour en évaluer l’effet sur la durée de vie de ces produits. Les biopolymères filmogènes et les biomolécules actives considérés comprennent des co-produits de l’agriculture Thaïlandaise comme la gélatine préparée à partir de peau de poisson-chat géant ou un extrait de graines de longane ayant un pouvoir antioxydant avéré