Active edible polysaccharide coating and interactions between solution coating compounds

To control pathogenic strain growth on food surface, anti-microbial edible coatings were obtained from hydroxy propyl methyl cellulose associated with nisin. The inhibitory activity of nisin was confirmed on Listeria innocua and Staphylococcus aureus. To improve packaging moisture barrier properties, stearic acid (SA) was used, but preliminary experiments showed a decrease in the inhibitory activity of coatings, probably from electrostatic interactions with the bacteriocin. The study of interactions between both the compounds was then conducted to subsequently optimize nisin desorption. First, the negatively charged carboxyl groups of SA were confirmed by trapping cationic ion method, allowing electrostatic interactions. Secondly, a comparative study of nisin fixation in SA or methyl stearate showed that SA–nisin interactions were mainly electrostatic. Finally, calcium ion addition to the nisin–SA mixture showed a potential application in order to improve packaging activity by increasing nisin desorption from coatings.