In his PhD thesis the chemist Javier Osés Fernández – Public University of Navarre – concludes that edible coatings could be the basis for innovative food packaging.
The coatings are based on various mixes of milk serum proteins, starch, and mesquite gum. According to Fernández edible coatings could help packagers meet the demand from food companies for new packaging that can help prolong the shelf life of products, while being recycable or biodegradable.
Currently, the three systems of conservation most used by the food industry are vacuum packing, nitrogen sweeping and aluminum foil. Protection is currently carried out with a mixture of synthetic chemical compounds that are not completely biodegradable.
Now packagers and researchers are exploring the use of edible coatings – transparent films that cover food items and act as a barrier to humidity and oxygen. Fernández research showed that such films can be used as a host for additives in the conservation of the properties of the product or simply in order to improve its appearance.
To compare the performance of edible coatings to synthetic packaging, Fernández prepared a number of samples of whey protein isolate (WPI), of mesquite gum and of starch, and stored them for six months at different humidity levels. The most efficient WPI films were those of greater thickness, with less amount of plastifier and that had been exposed to low relative humidity.
The second stage involved a similar experiment, but with films made of starch, known to be an efficient barrier to oxygen, and with which trials were undertaken. In this case, the thickness of the film did not influence the protector effect on the oil, but it was shown that starch films are more effective in ambiences with high relative humidity.
The final part of the PhD outlined the application of edible coatings with WPI on chicken breasts. The aim was to analyse the effect on their aspect and their properties. At the same time, the experiment was used to incorporate nisine, an antioxidant agent that penetrates the foodstuff little by little and thus offers an ongoing protection. The idea was to extend the conservation time for a chicken breast would go from the current 7 days to 15, but the results were negative. However, a very interesting line of research was opened as it has been shown that the coating formed a second skin on the breast and onto which various additives, such as antimicrobians, can be added.