Development of edible coating functionalized with hydroxyapatite, complexed with bioactive compounds for the shelf-life extension of food products

The main goal of food packaging is to protect the food from physical, chemical and biological contaminations. The environmental impact of conventional food packaging directed research towards new packaging strategies based on environmentally friendly and biodegradablenatural polymers. The nature of biopolymers influences the physicochemical and mechanical properties of films and coatingssuch as mechanical stability, transparency, moisture and gas barrier. Generally, polysaccharides are employed to avoid gas permeability, lipids limit water vapour transmission, and proteins improve the mechanical stability of the structure. Anovel way to preserve the safety of food products and prolong their shelf life is represented by the incorporationinto edible coatingsof active compounds, such as nutrients, antioxidants, antimicrobials, colorants, and flavorings, which are mainly used to improve the functional properties of coatings. However, the poor stability of these bioactive compoundsunder processing conditions and during storage makes it necessary to use a carrier system for the release of the compound from the coating to the product surface. Among severalcarriersystems adopted to protect active compounds, hydroxyapatite crystals seem to be attractive candidates for this application. Hydroxyapatiteis a calcium phosphate similar to that present in the human hard tissues as regard morphology and composition. It is used especially for the fabrication of inorganic scaffolds for bone replacement and tissue engineering.Thanks to its structure and composition, this mineral is able to chemically interact with different organic molecules such as proteins and antimicrobial peptides, representing a potential carrier for the delivery of bioactive compounds in the development of active systems. On the basis of the above considerations, my research project has been focused on the development and optimization of an alginate-based edible coating enriched with hydroxyapatite crystals complexed with active compounds, for the shelf life extension of food products. Among active compounds, the flavonoid quercetinhas been already used in different active systems mainly for its antioxidant capacity; However, my interest was also focused on its potential antimicrobial activity.The results on antimicrobial activity of quercetin glycoside compounds against Pseudomonas fluorescens, one of the most abundant Gram negative bacteria responsible for meat and meat products spoilageon obtained, showed a total bacterial reduction at 1000 mg/L and 500 mg/L of quercetin,Similar results were obtained when quercetin was loaded into hydroxyapatite structure, at the same quercetin amount. [...] [edited by Author]