Proyecto FONDECYT Regular 1130587

Influence of nanometric particles on the behavior of liquid drop impacts: Application to the coating of fruit cuticles.

Investigadores

• Investigador principal: Dr. Fernando Osorio Lira.
• Coinvestigadores: Dr. Olivier Skurtys, Dr. Ricardo Andrade Pizarro, Mg. Marcela Zamorano y Dr. Ricardo Villalobos.

Resumen

Coating operations have been widely employed in various industries including: pharmaceutical, agricultural, cosmetic, textile, and food. The reason to coat products generally is for decorative, protective, or functional purposes, but in most cases it is a combination of these. There are many advantages for the use of coating in food systems, such as, to extend the shelf-life of material by retarding the transmission of moisture and volatiles and to improve the consumer acceptability by altering the appearance and color of product including creating a glossy surface, and masking the undesirable taste. Moreover, coating can also be used to develop new type of foods like multilayered foods with different tastes, and to incorporate healthful additives, including probiotics or vitamins. Different matrix constituents have been evaluated for coating formation, among them polyssaccarids (HPMC, carrageenan, alginates, etc.) which show good mechanical and gas barrier properties, but present high water vapor permeability. To improve this characteristic different methods have been proposed, among them multilayered films, lipids addition and nanocomposites. Improved nanocomposites gas barrier film properties is due to the tortuosity path a gas molecule must follow around the nanoparticles through the polymer matrix, which increases the distance the gas must travel to cross the flim thickness. One of the nanoparticles in edible coatings/films is cellulose nanofiber which forms networks connected by hydrogens bonds and it is easily dispersed. In spite of the potential of the coatings in fruits, developed industrial applications are relatively few. Research in this area is developed to respond to specific food need for which are formulated and this may limit their versality and industry implementation. Edible coatings can be applied by different methods such as panning, fluidized bed, dipping, and spraying. Spray coating is among the most commonly used method to coat foods. Further, this has been identified as a more reliable technique to obtain uniform and reproducible films for evaluating polymers for coating processes. The fundamental problem to control and optimize the spray drop diameter before impact has been studied in detail these last years. However, to increase coating quality is also important to understand and control the liquid drop behavior after collision with the surface. Indeed, coating quality, i.e. its thickness, total coverage of the solid and its coating microstructure may depend not only on the final drop shape but also of its dynamic during the spreading after impact. The aim of this research is to develop coatings with a polysaccharide (carrageenan and HPMPC) matrix evaluating cellulose nanofiber and plasticizer (glycerol) incorporation on physico-chemical and rheological properties of edible coating suspensions. Wettability and impact behavior of coating suspension on fruits with different surfaces free energy. To control the film thickness they will be prepared by spin coating method. Edible films mechanical, thermal and barrier (water vapor and oxygen) properties will be evaluated to seek the effect of thickness and film composition. Edible coating forming suspensions-ECFS- will be applied by sprying to selected surface free energy fruits, determining operating conditions and ECFS formulation rendering an increase of fruit shelf life. Hydrodynamic behavior determination of the formation of coating of droplet impact and mechanical, thermal and barrier coating characteristics with different thickness will allow to select suspension compositions and spray system operating conditions to extend shelf life of the involved fruit with different surfaces free energy.