ABSTRACT
The rising consumer demand for safer, healthier, and fresher-like food has led to the emergence of new concepts in food packaging. In addition, the growing concern about environmental issues has increased the search for materials derived from non-petroleum sources and biodegradable options. Thus, active films based on biopolymers loaded with natural active compounds have great potential to be used as food packaging. However, several lipophilic active compounds are difficult to incorporate into aqueous film-forming solutions based on polysaccharides or proteins, and the hydrophilic active compounds require protection against oxidation. One way to incorporate these active compounds into film matrices is to encapsulate them in emulsions, such as microemulsions, nanoemulsions, Pickering emulsions, or double emulsions. However, emulsion characteristics can influence the properties of active films, such as mechanical, barrier, and optical properties. This review addresses the advantages of using emulsions to encapsulate active compounds before their incorporation into biopolymeric matrices, the main characteristics of these emulsions (emulsion type, droplet size, and emulsifier nature), and their influence on active film properties. Furthermore, we review the recent applications of the emulsion-charged active films in food systems.
ABSTRACT
Edible coating can improve fruits shelf life and, consequently, reduce their waste. Chitosan, which presents a potential for chemical modifications and capacity to form films, can be an alternative for coating due to its biocompatibility, biodegradability, and antimicrobial properties. Chitosan film can be obtained through casting method presenting suitable mechanical properties, such as resistance to traction and elongation, ability to adhere to surfaces and selective permeability to gases, such as O2 and CO2. However, it is highly permeable to water vapor, which can limit its potential coating use. The properties of chitosan films can be improved through the formation of composites by inserting nanoclays as montmorillonite in the polymeric matrix. The objective of this study was to develop and characterize chitosan/montmorillonite nanocomposites for fruit coating aiming for future applications in the field of smart packaging. Nanocomposites were characterized by its microstructure, thermal, mechanical, and physicochemical properties. X-ray diffraction analysis indicated changes in crystallinity with the insertion of montmorillonite. Nanocomposites became more transparent and significantly reduced its water permeability rate with 0.5% w/w montmorillonite addition. Elastic rigidity and tensile strength of the films were improved. Chitosan/montmorillonite nanocomposites demonstrated the potential to improve the storage time of Williams pears.
