Physically Cross-Linked Biopolymer Systems Based on Chitosan and Hydroxycinnamic Acids and Their Food Preservation Application Studies

Production of physically cross-linked biopolymer systems (PCBS) is attracting scientific and industrial attention due to its proven potential for applications in, for example, food, food packaging, food preservation, pharmaceuticals, and cosmetic industries. Its production versatility allows obtaining products in the form of films, powders, lyophilized products, edible coatings, and gel beads, among others. This review presents different methods for obtaining, characterizing, and applying these PCBS designed and produced using chitosan (CH) and hydroxycinnamic acids (HAs), resulting exclusively from noncovalent interactions. Each variable characterizing each component of the PCBS is evaluated, gaining a better understanding of their roles. The influence of different molecular weights, viscosities, and degree of deacetylation among other variables belonging to the biopolymer is presented, while the role of the type, amount, and position of the substituent groups on the HAs is shown using caffeic, ferulic, coumaric, chlorogenic, and rosmarinic acids as physical cross-linkers. The molar ratio between HAs and CH is a key factor when forming PCBS and in determining their final properties. Thus, we provide a comprehensive study of these PCBS obtained using CH and HAs, highlighting their environmental and sustainable aspects. Benefits from a materials standpoint regarding their competitive barrier effects and mechanical and thermal properties are also emphasized, especially toward their food packaging and food preservation applications.