Influence of the Structure of Alginate-Chitosan Materials on the Kinetics of Usnic Acid Release

Recent Advances in Sustainable Antimicrobial Food Packaging: Insights into Release Mechanisms, Design Strategies, and Applications in the Food Industry

“…Notably, the degradability and long-acting antimicrobial and antioxidant activities of materials using unmodified CS as a carrier or substrate are highly dependent on the acetylation modes of CS, which are challenging to control. 49,158,226,232 Therefore, Aguanell et al 49 Gorshkova et al 76 first prepared porous cryogels and aerogels using a sodium alginate-CS interpolymer complex through freeze drying and supercritical drying, respectively. Usnic acid (UA) was then loaded onto these gels via solution impregnation, resulting in two slow-release antibacterial gels.…”

“…However, it (i.e., CS nanoparticles or molecular fragments) is not the major long-term release component from composites, unlike the aforementioned inorganic, plant-derived agents, animal-derived agents, and microorganism-derived antimicrobials. Generally, CS undergoes premodification, such as sulfation, , carboxymethylation, acylation, or other in situ chemical modifications, , processing to nanoscale, , or integration with other biomass materials such as PLA, , cellulose, , and alginate . Next, the treated CS is combined with other antimicrobial agents through encapsulation, loading, cross-linking, and other technologies to finally form various antimicrobial microcapsules, ,, films, ,, coatings, ,, or gels ,,,, with slow- or controlled-release functions.…”

“…Generally, CS undergoes premodification, such as sulfation, , carboxymethylation, acylation, or other in situ chemical modifications, , processing to nanoscale, , or integration with other biomass materials such as PLA, , cellulose, , and alginate . Next, the treated CS is combined with other antimicrobial agents through encapsulation, loading, cross-linking, and other technologies to finally form various antimicrobial microcapsules, ,, films, ,, coatings, ,, or gels ,,,, with slow- or controlled-release functions. In these cases, the major release component is usually the other active antimicrobial agent, rather than CS.…”

“…The release duration of LZ from the hydrogels was at least 21 days. Additionally, Gorshkova et al 76 first prepared porous cryogels and aerogels using a sodium alginate-CS interpolymer complex through freeze drying and supercritical drying, respectively. Usnic acid (UA) was then loaded onto these gels via solution impregnation, resulting in two slow-release antibacterial gels.…”

“…In this pattern, the release of antimicrobial agents from SAFP is primarily driven by the swelling of substrates and carriers when they absorb solvents (Figure ). The release rate is influenced by factors such as the type, thickness, swelling rate, and swelling degree of substrates/carriers, the diffusion behavior of antimicrobial active ingredients within the swollen area, as well as the intrinsic characteristics of the food and its migration rate into the packaging. ,,,,− Swelling in SAFP is usually driven by hydrophilic components interacting with water molecules, a phenomenon common in biopolymers that are susceptible to moisture and humidity. ,,− When M t / M ∞ ≤ 0.6, swelling-dominated one-dimensional release can often be described by the power law model, also known as the Korsmeyer–Peppas model (see SEq 11 and Table S1 for details). − …”