Biomass-Derived Plant Extracts in Macromolecular Chitosan Matrices as a Green Coating for PLA Films

Exploring chitosan-plant extract bilayer coatings: Advancements in active food packaging via polypropylene modification

UV-ozone activated polypropylene (PP) food films were subjected to a novel bilayer coating process involving primary or quaternary chitosan (CH/QCH) as the first layer and natural extracts from juniper needles (Juniperus oxycedrus; JUN) or blackberry leaves (Rubus fruticosus; BBL) as the second layer. This innovative approach aims to redefine active packaging (AP) development. Through a detailed analysis by surface characterization and bioactivity assessments (i.e., antioxidant and antimicrobial functionalities), we evaluated different coating combinations. Furthermore, we investigated the stability and barrier characteristics inherent in these coatings. The confirmed deposition, coupled with a comprehensive characterization of their composition and morphology, underscored the efficacy of the coatings. Our investigation included wettability assessment via contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), which revealed substantial enhancements in surface concentrations of elements and functional groups of CH, QCH, JUN, and BBL. Scanning electron microscopy (SEM) unveiled the coatings' heterogeneity, while time-of-flight secondary ion mass spectrometry (ToF-SIMS) and CA profiling showed moderately compact bilayers on PP, providing active species on the hydrophilic surface, respectively. The coatings significantly reduced the oxygen permeability. Additionally, single-layer depositions of CH and QCH remained below the overall migration limit (OML). Remarkably, the coatings exhibited robust antioxidative properties due to plant extracts and exceptional antimicrobial activity against S. aureus, attributed to QCH. These findings underscore the pivotal role of film surface properties in governing bioactive characteristics and offer a promising pathway for enhancing food packaging functionality.

Assessing Antimicrobial Efficacy on Plastics and Other Non-Porous Surfaces: A Closer Look at Studies Using the ISO 22196:2011 Standard

The survival and spread of foodborne and nosocomial-associated bacteria through high-touch surfaces or contamination-prone sites, in either healthcare, domestic or food industry settings, are not always prevented by the employment of sanitary hygiene protocols. Antimicrobial surface coatings have emerged as a solution to eradicate pathogenic bacteria and prevent future infections and even outbreaks. Standardised antimicrobial testing methods play a crucial role in validating the effectiveness of these materials and enabling their application in real-life settings, providing reliable results that allow for comparison between antimicrobial surfaces while assuring end-use product safety. This review provides an insight into the studies using ISO 22196, which is considered the gold standard for antimicrobial surface coatings and examines the current state of the art in antimicrobial testing methods. It primarily focuses on identifying pitfalls and how even small variations in methods can lead to different results, affecting the assessment of the antimicrobial activity of a particular product.

Bioactive and Physico-Chemical Assessment of Innovative Poly(lactic acid)-Based Biocomposites Containing Sage, Coconut Oil, and Modified Nanoclay

The bioactivity of the versatile biodegradable biopolymer poly(lactic acid) (PLA) can be obtained by combining it with natural or synthetic compounds. This paper deals with the preparation of bioactive formulations involving the melt processing of PLA loaded with a medicinal plant (sage) and an edible oil (coconut oil), together with an organomodifed montmorillonite nanoclay, and an assessment of the resulting structural, surface, morphological, mechanical, and biological properties of the biocomposites. By modulating the components, the prepared biocomposites show flexibility, both antioxidant and antimicrobial activity, as well as a high degree of cytocompatibility, being capable to induce the cell adherence and proliferation on their surface. Overall, the obtained results suggest that the developed PLA-based biocomposites could potentially be used as bioactive materials in medical applications.