Active packaging based on PLA and chitosan-caseinate enriched rosemary essential oil coating for fresh minced chicken breast application

There is an urgent need to increase the food supplies to fulfil the demands of future generations as the population of the world is expected to grow beyond 10 billion by 2050. An essential component for ensuring global food security is to reduce food losses during the post-harvest stage. Active edible coatings and films are a promising sustainable preservation technology for shelf-life extension of food products by hindering decay kinetics of minimally processed fruits and vegetables (F&V), by restricting the mass transfer of moisture, aroma, or gases and carrying an active compound, such as an antioxidant or antimicrobial. Active protein-based coatings and films have the potential to extend the shelf-life of food products by decreasing their respiration rates, as they exhibit an excellent gas barrier and good mechanical properties as compared to other biopolymeric packaging. Among protein-based biopolymers, casein and its derivatives as packaging films have been extensively studied due to their low cost, complete biodegradability, and availability. Currently, there is no review study focusing on caseinate-based active coating and film, thus, this review aims to give insights on the composition, rheology, structure, and properties of caseinate-based formulations by critically discussing the results presented in the literature. A methodological approach was followed to obtain relevant literature to discuss the influence of additives on the shelf-life of F&V. Furthermore, changes in secondary structure of casein were observed after incorporation of bioactive compounds (i.e., phenolic acids). Likewise, there is a need to explore chemical interactions among bioactive compounds and biopolymer material by using in silico and laboratory trials as food additives have shown to influence the physicochemical properties of film and shelf-life of food products.

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Active Casein Coatings and Films for Perishable Foods: Structural Properties and Shelf-Life Extension

The increase in environmental concerns and the severe energy depletion as a result of using petroleum-based polymers have led to the introduction of biopolymers such as milk proteins as a hot topic due to their biodegradability, biocompatibility, and renewability. In the current review, we first discuss packaging composites based on milk proteins and their structural challenges. Then an overview of different functional and structural reinforcement methods, such as loading natural bioactive compounds, nanofillers, cross-linking agents, and plasticizers for milk protein-based packaging composites, is reported. The potential applications in the food packaging sector are discussed as well. Milk-based proteins are considered as valuable biopolymers with suitable thermal stability, non-toxicity, preventing moisture and flavors losses, exceptional functionalities due to their unique structure, and excellent gas barrier attributes. However, their limitations (moisture sensitivity, brittleness, low elasticity, etc.) should be addressed prior to further industrial applications to fill the gap between them and synthetic polymers. The main drawbacks of milk protein-based packaging systems can be modified by applying bioactive compounds, nanofillers, cross-linkers, plasticizers, etc. In conclusion, the modified milk protein-based biopolymers could be introduced as promising alternatives to petroleum-based polymers. However, selecting the correct milk protein source in addition to appropriate reinforcing agents and procedures based on food nature could guarantee a well-protected food with extended shelf-life and the least environmental impacts. 

Different strategies to reinforce the milk protein-based packaging composites

Biopolymers, like polysaccharides and proteins, are sustainable and green materials with excellent film-forming potential. Bio-based films have gained a lot of attention and are believed to be an alternative to plastics in next-generation food packaging. Compared to conventional plastics, biopolymers inherently have certain limitations like hydrophilicity, poor thermo-mechanical, and barrier properties. Therefore, the modification of biopolymers or their films provide an opportunity to develop packaging materials with desired characteristics. Among different modification approaches, the application of cold plasma has been a very efficient technology to enhance the functionality and interfacial characteristics of biopolymers. Cold plasma is biocompatible, shows uniformity in treatment, and is suitable for heat-sensitive components. This review provides information on different plasma generating equipment used for the modification of films and critically analyses the impact of cold plasma on packaging properties of films prepared from protein, polysaccharides, and their combinations. Most studies to date have shown that plasma treatment effectively enhances surface characteristics, mechanical, and thermal properties, while its impact on the improvement of barrier properties is limited. Plasma treatment increases surface roughness that enables surface adhesion, ink printability, and reduces the contact angle. Plasma-treated films loaded with antimicrobial compounds demonstrate strong antimicrobial efficacy, mainly due to the increase in their diffusion rate and the non-thermal nature of cold plasma that protects the functionality of bioactive compounds. This review also elaborates on the existing challenges and future needs. Overall, it can be concluded that the application of cold plasma is an effective strategy to modify the inherent limitations of biopolymer-based packaging materials for food packaging applications.

https://www.mdpi.com/2076-3417/12/3/1346/pdf?version=1643348726

Effect of Cold Plasma Treatment on the Packaging Properties of Biopolymer-Based Films: A Review

We are grateful to the Spanish government for the financial support from the national project RTA2012-00067-C02 (Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria, Spain and FEDER funds) and to the Conselleria d'Educacio of the Generalitat Valenciana (Spain) for A. Marin's PhD grant.

Lactic acid bacteria incorporated into edible coatings to control fungal growth and maintain postharvest quality of grapes.

The objective of this work was to investigate the effect of sodium caseinate concentration on physical-chemical properties of coating solutions and films obtained by casting as a starting point for the development of an active coating for minimally processed fruits or vegetables. Sodium caseinate solutions at different concentrations (4%, 8%, 10%, 12%, 14%) were used as a coating system. The coating viscosity and desorption kinetic were characterized. Minimally processed fennels were coated by dipping and the liquid and dry coating thickness were estimated by assessing the amount of coating on fennel during draining as a function of solution properties (concentration and viscosity). Film obtained by casting were also characterized in terms of equilibrium moisture content, color, and water vapor permeability. The potential of using the sodium caseinate solution to obtain active coating was investigated by adding gallic acid or rosemary oil to sodium caseinate solution at 4%. The antioxidant capacity of the coating was evaluated by DPPH test. Results show that sodium caseinate solutions follow a Newtonian behavior in the range of concentration investigated and the viscosity increased as solids concentration increased, following a power law. The drying rate was in the range 0.0063–0.00107 mgH2O·mgsolids−1·min−1·m−2 as a function of sodium caseinate concentration. The average liquid and dry coating thickness on fennels were in the range 20–70 and 0.7–6.4 μm, respectively. The water vapor permeability slightly decreased as the solid concentration increased. Active coating showed good antioxidant properties.

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Marika Valentino

Papers

Active Casein Coatings and Films for Perishable Foods: Structural Properties and Shelf-Life Extension

Active Biopolymer Coating Based on Sodium Caseinate: Physical Characterization and Antioxidant Activity