Development of acid-free chitosan films in food coating applications: Provolone cheese as a case study

Chitosan has been extensively explored in food coatings. Still, its practical application is largely hampered by its conventional wet processing in acetic acid, whose residuals negatively impact food quality and safety. Here, we propose a new method to formulate chitosan coatings for food applications by avoiding organic acid processing and validate them on a cheese model. The procedure entails modifying a previously reported process based on HCl chitosan treatment and neutralising the resulting gel. The obtained chitosan is solubilised in water using carbonic acid that forms in situ by dissolving carbon dioxide gas. The reversibility of water carbonation allows for easy removal of carbonic acid residues, resulting in acid-free chitosan films and coatings. The performance of the coating was tested against state-of-the-art chitosan-based and polymeric coatings. We preliminarily characterised the films' properties (water stability, barrier, and optical properties). Then, we assessed the performance of the coating on Provolone cheese as a food model (mass transfer and texture profiles over 14 days). The work demonstrated the advantage of the proposed approach in solving some main issues of food quality and safety, paving the way for an effective application of chitosan in future food contact applications.

Essential oil-loaded starch/cellulose aerogel: Preparation, characterization and application in cheese packaging

Novel antimicrobial emitting aerogels based on starch/cellulose/Thymus daenensis Celak essential oil (SC-TDEO) were developed and optimized for antimicrobial packaging of Koopeh cheese. An aerogel formulation containing cellulose (1 %; extracted from sunflower stalks) and starch (5 %) in a 1:1 ratio was selected for in vitro antimicrobial assay and subsequent cheese application. The minimum inhibitory dose (MID) of TDEO in the vapor phase against Escherichia coli O157:H7 was determined by loading various concentrations of TDEO onto the aerogel, and an MID of 256 μL/L_headspace was recorded. Aerogels containing TDEO at 25 × MID and 50 × MID were then developed and used for cheese packaging. During a 21-day storage period, cheeses treated with SC-TDEO_{50 MID} aerogel exhibited a significant 3-log reduction in psychrophile counts and a 1-log reduction in yeast-mold counts. Moreover, significant changes in the population of E. coli O157:H7 were observed in cheese samples. After 7 and 14 days of storage with SC-TDEO_{25 MID} and SC-TDEO_{50 MID} aerogels, the initial bacterial count became undetectable, respectively. Sensory evaluations indicated that the samples treated with SC-TDEO_{25 MID} and SC-TDEO₅₀ aerogels received higher scores compared to the control group. These findings demonstrate the potential of the fabricated aerogel to develop antimicrobial packaging suitable for cheese applications.

Development and characterization of fish gelatin-based biodegradable film enriched with Lepidium sativum extract as active packaging for cheese preservation

The physical and functional properties of gelatin-based films enriched with organic extracts from Lepidium sativum seeds were studied. Gelatin was extracted from the skin of dogfish (Squalus acanthias) and the functional gelatin-based films were used to preserve cheese during chilled storage. Ethanol extract (LSE3) and gelatin-based film enriched with LSE3 at 20 μg/mL showed high antioxidant potential using various complementary methods. No significant difference was measured in the mechanical parameters of the enriched films in terms of thickness, tensile strength and elongation at break. LSE3 incorporation at the highest level slighltly decreased the film L∗ value from 90.30 ± 0.10 to 88.10 ± 0.12, while the b∗ value increased from 0.91 ± 0.07 to 8.89 ± 0.12. Wrapping the cheese with gelatin-based film enriched with 20 μg LSE3/mL reduced the syneresis by 40% and stabilized the color, peroxidation and bacteria growth as compared to the unwrapped sample after 6 days of storage. In addition, cheese wrapped with the active gelatin-based film showed the lowest changes in texture parameters. Overall results suggest the use of the enriched gelatin film as active packaging material to preserve cheese quality.