Citrus Peel Extracts for Industrial-Scale Production of Bio-Based Active Food Packaging

Abstract

The thermal stability of four different commercial citrus peel extracts was tested and improved by an encapsulation process with β-cyclodextrins in a spray-dryer. All extracts after the encapsulation process maintained a good antioxidant capacity, with an apparent loss in total phenolic compounds of around 20–25%. In addition, all samples showed good antimicrobial activity (MIC 5-0.625 mg/mL) against Staphylococcus aureus, which was maintained after the encapsulation process (MIC 5-1.25 mg/mL). Based on the antioxidant and antimicrobial activity results, the best-encapsulated citrus extract was selected for incorporation into a polylactic acid/polyhydroxy butyrate (PLA/PHB) film. The latter was then produced on an industrial scale by cast extrusion and was found to be suitable for food contact as it showed overall migration values in different food simulants lower than the legislative limit of 10 mg of non-volatile substances per 1 dm2 of surface area. The UHPLC-HRMS analysis, performed to evaluate the migration of the active compounds, revealed about 13.41% release in food simulant A and 11.02% in food simulant B. Antimicrobial analysis conducted directly on the film showed a growth inhibition activity towards Escherichia coli and Staphylococcus aureus equal to 30 and 60%, respectively.

Upgrading the physiochemical and sensory quality of yogurt by incorporating polyphenol-enriched citrus pomaces with antioxidant, antimicrobial, and antitumor activities

“…The highest MIC, MBC, and MFC values were recorded in LP. Fiorentini et al ( 54 ) found that food-grade commercial citrus peel extract (5–0.625 mg/mL) inhibits the growth of Staphylococcus aureus , which was maintained after the encapsulation process (MIC 5–1.25 mg/mL).…”

Development of Coated PLA Films Containing a Commercial Olive Leaf Extract for the Food Packaging Sector

“…The latter allowed us to putatively identify the phenolic compounds characterizing the OL extract and food simulants A and B after migration from the coated PLA films. The untargeted analysis was conducted as reported by Fiorentini et al [16]. Ferulic acid (phenolic acids), quercetin (flavonols), catechin (flavanols), cyanidin (anthocyanins), luteolin (flavones and other flavonoids), resveratrol (stilbenes), and oleuropein (for tyrosol derivatives and lower-molecular-weight compounds) were used as qualitative and quantitative standards of their respective classes.…”

“…Based on the concentration of the commercial OL extract into the coating formulation (<50 mg/mL), the volume of the coated solution used for each coated PLA film (about 2 mL for 3.75 dm 2 surface), and the ratio between the coated PLA film and food simulants used for the migration tests (0.36 dm 2 in 36 mL), the maximum extract concentration that could potentially migrate into food simulants was evaluated. Moreover, the greatest concentration of the total equivalent phenolics that could migrate and the fractions of the migrated compounds were evaluated following the method reported by Fiorentini et al [16].…”

“…The MIC of the OL extract was assessed based on what was reported by Fiorentini et al, testing Escherichia coli ATCC 25922 and Salmonella enterica serovar Typhimurium DSM 17058, Listeria monocytogenes DSM 15675 and Staphylococcus aureus ATCC 33591 [16]. Briefly, fresh plate cultures were suspended in a sterile saline solution to achieve a turbidity of 0.5 McFarland.…”

“…The overall migration (M) test was performed with three different food simulants, as reported by Fiorentini et al [16], with some modifications. The selected food simulants were 10% ethanol (v/v), 3% acetic acid (w/v), and olive oil (i.e., simulants A, B, and D2, respectively) and the contact conditions 10 days at 40 • C. Furthermore, specimens of 0.36 dm 2 of each coated PLA film were cut and wrapped to obtain a pouch of 0.36 dm 2 with the coating side facing outward (reverse pouch) in order to check migration only from the coated side.…”