Emulsion-based edible chitosan film containing propolis extract to extend the shelf life of strawberries

• Published in: International journal of biological macromolecules 2024-07, Vol.273 (Pt 2), p.133108, Article 133108
• Main Authors: Akkuzu, Nisa, Karakas, Canan Yagmur, Devecioglu, Dilara, Karbancıoglu Guler, Funda, Sagdic, Osman, Karadag, Ayse
• Format: Article
• Language: English
• Subjects: anthocyanins; Antifungal activity; antioxidants; ascorbic acid; Botrytis cinerea; chitosan; Edible coating; electron microscopy; emulsions; firmness; oils; oxygen; permeability; phenolic compounds; propolis; shelf life; Storage; weight loss
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.133108

In this study, propolis was first loaded into a conventional oil-in-water emulsion, which was combined with a chitosan film-forming solution to produce propolis emulsion-loaded film (PEF). Strawberries inoculated with Botrytis cinerea coated with PEF and blank emulsion-loaded films (BEF) were stored for 14 days at 4 °C. Compared to BEF, PEF showed superior mechanical and oxygen barrier properties, as well as antioxidant activities, but higher moisture permeability. PEF showed less oil agglomeration on the film surface after drying, as demonstrated by scanning electron microscopy (SEM) analysis. Compared to uncoated strawberries, coatings did not have a significant effect on weight loss or firmness during storage. In contrast, coated strawberries showed elevated total phenolics, anthocyanins, and ascorbic acid retention; however, PEF-coating yielded higher values. Moreover, the PEF coating resulted in a significantly lower reduction of organic acid and total soluble solids. Mold growth was visible in both uncoated and BEF-coated strawberries after 7 days of storage, while PEF-coated fruits showed no visible mold until the end of storage. Starting from day 4, PEF-coated fruits showed lower mold counts (~2 log CFU/g) than other samples. Therefore, the PEF prepared in this study has application potential for the preservation of fresh fruits. [Display omitted] •Propolis emulsion-loaded films (PEF) showed superior oxygen barrier property.•Coating of strawberries did not reduce the softening during storage.•PEF-coating provided lower reduction of organic acid and total soluble solid.•PEF-coated strawberries retained higher anthocyanins during storage.•PEF-coating exhibited higher antifungal activity against Botrytis cinerea.