Biodegradable films with enriched anthocyanin for shelf life extension of food products -

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Biodegradable films with enriched anthocyanin for shelf life extension of food products

           

The anthocyanin extracted from the Phyllanthus reticulatus ripen fruits was incorporated into CS/MC matrix to develop active and intelligent films via solvent evaporation technique. It is biologically active and pH responsive smart films based on Chitosan (CS)/ Methylcellulose (MC) matrix integrated with Phyllanthus reticulatus (PR) ripen fruit anthocyanin. The incorporation of PR anthocyanin significantly blocked the UV light transmission of the CS/MC films. The water solubility, moisture retention capacity, and water vapor transmission rate were significantly enhanced with an increase in the PR anthocyanin content.  The CMPR films exhibited red color in acidic pH (pH -1) whereas yellowish in basic pH (pH -11). It also exhibited strong antioxidant activity as well as antibacterial activity against the common foodborne pathogens such as S. aureus, P. aeruginosa, and E. coli. It has potential application for monitoring the freshness of the fish fillets and it could be used as pH sensitive films for quality assurance as well as to extend the shelf life of packed seafood products.

Anthocyanin as extracted  from Phyllanthus reticulatus fruit. pH-sensitive films CS/MC based smart films were prepared via solvent casting evaporation technique. For CS film, the film forming solution was prepared by dissolving 1 g of CS in 100 mL Acetic acid solution (2% v/v) and filtered through a cotton filter to remove undissolved particles. For the preparation of CS/MC film solution, 0.5 g of MC was first dispersed in 30 mL Milli–Q water and stirred vigorously for 30 min and then, 20 mL of ice-cold Milli–Q water was added to it for complete dissolution of MC. Thereafter, CS solution was prepared as mentioned above and blended with MC solution using a magnetic stirrer at room temperature for 1 h. For CMPR films, different concentrations of PR fruit extract solution (5 wt%, CMPR–1 and 10 wt%, CMPR–2) was added to the CS/MC solution as prepared above and stirred for 1 h. Finally, all the film–forming solutions were cast on glass Petri dishes (10 cm radius) and dried at 27 ± 2 ◦C for 72 h. Dried films were peeled off and stored in a desiccator containing anhydrous CaCl2 (0% RH) until further study.

The practical packaging test of the intelligent pH-responsive films was carried out to determine their potential as a halochromic freshness monitoring label for packed food. For this, the deterioration time of fish freshness was investigated as follows. Briefly, the film sample was placed in a transparent polyethylene pack containing approximately 50 g of fish fillet. The packaged fish fillet was stored at room temperature for 48 h. The pH of the fresh fish fillet and the deteriorated fish fillet was determined using digital pH-meter.

The utilization of pH sensitive films to examine the changes in the freshness of the seafood products during their storage and transport is their paramount application. The deterioration of seafood products is mainly due to the enzymatic degradation of proteins. During the protein degradation process, the formation of basic volatile nitrogen takes place that enhances the pH of the product within the package. The CMPR-2 film was sealed within the package to monitor the freshness of the fish fillet stored at room temperature for 48 h. The CMPR-2 film turned to dark grey color in fresh fish fillet package and the initial pH of the fresh fish fillet was 6.9, while after 39 h the color of the CMPR-2 film was changed to slightly yellowish and the pH of the spoiled fish fillet was found to be 9.89. The color of the CMPR-2 film and pH response of the solution of PR anthocyanins are in good agreement with each other. This result showed that the CMPR films behaved as smart films for monitoring the freshness of the seafood.

Reference:

Gasti, T., Dixit, S., D’souza, O.J., Hiremani, V.D., Vootla, S.K., Masti, S.P., Chougale, R.B. and Malabadi, R.B., 2021. Smart biodegradable films based on chitosan/methylcellulose containing Phyllanthus reticulatus anthocyanin for monitoring the freshness of fish fillet. International Journal of Biological Macromolecules, 187: 451-461.