Preparation and Characterization of Bioactive Chitosan Film Loaded with Cashew (Anacardium occidentale) Leaf Extract.

Saroat Rawdkuen,Kittaporn Ngiwngam,Thomas Karbowiak,Pornchai Rachtanapun,Wirongrong Tongdeesoontorn,Khursheed Ahmad Shiekh,Mooksupang Liangpanth,Siriporn Luesuwan,Rinlanee Kraisitthisirintr

doi:10.3390/polym14030540

Saroat Rawdkuen, Kittaporn Ngiwngam + Show 7 more

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https://doi.org/10.3390/polym14030540

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Abstract

Chitosan is a biopolymer known for its rapid biodegradability and film-forming properties. This research aimed to synthesize and characterize chitosan films loaded with cashew leaf extract (CLE) obtained from immature and mature cashew leaves via aqueous and 70% ethanolic extraction methods. Freeze-dried CLE samples were dissolved in 50% dimethyl sulfoxide for in vitro analysis and chitosan film preparation. The total phenolic content of mature cashew leaves extracted in ethanol (MECLE) showed higher free radicle scavenging activity by a 2,2-diphenyl-1-picrylhydrazyl assay than the other extracts (p < 0.05). MECLE displayed a lower minimal inhibitory concentration, minimum fungal concentration, and higher zone of inhibition against Aspergillus niger compared to the other treatments (p < 0.05). Film-forming solutions were prepared using 2% chitosan, 2% chitosan with 5% mature cashew leaves extracted in deionized water (MACLE) (w/v), and 2% chitosan with 5% MECLE (w/v), respectively, to cast films. Of these, 2% chitosan (CH) with 5% MECLE (CH-MECLE-5) displayed the highest thickness and water vapor transmission rate, water vapor permeability, and oxygen transmission rate when compared to other film samples (p < 0.05). The CH-MECLE-5 film showed the highest inhibition zone of A. niger compared to the control and treated films (p < 0.05). The lightness (L*) of the CH-MECLE-5 film decreased with increment in b* values, which represented the yellow color of the film. In addition, two-photon microscopy revealed a uniform distribution via the auto-fluorescent 3D structure of MECLE in the CH-MECLE-5 film. Therefore, chitosan combined with 5% MECLE may be a potential bioactive and eco-friendly packaging film.

Highlights

The application of synthetic and non-biodegradable polymer-tailored packaging films in foods has led to alarming consequences for the environment [1]
It was postulated that the higher Total Phenolic Content (TPC) obtained in the mature cashew leaves extracted in ethanol (MECLE) sample extracted in 70% ethanol might have migrated inside the cashew leaf cells and washed out along with the cell matrix containing both polar and nonpolar phenolic compounds
Higher TPC and Diphenyl-1-picrylhydrazyl Free Radical Scavenging (DPPH) values were attained in the 5% MECLE sample

Summary

Introduction

The application of synthetic and non-biodegradable polymer-tailored packaging films in foods has led to alarming consequences for the environment [1]. Excessive production of synthetic packaging materials may directly have an impact on the sustainability of non-renewable petroleum-based resources [2]. Biopolymers can be obtained from the exoskeleton of crustaceans (chitosan), plants (cellulose, inulin, and starch), microbes (dextran and xanthan), and algae (alginate) [5]. Biopolymers with diverse structural and functional properties have been used, including cellulose, starch, chitosan, chitin, guar, locust bean gum, tara gum, glucomannan, xanthan, agar, carrageenan, pectin, alginates, gellan, curdlan, dextran, levan, arabinoxylans, and pullulan [6,7,8]. Biodegradable and edible films (BEFs) prepared from different hydrocolloids are gaining popularity worldwide in the food industry to replace synthetic petroleum-based packaging materials [9]. BEFs are non-toxic and can help to eliminate food safety concerns and increase the shelf-life of packaged foods [12]

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