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Hexanal, a C-6 aldehyde has been implicated to have antimicrobial properties. Hence, this study was conducted to determine the antifungal activities of hexanal vapor against major postharvest pathogens of banana viz., Colletotrichum gloeosporioides and Lasiodiplodia theobromae. The pathogens were cultured in vitro and exposed to hexanal vapor at 600, 800, 1,000 and 1,200 ppm. Mycelial growth of both fungal pathogens were inhibited completely at 800 ppm and the incidence of anthracnose and stem-end rot diseases reduced by 75.2% and 80.2%, respectively. The activities of peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase and glucanase had transiently increased in hexanal vapor treated banana by 5 to 7 days and declined thereafter. Postharvest treatment of banana with hexanal vapor resulted in phospholipase D inhibition and also resulted in cell wall thickening of the treated fruit, which impeded the penetration of the pathogenic spores. This was further confirmed by scanning electron micrographs. The defense-related protein intermediaries had increased in hexanal vapor treated banana fruit, which suggests induced resistance against C. gloeosporioides and L. theobromae, via., the phenylpropanoid pathway which plays a significant role in hindering the pathogen quiescence. Delayed ripening due to inhibition of phospholipase D enzyme, inhibition of mycelial growth and induced systemic resistance by defense enzymes collectively contributed to the postharvest disease reduction and extended shelf life of fruit.

Excessive exploitation of petroleum-based plastics and synthetic fibers is harming the environment. This study isolated nano-fibrillated cellulose (NFC) from plant fiber (Agave americana). The as-extracted Agave fibers were chemically treated (alkali, bleaching, and acid hydrolysis coupled with ultrasonication). Functional and structural analysis were performed using Fourier-transform infrared spectroscopy and X-ray diffraction. The surface morphological changes and thermal decomposition behavior were studied by scanning electron microscopy and by thermogravimetry and derivative thermogravimetry, respectively. Fourier-transform infrared peaks confirmed the absence of lignin and hemicellulose in the NFC samples. X-ray diffraction data revealed that the crystallinity index increased from 50.1% to 64.1% from the raw fiber to the NFC. Thermogravimetry and derivative thermogravimetry showed that the stability increased notably from the raw fiber to the NFC stage. The average particle size was 18.2 nm ± 10.14 nm in the NFC sample, which was confirmed by transmission electron microscopy.

A nano-film was developed using nano-fibrillated cellulose (NFC) obtained from banana (var. Poovan) pseudostem. The NFC was prepared by alkali treatment followed by bleaching and acidification, as described and characterized in the authors’ previous paper. The NFC was used as base material for the development of nano-film. The nano-film was prepared via solvent casting with NFC (4%), polyvinyl alcohol (5%), and polyacrylic acid (5%) at a v/v ratio of 5:8:1. The nano-film was characterized using ultraviolet-visible (UV-VIS) spectroscopy, Fourier transform infrared (FT-IR), thermal gravimetric analyzer, scanning electron microscopy (SEM), gas permeability tester (GPT), texture profile analyzer, and digital thickness gauge meter. The data showed that the developed nano-film was UV protectant, possessed strong cross-linking, had high oxygen barrier capacity, was thermally stable up to 356 °C, and had high tensile strength than conventional film. To assess the protective quality of developed nano-film, tomato fruits were covered, and the shelf life was determined using physiological and biochemical attributes. The study revealed that nano-film developed from NFC possessed tomato preserving capacity for 15 days under ambient storage condition. Overall, the data suggested that banana fibres could be a potential source of NFC to develop biodegradable nano-film.

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