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High-throughput coating with biodegradable antimicrobial pullulan fibres extends shelf life and reduces weight loss in an avocado model


Food waste and food safety motivate the need for improved food packaging solutions. However, current films/coatings addressing these issues are often limited by inefficient release dynamics that require large quantities of active ingredients. Here we developed antimicrobial pullulan fibre (APF)-based packaging that is biodegradable and capable of wrapping food substrates, increasing their longevity and enhancing their safety. APFs were spun using a high-throughput system, termed focused rotary jet spinning, with water as the only solvent, allowing the incorporation of naturally derived antimicrobial agents. Using avocados as a representative example, we demonstrate that APF-coated samples had their shelf life extended by inhibited proliferation of natural microflora, and lost less weight than uncoated control samples. This work offers a promising technique to produce scalable, low-cost and environmentally friendly biodegradable antimicrobial packaging systems.

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Fig. 1: Direct coating of avocados with rinsible PFs.
Fig. 2: Morphology and chemical composition of PFs and APFs.
Fig. 3: Direct contact assay of antimicrobial and antifungal activity of APFs.
Fig. 4: Effect of APF coating (5.0 mg cm2) on avocado rotting.
Fig. 5: The effect of APF coating on avocado colour, firmness and pH during storage at 22°C.

Data availability

The data that support the findings of this study are available from the corresponding authors upon reasonable request. Source data are provided with this paper.


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We thank the Nanyang Technological University–Harvard T. H. Chan School of Public Health Initiative for Sustainable Nanotechnology for funding support (project number NTUHSPH 18003). This work was performed in part at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by the National Science Foundation under NSF award number 1541959 and at the Harvard MRSEC (grant numbers DMR-1420570 and DMR-2011754).

Author information

Authors and Affiliations



K.K.P. and P.D. supervised the research. K.K.P., P.D., H.C., J.X. and L.A.M. designed the study. H.C., J.X., Z.A. and M.M.P. conducted the experiments and analysed the data. L.A.M., T.X. and J.F.Z. provided support to perform experiments and data analysis. All authors discussed the results and contributed to the writing of the final manuscript.

Corresponding authors

Correspondence to Philip Demokritou or Kevin Kit Parker.

Ethics declarations

Competing interests

Harvard University filed for intellectual property relevant to this manuscript, listing K.K.P., P.D., H.C. and L.A.M. as inventors. The remaining authors declare no competing interests.

Peer review

Peer review information

Nature Food thanks Feng Jiang, Long Yu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–8, Table 1 and description of Supplementary Videos 1 and 2.

Reporting Summary

Supplementary Data 5

The effect of antimicrobial pullulan fibre’s surface density on the weight loss of avocados.

Supplementary Data 6

The effect of antimicrobial pullulan fibre coating on avocados’ natural microflora.

Supplementary Data 7

The effect of antimicrobial pullulan fibre coating on the exocarp discoloration of avocados.

Supplementary Video 1

Direct coating avocados with pullulan-based fibres.

Supplementary Video 2

Pullulan fibre coating on avocado was removed by rinsing in water.

Source data

Source Data Fig. 2

Unprocessed data of fibre diameter distribution, X-ray diffraction and Fourier transform infrared spectroscopy.

Source Data Fig. 3

Unprocessed data of antimicrobial and antifungal activity.

Source Data Fig. 4

Unprocessed data of avocado weight and natural microflora (including total aerobic bacteria, yeast and mould).

Source Data Fig. 5

Unprocessed data of avocado’s colour, firmness and pH.

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Chang, H., Xu, J., Macqueen, L.A. et al. High-throughput coating with biodegradable antimicrobial pullulan fibres extends shelf life and reduces weight loss in an avocado model. Nat Food 3, 428–436 (2022).

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