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Thymol-Loaded Polymeric Nanoparticles Improve the Postharvest Microbiological Safety of Blueberries

Syarifah Ab Rashid1,2orcid tiny, Woei-Yenn Tong3*orcid tiny, Chean-Ring Leong1orcid tiny, Wen-Nee Tan4orcid tiny, Chee-Keong Lee5,6orcid tiny, Mohd Razealy Anuar3orcid tiny, Siew-Hway Teo3orcid tiny, Siti Khalida Abdull Lazit3, Jun-Wei Lim 7,8orcid tiny and Nur Amiera Syuhada Rozman1

1Universiti Kuala Lumpur, Branch Campus Malaysian Institute of Chemical and Bioengineering Technology, Lot 1988 Kawasan Perindustrian Bandar Vendor, Taboh Naning, 78000 Alor Gajah, Melaka, Malaysia

2School of Biological Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia

3Universiti Kuala Lumpur, Institute of Medical Science Technology, A1-1, Jalan TKS 1, Taman Kajang Sentral, 43000 Kajang, Selangor, Malaysia

4Chemistry Section, School of Distance Education, Universiti Sains Malaysia, 11800, Penang, Malaysia

5Bioprocess Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 USM, Minden, Penang, Malaysia

6Renewable Biomass Transformation Cluster, School of Industrial Technology, Universiti Sains Malaysia, 11800 USM, Minden, Penang, Malaysia

7HICoE-Centre for Biofuel and Biochemical Research, Institute of Self Sustainable Building, Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Seri Iskandar, 32610 Perak Darul Ridzuan, Malaysia

8Department of Biotechnology, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 602105, India

Article history:

Received: 7 December 2021

Accepted: 23 February 2023

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blueberries; microbiological safety; nanoparticles; postharvest treatment; thymol

E WEB Goal 02The content of this publication has not been approved by the United Nations and does not reflect the views of the United Nations or its officials or Member States.


Research backgroundThe presence of Yersinia enterocolitica on raw food products raises the concern of yersiniosis as most of the berries are consumed raw. This is a challenging issue from the food safety aspect since it could increase the occurrence of foodborne diseases among humans. Thus, it is crucial to implement an effective sanitation before the packaging.

Experimental approach. This study aims to synthesize and characterize thymol-loaded polyvinyl alcohol (Thy/PVA) nanoparticles as a sanitizer for postharvest treatment of blueberries. Thy/PVA nanoparticles were characterized by spectroscopic and microscopic approaches, prior to the analyses of antimicrobial properties.

Results and conclusionsThe diameter size of the nanoparticles was on average 84.7 nm, with a surface charge of −11.73 mV. Based on Fourier transform infrared (FTIR) measurement, the Thy/PVA nanoparticles notably shifted to the frequency of 3275.70, 2869.66, 1651.02 and 1090.52 cm–1. A rapid burst was observed in the first hour of release study, and 74.9 % thymol was released from the PVA nanoparticles. The largest inhibition zone was displayed by methicillin-resistant Staphylococcus aureus (MRSA), followed by Y. enterocolitica and Salmonella typhi. However, amongst these bacteria, the inhibition and killing of Y. enterocolitica required a lower concentration of Thy/PVA nanoparticles. The treatment successfully reduced the bacterial load of Y. enterocolitica on blueberries by 100 %.

Novelty and scientific contributionThymol is a plant-based chemical without reported adverse effects to humans. In this study, by using the nanotechnology method of encapsulation with PVA, we improved the stability and physicochemical properties of thymol. This nanoparticle-based sanitizer could potentially promote the postharvest microbiological safety of raw berries, which may become an alternative practice of food safety.

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