https://doi.org/10.17113/ftb.61.02.23.7595

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

Syarifah Ab Rashid^1,2, Woei-Yenn Tong^3*, Chean-Ring Leong¹, Wen-Nee Tan⁴, Chee-Keong Lee^5,6, Mohd Razealy Anuar³, Siew-Hway Teo³, Siti Khalida Abdull Lazit³, Jun-Wei Lim ^7,8 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 Minden, 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

Keywords:

antimicrobial activity; blueberries; nanoparticles; postharvest; thymol

Summary:

Research background. The presence of Yersinia enterocolitica on raw food products raised the concern of yersiniosis as most of the berries were consumed raw. This event is a challenging issue for food safety division since it could raise foodborne diseases among humans. Thus, it is crucial to implement an effective sanitation before the packaging process.

Experimental approach. This study was aimed to synthesize and characterize thymol-loaded polyvinyl alcohol (Thy/PVA) nanoparticles 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 conclusions. On average, the diameter size of the nanoparticles was 84.7 nm, with a surface charge of -11.73 mV. Based on Fourier transform infrared (FTIR) observation, the Thy/PVA nanoparticles have notably shifted on the frequency at 3275.70, 2869.66, 1651.02 and 1090.52 cm-1. A rapid burst was observed at the first h of release study, and 74.9 % of thymol was released from 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 has successfully reduced the bacterial load of Y. enterocolitica on blueberries by 100 %.

Novelty and scientific contribution. Thymol is a plant-based chemical with no reported adverse effects to humans. In this study, the use of nanotechnology has improved the stability and physicochemical properties of thymol by using PVA as encapsulant. This nanoparticles-based sanitizer could potentially promote the postharvest microbiological safety of raw berries, which may become an alternative practice of food safety.