Improving the performance of nisin as a natural food additive through the use of nanotechnology

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Celen, Teyfik ORCID: https://orcid.org/0009-0003-2630-0538 (2023). Improving the performance of nisin as a natural food additive through the use of nanotechnology. University of Birmingham. Ph.D.

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Abstract

Nisin is the most famous natural food antimicrobial used in many countries. However, the direct introduction of nisin into food products decreases the duration of its antimicrobial activity, limiting its widespread use in the food industry. Nisin-loaded nanostructures are effective tools which prolong nisin’s antimicrobial performance during the shelf life of food products due to their sustained release properties. However, further investigation is still needed to deliver nisin with easy-to-prepare, cost-effective, food-grade nanocarriers in food. Additionally, novel approaches need to be followed to develop smart nisin carriers (e.g. stimuli-responsive delivery) and thus deliver nisin on demand in food systems in case of
contamination or unmaintained cold chain during the storage of food products. In this project, Polyion Complex (PIC) nanoparticles were used as an easy and affordable platform to develop novel nisin-delivery systems. In each chapter, using different anionic polymers, a straightforward electrostatic complexation method was followed to prepare nisinloaded PIC nanoparticles. Firstly, using commercially available Carboxymethylcellulose (CMC), a new example of a cheap and food-grade nisin-carriers displaying sustained antimicrobial activity properties (Chapter 2). Secondly, hyaluronic acid (HA) was employed as an enzymatically degradable (by hyaluronidase) polymer to encapsulate nisin (Chapter 3). Thus, the first example of enzyme-responsive nisin carriers was developed against hyaluronidase-producing foodborne pathogens (i.e. Staphylococcus aureus). Finally, a synthetic thermoresponsive polymer, poly(Valine-Proline-Glycine-Valine-Glycine-OH), was
employed to prepare PIC nanoparticles loading with nisin (Chapter 4). In this way, the first example of thermoresponsive nisin-carrier was developed to achieve enhanced antimicrobial activity above a critical temperature (i.e. 40o and above ) at which specific foodborne pathogens (e.g. Clostridium perfringens) can rapidly grow in food.

All nanoparticles prepared in this project were characterised by DLS, zeta potential, TEM, and encapsulation efficiency experiments. Additionally, special antimicrobial activity experiments were designed to monitor sustained (Chapter 2) or responsive antimicrobial activity properties
(Chapters 3-4) of these nanoparticles against relevant gram-positive foodborne pathogens and spoilage organisms.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):

Supervisor(s)	Email	ORCID
O'Reilly, Rachel	UNSPECIFIED	UNSPECIFIED
Fernández-Trillo, Paco	UNSPECIFIED	UNSPECIFIED
Miri, Taghi	UNSPECIFIED	UNSPECIFIED
Onyeaka, Helen	UNSPECIFIED	UNSPECIFIED