Methane (CH₄) is a potent greenhouse gas with a global warming potential approximately 84-86 times higher than carbon dioxide (CO₂) over a 20-year period. Reducing CH₄ emissions is essential to achieving the EU’s climate neutrality goals under the European Green Deal and the EU Methane Strategy. Ruminant livestock are responsible for up to 90% of agricultural CH₄ through enteric fermentation. With the global population expected to reach 9.7 billion by 2050, growing food demand will further intensify emissions, underscoring the urgent need for scalable, sustainable mitigation technologies.

Current CH₄ reduction approaches include feed additives, dietary manipulation, vaccination, and microbial inhibitors. However, these methods often suffer from limited efficacy, short duration of action, high cost, or the need for frequent supplementation, making them impractical for large-scale adoption. To overcome these limitations, this project proposes the development of a polymer-based sustained-release formulation that continuously delivers a natural, long-acting, CH₄-reducing compound in the rumen.

Mustard oil, produced from mustard cake, a common high-protein feed for animals, contains natural compounds like allyl isothiocyanate (AITC), known for their antimicrobial and anti-inflammatory effects. This project aims to develop a sustained-release formulation using mustard oil and biodegradable polymers to help reduce CH₄ emissions from ruminant animals. After assessing AITC’s properties and antibacterial activity, it was blended with five biodegradable polymers of both synthetic (PCL, PEO) and natural (PHB, PLA, Chitosan) origin by solvent casting. FTIR and DSC analyses showed clear miscibility of AITC with PCL and PHB, without new or shifted peaks, and compatible thermal behaviour, further supported by SEM images confirming uniform dispersion within these polymer matrices. Antimicrobial assays using both Gram-positive and Gram-negative rumen bacteria also produced promising results, highlighting that PCL and PHB are the most suitable biodegradable polymers to act as matrix materials for incorporating AITC to formulate a sustained-release formulation for CH₄ mitigation.