Cinnamon and oregano show antimicrobial prowess in active packaging

Monday 30 August 2010

Incorporating cinnamon and oregano essential oils (EO) into certain plastics provides antimicrobial properties, new research into active packaging has found.

But the study from a group of Spanish scientists concluded the main factor inhibiting growth of bacteria and moulds was related not to the total amount of active chemical released but instead to when these compounds reached the surface of material – known as the critical time.

The type of packaging material used also played an important role in the efficacy of the antimicrobial performance.

Essential oils
Based on a growing use of natural antimicrobials of plant origin, the team selected cinnamon and oregano as previous research had suggested the essential oils contained compounds that made them the most effective among these substances.

The antimicobial constituent of cinnamon is the compound cinnamaldahyde – which is believed to have the highest anti-fungal activity among aliphatic aldenhydes. Carvacrol and thymol are the relevant compounds in oregano, said the researchers led by Christina Nerin. The work was published in the journal Foodbourne Pathogens and Disease.

The substances were used to measure the effectiveness of inhibiting growth of Gram-positive Listeria monocytogenes, Gram-negative Salmonella chloreraesuis, the yeast Candida albicans and the mould aspergillus flavus.

The inhibition tests saw plates of solidified agar media inoculated in triplicate in a petri dish. The cover of the dish was replaced with active films and stored in appropriate conditions for the incubation period. After this time the number of colonies formed on the polypropylene (PP), and PE/EVOH materials.

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