Cinnamon-essential oil shows shelf-life extension
The oil was tested for its antifungal activity and the promising results suggest the essential oil from cinnamon may be used as a preservative in certain food applications.
“Essential oils are known to be effective against a wide spectrum of micro-organisms and leave no detectable residues,” wrote lead author Nikos Tzortzakis in the journal Innovative Food Science and Emerging Technologies.
“These findings may have considerable commercial significance. There would seem to be real commercial potential for oil vapour-enrichment,” added Tzortzakis from the Greek National Agricultural Research Foundation.
The tide is currently turning against chemical-based anti-fungal additives for food use, opening up opportunities for alternatives from natural sources. The reasons for this are manifold and include general consumer preferences for natural foods, legislative changes, and the isolation of antibiotic resistant pathogens.
Tzortzakis tested cinnamon oil in the range of 25 and 500 ppm for its activity against certain fungi, including Colletotrichum coccodes, Rhizopus stolonifer Botrytis cinerea, Cladosporium herbarum, and Aspergillus niger. The in vitro experiments showed that the anti-fungal activity was related to the concentration of the essential oil.
When the 25 ppm concentration was test, a 63 per cent reduction in the production of fungal spores was observed. At a concentration of 500 ppm, “fungal sporulation (except for B. cinerea) was completely retarded,” reported Tzortzakis.
Germination of the produced spores was also affected by the cinnamon essential oil, with a reduction observed for C. coccodes, B. cinerea, C. herbarum and R. stolonifer.
Out of the lab and into practice
Tzortzakis then tested the essential oil in pepper and tomato fruit. The fruit were wounded and then inoculated with the fungi. In the pepper fruit, an acceleration of B. cinerea and C. coccodes growth was observed. No differences were observed for the tomato fruit, however, he said.
Tzortzakis rationalised this as the cinnamon essential oil lowering the resistance of the fruit to the fungi. To explore this further, the fruit were pre-exposed to the essential oil and then exposed to the fungi and stored for three to seven days.
A significant reduction in fungal growth was observed for the tomato fruit over three days and using the 500 ppm cinnamon essential oil, but overall there was no suppression of growth.
“Indeed, according to preliminary observations, essential oil-enrichment may pose fungal suppression on the reproductive phase (spore production and spore viability) and this should explore further in details,” he said.
Tzortzakis confirmed that the study area is ongoing with current trials “focussing on the mechanisms underlying the impacts of essential oil volatiles on disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load in the storage/transit atmospheres as well as the use of essential oil as an alternative food preservative.”
Source: Innovative Food Science and Emerging Technologies
Published online ahead of print, 20 September 2008, doi: 10.1016/j.ifset.2008.09.002“Impact of cinnamon oil-enrichment on microbial spoilage of fresh produce”Author: N.G. Tzortzakis