Compounds in packaging prevent bread spoilage
September 02, 2008
by Jeff Gelski
ZARAGOZA, SPAIN — Active compounds on paper may provide antimicrobial activity to the packaging material of bread, according to a study in the Aug. 13 issue of the Journal of Agricultural and Food Chemistry.
The study, called "New Cinnamon-Based Active Paper Packaging against Rhizopusstolonifer Food Spoilage," involved researchers from the University of Zaragosa in Zaragosa, Spain. The researchers concluded, "The use of this active paper packaging is a smart alternative for protecting bread from fungal infestation since no direct contact between the food and the packaging is required."
They chose cinnamaldehyde, a fortified cinnamon essential oil, since it has shown to have the strongest antimicrobial activity when compared to the other constituents of essential oils. Rhizopusstolonifer fungus, or black bread mold, is a prevalent spoiler of white bread and bakery products, as are Aspergillus and Pencillium genera. Rhizopusstolonifer stolonifer infests the product within a short time when bread is stored in an enclosed, humid environment.
Researchers inoculated one side of a slice of bread in the center with R. stolonifer and placed the slice in the middle of two noninoculated slices. The slices then were packed manually with the active paper, or the paper with cinnamaldehyde. Bread packages were stored at 25° Celsius (77° Fahrenheit), plus or minus 1° Celsius, for 3 days and 10 days. After this period, the whole slice was ground in a mortar and 7 grams of both the inoculated slice and nonincoulated slices were weighed aseptically.
Nominal concentration of cinnamaldehyde ranged from 1% to 6% in the coating of the paper. When R. stolonifer was exposed to the atmosphere with 6% of the fortified cinnamon essential oil in the active coating, it was in inhibited in all five replicates. Total inhibition also was obtained in four of the five replicates when 4% of the essential oil was used and in two of the five replicates when 2% of the essential oil was used. No inhibition was obtained when 1% of the essential oil was used.
The researchers wrote, "There was no direct contact between the active packaging and the inoculated bread slices because they were placed in the middle of two noninoculated slices. For this reason, the inhibition must take place by vapor-phase transfer from the packaging and not by direct migration of the active compounds; therefore, our hypothesis is based on the release of the active chemicals from the active coating to the internal atmosphere in the packaging; this atmosphere is responsible for the antifungal activity."
The researchers added further work is in progress to learn more about the rate of migration of the active compound and its relationship with antifungal effects.