Chlorophyll fluorescence, fermentation product accumulation, and quality of stored broccoli in modified atmosphere packages and subsequent air storage
2001
Toivonen, P.M.A. | DeEll, J.R.
Earlier work showed that chlorophyll fluorescence changes of broccoli (Brassica oleracea L., Italica group) were associated with the accumulation of CO2 in modified atmosphere packages (MAP) during storage. This work was initiated to determine whether the chlorophyll fluorescence changes in broccoli from high CO2 MAP are persistent after the packages are opened and the broccoli is allowed to aerate. PD-961 EZ bags, which allow the CO2 to accumulate (approximately 11 kPa CO2), were used in this study. During 28 days in MAP at 1 degree C, the broccoli gradually developed slight to moderate alcoholic off-odors and accumulated ethanol, acetaldehyde, and ethyl acetate in the tissues. These levels dissipated slightly on opening of the bags and holding the broccoli in 1degrees C air storage for 4 days. Chlorophyll fluorescence measurements (Fv/Fm, T1/2, Fmd, and phiPSII) declined for broccoli with the accumulation of these anaerobic products and the fluorescence measurements recovered slightly after the bags were opened and the broccoli was held in air at 1 degree C for 4 days. Chlorophyll fluorescence measurements were found to be highly correlated with the anaerobic volatile content in broccoli during MAP storage and after opening of the MAP. Chlorophyll fluorescence measurements were also highly correlated with the perceived off-odors that were noted for the broccoli after longer storage durations in MAP.
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