Chlorophyll fluorescence, fermentation product accumulation, and quality of stored broccoli in modified atmosphere packages and subsequent air storage

Earlier work showed that chlorophyll fluorescence changes of broccoli (Bras sica oleracea L., Italica group) were associated with the accumulation of C O, in modified atmosphere packages (MAP) during storage. This work was init iated to determine whether the chlorophyll fluorescence changes in broccoli from high CO2 MAP are persistent after the packages are opened and the bro ccoli is allowed to aerate. PD-961EZ bags, which allow the CO, to accumulat e ( similar to 11 kPa CO2), were used in this study. During 28 days in MAP at 1 degreesC, the broccoli gradually developed slight to moderate alcoholi c off-odors and accumulated ethanol, acetaldehyde, and ethyl acetate in the tissues. These levels dissipated slightly on opening of the bags and holdi ng the broccoli in 1 degreesC air storage for 4 days. Chlorophyll fluoresce nce measurements (Fv/Fm, T-1/(2), and phi (PSII)) declined for broccoli wit h the accumulation of these anaerobic products and the fluorescence measure ments recovered slightly after the bags were opened and the broccoli was he ld in air at 1 degreesC for 4 days. Chlorophyll fluorescence measurements w ere found to be highly correlated with the anaerobic volatile content in br occoli during MAP storage and after opening of the MAP. Chlorophyll fluores cence measurements were also highly correlated with the perceived off-odors that were noted for the broccoli after longer storage durations in MAP. (C ) 2001 Elsevier Science B.V. All rights reserved.