Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/11/2006
Publication Date: 4/1/2006
Citation: Cleary, K.A., McFeeters, R.F. 2006. Effects of oxygen and turmeric on the formation of oxidative aldehydes in fresh-pack dill pickles. Journal of Agricultural and Food Chemistry. 54:3421-3427. Interpretive Summary: Pickle products are increasingly packaged in plastic containers for customer convenience, to avoid breakage, and to reduce shipping weight. However, products in plastic containers typically have a shorter shelf-life than comparable products packaged in glass jars. One of the reasons for reduced shelf life is that the oxygen in air migrates into plastic containers during storage and causes development of off-odors. This project identified and measured compounds formed in fresh-pack dill pickles that may be responsible for off-odors. Turmeric, which is used as a natural yellow coloring in pickle products, was shown to also be an effective antioxidant and to prevent the formation of off-odor compounds when oxygen was intentionally injected into pickle products. This result suggests that turmeric may help extend the shelf life of pickle products in plastic packages.
Technical Abstract: Oxidative off-flavors can develop in pickle products after exposure to oxygen. Plastic containers, which are becoming more common in the pickle industry, can allow oxygen to migrate into the containers during storage. Curcumin is the primary yellow color in turmeric, which has been used for many years as a natural colorant in pickled cucumber products. Curcumin has been shown to have substantial antioxidant activity in various biological and food systems. Our objective was to determine if turmeric, at levels suitable for use in pickle products, would be effective in inhibiting formation of oxidative aldehydes in fresh-pack dill pickles after exposure to oxygen. Fresh-pack dill pickles were made from commercial pickling cucumbers and packed in glass containers. Oxygen and turmeric were added to the pickles during storage. Volatile aldehydes in the pickles were analyzed using purge and trap sampling and gas chromatography-mass spectrometry for identification and quantitation. Commercial pickle products were also analyzed for their volatile aldehyde content. Formation of hexanal and other aldehydes, including pentanal, 2-hexenal, and heptanal, increased as the amount of oxygen in the container increased. Turmeric was found to retard formation of these aldehydes with greater effectiveness as turmeric concentration increased from 16 to 250 ppm. Turmeric maintained aldehyde levels near the concentrations found in commercial fresh-pack pickles packaged in glass containers when oxygen was added to jars of pickles in amounts comparable to that which would enter a plastic container during a 1-year storage period. Thus, turmeric was determined to be an effective antioxidant at concentrations appropriate for coloring in pickles.