Submitted to: Institute of Food Technology
Publication Type: Abstract Only
Publication Acceptance Date: 4/12/2005
Publication Date: 4/17/2005
Citation: Beaulieu, J.C., Lea, J.M. 2005. Formation of secondary flavor compounds in minimally processed fruits. Institute of Food Technology. 18C-2.
Technical Abstract: Most volatile flavor compounds are esters, alcohols, aldehydes, ketones, lactones, and sulfur-containing compounds. Aldehydes are generally formed enzymatically or oxidatively and are seldom considered endogenous in intact fruit. Lipoxygenase catalyzes the formation of aldehydes, such as, hexanal, (E)-2-hexenal, (E,Z)-2,6-nonadienal, and (E)-2-nonenal. These compounds, albeit, not considered endogenous to fruit, are known to be flavor-important in tomato and cucumber. The induction or presence of secondary volatiles in stored processed fruits might affect flavor attributes. The goal, therefore, was to compare endogenous versus secondary aldehyde production in cantaloupe, honeydew, mango, and watermelon by sampling unprocessed tissue and fruit blended under various protocols. A lipoxygenase inhibitor, n-propyl gallate (nPG), and oxygen exclusion were employed. SPME (DVB/Carboxen/PDMS fiber) with GC-MS was used to isolate and identify target compounds. In cantaloupe and honeydew, esters, alcohols, and aldehydes were recovered. Nominal aldehydes were present in cantaloupe, mango, or watermelon tissue cores. Oxygen exclusion and nPG had similar results regarding blocking formation of most aldehydes during cantaloupe sampling. Hexanal, (E,Z)-2,6-nonadienal, and (E)-2-nonenal were reduced 89%, 97% and 94%, respectively, in nPG-blended honeydew. In mango, mostly terpenes were recovered, however, hexanal, and (E,Z)-2,6-nonadienal were also recovered, and completely inhibited by nPG blending. In watermelon, aldehydes, alcohols, and ketones were recovered. Hexanal, (E)-2-hexenal and (E)-2-nonenal were reduced by 90%, 68%, and 95% when blended with nPG. Lipoxygenase generated compounds were present in blended samples and were reduced substantially by inhibitors. These compounds are believed to be important regarding typical flavor/aroma attributes in these fruits. Like tomato and cucumber, our data indicates that some flavor-important secondary compounds are not formed until maceration or tissue disruption. Evaluation of processing aids to inhibit aldehyde production, and analysis of secondary compounds after processing, and during fresh-cut fruit storage, could help the industry deliver products with improved consumer satisfaction.