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Research Project: Improved Vegetable Processing Methods to Reduce Environmental Impact, Enhance Product Quality and Reduce Food Waste

Location: Food Science and Market Quality and Handling Research Unit

Title: Quantification of cucurbitacin C in bitter cucumber and its reduction by fermentation and acidification

item FAN, XINYUE - North Carolina State University
item Johanningsmeier, Suzanne
item SCHULTHEIS, JONATHAN - North Carolina State University
item STARKE, KEITH - North Carolina State University
item OSBORNE, JASON - North Carolina State University
item COLLINS, MAXTON - North Carolina State University

Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2024
Publication Date: 2/8/2024
Citation: Fan, X., Johanningsmeier, S.D., Schultheis, J., Starke, K., Osborne, J., Collins, M. 2024. Quantification of cucurbitacin C in bitter cucumber and its reduction by fermentation and acidification. Journal of Food Composition and Analysis. 129:106065.

Interpretive Summary: Although bitterness is rare in pickling cucumber, there are sporadic cases of extreme bitterness that make the finished pickles unpalatable. Scientists at the USDA Agricultural Research Service and North Carolina State University used advanced mass spectrometry to detect and quantify bitter components in pickling cucumber. The bitter components were more abundant in larger size fruits and most concentrated in the seed cavity. Fermentation decreased the main bitter component 10-fold, while pickling by direct addition of acid only reduced it 3-fold. This study showed that fermentation has potential as a de-bittering method for pickling cucumber.

Technical Abstract: Cucurbitacins are seldom found in pickling cucumber, but when present, make finished products unpalatable. Liquid chromatography-time-of-flight mass spectrometry was employed to determine cucurbitacins in ‘Hanzil’ (bitter) and ‘Vlaspik’ (non-bitter) pickling cucumbers subjected to acidification or fermentation. Cucurbitacins C (CuC) and C-glycoside were putatively identified in ‘Hanzil’ cucumber fruits while undetectable in ‘Vlaspik’. The major cucurbitacin in ‘Hanzil’, CuC, increased in concentration with cucumber size, ranging from 28 ppm in size 2A to >74 ppm in size 4+ fruits. Endocarp had the highest CuC concentration (88.7 ± 44.3 ppm) followed by mesocarp (30.6 ± 15.1 ppm) and exocarp (2.58 ± 1.75 ppm). CuC was 3-fold lower in acidified cucumber (15.7 ± 10.3 ppm) and 10-fold less in fermented cucumber (4.90 ± 3.94 ppm) than when fresh (47.9 ± 22.8 ppm). Fermentation has potential for de-bittering of cucurbits, and oversized bitter cucumbers could serve as a source of CuC for exploration of bioactivities.