2019 ASHS Annual Conference

Application of methyl jasmonate enhances the potential health-promoting compound, glucosinolates (GS), especially inducible indole GS-neoglucobrassicin in broccoli by mimicking insect attack. This application also increases the concentration of neoglucobrassicin-derived hydrolysis products, which were shown to be anti-carcinogenic. However, neoglucobrassicin were also associated with the perception of bitter flavor, and the sensorial quality of neoglucobrassicin-derived hydrolysis products are not clear. Because GS and the hydrolysis products may change the sensorial perception of the broccoli, the consumer acceptance of both raw and cooked MeJA-treated broccoli was investigated. The aim of this study was to determine if an untrained consumer panel can detect differences between control and 250 µM MeJA treated broccoli (raw or steamed 4 min) by sensory evaluation (triangle test, attribute test, and preference test) and to determine the key compounds responsible for the potential different overall preference of MeJA-treated and untreated broccoli.

Results of the triangle test showed that panelists were able to correctly identify the odd raw broccoli samples (p<0.05) but not the odd steamed broccoli samples (p>0.05), which is consistent with preference test results. Panelists only showed significant preference (p<0.05) of raw control broccoli, while no preference was found between steamed MeJA-treated and steamed control broccoli. MeJA treatment significantly increased neoglubrassicin by 7.6-fold in raw broccoli. N-methoxyindole-3-carbinol, N-methoxyindole-3-acetonitrile, and N-methoxyindolyl-3-carboxaldehyde (neoglubrassicin-derived hydrolysis products) were significantly increased (p<0.05) in raw MeJA-treated broccoli compared to raw control broccoli. After 4 min steaming, MeJA-treated broccoli still contained 7.8-fold more neoglucobrassicin and 50% more total GS than untreated broccoli. Four-minute steaming process may deactivate endogenous myrosinase and lead to the decrease in hydrolysis products; however, intact GS can be hydrolyzed by human gut microbes. Therefore, the higher concentration of GS in steamed broccoli still contributed higher nutritional quality. We included nine GS, 16 GS hydrolysis products, eight volatile compounds, and 14 primary metabolites for partial least square regression model. The model showed that N-methoxyindole-3-carbinol, N-methoxyindolyl-3-carboxaldehyde, and N-methoxyindole-3-acetonitrile were the most important metabolites in determining the overall liking of broccoli samples. The results suggest that the concentration of neoglucobrassicin-derived hydrolysis products in MeJA-treated broccoli have potential for use as an ingredient to boost the nutrition quality and/or as a value-added ingredient in precooked meals.