2018 ASHS Annual Conference

Application of methyl jasmonate (MeJA) has been reported to enhance the potential health-promoting compound, glucosinolates (GS), especially inducible indole GS-neoglucobrassicin by mimicking insect damage. When plant cells are raptured, myrosinase hydrolyzes GS into its hydrolysis product that may impact consumer acceptance of brassica crops even though myrosinase is usually inactivated during cooking. To our knowledge, there is no report on the consumer acceptance and sensory evaluation on MeJA-treated broccoli (insect-damaged produces). 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) using sensory evaluation (triangle test, attribute test, and preference test). To further associate the phytochemical profiles with the sensory evaluation, we measured the change in GS, GS hydrolysis profiles, and primary metabolites from broccoli tissue. 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 cooked broccoli samples (p>0.05), which is consistent with attribute and preference test results. While there was no significant difference in appearance, the raw control broccoli was rated more favorably in taste, texture and overall liking (p<0.05). On the other hand, panelists showed no preference between steamed MeJA-treated and steamed control broccoli in any of the attributes tested (p<0.05). MeJA treatment significantly induced neoglubrassicin compared to the control broccoli (7.6-fold) and this increment was observed after steaming as well (7.8-fold). MeJA treatment also significantly decreased total aliphatic GS concentration by 25%. N-methoxyindole-3-carbinol and N-methoxyindolyl-3-carboxaldehyde, neoglubrassicin-derived hydrolysis products were significantly increased 7.6-fold and 2.4-fold in raw MeJA-treated compared to raw control broccoli. There was significantly less serine in raw MeJA-treated compared to raw control broccoli; however, after steaming the level of galactose, citric acid, and serine was not statistically different between control and MeJA-treated broccoli. Steaming significantly reduced total neoglubrassicin in control (22.3%) and MeJA-treated broccoli (20.5%) compared to raw broccoli. N-methoxy indole-3-carbinol was decreased by 89.8% (control) and 96.2% (MeJA treatment). Notably, N-methoxy indole-3-acetonitrile was under detection limit in both samples. The decrement of hydrolysis products may result from deactivation of endogenous myrosinase during steaming; therefore, the hydrolysis process was interrupted. This study showed that consumer attribute testing was less favorable toward MeJA-treated raw broccoli; however, cooking the broccoli negated this effect. Partial least square regression model indicates that N-methoxyindole-3-carbinol, N-methoxyindolyl-3-carboxaldehyde, and N-methoxyindole-3-acetonitrile are the most important on sensory quality.