What makes some cucumbers taste bitter? ASK THE HORT AGENT
Question What makes some cucumbers taste bitter?
Answer Cucumbers, as well as squash, cantaloupe, watermelon, pumpkin and zucchini, are in the Cucurbitaceae family. These plants have the ability to produce chemicals called cucurbitacins. Some wild plants are so bitter they are inedible. Some can even kill small animals. Cucurbitacins are toxic at high levels, but they are so bitter it is difficult to eat enough to get sick. The worst that usually happens is an upset stomach for a few hours. Plants we grow in the garden have been selected for low levels of these bitter compounds (a notable exception is bitter melon used in Asian cuisine where the bitterness is a prized part of the flavor).
Bitter cucurbitacin is found mainly in the vegetative parts of the plant like leaves, stems and roots. On occasion and to a lesser degree, it spreads to the fruiting structure. It doesn't accumulate evenly within each cucumber and can vary in concentration from one fruit to another.
When preparing your slicing cucumbers, keep in mind that the bitter compound is likely to be more concentrated in the stem end than in the blossom end of the cucumber. It is also more prevalent in the peel and in the light green area just beneath the peel. It is less likely to be found in the deeper interior of the fruit.
Cucumbers growing under some type of stress, such as lack of water, extreme heat or really cool periods, are often somewhat bitter. Misshapen fruits are more likely to be bitter than well-shaped fruits. Some scientists even think that varying levels of fertilizers, plant spacing and irrigation frequency may affect cucurbitacin levels. Bitterness seems to vary with the type of cucumber grown. But you can expect some degree of bitterness from time to time in most any variety of cucumber.
According to research, some people are more genetically programmed to detect bitter compounds in foods. People who prefer sugar in their coffee are said to have the “bitter taste gene.” Their tongue is more sensitive to bitter compounds. This is supposed to be an evolved trait that protects people from eating bitter plants. In nature, bitter usually equals toxic.
Scientists also believe this partially explains why many children don’t want to “eat their vegetables.” A child’s taste buds are more sensitive than adults’, especially if they have the bitter taste gene. (http://www.ivanhoe.com/science/story/2005/05/08a.html)
Ironically, many bitter compounds like cucurbitacin are now being identified as beneficial in small quantities. For example, cucurbitacin is being investigated as a cancer-fighting agent. The bitter gene may have helped us humans reduce our losses when we were figuring out what to eat. It may now be increasing our disease risk through lowered intake of beneficial compounds.
For more info about bitter tasting cucumbers, check out http://cuke.hort.ncsu.edu/cucurbit/cuke/cukehndbk/cukebitterness.html If you do not have internet access, then call me at 910-893-7533 or email me at gpierce@harnett.org
Most Southerners must have the bitter taste gene because we like sweet tea, sweet pickles, sweet potatoes and sweet muscadine wine. According to research at Duke, you might even say we’re more evolved. (http://www.dukemednews.org/news/article.php?id=9145)
Gary L. Pierce
Horticulture Extension Agent
Harnett County | 
