CORVALLIS, Ore. – Why are some cucumbers bitter, while others are not?

A natural organic compound called cucurbitacin is the culprit, according to Oregon State University vegetable breeder Jim Myers.

"Wild cucumbers contain relatively large concentrations of cucurbitacin and are highly bitter," he said, "while their domestic cousins we grow in the garden and buy in the store, tend to have less but varying amounts of the bitter compound."

Cucurbitacin is found mainly in the vegetative parts of the plant such as leaves, stems and roots. On occasion and to a lesser degree, it spreads to the fruit. It doesn’t accumulate evenly within each cuke, however, and can vary in concentration from one fruit to another.

When harvesting slicing cucumbers, take note: 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 – and less likely to be found in the deeper interior of the fruit.

Vegetable scientists have several explanations about why some cucumbers become more bitter than others. Cucumbers picked from vines growing under some type of stress, such as lack of water, are often somewhat bitter. Misshapen fruits are more likely to be bitter than are the well-shaped fruits. More complaints come about bitter cucumbers grown during cool periods than during warm times. Fertilizers, plant spacing and irrigation frequency may also affect bitterness.

James M. Stephens, vegetable crops professor at the University of Florida Institute of Food and Agricultural Sciences, came up with a method of peeling a cucumber to avoid serving bitter-tasting cukes.

Start peeling at the blossom end of the fruit. Slice away one strip of the green peel toward the stem end and stop about one inch from the stem. Then wash off the knife blade and repeat peeling from blossom to stem end until the fruit is peeled. Rinse the knife again and cut up the cucumber as needed.

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 commonly grown, Myers said.

Was this page helpful?

Related Content from OSU Extension

Have a question? Ask Extension!

Ask Extension is a way for you to get answers from the Oregon State University Extension Service. We have experts in family and health, community development, food and agriculture, coastal issues, forestry, programs for young people, and gardening.