The crunchy, water-laden cucumbers are hot favourites to beat the heat during summer. But it is a pity that at times our taste buds are disgusted with the bitterness in some of them that we do not hesitate to spit them out immediately. The miscreant behind the bitterness is a compound called cucurbitacin. This compound is found mainly in the leaves, stems and roots of the plant. It spreads to the fruits occasionally and to a lesser degree. It does not accumulate evenly within each cucumber and can vary in concentration from one fruit to another. It is prevalent to a greater extent in the stem end rather than the blossom end of the fruit and also in the green peel.
Wild cucumbers contain relatively large concentrations of this compound and are unfit for consumption whereas commercially cultivated varieties contain such low concentrations that it does not affect the taste.
Studies have shown that cucumber leaves with a high total Nitrogen as well as amino acid content promote Nitrogen metabolism which in turn favours enzymatic synthesis of curcurbitacin, thus inducing bitterness into the leaves and fruits.
It is also interesting to know that stress triggers a higher concentration of cucurbitacin in cucumbers and turns them bitter. High temperatures, wide temperature swings, too little water, uneven watering practices (too wet followed by too dry), low soil fertility and low soil pH are possible stress factors. Over mature or improperly stored cucumbers may also develop a mild bitterness.
Cutting the ends of the cucumber and peeling the skin may help in reducing the bitterness. Salting the cucumber slices and draining off the juice that is exuded also helps in removing the bitterness. This works on the principle of osmosis. But some fruits may remain bitter all the way through, no matter what you do and they should be discarded. It all depends on the extent of stress to which they have been exposed.
To save yourself from the embarrassment of serving a bitter coleslaw or salad, always taste a little portion of the peeled cuke, ensure it is devoid of bitterness and then incorporate it into your preparation :-).