WHY DO VEGETABLES SUCH AS CUCUMBER, SNAKE GOURD AND BOTTLE GOURD SOMETIMES TASTE BITTER?

Bitterness in cucumber and other cucurbitaceae vegetables is due to the presence of compounds called cucurbitacins. Chemically these are tetracyclic triterpenes having high oxidative levels. They occur in nature as free glucosidesor as complicated mixtures, at high concentrations, in fruits and roots, for example in a wild variety of cucumber called cucumis hardwikii. High temperature above 92 degrees has been implicated in the increase of bitterness in fruits, although there is no evidence to support this. Conversely more bitter cucumbers are seen growing during the cooler growing season.