The other similar looking calabash tree is of the Crescentia alata species, the difference can be seen in their respective fruits, the Crescentia alata are more rounded, while that of the Crescentia cujete fruits is egg shaped. The fruit takes up to several months to ripen by turning brown and dropping off the tree.
In their native countries, it has been documented that its fruit’s woody shell with its pulpy inside removed when dried are hollowed out to make receptacles, cups and bowls.
Locally in Malaysia, it is planted generally as an ornamental tree or as a shade tree. Other uses of the plant include boiling the flesh of the fruit pulp in water and drinking its content to treat high cholesterol and cancer (be warned that this practice is not substantiated with any documented medical studies for its efficacy). In Suriname's traditional medicine, the fruit pulp is used to treat respiratory problems. There are also conflicting reports on the Calabash tree fruit, one that stands out is from the Forest Service (U.S.A) which states that the fruit is poisonous but there is plenty of conflicting research on this subject.
There is a published study performed on the nutritive and anti-nutritive compositions of Calabash Fruit Pulp by Mare Nwosu Ogbuaga, Department of Chemistry, Micheal Okpara University of Agriculture, Nigeria with the following conclusions:
“The values of the ash, crude protein, fiber and carbohydrate in the dry pulp as well as the ether and thiamin values in the wet pulp are very reasonable. The values of the mineral elements are also high. These are indications that the pulp, in addition to its useful contributions to human health, as a result of the presence of phytochemicals, can also make useful contributions to human nutrition”.
From the conclusion of this study, it appears that there is no harm from consuming the pulp of the Calabash tree fruit and some good might actually come out of it. But I can imagine it would be far from tasting like milkshake, fruit juice or beer