Picking Edible and Medicinal Plants: Exotic “Apples” and “Pears”

Introduction

Today many exotic fresh fruits and vegetables are imported into the United States from temperate and tropical countries worldwide. Ethnic restaurants, particularly Indian and Southeast Asian restaurants, will often import specific fruits and vegetables or purchase them from local specialty growers or ethnic groceries to serve native dishes to their patrons. Many of these imported species have now been introduced into the temperate and tropical Americas, including the United States.

Momordica Species: Balsam Apples and Pears

Momordica species plants bear both edible and inedible fruits with medicinal properties. Momordica balsamina (Figure 1), the balsam apple, and Momordica charantia (Figure 2), the balsam pear, are closely related members of the cucumber or Cucurbitaceae family, and, like cucumbers, they are tropical vines with trailing tendrils that produce yellow tubular flowers and large, elongated fleshy fruits.

Figure 1

The balsam apple, Momordica balsamina, produces bright reddish-orange fruits, or “apples,” that burst open when ripe, revealing inner pulp and red aril–covered seeds.

Figure 2

The balsam pear or bitter melon, Momordica charantia, produces an edible fruit, or “pear,” which is typically harvested for cooking while still green and unripe, rather than when yellow, ripe, and bursting to reveal its inner pulp and red aril–covered seeds.

The vines are native to Africa, India, and Southeast Asia, and were introduced into Europe in the 16th century and to the Americas and Caribbean in the 17th century. The vines may establish themselves as invaders or as intentionally planted ornamentals on fences or trellises or in greenhouses. Later, the vines can only be differentiated by their colorful fruits and seeds, which contain a wide variety of flavonoids, glycosides, saponins, and terpenes, collectively known as “momordin.” ¹

Momordica Balsamina: The Balsam Apple

Momordica balsamina, the balsam apple, produces bright reddish-orange fruits, or “apples,” that burst open when ripe, revealing inner pink pulp and colorful, red aril or exterior-covered seeds (Figure 1). Although the red seed covering or aril is reputed to be edible, the fruit or apple and its peeled seeds are poisonous. If ingested raw or cooked, they can produce a delayed muscarinic toxidrome characterized by nausea, salivation, emesis, diarrhea, and, less commonly, hypoglycemia. Although momordin extracted from M balsamina is a toxalbumin, stereochemically similar to ricin, gastrointestinal toxicity after balsam apple ingestions is short-lived and inconsequential. The management of ingestions is supportive with rehydration with oral or intravenous fluids. There are no known antidotes for M balsamina poisoning.

Medicinal Properties of the Balsam Apple

In the Creole culture of south Louisiana, the balsam apple or “giddy-giddy” is revered for its topical antipruritic and antimicrobial activities. Extracts of boiled leaves and fruit can be mixed with isopropyl alcohol or witch hazel and applied as highly effective topical antiseptics and antipruritics on insect bites, blisters, and sores in the field. Similar preparations have also been used as effective topical antivirals applied to virally induced fever blisters (caused by herpes simplex viruses) and warts (caused by human papilloma viruses).

Although untested in randomized, placebo-controlled trials, the antiviral properties of balsam apple extracts have been confirmed by molecular-level experiments in vitro. Momordin obtained from M balsamina has been demonstrated to exhibit ribosomal-inhibiting properties, like ricin. ² In addition, a component of momordin from M balsamina, known as balsamin, has been demonstrated to inhibit HIV-1 replication in experimentally infected CD4⁺ T cells without cytotoxic effects. ²

Momordica Charantia: The Balsam Pear

Momordica charantia, the balsam pear or bitter melon, produces an edible fruit, or “pear.” The balsam pear fruit is elongated and oblong in shape with a warty exterior, resembling a cucumber. When fully ripe, the fruit turns yellow in color and bursts open to reveal its yellowish pulp and inner, red-exterior or aril-covered seeds (Figure 2). The fruit is edible, but should be selected for cooking while still green and unripe. In China and India, green and unripe balsam pear fruits are known regionally as “bitter cucumbers.” Green balsam pear fruit will provide a less bitter taste and a better, less watery texture then overripe yellow fruit when cooked (Figure 3).

Figure 3

Unripened and green balsam pears hanging on the vine and ready to be picked for preparation typically as stuffed vegetables or stir-fries.

The fruits are cooked and prepared in revered, traditional side dishes and served as either stuffed vegetables or as stir-fried (tempura) vegetables. When they are properly prepared, balsam pears have a taste and texture similar to cucumber, green bell pepper, or chayote (“prickly pear” or “mirliton”). Balsam pear dishes are very popular in many cultures, especially in Indian, Vietnamese, Taiwanese, and Okinawan cuisines. Asian restaurant patrons may find balsam pears on menus under their native names or may select balsam pears in ethnic groceries or exotic gardens for home preparation.

Medicinal Properties of the Balsam Pear

Momordica charantia–containing beverages have been used as traditional folk remedies for gastrointestinal disturbances and diabetes throughout Africa, China, and India for centuries. Extracts of balsam pear fruits have structural similarities to animal insulins, and can lower blood glucose levels in patients with diabetes. ³ Although the mechanisms of the hypoglycemic effects of momordin extracted from M charantia remain unknown, clinical trials of M charantia extracts have confirmed moderate hypoglycemic effects in man that may augment and potentiate insulin and oral hypoglycemic agents. ³ Well-designed randomized, controlled clinical trials will be required to further evaluate the efficacy of balsam pear as an antidiabetic and its impact on fasting blood glucose levels and hemoglobin A1c as biomarkers of effective blood glucose control. Reported overingestions of balsam pear have been associated with hypoglycemia, which can be reversed with glucose infusions. ³

Conclusions

Although extracts of balsam apples do make effective topical antimicrobials, the balsam apple is inedible and significant ingestions of any of its parts may cause adverse gastrointestinal effects and hypoglycemia (Figure 1). People should avoid eating balsam apples, which may be found hanging from vines growing on fences, trees, or trellises throughout the temperate United States. In addition, green and unripe balsam apples may resemble desirable and edible green and unripe balsam pears in color and appearance; but balsam apples have globular shapes and spiny, not warty, exteriors. Edible balsam pears do resemble familiar cucumbers in their green stages (Figure 3). Foragers mistaking green balsam pears for cucumbers will be surprised, but not harmed, by their very bitter, watery taste if consumed raw.

Recommendations

Even the most experienced wilderness foragers may mistake inedible plants for edible plants during different growing seasons regionally and, especially, at different altitudes. Recent immigrants may also mistakenly identify inedible plants in their newly adopted home countries as edible plants in their native countries. Exotic fruits and vegetables should be purchased for consumption at groceries and at farmers’ markets and not picked in the field, especially by untrained and inexperienced plant-food foragers. Nevertheless, plants should never be discounted as sources of highly effective pharmaceuticals. “Even at the dawn of [the] 21st century, 11% of the 252 drugs considered as basic and essential by the WHO [World Health Organization] were exclusively of flowering plant origin.” ⁴