Eggplant is a vegetable that many people love to eat. But some people have heard that eggplants contain toxins. What's going on with that?
It turns out that plants in the nightshade family often contain certain types of alkaloid secondary metabolites, the most common of which is solanine, the same glycoalkaloid found in sprouting potatoes. Most alkaloids can be used as medicine, and solanine is no exception. It has functions such as strengthening the heart, lowering blood pressure, inhibiting cancer cells, and suppressing microorganisms, and it is one of the sources of eggplant's health benefits. However, excessive intake by humans can lead to poisoning. Its toxic mechanism involves changing the membrane potential and ion flow of mitochondria, thereby inducing mitochondrial apoptosis. Plants produce these alkaloids to enhance their resistance to microorganisms and reduce animals' desire to eat them. Solanine is produced in the stems and leaves and then transported to the fruit to protect their offspring.
Chinese scholars have studied the distribution of solanine in eggplants and have discovered some interesting patterns. The solanine in eggplants is mainly found in the flesh, not in the skin. However, the color of the eggplant skin is closely related to the solanine content in the flesh. Purple eggplants have a higher content, while green eggplants have a lower one. In other words, the darker the color, the higher the content, which is basically consistent with the general pattern of health-promoting component content in vegetables. The study also found that in unripe eggplants, the solanine content is higher than in fully ripe ones. This is understandable, as both plants and animals would naturally strive to strengthen the protection of their immature offspring. During the peak harvest season, solanine content in eggplants is high, but towards the end of the growing season, it is low. It's obvious that the latter has entered a period of decline and has little ability left to protect its offspring.
The solanine content in eggplants is relatively low, with even the highest varieties not exceeding 0.8 milligrams per gram of dry weight. Eggplants have a moisture content of about 93%. Converting this to fresh eggplant, you would need to eat about 450 grams of these high-solanine eggplants to potentially reach an intake of 25 milligrams, which might cause discomfort such as nausea and vomiting. It would take an intake of 400 milligrams of solanine to be potentially fatal to an adult. Therefore, under normal circumstances, eating half a jin (about 250 grams) of eggplant in a meal will not cause any trouble.