As the Qingming Festival approaches, the toon tree sprouts tender buds, emitting a delicate fragrance. Toon not only has a unique flavor but is also highly nutritious, rich in potassium, calcium, magnesium, and vitamin B, ranking among the top vegetables. Furthermore, toon is beneficial for preventing chronic diseases. It contains components that inhibit various pathogenic bacteria, anti-tumor, blood lipid-lowering, and blood sugar-lowering ingredients, as well as a considerable amount of polyphenolic antioxidants.
Toon with Tofu
However, toon contains high levels of nitrates and nitrites, and its protein content is higher than that of ordinary vegetables, posing a risk of forming the carcinogen nitrosamine. Therefore, improper consumption may harm our health. So, how should we eat toon?
First, choose the tenderest toon buds
Research has found that the nitrate and nitrite content in toon varies by region, variety, and growth stage. Most importantly, the nitrate content is lower in the initial stage of sprouting. As the toon buds continue to grow, their nitrate content also rises. After mid-April, the nitrate content in toon buds in most areas exceeds the standards set by the World Health Organization and the Food and Agriculture Organization of the United Nations. This means that the younger the toon bud, the less nitrate it contains, and consequently, the less nitrite will be produced during storage.
Second, choose the freshest toon buds
After mid-April, although the nitrate content in toon buds increases, the nitrite content remains low. Therefore, eating fresh toon buds is unlikely to cause nitrite poisoning. However, after harvesting, a large amount of nitrate converts into nitrite during storage at room temperature, creating a safety hazard. The reason why toon buds are said to have high nitrite content is precisely this.
In other words, toon buds freshly picked from the tree and eaten immediately are safe. Toon buds bought from the market, having already undergone transportation, will have a significantly increased nitrite content. If the leaves fall off at the slightest touch, a large amount of nitrite must have been produced.
Third, blanch to remove nitrates and nitrites
If the toon buds are not fresh enough but still fragrant, and it's a pity to throw them away, you can blanch them. Blanching in boiling water for about 1 minute can remove more than two-thirds of the nitrites and nitrates, while also better preserving the green color of the toon. Whether for cold salads, stir-fries, or deep-fried toon fish, it's advisable to blanch them first, which can greatly improve the safety of eating toon. Since the aromatic components of toon mainly come from essential oils, which are water-insoluble, blanching will not significantly affect the flavor of the dish.
Fourth, blanch before quick-freezing
Toon is a seasonal vegetable, and many people like to freeze it for consumption throughout the year. However, toon should also be blanched before quick-freezing. Research data shows that blanching for 50 seconds before freezing not only greatly improves safety but also better preserves vitamin C. After 2 months of frozen storage, the vitamin C content in blanched toon is equivalent to 71% of that in fresh toon, compared to only 35% in unblanched toon. At the same time, both the color and flavor are superior for toon that is blanched before freezing. After blanching, pack the toon in sealed plastic bags and place it in the freezer compartment of the refrigerator. It can be stored for more than a month, maintaining its tender green color and fragrant characteristics.
Fifth, pickle the toon buds for a longer time
Many people like to salt-pickle toon for two or three days before eating, which is a very unsafe habit. Because after pickling, the nitrite content in toon rises sharply, peaking in three to four days (when the salt added is 10%-20%), far exceeding the permitted standards. Blanching before pickling can greatly reduce the nitrate content, thereby lowering the risk of eating pickled toon. However, the safest practice is to pickle the blanched toon for 2 weeks, until the nitrite content has decreased, before eating. Adding ingredients like vitamin C, tea, ginger, and garlic can reduce the nitrite content during pickling.
Finally, eat toon with foods rich in vitamin C.
Toon itself has a higher vitamin C content than ordinary vegetables and fruits. If you can eat fresh toon, vitamin C can help block the formation of the carcinogen nitrosamine. If the toon is not fresh enough, you can eat it with other fresh vegetables and fruits to avoid the potential hazards of nitrites as much as possible. Research has shown that when the molar ratio of vitamin C to nitrite is 2:1, the synthesis of nitrosamine carcinogens can be effectively blocked.
The fragrance tofu