[Creative Cultivation Program] Does purple sweet potato still contain anthocyanins after being cooked? Two cooking methods recommended

Author: Xue Qingxin

Review: Song Shuang

Purple sweet potato is a common food on the table, and it can be used to make a lot of delicious and beautiful food. For example, purple sweet potato fairy bean cake, purple sweet potato rice paste, purple sweet potato steamed buns, purple sweet potato porridge, etc. The color alone is pleasing to the eye, full of anthocyanins!

Many people say that they eat purple sweet potatoes just for the anthocyanins. However, some people are still wondering: Will the anthocyanins in purple sweet potatoes be lost due to heat during the cooking process? Are the anthocyanins in the purple sweet potatoes still there when we eat them?

In this article, let’s talk about anthocyanins in purple sweet potatoes and how to cook them to maximize their retention.

1 Is purple sweet potato genetically modified?

Because of the bright color of purple sweet potatoes, many people think that purple sweet potatoes are genetically modified. This is really a misunderstanding of purple sweet potatoes. Purple sweet potatoes are actually a kind of sweet potato, which can be understood as purple sweet potatoes, and are not genetically modified.

Compared with the red sweet potato we often eat, the biggest advantage of purple sweet potato is that it is rich in anthocyanins; and the biggest advantage of red sweet potato is that it is rich in β-carotene.

2 What are the health benefits of anthocyanins?

Purple sweet potatoes give people a "very healthy" feeling from their appearance. The purple color of purple sweet potatoes comes from the rich anthocyanins. The anthocyanin content of different varieties of purple sweet potatoes also varies to a certain extent. An experiment compared the anthocyanin content of different varieties of purple sweet potatoes. Among them, the Shandong cotton purple sweet potato has the highest content, up to about 80mg/100g[1], which is the most recommended.

▲Picture: From the literature

Anthocyanins are flavonoid compounds that have antioxidant and free radical scavenging properties. Studies have shown that anthocyanins are more capable of scavenging free radicals than vitamin C and vitamin E, which is helpful in preventing cancer and cardiovascular disease. [2]

In addition, studies have shown that anthocyanins in purple sweet potatoes can repair liver damage and help the body downregulate the expression of inflammatory factors, which has anti-inflammatory effects. Several studies have confirmed that anthocyanins in purple sweet potatoes can inhibit the proliferation of cervical cancer cells and liver cancer cells. [2]

Especially for office workers who use their eyes a lot every day, eating foods rich in anthocyanins can help protect their eyesight. Not only can they help their eyesight adapt to dark environments as quickly as possible, but they can also improve myopia and relieve blurred vision caused by visual fatigue. [2]

3 Does steamed purple sweet potato still contain anthocyanins?

There are still some!

Many people worry that anthocyanins in purple sweet potatoes will be lost due to heat after being cooked. In fact, anthocyanins are very stable and relatively heat-resistant.

Some people have conducted experiments to study the effect of temperature on purple sweet potatoes. The results showed that after heating at 60°C for 30 minutes, the anthocyanin content in purple sweet potatoes only slightly decreased; however, when the temperature was raised to 80°C and 100°C and heated for 5 hours, the anthocyanin preservation rate could still reach more than 80%. [3]

Another study found that the retention rates of anthocyanins in purple sweet potatoes after steaming, boiling, baking, and microwave were 90.11%, 63.54%, 76.95%, and 88.10%, respectively. [4] The loss of anthocyanins in purple sweet potatoes is the greatest when boiled, probably because anthocyanins are water-soluble pigments, and some of them will be lost in the boiling process. In particular, when purple sweet potatoes are boiled in alkaline water (hard water), not only will the stability of anthocyanins deteriorate, but the boiled water will also appear blue-green (if there are children at home, you can add some white vinegar to the water with your children and observe the color change). [3]

Therefore, if you want to consume more anthocyanins through purple sweet potatoes, steaming and microwaving are recommended cooking methods.

4 How to store purple sweet potatoes?

If you want to eat more anthocyanins, you really need to pay attention to the storage method of the purple sweet potatoes you buy. Direct sunlight will cause anthocyanins to degrade, and the longer they are placed in sunlight, the lower the retention rate of anthocyanins will be.

Data show that after being placed in sunlight for 7 days, the retention rate of anthocyanins in purple sweet potatoes is only about 50%, but if stored away from light, the retention rate can still reach about 100%. [3]

Therefore, the purple sweet potatoes you buy must be stored in a cool, dry place away from light!

Summarize:

Purple sweet potatoes are rich in anthocyanins, and eating them regularly is good for your health. According to the "Dietary Guidelines for Chinese Residents", it is recommended to eat 50 to 100 grams of potatoes every day, which is about the amount of a woman's fist. To consume more anthocyanins, steaming or microwave cooking is recommended.

In addition, remember to store the purple sweet potatoes you bought away from light!

References:

[1] Zhang Yi, Niu Fuxiang, Sun Jian, et al. Comparison of anthocyanin content and in vitro antioxidant activity of purple sweet potatoes from different regions[J]. Jiangsu Agricultural Science, 2017, 45(21): 205-207. DOI: 10.15889/j.issn.1002-1302.2017.21.058.

[2] Zhong Lanlan, Tu Di, Yang Ya, et al. Research progress on the physiological functions of anthocyanins and their application prospects[J]. Progress in Biotechnology, 2013, (5): 346-352. DOI: 10.3969/j.issn.2095-2341.2013.05.07.

[3] Xie Chengcheng, Wang Yong, Gong Lijing. Study on the stability of natural food pigment purple sweet potato anthocyanin[J]. Food Industry, 2012, v.33; No.189(06):99-102.

[4] Kong Shuangshuang. Effects of different ripening methods on the quality of purple sweet potato[J]. Food Research and Development, 2016, (6): 34-38.

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