Hebei reader Ms. Gao asked: recently bought spinach green black, really dare not eat, is not the fertilizer application?
Fan Zhihong, associate professor, School of food science and nutrition engineering, China Agricultural University, a: This is a grievance for spinach. Spinach is a kind of vegetable that can be planted all the year round. It has strong cold resistance, including spring spinach, summer spinach, autumn spinach and winter spinach.
Winter spinach is sown before winter, dormant in winter and harvested in spring. In order to improve its frost resistance, it is necessary to fertilize and nourish spinach before dormancy, but this is the necessary measure to help spinach survive the winter. Its effect is to increase the chlorophyll content, fully hypertrophy the leaves, strengthen photosynthesis, so as to accumulate nutrition for spinach. Plants, like people, are "strong" to resist the cold.
In contrast, the astringency of spinach grown in cold conditions is smaller and tastes more delicious. In summer, the astringency of spinach is heavier and the oxalic acid content is higher. In fact, oxalic acid is not a bad thing in plants, it can play an anti-oxidation, disease and insect resistance effect, indirectly help reduce the amount of pesticides, so we don't have to be disgusted with oxalic acid.
For green leafy vegetables, it is the state of high nutritional value that leaves are green and black. The darker the green leaves are, the more chlorophyll is, the more nutrients are synthesized, and the higher the nutritional value is.
The leaf color of greenhouse vegetables and hydroponic vegetables tends to be lighter. One of the reasons is the lack of light and chlorophyll. In addition, the contents of folate, vitamin K, lutein and magnesium in green leafy vegetables are all in direct proportion to the contents of chlorophyll.
For many people, the nutritional value of spinach seems to be "containing more iron to replenish blood". In fact, spinach is a real health vegetable. The results of nutrition research are enough to make it proud:
It is rich in potassium, which is no less than that of banana and kiwifruit; it is rich in magnesium, which is the highest grade in vegetables, and its calcium content is not low;
Rich in lutein, UK research confirmed that it is the vegetable with the most lutein content in European food supermarkets, lutein and carotene are of great benefit to eye health;
Rich in folic acid and vitamin K, even compared with other green leafy vegetables, light colored vegetables are inferior to it by order of magnitude;
Rich in dietary fiber, good for preventing constipation, rich in a variety of antioxidants, oxygen free radical absorption capacity in vegetables is the highest;
Other nutrients, including vitamin C, carotene and vitamin B2, are higher than the average level of vegetables. It's a pity to miss this delicious and nutritious food because of some misunderstandings. While spinach is on the market, you may as well eat more.
Source: People's Daily - life times
Health care assistant:
1. When do I need to wear a mask?
(1) Go to public places (such as shopping malls, supermarkets, hospitals, pharmacies, gyms, etc.);
(2) Take public transport;
(3) External service positions (such as service hall, front desk and other staff);
(4) Hold collective meetings;
(5) Closed environment such as office with more staff.
2. How to choose a mask?
Option 1: disposable medical mask, continuous wear for 2-4 hours, replace immediately after pollution or humidity;
Option 2: N95 medical protective mask shall be worn continuously for 4 hours and replaced immediately after pollution or humidity.
Generally, disposable medical masks are used. Cotton masks and sponge masks are not recommended.
3. Use mask correctly
(1) Clean hands before wearing masks;
(2) Nose clip side up, dark side out;
(3) The mask is fixed on the face by hand to cover the mouth, nose and mandible;
(4) After the ear belt is pulled to the ear, adjust the tightness of the ear belt. Under the premise of not causing discomfort to the head and face, the strap should be pulled to the tightest position;
(5) Press the fingertips of both hands along the metal plate of the bridge of nose from the center to both sides, and then press them inward slowly until they are close to the bridge of nose;
(6) Adjust the mask properly to make the mask fully fit the face.
4. How do special people wear masks?
(1) When pregnant women wear protective masks, they should pay attention to the combination of their own conditions and choose products with better comfort.
(2) The elderly and chronic patients with cardiopulmonary disease will cause discomfort and even aggravate the original condition after wearing, so they should seek professional guidance from doctors.
(3) Children are in the stage of growth and development, their face shape is small, so children's protective masks are selected.