Is it okay to drink freshly squeezed vegetable juice often?

　　A food analysis laboratory conducted an experiment to measure the amount of vitamin C lost after juicing fruits and vegetables. Fruits and vegetables selected for the experiment included cucumbers, pears, carrots and watermelons.

　　Experimental results show that vitamin C in fruit and vegetable juices is lost to varying degrees, and in the most serious cases, more than 90% is lost. Such experimental results make people feel a bit incredible. Are the nutrients in fruits subject to such serious losses after juicing?

　　Experts say that the loss of vitamin C in fruits is mainly due to oxidation reactions. The scientific name of vitamin C is ascorbic acid, which has antioxidant effects. When vegetables and fruits are squeezed into juice, the cells in the vegetables are destroyed, and vitamin C is exposed to the air and undergoes oxidation.

　　Different fruits lose different amounts of vitamin C after juicing. The vitamin C content in cucumbers, pears and carrots is less than 1 mg per 100 grams, while the vitamin C content in watermelon juice is only lost less than 20%. This is because watermelon is acidic and is not easily oxidized compared to the first three fruits and vegetables.

　　Experts analyze that there are roughly the following types of juices sold on the market today:

　　1. Refrigerated and fresh-keeping juice: This kind of juice is freshly squeezed and basically does not add sugar or sweeteners. This juice must be stored at low temperature and consumed within a short period of time, generally no more than a week.

　　2. Pure juice: stored at room temperature, the shelf life is more than half a year. Most of this type of juice is made from concentrated juice produced in the fruit production area, added with water to restore the concentration of the original juice, and then subjected to instant high-temperature sterilization.

　　3. Fruit juice drinks: There are many varieties of sparkling juice drinks and non-sparking juice drinks, and the juice content is also different.

　　Experts say that for freshly squeezed juices with high juice concentration, high-temperature heating is often used to kill bacteria and ascorbic acid oxidase in the juice in a short time. This ascorbic acid oxidase is what promotes the oxidation of vitamin C, which homemade juice cannot do.

　　In addition, freshly squeezed juices sold in supermarkets are sealed and kept out of the air. Vitamin C is not easily oxidized in an air-free environment. Therefore, the vitamin C content of processed juice can be guaranteed to a certain extent.

　　There are also many fruit juice drinks on the market. The concentration of juice is generally only 10%, which makes it difficult to ensure the content of vitamin C, so vitamin C is added to this part of the juice. Although the content of vitamin C is guaranteed, there are currently no clear research results on how well the human body absorbs and utilizes artificially added vitamin C. Therefore, it is not certain how much vitamin C can be ultimately consumed by drinking such a fruit juice drink.

　　Whether it is home-squeezed juice or freshly squeezed juice bought from the supermarket, you must pay attention to the storage conditions. Feng Shuangqing said that it is generally not recommended to store juice and should be consumed as soon as possible. For some large-packaged juices, if you can’t finish them all at once, you should store them properly.

　　During storage, the component of juice that loses the fastest is vitamins. Generally speaking, the more acidic the juice, the longer the vitamin C can be stored.

　　Because vitamin C is most stable under acidic conditions, microorganisms are not prone to multiply. Hawthorn juice, citrus juice, Grape After opening, the juice can be stored in the refrigerator for 3 to 5 days, while peach juice, pear juice, etc. with lower acidity are best consumed within 2 days after opening.

　　In addition, many consumers think that sealing the juice and placing it in the refrigerator can solve the storage problem. In fact, the refrigerator can only slow down the rate of nutrient loss. The chemical reaction in the juice continues, and the nutrients continue to be lost.

　　The concept that children should drink more juice seems to be deeply rooted in the hearts of the people, but recently many scholars have questioned this. Alt Einstein Medical Center in the United States has treated more than 100 cases anemia A retrospective survey of children found that more than 80% of them have a hobby of drinking fruit juice.

　　Experts say that fruit juice is rich in fructose, and excessive intake will affect the body's absorption of copper. The trace element copper is a component of many enzymes in the body. It is involved in iron metabolism in the body, so copper deficiency can also cause anemia. However, for Chinese children, the main problem caused by juice is excessive calories.

　　Since the fruit juice drinks that domestic children are currently exposed to generally have high sugar content, they will bring high calories. For some children, insufficient calories can cause a loss of appetite and affect normal eating.

　　If you stay in this situation for a long time, it will inevitably lead to insufficient intake of protein, minerals and other trace elements. For children with a strong appetite, drinking a lot of juice after eating a main meal will eventually lead to an increase in obesity rates.

　　Many elderly people like to squeeze vegetables and fruits into juice because of their bad teeth, thinking that this will help digestion.

　　Experts say that squeezing vegetables and fruits into juice for drinking not only does not help digestion, but also causes constipate . Because fruits lose a lot of dietary fiber necessary for the human body during the process of juicing. The insoluble fiber in it can prevent gastrointestinal system lesions, stimulate intestinal peristalsis and promote defecation.

　　In addition, dietary fiber can also affect blood sugar levels, reduce diabetic patients' dependence on drugs, prevent excess calories, control obesity, prevent gallstones, and lower blood lipids.

　　This situation is most likely to occur in the elderly, especially those with poor teeth. In fact, a large part of the cause of constipation is that the diet is too refined, resulting in insufficient fiber intake. A refined diet is reflected in food on the one hand, and drinks on the other hand. It is especially undesirable to use fruit juices instead of fruits and vegetables.