Nutritious food additives (12 points)
①Pears, apples, bananas, potatoes, and other fruit and vegetable juices easily change color. After discoloration, it is not only ugly, but the taste is also affected. How to do? Add lemon juice.
②Various polyphenol compounds are contained in fruits and vegetables. After peeling, these compounds are exposed to the air and oxidized to form kūn compounds. This quinone compound easily connects to each other and becomes "brown pigment", which makes these foods discolored. And lemon juice contains a large amount of "ascorbic acid", which can reduce the quinone to the original polyphenol state; it can also be directly oxidized, thereby consuming the oxygen around the polyphenol, thereby protecting the polyphenol from oxygen attack. In this way, ascorbic acid sacrifices self, protects the vulnerable polyphenols, and maintains the "fresh" color of fruits and vegetables.
③ In the food industry, people can directly add ascorbic acid according to the action mechanism of lemon juice. In fruit and vegetable juices sold in supermarkets, ascorbic acid is added to many wines to maintain their appearance and flavor.
④Ascorbic acid does not stop there. Nitrite is often added to cooked meat products. Nitrite has two functions: one is to react with myoglobin to make it appear attractive red; the other is to inhibit bacterial growth and achieve antiseptic function. Adding ascorbic acid can accelerate the previous reaction, thereby speeding up the "color development" process. Many people consider nitrite to be a "carcinogen." In fact, it is not carcinogenic in itself. Only when it reacts with amino acids in the meat, the nitrosamine produced is a carcinogen. If ascorbic acid is added to the meat, it will inhibit this transformation and reduce the "likely" carcinogenic risk of nitrite. Ascorbic acid is sometimes added to meat products that do not require nitrite. Because the oxidation of fat in meat will release a bad taste, which is commonly known as "Hala flavor". If ascorbic acid is added, it will preemptively consume the surrounding oxygen, thereby protecting the oil from oxidation and helping to maintain the "freshness" of the meat.
⑤Ascorbic acid itself is easily oxidized to produce deoxyascorbic acid. These deoxyascorbic acid are not willing to "loser," they will take other people's hydrogen atoms to rebuild their homes. People take advantage of this feature. In pasta processing, ascorbic acid is often added to improve dough properties and increase dough texture. Flour contains gluten, which has many sulfonyl groups-that is, sulfur atoms with a hydrogen atom, and deoxyascorbic acid will plunder its hydrogen atoms. When we knead the dough, the hydrogen atoms in the thiol group will be taken away by deoxyascorbic acid, and the remaining sulfur atoms will be connected one by one to form a so-called disulfide bond. When a large number of disulfide bonds are formed, gluten in the dough forms a huge network, which strengthens its muscles.
⑥ In most cases, food additives are used to improve flavor, mouthfeel, and increase food stability. They are not of nutritional significance. But ascorbic acid does not belong to this "most". When used as a food additive, it is often called "ascorbic acid". And it itself is the nutrient required by the human body-vitamin C. Vitamin C is unstable. Air, light, heat, and contact with metal containers can make it inactive or decompose. However, it is this instability that gives it good "oxidation resistance". In the body, it protects cells from oxidative damage. When added to food, it oxidizes itself to protect other ingredients in the food.