1, the taste of spoiled food
1. Haraway
Foods containing more grease for a long time, such as oils, cakes, dried salted fish, walnuts, peanuts, melon seeds, etc. It will produce a bitter, hemp, spicy and unpleasant taste, which is commonly known as "spicy" by ordinary people. This is because oil is prone to oxidation and rancidity, which leads to spicy taste.
2. A rancid smell
Fish, pork, eggs, tofu, dried tofu and other foods rich in protein go bad, which will produce rancid smell. Under the action of microorganisms and enzymes, protein will be decomposed into organic amines, sulfides, fecal odor, aldehydes and other substances, which have a foul smell.
3. Sour taste
Foods rich in carbohydrates, such as grains, sugar and their products, will have their own sour or rancid characteristics when they go bad. Carbohydrate will decompose to produce monosaccharide, disaccharide, organic acid, alcohol and aldehyde, so it will produce sour taste or wine taste. Rice turns sour, cakes turn sour and fruits rot.
4. musty smell
Food contaminated by mold, such as grains, peanuts, bread, cakes, rice, steamed bread, etc. In a warm and humid environment, it is often moldy and deteriorated. Mold may produce toxins, such as aflatoxin, which we are familiar with.
5. Ammonia smell
Salted fish, dried shrimps, dried shrimps, shredded squid, scallops, dried fish and other aquatic products. If dried aquatic products such as dried shrimps are stored for too long, they will have obvious ammonia smell and turn pink in color. This is mainly because the protein contained in them is decomposed into peptides and amino acids by microorganisms, and then further decomposed into lower amines and ammonia. Lower amines are not only toxic, but also easily combine with nitrite in aquatic products to form a strong carcinogen-nitrosamines. If the above food is found to have ammonia smell or other peculiar smell, it should be resolutely thrown away, because even after washing with water, it is not safe to eat.
2. The harm of eating spoiled food
1. Moldy peanuts, corn, rice and their products: contain a lot of aflatoxin, which can cause fever, vomiting, jaundice, coma, spasm and even acute poisoning death. Yellow koji toxin has high temperature resistance, strong carcinogenicity and strong destructive power to liver. Therefore, it is best to store the purchased grain in a ventilated, dry, low-temperature and oxygen-deficient place, so don't eat it if it is moldy.
2. Deteriorated Fish, Shrimp and Crab: Enzymes produced by some bacteria, yeasts and molds decompose protein in aquatic products after death, producing toxic substances such as amines, ammonia and hydrogen sulfide. When poisoned, the symptoms are skin flushing, conjunctival congestion, chest tightness, headache, vomiting and diarrhea. When the fish eyes are cloudy, the scales are dim, and the shrimp and crab shells are red, they are not fresh.
3. Moldy sugarcane: mainly manifested as dull skin, dark color, soft texture, light brown pulp, musty or sour taste. Corynebacterium saccharum, a mildew-toxic fungus in sugarcane, can produce neurotoxins, which mainly damage the central nervous system. After eating, digestive dysfunction and nervous system symptoms appear one after another, and patients often die of respiratory failure.
4. Unsanitary homemade fermented foods: Homemade fermented foods such as stinky tofu and bean paste are not heated or heated sufficiently when they are eaten due to poor sanitary conditions, long storage time and anoxic environment, which causes Clostridium botulinum to produce botulinum toxin and cause poisoning. Symptoms such as blurred vision, unclear speech, dilated pupils, muscle paralysis and respiratory failure. Until death.
5. Partially rotten apples: After apples are partially spoiled, we often like to cut off the bad parts before eating. In fact, the whole apple has been polluted and deteriorated by bacteria, but it has not shown rot for the time being. When you eat it, you will feel bitter and even have poisoning phenomena such as nausea and vomiting.
6. Long-spotted sweet potatoes: Sweet potatoes are stored for too long, wet and damaged, and are prone to black spot disease, which makes the epidermis grow brown or black spots, or dry and sunken, and the potato heart becomes hard and bitter. The toxins contained in sweet potatoes are heat-resistant, so eating raw or cooked sweet potatoes with dark spots will cause symptoms such as poisoning, nausea, vomiting, abdominal pain, diarrhea, and even fever, asthma, convulsions, coma and even death in severe cases. Therefore, once the sweet potato has dark spots, hardness, bitterness and musty taste, don't eat it again.
7. Rotten ginger: Rotten ginger produces a highly toxic safrole. Poisoning after eating causes liver cell damage, and even induces serious consequences such as esophageal cancer and liver cancer. Therefore, you must buy dried ginger that is not rotten or even stale. Keep dry during storage to avoid frostbite.
8. Rootless bean sprouts: Generally, when you have soybean sprouts and mung bean sprouts, you only need to filter the water and keep warm every day, but we will also see some fat and rootless bean sprouts in the market, which will leave some chemicals, which will cause poisoning if you eat them in large quantities for a long time. You can buy relatively safe "stupid" bean sprouts, or try to grow some yourself.
3. Can I eat it after cooking?
Food will go bad if it is not properly preserved. Many people think that spoiled food can be eaten after it is cooked, which is wrong.
The toxin secreted by bacteria before entering human body is very resistant to high temperature and is not easy to be destroyed and decomposed.
Therefore, this method of using heat and pressure to treat spoiled food is unscientific, and spoiled food must be thrown away, and never lose big because of small.
4. How to prevent food from going bad?
First, the low temperature storage method
Low temperature storage is a common method to store cooked food. Its main principle is to effectively inhibit the growth and reproduction of microorganisms, reduce the activity of enzymes, weaken the chemical reaction in food, and better maintain the original flavor and nutritional value of food.
Low temperature storage can be divided into refrigeration method and freezing method according to its temperature, and the refrigeration temperature is above freezing point.
Frozen foods mainly include vegetables, fresh meat, fresh fish, fruits, dairy products, cooked products and semi-finished products. Freezing method is to freeze food in an environment below freezing point, which is suitable for storing animal food. Freezing can preserve food for a long time without spoilage. But after long-term storage, although the quality of food has not changed much. However, with the decrease of moisture, its back-nourishing value decreases and its taste becomes worse. In addition, when more than two kinds of food are stored in the same freezer, they should be sealed and isolated with non-toxic food bags. Prevent odors from polluting each other. At the same time, it can also reduce the loss of water in food.
Second, the high temperature storage method
Food storage in catering industry often adopts high temperature storage method, because microorganisms have weak tolerance to high temperature and can effectively kill microorganisms when the temperature rises. Destroy the activity of enzyme. It can prevent the influence of microorganisms on food and achieve the purpose of storing food. The method is to thoroughly soak or steam the food with boiling water (reaching a high temperature above 100 degrees), and take it out or soak it in the original soup. Keep it in a cool and ventilated place without stirring to prevent food from being contaminated again. This method can keep food from spoiling for a long time. This method is suitable for the preservation of finished and semi-finished products of animal foods, and also for the preservation of dry foods such as water.
Third, the ventilation storage method
Ventilation storage method is mainly suitable for preserving grain, dry grain and food that needs air drying. Are afraid of mold and cover. For example, rice, noodles, peanuts, vegetables and other foods need ventilation when stored. This can make mold difficult to grow, keep the original ingredients of food and reduce mildew.
Four, vacuum sealing preservation method
The method of vacuum sealing preservation is to make food not contact with microorganisms in the air under vacuum. A method for sealing and preserving foods, such as canned products and vacuum-packed products. This method is suitable for the preservation of various foods.
With the continuous development of science and technology, there are more and more ways to store food, such as nuclear radiation storage and modified atmosphere storage.
Methods are all advanced methods, the main principle of which is to control or kill microorganisms growing in food and delay the metabolism of internal tissues of raw materials, so as to prolong the storage time of food, improve the storage quality and achieve the purpose of preservation.