Although these problems are closely related to health, do you know? Every oil product has its own attributes, and cooking according to the attributes is the most fundamental way to maintain health; Moreover, greasy food is unacceptable, but "oil-free life" without oil at all because you want to lose weight is by no means the best choice to stay healthy. Gao, an assistant professor in the Department of Food Science at Fu Jen Catholic University, pointed out that there are three main types of edible oil: 1. Simple oil is an oil composed of glycerol and fatty acids, and edible oil is a simple oil. After ingestion, the human body can synthesize the following two kinds of fats by itself. 2. Complex lipids mainly constitute some fat components in the human body. For example, phospholipids can form lipoproteins. In fact, natural oils and fats also contain complex lipids, but in the process of industrial refining, such unnecessary parts will be removed and refined into simple oils and fats with simpler components. 3. Derived lipids There is also a lipid that does not contain glycerol and fatty acids, which is very similar to the characteristics of oil, but the structure is different. Cholesterol is one of them. Is it feasible to squeeze oil by yourself? Professor Gao said that the recent upsurge of "squeezing oil at home" caused by food safety problems is not bad, but there are several problems worthy of our consideration: 1 First, the oil yield is very low. Taking peanut oil as an example, ordinary families can only simply grind and filter, unlike industrial processes that can release more oil by heating and increasing the crushing intensity, so it is not economical and many can be used. 2. Many people choose to squeeze lard, because lard is the easiest oil to squeeze out, and it can also be squeezed out by dry frying, but lard is not recommended for daily consumption, and long-term intake may cause cardiovascular diseases. 3. Furthermore, due to the poor technology, there are many impurities in the homemade oil that have not been filtered. Maybe they are harmless to human body, but what will happen during cooking and preservation is unknown, but it will cause certain risks. Refining is a necessary procedure. Based on the above reasons, refining petroleum products is a necessary procedure in the current food industry, with the aim of enhancing the purity of petroleum. Because freshly squeezed oil contains a lot of free fatty acids, phospholipids, sterols and so on. , it is easy to make the oil have a strange smell, suspended solids, and even produce free radicals, which will reduce the quality of the oil. As you can imagine, if a bottle of oil goes bad within a week after you buy it home, or you find a pile of suspended matter, it may be difficult. The seven relationships between oil and life are becoming more and more common among obese people. In modern times, 9 out of every 10 people are losing weight, and 8 will fail. I'm afraid oil has long been a "public enemy of the whole people", and everyone doesn't want to get involved. However, Lai Qiaoyi, a nutritionist at Yadong Memorial Hospital, pointed out that it is necessary to eat oil in moderation, because it is closely related to the normal operation of body functions, and it has the following functions: function 1: providing heat and storing energy. Oil can produce 9 calories per gram, which is more economical and efficient than protein and sugar. When the human body needs a lot of energy, the intake of oil is very important. For example, when a baby grows fast, its body weight will increase by 3 times 1 year, but its stomach capacity is very small, so the fat in breast milk or infant milk powder can supply up to 55% of calories. On the other hand, fat can also store the inexhaustible energy of the body, so the weight will increase by 1kg for every increase of about 7,700 calories, and the reason why women have more fat in their breasts and buttocks is also for pregnancy and lactation. Role 2: Providing Essential Fatty Acids Professor Gao believes that the most important and irreplaceable purpose of oil intake is actually to obtain essential fatty acids, including flax oleic acid and hypoflax oleic acid. The so-called essential fatty acids are fatty acids that cannot be synthesized by the human body itself. As long as there are these two raw materials, the human body can synthesize other fatty acids we need by itself, and the content of essential fatty acids is the highest in vegetable oil, so vegetable oil will be recommended as daily edible oil at present. Essential fatty acids are closely related to the regulation of human body, similar to hormones. If it is insufficient, it will destroy the skin structure and easily dehydrate and dry. Function 3: Carrying fat-soluble vitamins is a very important function. Fat will bring fat-soluble vitamins A, D, E and K into the small intestine for easy absorption. Therefore, if there is a lack of oil intake, the absorption of vitamins A, D, E and K will also decrease. Function 4: barrier protection grease can form fat, which exists in the periphery of internal organs and has a protective effect similar to that of a cushion. When walking or colliding, it can play a buffering role, prevent earthquakes and reduce injuries. In addition, subcutaneous fat has the function of keeping out the cold, which can isolate and protect internal organs from harm. Women have more fat in the chest, abdomen and buttocks, which is also to protect the reproductive organs. When the body fat is exhausted, you may feel pain when sitting or lying down, and your skin will be particularly sensitive to low temperature, even at room temperature. Function 5: It forms the structure of human body and has the function of regulation. As mentioned earlier, the complex lipids "phospholipid" and "cholesterol" are components of cell membrane and lipoprotein. Proper cholesterol can help development and growth, form bile and choline, and is also related to the synthesis of vitamin D and hormones. Therefore, women often lose weight in menopause, hormonal imbalance, which just ignores the importance of oil intake. Function 6: Increasing satiety can slow down the emptying speed of chyme in the stomach and improve satiety. So I feel very hungry during my weight loss, and adopting a low-oil diet may be one of the reasons. Function 7: It can provide flavor for food. Professor Gao pointed out that many spices are fat-soluble, and they must be dissolved in oil to bring flavor to food. For example, frying seasoning with oil will give off a strong fragrance, because fat will bring fragrance to taste and smell cells. But if the food is cooked first and then the seasoning is added, the taste will be different. How to eat oil is healthy? Nutritionist Lai Qiaoyi said that if you eat too much oil, obesity, hypertension, diabetes, cardiovascular diseases and so on. Will form, harmful to health. However, insufficient intake will also bring some risks, such as constipation, dry skin and decreased immunity. Severe cases will hinder cholesterol metabolism, make cholesterol too high and even accumulate in the liver, forming fatty liver (deleted); Or unable to synthesize hormones and estrogen, causing endocrine disorders. In addition, the lack of fat will also delay the development of newborns, so it is very important to eat the right amount of fat. How to get the right amount of oil? Nutritionist Lai Qiaoyi suggested that for the average healthy adult, the daily calorie intake should be about 30% of oil. Among them, polyunsaturated fatty acids are less than 10%, monounsaturated fatty acids are 20% and saturated fatty acids are less than 7%. Taking 2000 calories per day as an example, the intake of polyunsaturated fatty acids is about 1 tablespoon (15g), the intake of monounsaturated fatty acids is about 2.5 tablespoons (40g), and the intake of saturated fatty acids should not exceed 1 1g (equivalent to 2 ounces of low-fat red meat,/kloc-0 In fact, it is not difficult to reach this standard. Try to choose low-fat meat, low-fat milk, edible oil or polyunsaturated fatty acid edible oil in your daily diet, and you can almost reach the standard. Saturation? Unsaturated? Compare various oils! The choice of oil for cooking mainly depends on the cooking method and the nature of the oil. As for the attributes of oil products, how to distinguish them? Professor Gao pointed out that they are mainly distinguished according to their sources and saturation. 1 class: animal oil: lard, butter, chicken oil, emulsifiable concentrate, etc. Intrinsic saturated fatty acid accounts for more than 20%, which belongs to high melting point saturated oil and is solid at room temperature. Suitable cooking methods have high stability, high temperature resistance and are not easy to be oxidized and deteriorated, so they are more suitable for frying. Influence on health Because eating deteriorated oil may cause cancer risk, it is relatively safe to use animal oil when frying at high temperature for a long time. However, eating too much animal oil can also increase cholesterol, cause blood vessel blockage and increase the risk of cardiovascular diseases. Therefore, from a nutritional point of view, it is not recommended that people often eat this oil. The second category: vegetable oil Lai Qiaoyi nutritionist pointed out that vegetable oil can be divided into two categories: monounsaturated vegetable oil and polyunsaturated vegetable oil, which are introduced respectively below. Polyunsaturated vegetable oils include soybean oil, sunflower seed oil, grape seed oil and corn oil. It contains omega-6 and omega-3 fatty acids, and polyunsaturated fatty acids account for more than 20%, belonging to unsaturated oil. Compared with saturated fatty acids, cooking methods suitable for cooking are unstable in oil quality, prone to oxidation, rancidity and deterioration, producing free radicals, not suitable for high-temperature cooking and frying, and not suitable for long-term reuse. Influence on health Unsaturated oil is not easy to cause cardiovascular diseases. Omega-3 polyunsaturated fatty acids are easily lacking in modern diet, which can reduce triglycerides, protect blood vessels and help brain development. Vegetable oils, such as olive oil, bitter tea oil, sesame oil, peanut oil, mustard oil, rapeseed oil and safflower seed oil. Featured with omega-9 fatty acids, monounsaturated fatty acids account for more than 60%, which also belongs to unsaturated oil. Unsaturated vegetable oil, suitable for cooking, is more stable (but lower than saturated oil) and less prone to generate free radicals when heated, but it is also not suitable for cooking at high temperature for a long time. Generally speaking, the smoke point of unsaturated oil is low and unstable, which is not suitable for high-temperature cooking, but the smoke point of safflower seed oil is relatively high, so it can be used for short-term low-temperature frying for health reasons. The impact on health is as difficult to cause cardiovascular diseases as polyunsaturated vegetable oil, and it can reduce bad cholesterol (LDL-C) and maintain good cholesterol. Exception among vegetable oils: Although coconut oil, palm oil coconut oil and palm oil are also vegetable oils, they are highly saturated oils like animal oils. Their oils are stable and suitable for frying, but they also increase the risk of cardiovascular diseases and are not suitable for regular use as general daily edible oils. Category III: Aquatic animal oils Fish oil and cod liver oil are exceptions among animal oils, and they are polyunsaturated oils. Appropriate cooking methods are not suitable for cooking, not edible oil, but often used as a health food. It contains essential fatty acids, such as EPA and DHA, and has the functions of diminishing inflammation, promoting the development of brain system, preventing cardiovascular diseases and regulating immune system. Cod liver oil is somewhat different from fish oil, and contains more vitamins A and D, which is related to protecting eyes and maintaining bone metabolism. Clever choice of home oil cooking method is different every day. How to choose so many kinds of oils? Professor Gao and nutritionist Lai Qiaoyi gave the following advice to mothers: 1. You can choose two kinds of oils, one is polyunsaturated oil and the other is monounsaturated oil. The former can be used for stir-frying at low temperature, while the latter can be used for cooking at higher temperature, such as frying and low-temperature frying. Safflower seed oil is a good choice. It is best to buy a small package, 2? After three months, use different kinds of oils, such as sunflower seed oil this time and soybean oil next time, which can avoid the problem of insufficient intake of some essential fatty acids, because most of the essential fatty acids come from vegetable oil. It doesn't matter if only one kind of oil is used at a time, because ordinary home-cooked dishes, even fried, won't be fried for too long and reused too many times like vendors outside, so it doesn't matter if vegetable oil is used occasionally for a short time. In fact, each oil has different flavor, so you can choose it according to your own preferences. For example, some people especially like the aroma of dry noodles mixed with bitter tea oil. Olive oil is edible oil? Seasoning oil? Can olive oil be used for cooking at a higher temperature? Teacher Gao pointed out that there are actually several grades of olive oil, and there are three common types in the market: "extra virgin" (the first cold-pressed olive oil has the greenest color, the strongest fragrance and the richest nutrients), "virgin" and "pure pressed". In Europe and America, extra virgin olive oil is not regarded as edible oil, but a condiment, which is directly used to mix ingredients. What matters is the flavor of olive oil itself and the unique olive polyphenols (which will disappear when heated), so it is not suitable for frying; Virgin level is not suitable for speculation; But when it comes to pure grade or "blended oil" mixed with other oils and fats, it is no problem to fry it at low temperature for a short time. How to judge the quality of oil products? When cooking, visually judge whether the oil is suitable for repeated use, mainly to judge whether it has deteriorated. Teacher Gao said that ordinary consumers can only make a rough observation by the following visual methods because they don't have professional equipment in the laboratory: 1. Looking at the color of oil, the darker the color, the more serious the deterioration, but if the fried food is salted and contains soy sauce or pigment, this standard is not accurate. 2. Observe the smoke spots. If the smoke point of the oil becomes very low, it will start to emit white smoke when it is heated to about170 C, indicating that the oil quality may have deteriorated. Special thermometers are sold in food materials stores. Observe whether there are many bubbles on the surface of the oil when it is heated, and the food has not been put in. Bubbles usually appear or even bubble violently, indicating that frying has been going on for too long. 4. Oil will polymerize and become sticky at high temperature for a long time, resulting in oily smell (similar to the smell of smelly rags). It has been proved that this oil is harmful to human body. The safe use of "oil" skills affects the four enemies of oil quality: air, temperature, light, and metals that catalyze oxidation reactions. 1. The oil temperature should not be too high when cooking, 175℃ or so? 195 C is more appropriate. 2. The oil pan should not be too large, and the contact surface between oil and air is too large, which will also accelerate the oxidation reaction. Therefore, a pot with deeper depth and smaller caliber is theoretically better than a pot with a wide mouth. 3. Try not to let water mix into the oil pan, because water will bring oxygen, which will also accelerate the oxidation of engine oil and make the oil quality deteriorate faster. 4. Try to pick up flour and food residues when frying, because these substances will also react with hot oil, making oleic acid rancidity more serious. 5. Don't add fresh oil to dilute when you feel that the oil quality is not good. Doing so will spoil the fresh oil, so you need to change the whole pot at one time, which is different from changing water in a fish tank! 6. Avoid using containers made of copper or iron to hold grease, because copper and iron may release pro-oxidation substances and produce oxidation. 7. If you buy oil in a large package, it is best to use oil in a small plastic bottle and keep it away from light and high temperature. 8. Don't put the oil near a heat source (such as a stove), because the temperature rise will also accelerate the deterioration of the oil. 9. Containers containing petroleum products must be sealed and try not to contact with air. 10. The engine oil can be reused under the condition of good quality, but it is best not to use it overnight, because the impurities in the old engine oil will continue to oxidize, so it is better to use it up as soon as possible. Senior position: Assistant Professor, Department of Food Science, Fu Jen Catholic University Education: Institute of Food Nutrition, Fu Jen Catholic University Doctoral Expertise: Food Processing, Food Analysis and Health Food Development Lai Qiaoyi Education: Nutritionist Group, Institute of Food Science and Technology, Taiwan Province Provincial University, Department of Nutrition Science, Fu Jen Catholic University Experience: Nutritionist of Yadong Hospital * For more details, please refer to: BabyLife Parenting Life 2065 438+02 04. :./