Latin name of palm Trachycarpus fortunei
Other names of palm trees, Davidia
Family Palmae
Distribution: native to China, Japanese, Indian and Burmese. Palm is widely distributed in China; It starts from southwestern Shaanxi in the north, reaches Guangdong, Guangxi and Yunnan in the south, reaches the Tibet border in the west, and reaches Shanghai and Zhejiang in the east. From the mouth of the Yangtze River, it is most widely distributed along the 511-kilometer wide area on both sides of the upper reaches of the Yangtze River.
morphological characteristics: evergreen trees, up to 15 meters. No root, dense fibrous roots. The stem is cylindrical, erect, unbranched, and has a residual old petiole base that does not fall off, and is wrapped by dark brown leaf sheath fibers. The leaves are large, clustered at the top of the trunk, palmately divided into many long and narrow lobes, which are hard and shallow at the top. Petiole is extremely long. Dioecious, flowering in May, pale yellow, with spikes arranged in panicles. Drupe kidney-shaped, initially cyan, ripe from 11 to 12 months, and dark brown when ripe.
I. Basic information of palm oil
Palm oil is squeezed from palm fruit of oil palm trees. Palm trees originated in West Africa, spread to Malaysia at the end of 18, and gradually widely planted in Southeast Asia. At present, palm trees are planted in many countries in Southeast Asia, South America and Africa. Palm fruit is boiled, crushed and squeezed to obtain crude palm oil, and refined palm oil (RBD PO) and palm salad oil (RBD PKO) are obtained by refining crude palm oil and removing free fatty acids, natural pigments and odor. According to different needs, palm oil with different melting points such as 24 degrees, 33 degrees and 44 degrees can be obtained by fractionation. Palm oil is rich in nutrients and oxidation resistance, and is widely used in food industry and chemical industry. The hydrolysis of lipase or fatty acid catalase in palm fruit makes the quality of palm oil unstable, so it is necessary to fill the storage tank with nitrogen to ensure its quality.
(I) the development history of palm oil
Palm oil is squeezed from the palm fruit (Elaeis Guineensis) of oil palm trees, and it has been used as a natural food for more than 5,111 years. Oil palm is a kind of crop that blooms and bears fruit in all seasons and has a harvest all the year round. The commercial production of oil palm can last for 25 years. Oil palm is the most efficient oil-producing plant in the world. Palm trees usually begin to bear fruit in 2-3 years, and enter the peak period in 8-15. After 18-21 years, they begin to age and reduce their output. At this time, they usually need to be cut down and replanted. Palm fruits grow on the big fruit clusters of palm trees, and each fruit cluster has about 2111 palm fruits. Palm oil originated in West Africa. Palm trees were introduced to Malaysia in 1871, when they were only used as decorative plants. It was not until 1917 that the first commercial planting was carried out. In the 1961s, Malaysia began to increase palm oil production on a large scale in order to reduce its trade dependence on rubber and coffee. Now the improved palm products have been widely planted in tropical Africa, Latin America and Southeast Asia. Palm oil production is highly concentrated in Malaysia and Indonesia.
(II) Production technology of palm oil
People can obtain crude palm oil (CPO) and palm kernel cake (PE) from palm pulp by boiling, crushing and squeezing; At the same time, in the process of crushing, the palm fruit (palm kernel) is separated, and then crushed and shelled, and the remaining nuts are squeezed to obtain crude palm kernel oil (CPKO) and palm kernel meal (PKE). Oil palm fruit contains two different oils, and palm oil is obtained from pulp. Palm kernel oil is obtained from palm seeds (kernels), of which the former is more important. All these products have been effectively applied to food, chemical industry, agriculture and other fields. It can be said that palm is a good economic plant.
after the primary extraction, crude palm oil and crude palm kernel oil are sent to a refinery for refining, and after removing free fatty acids, natural pigments and odors, they become salad-grade oils-refined palm oil (RBD PO) and palm oil salad oil (RBD PKO). Refined palm oil is nearly colorless and transparent in liquid state and nearly white in solid state. In addition, according to the needs of different users, palm oil can be further fractionated and treated to form palmitoleic acid (PFAD), palm liquid oil (OLEAN) and palm stearin (STEARINE or ST). There are many lipolytic enzymes in oil palm fruit, so the harvested fruit must be processed or "fermented" in time. Palm crude oil is easy to hydrolyze itself to generate more free fatty acids, and the acid value increases rapidly, so it should be refined or separated in time.
Palm oil is rich in carotene (1.15%-1.2%), which is dark orange-red. This pigment cannot be effectively removed by alkali refining, but the oil color can be removed to light yellow by oxidation. Under the action of sunlight and air, palm oil will gradually decolorize. Palm oil is slightly sweet and has a pleasant violet fragrance. It is semi-solid at room temperature, and its consistency and melting point depend largely on the content of free fatty acids. Palm oil with low free fatty acid content is called "soft oil" and palm oil with high free fatty acid content is called "hard oil" in the international market < P > (III) Nutritional components of palm oil < P > Palm oil is also called "saturated fat" because it contains 51% saturated fat. Oil is a mixture of saturated fat, monounsaturated fat and polyunsaturated fat. The human body's digestion and absorption rate of palm oil exceeds 97%. Like all other vegetable edible oils, palm oil itself contains no cholesterol.
As a kind of oil with high saturation, palm oil has been speculated that it may increase the cholesterol content in human serum. However, after further experimental demonstration by many experts, it is found that eating palm oil will not increase serum cholesterol, but will decrease it, because a large number of research data show that different saturated fatty acids have different effects on blood lipids. Palm oil is rich in neutral fatty acids, and the content of substances that promote cholesterol increase is very small (1%). Palm oil is rich in natural vitamin E, triene tocopherol (611-1111mg/kg) and carotenoids. Some researchers have studied different races (Europe, America, Asia), and the results show that palm oil is an edible vegetable oil that fully meets the needs of human health.
(IV) Main uses of palm oil
Palm oil has two major characteristics. First, it contains more saturated fatty acids, has good stability and is not prone to oxidative deterioration. Second, palm oil is rich in vitamin A(511-711ppm) and vitamin E(511-811ppm). Separating palm oil to separate solid fat from liquid oil, wherein the solid fat can be used as chocolate instead of expensive cocoa butter; Liquid oil is used for cold salad, cooking or frying, and its taste is light and refreshing. A large amount of unseparated palm oil is used in soap industry. Soaps produced from palm oil can foam durably and have strong decontamination ability. Palm oil can also be used for tinning tinplate and rolling aluminum foil. Therefore, palm oil is widely used in catering industry, food manufacturing industry and grease industry in the world.
1. Application of palm oil in catering industry
History shows that palm oil has been used in catering for more than 5,111 years. Compared with other edible oils and fats, palm oil products show greater advantages in frying and grilling foods, which are mainly due to the following three reasons:
(1) It has excellent oxidation resistance (frying resistance): This is mainly because palm oil has moderate unsaturation and does not contain linolenic acid, while rich natural vitamin E and triene tocopherol are natural and efficient antioxidants, which makes palm oil more suitable for frying and grilling foods than other oils and fats.
(2) It is composed of nutritious fatty acids: palm oil contains 51% unsaturated fatty acids, has no trans-acid, and is not easy to polymerize with acids.
(3) economy: the cost of oil has always been an important consideration for the catering industry to choose frying and barbecue oil. Oil palm is a high-yield perennial oil plant, which can be harvested for about 21 years once planted, and the annual oil output per unit area is much higher than that of other plant oils, and the output is relatively stable, which makes palm oil become the most edible vegetable oil with price advantage in the world. Oil palm is the most productive oil crop. One hectare of land produces an average of 3.5 tons of palm oil and 1.4 tons of palm kernel oil every year. Its production efficiency is much higher than that of similar vegetable oil, which also means that the output of palm oil per hectare is 9-11 times that of soybean.
At present, the main index of edible refined palm oil in China is that the melting point is not more than 24℃-33℃, which is used for cooking and frying food (bread, biscuits, etc.), and the annual demand accounts for the vast majority of imports.
2. The food industry application of palm oil
Palm oil is generally processed into shortening, margarine, hydrogenated palm oil, frying oil and special oil in the food industry application. Like other edible oils, palm oil is easily digested and absorbed, and promotes health. Palm oil is an important component in fat, which has mild properties and is a good material for making food. Judging from the composition of palm oil, its high solid glycerin content keeps food stable without hydrogenation and effectively resists oxidation. It is also suitable for hot climate and becomes a good seasoning for cakes and bakery products. Because of these characteristics, palm oil is deeply loved by food manufacturing industry.
(1) shortening: shortening is different from margarine, which is 81% oil and 21% water, while shortening is 111% pure oil. There are many kinds of shortening. Strictly speaking, each kind of food needs special shortening, but there are also general shortening suitable for many kinds of foods, which are usually used for frying and baking foods, such as French fries, cakes, biscuits, sandwich cakes and bread. Usually, shortening needs to be matched with different ingredients in the production and use process, so that it can be applied to different products, such as ice cream and biscuits with different flavors.
(2) margarine: margarine is an emulsion composed of water and oil. It was originally developed to imitate butter, but now it has formed many types of products, among which palm liquid oil is suitable for making liquid margarine, and palm stearin is more suitable for making solid margarine.
(3) Hydrogenated palm oil: Hydrogenated palm oil has a wide market in India, Pakistan and Middle East countries, and these markets usually use it as a butterfat product.
(4) frying oil: this is one of the most extensive uses of palm oil in the food industry, mainly because it has good oxidation resistance (its rich tocopherol is a natural and efficient antioxidant), is not easy to polymerize with acids, and has a healthy fatty acid composition (51% unsaturated fatty acid, no trans acid). In the production of instant noodles in most countries, including China, palm products are mostly used to fry flour cakes. In China market, some fried foods with local characteristics (such as fried breakfast and fried snacks) have also begun to use palm products to make them.
(5) Special grease: Palm oil and palm kernel oil are ideal raw materials for producing special grease, which is mainly used in the production of candy, especially chocolate food. Among them, palm kernel stearin is also called "cocoa butter substitute" because its physical properties are very close to cocoa butter.
Palm oil is increasingly widely used in food industry, mainly because it has good natural oxidation resistance, unique physical characteristics, nutritional composition suitable for human health and obvious economy. With the continuous efforts of oil research institutions, palm oil will be more widely used in various fields of food industry.
3. Industrial uses of palm products
In recent years, the industrial uses of palm oil have developed rapidly. In developed countries, a large number of palm oil has been used for industrial purposes. In China, palm industrial products are known as "industrial monosodium glutamate", which shows its wide application. Refined palm oil for industrial use requires a melting point of not less than 44℃. It is mainly used to make soap, stearic acid and glycerol, and the annual demand is basically more than 111,111 tons. In recent years, with the rising price of crude oil, the theme of biofuel has been excavated again, and the use of palm oil as biofuel has been discovered, which has become a new growth point of palm oil use in the future.
Palm oil is mainly divided into two categories in industrial application: one is directly obtained from palm products, such as soap, epoxy palm oil and its polyols, polyurethane and polyacrylate products. The other is oil chemical products, such as fatty acids, esters, fatty alcohols, nitrogen compounds and glycerol. On the basis of these products, various derivatives can be produced by different chemical methods. The main raw materials of oil chemical industry are oils rich in carbon chain lengths of C12-C14 and C16-C18, among which palm kernel oil, palm stearin and palmitic acid are the main raw materials.
(V) Storage methods of palm oil
In palm oil, the formation of acid is caused by the hydrolysis of either lipase or fatty acid catalase in palm fruit. In undamaged fruits, the free fatty acids are very low, but once the cells are damaged, the fruit lipase is activated, and the free fatty acids will rise sharply in the early stage; Then, the rise of free fatty acids slowed down until lipase activity was passivated. The content level of free fatty acids in palm oil actually depends on three factors: the degree of immaturity of fruit (over-ripe fruit is easy to be damaged); The degree of pre-treatment (fermentation) of ear; And the delay time between harvesting and lipase inactivation.
Iron is removed during oil production, which can indirectly control oxidation. At the same time, pay attention to control all environmental conditions that promote oil oxidation. Conveyors and hoists shall be cleaned regularly; Prevent oil pollution caused by soil and debris brought by planting areas. Never use fittings made of copper, brass or bronze to prevent contact between copper and oil. The reason is that copper is a strong oxidant. Keep the temperature as low as possible on the premise of not interfering with oil extraction. At the same time, try to make the oil less exposed to the air.
during storage, a refrigerator can be installed behind the vacuum drying section of the factory to reduce the temperature of oil to 45-51℃ before it enters the storage tank. After the oil is put into the tank, the tank is filled with inert gas (carbon dioxide, nitrogen). Some antioxidants can also be added to the oil to passivate trace metals, so as to eliminate the oxidation during the storage of oil. In addition, when oil is stored in a large container, the oxidation can also be controlled, and the splash of oil during loading and unloading can also be reduced.
Precautions during transportation and unloading: First, the paint of the tank is epoxy resin, and the cleaning of the tank should be checked before loading oil. Second, spray and cover with inert gas. Third, the oil is loaded without spilling. Fourth, the oil temperature is kept at 32-41℃ during shipping. Before loading, heat the oil to raise its temperature at a rate not exceeding 5℃ every 24 hours. Fifth, the loading temperature of oil should not exceed 55℃. Sixth, when the deodorized palm oil is transported to the destination, it is put into an oil tank coated with epoxy resin and filled with nitrogen.