Liquid oil turns into solid fat
Butter is a favorite food in Europe and America. It is fat extracted from milk, also known as butterfat or butter. It is a yellow semi-solid which is made by fermenting, stirring, solidifying and pressing the milk after separating the dilute emulsifiable concentrate with a grease separator, so it is also called butter. It contains more than 8% fat, most of the rest is water, and a small amount of lactose, protein, minerals, vitamins and pigments, etc. It has a light and salty taste and is used for spreading bread on the table and making cakes and sweets. It was also loved by many people after it was introduced into China.
In the late 196s, when there was a butter panic in France, money and love could not be exchanged for butter. Considering the supply of his army, French Emperor Charles Louis Napolé on Bonaparte issued an order: Considering the people's situation, he offered a bonus to reward the invention of a substitute as nutritious and delicious as butter.
French industrial chemist Hippolyte Mege-Mouris (1817-188) was tempted by the prize money to develop margarine. Success was achieved in 187. The method is as follows: firstly, beef tallow (beef fat), potassium carbonate and pepsin (present in gastric juice of vertebrates such as pigs and sheep) are boiled at 45℃ until the beef tallow and other tissues are completely separated, then put into a hydraulic press to separate the beef tallow from other tissues, and then salt and milk protein are added into the beef tallow to be mixed and stirred until it reaches a proper consistency, thus obtaining the artificial butter. Meige-Murray won the prize, obtained the patent in France and England in 1869, and built a factory in Poissey near Paris the following year.
Stephen Miall．A history of the British chemical industry．Great Britain：Society of chemical industry，1931。
Later, there were many improvements, such as replacing butter with vegetable oil, adding egg yolk, vitamin A and vitamin D, and adding lecithin as emulsifier. In 1872, F. Boudet obtained an improved patent, emulsified it with skimmed milk and water, and cooled it with ice to produce a granular solid that looks like a pearl, so the product was called "Oleumargarine". "Oleum" is "oil" in Latin; "margarine" means "pearl", and the two words together are "oil pearl". Later, "Oleum" was omitted, and it was directly called "margarine". We seem to be transliteration and free translation, called "Maggie Lin", which remains in our dictionary and becomes synonymous with margarine.
a few years later, Maggie Lin was made in European countries and the United States. However, influenced by people's prejudice, it is considered as a kind of earth butter, and its manufacture is prohibited in countries such as Canada and South Africa.
Today's Maiqilin is made from vegetable oil by hydrogenation, that is, catalytic hydrogenation. After chemical analysis in the 19th century, chemists determined that the main components of semi-solid animal fats such as butter, tallow and lard are glycerides of saturated fatty acids, that is, the carbon atoms in the molecular structure are completely connected by single bonds, while the main components of liquid vegetable fats such as soybean oil, peanut oil and cottonseed oil are glycerides of unsaturated fatty acids, that is, the molecular structure contains carbon atoms connected by double bonds or triple bonds. Hydrogenation reaction is to add hydrogen atoms to the molecules of unsaturated compounds to transform them into molecules of saturated compounds.
catalytic hydrogenation is the research result of French chemist Sabathier (1854-1941) and his colleague Sandler (1856-1936). The two of them began to study heterogeneous catalytic reactions in organic chemistry in 1897, which proved that different catalysts would produce different reactions. In 19, they tried to combine nickel with ethylene to form volatile compounds of nickel, but unexpectedly obtained ethane. After analysis, it is determined that ethylene is partially decomposed into carbon and hydrogen, and hydrogen and undecomposed ethylene are catalyzed by nickel to form ethane.
ethylene is an unsaturated hydrocarbon with carbon-carbon double bonds in its molecular structure, while ethane is a saturated hydrocarbon with carbon-carbon single bonds in its molecular structure.
in this way, they transformed unsaturated compounds into saturated compounds and completed the hydrogenation reaction. Then they turned unsaturated benzene into cyclohexane:
In p>191, they published a research result that the vapor of unsaturated substances and excess hydrogen passed through reduced nickel and could be converted into saturated compounds at a proper temperature. They also pointed out that this direct hydrogenation reaction can convert liquid fatty acids (oleic acid, etc.) into solid fatty acids (stearic acid, palmitic acid, etc.), and this reaction is very easy. As long as the nickel catalyst is suspended in the oil and hydrogen is introduced, the liquid oil will be converted into solid fat.
This opens the way for oil hydrogenation and margarine.
Sabathier won the Nobel Prize in chemistry in 1912.
in the same period, Russian-born American chemist Ipatieff (18671952) also experimentally confirmed that finely ground nickel can catalyze the hydrogenation of unsaturated hydrocarbons to saturated compounds, and proved that this reaction process is very effective under high pressure. In order to achieve this goal, he designed an instrument called Ipatieff bomb, that is, an autoclave which can heat a substance above the boiling point under pressure.
in p>192, German chemist K. Norman obtained the patent of "hardening oil by catalytic hydrogenation" according to Sabathier's theory. He pumped hydrogen into the oil containing dispersed and suspended nickel powder to harden the oil, filtered off the nickel, and added pigments and vitamins to make margarine. He has set up factories in European countries and the United States to produce semi-solid or pasty margarine from cheap soybean oil, peanut oil and cottonseed oil, which is used to make margarine, cakes, bread, cheese, biscuits and peanut butter. China is also engaged in industrial production. China Food Publishing House wrote in a booklet entitled "Processing Technology of margarine and shortening" published in 1988: "In the preparation of nickel catalyst, firstly, metallic nickel is made into easily decomposed organic acid salt, such as methanol salt (Ni(OOCH)2), and then the organic acid salt is suspended in oil and decomposed by heating, and nickel is reduced to metallic state, and diatomite is used as the carrier."
Ni（OOCH）2? 2H2O══Ni+2CO2+H2+2H2O In the process of high-temperature and high-pressure hydrogenation of oils and fats, some unsaturated double bonds of oils and fats may be isomerized, resulting in a large number of trans fatty acids. According to the research report of China's food sector, eating too much trans fatty acids may increase the risk of cardiovascular diseases, diabetes and other diseases. What are trans fatty acids? What is isomerization?
Let's start with the examples of butane and isobutane. Their chemical molecular formula is C4H1, which is composed of the same number of carbon atoms and the same number of hydrogen atoms, but their atoms are connected in different ways and orders:
, four different atoms and atomic groups are on four sides, and they are all the same when they are turned around or turned around, and no two isomers can be shown. From the perspective of spatial arrangement, the two are mirror images of each other and cannot overlap.
He also pointed out that two carbon atoms combined by a double bond can't rotate like relying on a single bond. If the positions of atoms or groups connected to unsaturated carbon atoms are different, these atoms or groups have the possibility of two spatial arrangements, such as fumaric acid and maleic acid.
two identical atoms (H atom) and atomic group (COOH atomic group) in maleic acid are on the same side of the CC double bond, which is cis-butadiene acid; In fumaric acid, the two are on both sides, that is, trans-butadiene acid, and they are isomers of each other. Fatty acids combined in vegetable oils and fats are mainly oleic acid, linoleic acid, etc. Their cis-form structures are as follows: < P > All hydrogen atoms (H) in their molecules are on the same side of C=C, that is, cis-form fatty acids, and on different sides, that is, trans-form fatty acids.
Nowadays, many experts call on enterprises to improve their technology, choose "good oil" as raw materials, and reduce the content of trans fatty acids in food and oil. Enterprises should actively indicate the content of trans fatty acids in packaged food on the nutrition label.