Hydrolysis of fat

Soaps (Section 19 5) Cleansing substances obtained by the hydrolysis of fats m aqueous base Soaps are sodium or potassium salts of unbranched carboxylic acids having 12-18 carbon atoms... 

Commercially, soap is most commonly produced through either the direct saponification of fats and oils with caustic or the hydrolysis of fats and oils to fatty acids followed by stoichiometric (equal molar) neutralization with caustic. Both of these approaches yield workable soap in the form of concentrated soap solutions (- 70% soap). This concentration of soap is the target on account of the aqueous-phase properties of soap as well as practical limitations resulting from these properties. Hence, before discussing the commercial manufacturing of soap, it is imperative to understand the phase properties of soap. 

Fatty Acid Neutralization. Another approach to produce soap is through the neutralization of fatty acids with caustic. This approach requires a stepwise process where fatty acids are produced through the hydrolysis of fats and oils by water, followed by subsequent neutralization with appropriate caustics. This approach has a number of inherent benefits over the saponification process. 

Fig. 4. Process stream diagram for the production of fatty acids through hydrolysis of fats and oils. Steam is at 5.2—6.2 MPa (750—900 psi). To convert MPa...

Two important widely used sulfonic acids are known as TwitcheU s reagents, or as in Russia, the Petrov catalysts. These reagents are based on benzene or naphthalene ( ) and (12), [3055-92-3] and [82415-39-2] respectively. The materials are typically made by the coupling of an unsaturated fatty acid with benzene or naphthalene in the presence of concentrated sulfuric acid (128). These sulfonic acids have been used extensively in the hydrolysis of fats and oils, such as beef tallow (129), coconut oil (130,131), fatty methyl esters (132), and various other fats and oils (133—135). TwitcheU reagents have also found use as acidic esterification catalysts (136) and dispersing agents (137). 

Hydrolysis by Steam. High pressure steam, 4.5—5.0 MPa (650—725 psi), at 250°C in the absence of a catalyst hydroly2es oils and fats to the fatty acids and glycerol (20). The reaction is commonly carried out continuously in a countercurrent method. The glycerol produced during the reaction is continuously extracted from the equiUbrium mixture with water. A yield of 98% can be achieved. Currentiy, the preferred method to produce soaps is steam hydrolysis of fats followed by alkaU neutrali2ation of the fatty acids. 

The hydrolysis of fats is improved by running in a counter-current extraction column (Donders et al., Proc. 4th Europ. Symp. Chem. React. Eng., Pergamon, 1968, pp. 159-168). 

Not many operating data of large-scale hquid/hquid reactions are published. One study was made of the hydrolysis of fats with water at 230 to 260°C (446 to 500°F) and 41 to 48 atm (600 to 705 psi) in a continuous commercial spray tower. A small amount of water dissolved in the fat and reacted to form an acid and glycerine. Then most of the glycerine migrated to the water phase. Tlie tower was operated at about 18 percent of flooding, at which condition the HETS was found to be about 9 m (30 ft) compared with an expec ted 6 m (20 ft) for purely physical extrac tion (Jeffreys, Jenson, and Miles, Trans. In.st. Chem. Eng., 39, 389-396 [1961]). A similar mathematical treatment of a batch hydrolysis is made by Jenson and Jeffreys (In.st. Chem. Engrs. Symp. Ser, No. 23 [1967]). 

Fatty acid (Section 26.2) Carboxylic acids obtained by hydrolysis of fats and oils. Fatty acids typically have unbranched chains and contain an even number of carbon atoms in the range of 12-20 carbons. They may include one or more double bonds. 

Glycerol is obtained by the hydrolysis of fats and oils, and purified by distillation under reduced pressure with superheated steam. 

The catalytic oxidation of long-chain paraffins (C18-C30) over manganese salts produces a mixture of fatty acids with different chain lengths. Temperature and pressure ranges of 105-120°C and 15-60 atmospheres are used. About 60 wt% yield of fatty acids in the range of C12-C14 is obtained. These acids are used for making soaps. The main source for fatty acids for soap manufacture, however, is the hydrolysis of fats and oils (a nonpetroleum source). Oxidation of paraffins to fatty acids may be illustrated as ... 

The raw materials for the manufacture of soap, the alkali salts of saturated and unsaturated C10-C20 carboxylic acids, are natural fats and fatty oils, especially tallow oil and other animal fats (lard), coconut oil, palm kernel oil, peanut oil, and even olive oil. In addition, the tall oil fatty acids, which are obtained in the kraft pulping process, are used for soap production. A typical formulation of fats for the manufacture of soap contains 80-90% tallow oil and 10-20% coconut oil [2]. For the manufacture of soft soaps, the potassium salts of fatty acids are used, as are linseed oil, soybean oil, and cottonseed oil acids. High-quality soap can only be produced by high-quality fats, independent of the soap being produced by saponification of the natural fat with caustic soda solution or by neutralization of distilled fatty acids, obtained by hydrolysis of fats, with soda or caustic soda solutions. Fatty acids produced by paraffin wax oxidation are of inferior quality due to a high content of unwanted byproducts. Therefore in industrially developed countries these fatty acids are not used for the manufacture of soap. This now seems to be true as well for the developing countries. 

In the hydrolysis of fats, a small amount of water dissolves in the fat and reacts to form an acid and glycerine. Then the glycerine migrates to the water phase. The differential equation representing this process was derived and checked against a plant test by Jeffreys, Jenson Miles (Trans Instn Chem Engrs 29 389-396, 1961). Flow rates per unit cross section are L of the fat stream, G of the water stream.. Other symbols are,... 

The presence or absence of pancreatic enzymes can only be satisfactorily decided by intraduodenal intubation and direct examination of samples of small intestinal contents after the administration of a suitable stimulus to pancreatic secretion (Fll). It is not sufficient to look at one enzyme only, such as trypsin, since a specific deficiency of lipase can occur (Sll). Assessment of the degree of hydrolysis of fat in the stools is quite unreliable as a guide to pancreatic enzyme activity (CIO). 

Base hydrolysis of fats with sodium or potassium hydroxide liberates glycerol and the salt of the carboxylic acid(s). This reaction was the basis of soap making the salt, or mixture of salts, is a soap with characteristic detergent properties. The relationship of ester hydrolysis to soap-making remains, in that base hydrolysis of esters is still commonly referred to as saponification. 

Further findings relevant for the establishment of the chemical nature of enzymatic catalysis and technical apphcation followed within rather short time. Croft-Hill performed the first enzymatic synthesis, that of isomaltose, in 1898, allowing a yeast extract (df-glycosidase) to act on 40% glucose solution (Sumner and Somers, 1953). In 1900 Kastle and Loevenhart found that the hydrolysis of fat and other esters by lipases is a reversible reaction and that enzymatic synthesis can occur in a dilute mixture of alcohol and acid (Sumner and Myiback 1950). This principle was utilized for the synthesis of... 

Hydrolysis of fats with alkali (e.g., sodium hydroxide) yields salts of the fatty acids, and those of the alkali metals, such as sodium or potassium, are useful as soaps ... 

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