Hydrolysis of oils and fats

Lipolysis. Free fatty acids (FFA) result from lipolysis (hydrolysis) of oils and fats. This is determined by the FFA or acid value. The crude oils and animal fats usually have a FFA content exceeding 1 percent. The FFA content is lowered to less than 0.1 percent by the refining of oil or fat. 

Base catalyzed hydrolysis. Historically, soaps were produced by alkaline hydrolysis of oils and fats, and this process is still referred to as saponification. Soaps are now produced by neutralization of fatty acids produced by fat splitting (see below), but alkaline hydrolysis may still be preferred for heat-sensitive fatty acids. 

Fatty acids, soaps and fatty acid methyl esters are the most extensively used oleochemicals [13]. The free fatty acids are prepared by hydrolysis of oils and fats by alkalis. This procedure named saponification proceeds at high temperature and pressure and leads to crude soaps the acidification of which gives fatty acids. They are subjected to various purification procedures, and finally isolated individually or as mixtures of carboxylic acids of the general formula RCOOH or as soaps RCOOM. The carboxylic acid methyl esters can be produced in two ways by esterification of the isolated carboxylic acid with methanol or by low-temperature... 

Twitchell reagent n. Reagent employed for the splitting or hydrolysis of oils and fats, and made by the interaction of sulfuric acid, oleic acid and naphthalene. 

Lipases are water-soluble enzymes that naturally catalyze the hydrolysis of oils and fats, insoluble substrates, acting at the oil-water interface. Their optimum activity of lipases is reached in emulsions, where high substrate surfaces can be obtained and substrate concentrations exceed the critical micelle concentration (Meyer et al., 1990). 

During the hydrolysis of oils and fats by ordinary lipases, partial glycerides tend to accumulate and the rate of hydrolysis of the triacylglycerol decreases. This phenomenon has been exploited in producing diacylglycerols. 

The enzymatic hydrolysis of oils and fats by lipase from castor seed was described as early as 1902 (26). In spite of a host of Information on the action of lipases (27. 28). however, the first commercial application of such a process was described as late as 1981 for the production of soaps from plant oils (25). 

HYDROLYSIS OF OILS AND FATS WITH CANDIDA LIPASE... 

The observations of Goldschmidt on the hydrolysis of esters are in contradiction to the data obtained by Norris and McBain (J.G.S. cxxi. 1362, 1922) who obtained the normal temperature coefficient of 1 5 and the 8rd relationship for the saponification of oils and fats by aqueous alkali. 

Alkenoic acids are formed by heating of oils and fats of animal or plant origin. They can also be prepared by hydrolysis of the corresponding esters158). The Wittig reaction of alkanals 215 with alkoxycarbonylmethylene-triphenylphos-phorane 217 affords the ( )-2-alkenoic esters 218 in about 95 % yield of the ( )-isomer. Alkaline hydrolysis of the esters 218 gives the ( )-2-alkenoic acids 220 (Scheme 41). 

Hydrolysis, the reaction of fats and oils with water, and oxidation, the chemical reaction in which oxygen combines with another substance with the liberation of heat, are the two basic processes that result in the deterioration of oils and fats. Oxidation is mostly responsible for much more of the deterioration of fats and oils than hydrolysis. 

One of the largest uses for lipases174 may be in the hydrolysis and transesterification of oils and fats.175 The reactions with enzymes are much gentler than the ones used today, such as hydrolysis of a fat or oil in water at 150 260 C for 3-24 h. They are also less capital-intensive. Lipases can be used for the hydrolysis and subsequent reesterification with butyl alcohol of olive and rapeseed oils in 100% conversion. An Aspergillus lipase hydrolyzed various fats and oils in the presence of an aqueous buffer in 90-99% yields in 2-24 h.176 Much of the lipase remained in the emulsion at... 

Industry uses a number of analytical methods to characterize oils and fats, in terms of a number of parameters which include moisture, titer (solidification point), free fatty acid, unsaponifiable material, iodine value, peroxide value, and color. Moisture content of the oils and fats is an important measure for storage stability at elevated temperature because it facilitates hydrolysis which in turn impacts odor and color quality. Titer is a measure of the temperature at which the material begins to solidify, signifying the minimum temperature at which the material can be stored or pumped as a fluid. Free fatty acid is a measure of the level of hydrolysis the oils and fats have undergone. Increased fatty acid content usually negatively impacts product color stability because fatty acids are more susceptible to oxidation. Unsaponifiable material is a measure of the nontriglyceride fatty material present, which affects the soap yield of the material. The iodine value is a measure of the amount of unsaturation present in the oils and fats. Peroxide value is a measure of the... 

SNG Substitute natural gas. soaps Sodium and potassium salts of fatty acids, particularly stearic, palmitic and oleic acids. Animal and vegetable oils and fats, from which soaps are prepared, consist essentially of the glyceryl esters of these acids. In soap manufacture the oil or fat is heated with dilute NaOH (less frequently KOH) solution in large vats. When hydrolysis is complete the soap is salted out , or precipitated from solution by addition of NaCl. The soap is then treated, as required, with perfumes, etc. and made into tablets. 

Sulfated Natural Oils and Fats. Sulfated natural triglycerides were the first nonsoap commercial surfactants introduced in the middle of the nineteenth century. Since then sulfates of many vegetable, animal, and fish oils have been investigated (see also Fats AND FATTY oils). With its hydroxyl group and a double bond, ricinoleic acid (12-hydroxy-9,10-octadecenoic acid) is an oil constituent particularly suited for sulfation. Its sulfate is known as turkey-red oil. Oleic acid is also suited for sulfation. Esters of these acids can be sulfated with a minimum of hydrolysis of the glyceride group. Polyunsaturated acids, with several double bonds, lead to dark-colored sulfation products. The reaction with sulfuric acid proceeds through either the hydroxyl or the double bond. The sulfuric acid half ester thus formed is neutralized with caustic soda ... 

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. 

Discussion. For oils and fats, which are esters of long-chain fatty acids, the saponification value (or number) is defined as the number of milligrams of potassium hydroxide which will neutralise the free fatty acids obtained from the hydrolysis of 1 g of the oil or fat. This means that the saponification number is inversely proportional to the relative molecular masses of the fatty acids obtained from the esters. A typical reaction from the hydrolysis of a glyceride is ... 

Fats and oils usually contain fatty acids in their free form as a result of spontaneous hydrolysis of the parent TG compounds. These free fatty acids (FFAs) are usually linear molecules with 4—24 carbon atoms that may be saturated or unsaturated with typically 1-3 C=C double bonds. Other compounds, such as pigments, waxes, sterols, glycolipids, lipoproteins, hydrocarbons, long chain alcohols, carbohydrates and vitamins (E, A and D), can also be found in oils and fats in minor concentrations. 

Palmitic acid is present as cetyl ester in spermaceti from which, by hydrolysis, the acid may be obtained it is present in bee s wax as the mehssic ester and in most vegetable and animal oils and fats, in greater or lesser amounts, as glyceryl tripalmitate or as mixed esters, along with stearic and oleic adds, Palmitic acid is separated from stearic and oleic acids by fractional vacuum distillation and by fractional crystallization. With NaOH, palmitic add forms sodium palmitate, a soap, Most soaps are mixtures of sodium stearate, palmitate, and oleate. 

Raw materials. It is possible to use any fatty acid as a feed material for sulphonation but economic considerations dictate that oleochemical material be preferred. Fatty acids are readily obtained from vegetable and animal oils and fats which are fatty acid triglycerides. These are transesterified to generate glycerol and three moles of a fatty acid ester, normally a methyl ester. The methyl ester can be distilled to give a specific cut and the fatty acid finally isolated by hydrolysis or hydrogenation of the ester. It is common to use animal fats (tallow) in which case the dominant C chains are 16 and 18. 

Mottram, H.R. (1999) The Application of HPLC-APCI MS to the Regiospecific Analysis of Triacylglycerols in Edible Oils and Fats. PhD thesis, Department of Chemistry, University of Bristol, UK. Movia, E. and Remoli, S. (1977) Application of enzymic hydrolysis to determine the genuineness of butter., Bollettino dei Chimici dei Laboratori Provinciali, 3, 187-192. 

Determination of the composition of different oils and fats is a very common application of the GC analysis of fatty acids. The samples under analysis are usually hydrolysed first and free fatty acids are esterified. Kleiman et al. [138] used the methanol—BF3 method for determining acyl groups in oils. Barnes and Holaday [139] started directly with ground peanuts when analysing the composition of their fats. After hydrolysis for 8 min by heating at 80°C with a methanolic solution of NaOH they carried out the esterification with 10% of methanol—BF3 at 95°C for 5 min. n-Propyl esters were utilized for the analysis of fatty acids in soaps [140]. After evolving fatty acids with the aid of orthophosphoric acid, the esters were prepared by heating with /7-propanol at 90°C for 2 min. 

Most naturally occurring fats and oils are mixtures of triglycerides containing a variety of saturated and unsaturated fatty acids. Even the individual triglycerides are often mixed, containing two or three different fatty acids. In general, oils from plants and cold-blooded animals contain more unsaturations than fats from warm-blooded animals. Table 25-2 gives the approximate composition of the fatty acids obtained from hydrolysis of some common fats and oils. 

Diacetyl Tartaric Acid Esters of Mono- and Diglycerides occur over a range in appearance from sticky, viscous liquids through a fatlike consistency to a waxy solid, depending on the iodine value of the oils or fats used in their manufacture. They are the reaction product of partial glycerides of edible oils, fats, or fat-forming fatty acids with diacetyl tartaric anhydride. The diacetyl tartaroyl esters are miscible in all proportions with oils and fats. They are soluble in most common fat solvents, in methanol, in acetone, and in ethyl acetate, but are insoluble in other alcohols, in acetic acid, and in water. They are dispersible in water and resistant to hydrolysis for moderate periods of time. The pH of a 3% dispersion in water is between 2 and 3. 

The most important chemical reactions for triglycerides (fats and edible oils) are hydrolysis, methanolysis, and interesterification. The other reactions, such as hydrogenation, isomerization, polymerization, and autoxidation that are primarily relevant to the processing of edible oils and fats are also discussed in this section. 

Unsaponifiable matter. Oils and fats contain variable amounts of sterols, hydrocarbons, tocopherols, carotenoids, and other compounds, collectively referred to as unsaponifiable matter because they do not produce soaps upon hydrolysis (Table 6). The sterol and tocopherol composition of commodity oils is discussed in another chapter. Some of these minor components are removed during refining, and the resulting concentrates may be useful byproducts, for example, tocopherol antioxidants. Characteristic fingerprints of minor components, particularly phytosterols and tocopherols, are also used to authenticate oils and detect adulteration (18). 

Oleochemical Route. Oleochemicals. Oleochemicals are chemicals derived from oils or fats. They are analogous to petrochemicals, which are chemicals derived from petroleum. The hydrolysis or alcoholysis of oils or fats form the basis of the oleochemical industry. The hydrolysis of the triglycerides composing oils and fats produces fatty acids and glycerol. If oils or fats are made to react with an alcohol instead of with water, the process is alcoholysis, and the products are fatty acid esters and glycerol. 

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