Production 7, 18 sterol esters

Certain classes of lipids are susceptible to degradation under specific conditions. For example, all ester-linked fatty acids in triacylglycerols, phospholipids, and sterol esters are released by mild acid or alkaline treatment, and somewhat harsher hydrolysis conditions release amide-bound fatty acids from sphingolipids. Enzymes that specifically hydrolyze certain lipids are also useful in the determination of lipid structure. Phospholipases A, C, and D (Fig. 10-15) each split particular bonds in phospholipids and yield products with characteristic solubilities and chromatographic behaviors. Phospholipase C, for example, releases a water-soluble phosphoryl alcohol (such as phosphocholine from phosphatidylcholine) and a chloroform-soluble diacylglycerol, each of which can be characterized separately to determine the structure of the intact phospholipid. The combination of specific hydrolysis with characterization of the products by thin-layer, gas-liquid, or high-performance liquid chromatography often allows determination of a lipid structure. 

The heterogeneous class of compounds marked by solubility in so-called lipid solvents (acetone, hydrocarbons, ether, etc.) and relative insolubility in water, has traditionally been called lipids (3). This historical classification, based upon isolation procedures from natural products, is obviously too broad for simple generalizations since it includes triglycerides, fatty acids, phospholipids, sterols, sterol esters, bile acids, waxes, hydrocarbons, fatty ethers and hydrocarbons. For the purposes of this chapter, we will consider lipids to be fatty acids and their derivatives. 

Although lanolin and human sebum are both products of sebaceous glands, their compositions are very different.9 Lanolin contains sterol esters, unlike human sebum, which contains mainly triglycerides, and squalene, which is a precursor of cholesterol. 

Paraffin followed by candelilla wax and microcrystalline waxes, and eventually by beeswax, are considered as the most effective moisture barriers derived from edible waxes (Morillon et al. 2002). There is no satisfactory chemical definition for the term wax which is used for a variety of products of mineral, botanical and animal origin that contain various kinds of fatty materials (Table 23.4). The term resins or lacs can also be used for plant or insect secretions that take place along resins ducts, often in response to injury or infection, and result in more acidic substances (Hernandez 1994). However, all waxes tend to contain wax esters as major components, that is, esters of long-chain fatty alcohols with long chain fatty acids. Depending on their source, they may additionally include hydrocarbons, sterol esters, aliphatic aldehydes, primary and secondary alcohols, diols, ketones, triacylglycerols, and so on. 

The analysis of sterols and sterol esters has been proposed as one way to identify oils in blends (311, 312). Johansson and Croon (313) discussed the use of 4-des-methyl-, 4-monomethyl-, and 4,4-dimethylsterols in characterizing different vegetable oils, and the results are summarized in Table (8). The levels of total sterols and sterol classes as well as the relative distribution of the individual sterol members vary between oils. The presence of steradienes can also be used as a marker for the presence of refined oils (314, 315). High oleic acid oils can easily be used to adulterate olive oil. The presence of rapeseed oil in other oils can be detected by the analysis of brassicasterol and its dehydration product, campestatriene. The presence... 

Reactions in SCCO2 have also been used for the production of minor lipid components, such as tocopherols and sterol esters. The synthesis of D, L, ot-tocopherol in SCCO2 and nitrous oxide by condensation of trimethyUiydroquinone with iso-phytol in the presence of various Bronsted or Lewis acids as catalysts resulted in... 

The richest sources of vitamin E in the diet are vegetable oils. a-Tocopherol is the major contributor to the total vitamin E activity in some oils, but others contain substantial amounts of y-tocopherol (Figure 6.5). Typically, wheat germ, sunflower, cottonseed, and safflower oils contain about 1700, 500, 400, and 350 mg of a-tocopherol equivalent kg-1, respectively. Tocopherols are concentrated in deodorizer distillate (DOD) during the deodorization step. As a result, DOD is a good source of natural tocopherols that are used to make natural vitamin E. DOD is composed of FAs, mixed mono-, di-, or triacylglycerols, sterols, tocopherols, sterol esters, hydrocarbons, and oxidation by-products. DOD is frequently collected and sold. A... 

Lipases have also been employed to isolate tocopherols and sterols, important antioxidants from deodorizer distillate, a by-product formed during the deodoriza-tion step of seed oil purification, by hydrolyzing MAG and DAG in the distillate, and by esterifying sterols into sterol esters. The latter serves as antioxidant in non-polar food products such as margarine (e.g., Benacol from the Raisio Group, Finland and Take Control from Unilever, Englewood Cliffs, New Jersey, U.S.A.). PUFA-sterol esters would provide the benefits of essential fatty acid intake and antioxidant protection. 

Fitzpatrick KC. Sterol ester products face US hurdles. INFORM 1999 10 172-176. 

Chlorophylls are produced by all photosynthetic organisms — and even by some nonphotosynthetic bacteria — and details of their structures depend on their source. Collectively they represent a considerable reserve of organic carbon and nitrogen, although little seems to have been established on their persistence. A wide range of transformation products of chlorophylls has been recovered from the sediments of a freshwater eutrophic lake, and these included the unusual sterol esters of pyrophaeophorbides (Eckardt et al. 1995). It is also presumable that such chlorophyll transformation products produce the pyrroles and indoles that have been described in sediment pyrolysates noted above. 

The growing recognition of the health benefits associated with phytosterol esters leads to the marketing of new products. Several companies have marketed stanol and sterol ester products. In 1995/1996, Raisio Company from Finland introduced the margarine Benecol with 9% of sitostanol ester. Benecol was also launched in the United States in May 1999. In 1999, Unilever launched its product. Take Control , which contained vegetable oil derived sterol esters. In addition to existing products on the market in 2000, Phytrol , unesterified taU oil phytosterols, was announced (Hicks and Moreau, 2001). 

An alternate route to the 5,7-diene system is by the hydride induced decomposition of A 7-toluenesulfonylhydrazones (113) (31, 41). The corresponding 7-oxo-steroids (114) can be prepared by allylic oxidation of A -sterol esters with chromium trioxide-amine complexes in methylene chloride at room temperature (163). The attractive feature of this method is that the product formed in the toluenesulfonyl hydrazone decomposition is virtually free of the 4,6-diene isomer. 

In the food area, due to the characteristics of oleic acid mentioned above and the specificity of lipases by the type and positions of fatty acid on the glycerol, it is possible to synthesize lipids rich in oleic acid with improved physicochemical, nutritional and biological properties (Lin and Huey, 2009 Sellami et al., 2012 Farfan et al., 2013). The lipase-catalyzed reaction between oleic acid and phytosterols also produces sterol esters with higher solubility, which contributes to practical applications in food products (Pan et al., 2012). 

King, JW Snyder, JM Frykman, H Neese, A. Sterol ester production using lipase-catalyzed reactions in supercritical carbon dioxide. European Food Research Technology, 2001, v. 212 (5), 566-569. 

The phytosterols are of interest from a nutritional and physiological point of view because they lower the concentration of cholesterol and LDL in the blood plasma (cf. 3.5.1.2). The absorption of cholesterol is inhibited, a significant effect being reached with an intake of 1 g/day of phytosterol. Since the normal dietary intake amounts to only 200-400 mg/day of phytosterol, margarines are enriched with phytosterols. However, as the free sterols are only poorly soluble in the fat phase, sterol esters are used in the production of margarine. Sterol esters are hydrolysed in the digestive tract. The starting material for the extraction of phytosterols is plant oils and tall oil (Swedish tall = pine), which accumulates as a by-product in the production of paper and pulp. Tall oil is rich in phytostanols, mainly P-sitostanol. 

Australia, plus the newer and much less developed markets of New Zealand and Brazil. Benecol , launched by Raisio in Finland in 1995, but now licensed by McNeil Consumer Products (a subsidiary of Johnson Johnson) outside Scandinavia, was launched in the USA just after Take Control, but was first onto the UK and Continental European markets. There is a third contender, Goodman Fielder s Meadow Lea Logicol in Australia and New Zealand, where vegetable oil-derived plant stanol and sterol esters were formally approved as novel food ingredients in edible oil spreads by the Australia New Zealand Food Authority (ANZFA now renamed Food Standards Australia New Zealand) in June 2001. 

In June 2001, plant sterol esters were formally approved for use in spreads by ANZFA. However, the products must contain an advisory statement that they are unsuitable for infants, children and pregnant women, and that people using cholesterol-reducing medications should seek medical advice before using the spreads. 

Netherlands, and Ireland. Thus, the longest experience of consumption of plant stanol ester-enriched products is a 6-year period in Finland. Sterol ester-enriched spreads were first launched in 1999 in the USA by Lipton Ltd as Take Control margarine. Today sterol ester-enriched margarines are available worldwide under brand names such as Take Control , Flora ProActive , Becel ProActive , and Rama Proactive from Unilever/Lipton, or Logicol from Goodman Fielder Ltd. Other spreads include vegetable oil-based cream cheeses available in Finnish, UK, and other European markets. 

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