Lipids minor constituents

Lactones are minor constituents in pork fat compared to beef fat, but 5-decalactone was highly concentrated in the FI fraction of the 207 bar/50 C extract The furans, furanones and thiazoles were undoubtedly formed from Maillard reaction precursors and this type of volatQe would be more prevalent in the lipid fraction of cooked pork compared to pork fat alone. 

Egge, H., Murawski, U., Ryhage, R., Gyorgy, P., Chatranon, W. and Zilliken, R 1972. Minor constituents of human milk. IV Analysis of the branched chain fatty acids. Chem. Phys. Lipids 8, 42-55. 

Extraction of fat by supercritical carbon dioxide was investigated as an important option for minimizing the expanded use of frequently flammable and carcinogenic solvents in food analysis. Unfortunately, the presence of moisture in foods has an adverse effect on the quantitative extraction of fat by supercritical fluid extraction (SEE). Hence, samples have to be lyophilized first. The total fat content of freeze-dried meat and oilseed samples was found to be comparable to values derived from Soxhlet-extracted samples (26). Besides, only small amounts of residual lipids could be recovered by an additional extraction of the SFE-extracted matrix by the Bligh and Dyer solvent extraction procedure. As far as the minor constituents are concerned, it was found that the extraction recovery ranged from 99% for PC to 88% for PA. Hence, Snyder et al. concluded that SFE can be used as a rapid, automated method to obtain total fat, including total phospholipids, from foods (26). 

Substances commonly found in starch granules are amylopectin, amylose, molecules intermediate between amylose and amylopectin, lipid (including phospholipids and free fatty acids), phosphate monoester and proteins/enzymes. The contents and the structures of amylopectin and amylose play major roles in the functional properties of starch. However, lipids, phospholipids and phosphate monoester groups have significant effects on starch functional properties, even though they are minor constituents. 

Chemical examination of Sarcophyton glaucum collected at Ishigaki island, Okinawa Prefecture, resulted in the isolation of seven cembranoid diterpenes, namely sarcophytol A (3), sarcophytol A acetate (4), sarcophytol B (5), sarcophy-tonin A (6), and minor constituents sarcophytol C (7), D (8), and E (9). These compounds were found to be susceptible to autooxidation while being purified. The structural determination of these compounds was made mainly based on proton and carbon nuclear magnetic resonance (NMR) spectral evidence and degradative studies by ozonolysis. X-ray crystallographic analysis for the two crystalline compounds, sarcophytol B (5) and D (8), has been reported. The total lipid extracts of S. glaucum comprise about 40% sarcophytol A (3), 5% each of sarcophytol A acetate (4) and sarcophytonin A (6), about 1% sarcophytol B (5), and minor amounts of sarcophytol C (7), D (8), and E (9). 

Minor Constituents Minor constituents in fats that can influence crystallization of TAG include the more polar lipids like DAG, MAG, free fatty acids. 

There are three potential mechanisms by which addition of minor lipids might affect crystallization. They may limit mass transfer rates of crystallizing TAG to the appropriate site for incorporation into the lattice, they may adsorb on the surface of the growing crystal or cluster and inhibit further incorporation of the crystallizing TAG, or they may actually be incorporated into the crystal lattice as a crystal forms and grows (4). Through any of these mechanisms, the minor constituents in a fat may affect the polymorphic form that is crystallized and often affects the crystal microstructure through preferential inhibition on certain crystal faces (28). 

Rice oil is a minor constituent of rough rice when compared with the carbohydrate and protein content. Two major classes of lipids are present those internal within the endosperm and those associated with the bran. The internal lipids contribute to the nutritional, functional, and sensory qualities of rice (7). 

Oil recovered by solvent extraction or mechanical pressing is termed crude soybean oil and contains various classes of lipids. It consists primarily of neutral lipids, which include tri-, di- and monoacylglycerols, free fatty acids, and polar lipids such as phospholipids. It also contains a minor amount of unsaponifiable matter that includes phytosterols, tocopherols, and hydrocarbons such as squalene. Trace metals are found in soybean oil in ppm concentration. When the oil is refined, concentrations of all minor constituents are reduced. The typical composition of crude and refined soybean oil is shown in Table 2.2. 

Cholesteryl esters are quantitatively minor constituents (5-15% of total lipids) of VLDLs but the amount of cholesteryl esters relative to TG in VLDLs increases when rats are fed a high cholesterol diet. The esterification of cholesterol is mediated by two distinct acyl-CoA cholesterol acyltransferases (ACATs) [11]. Inhibition of cholesterol esterification with an ACAT inhibitor in hepatocytes decreased apo B secretion in some studies but not in others. For example, severe reduction in cholesteryl ester content of hepatoma cells decreased apo B secretion, whereas increased cholesteryl ester content did not stimulate apo B secretion. In mouse liver and intestine, the majority of cholesteryl esters are made by ACAT2. Nevertheless, normal quantities of apo B-containing lipoproteins are produced in mice lacking ACAT2 despite the absence of essentially all hepatic ACAT activity. However, ACAT2-deficient mice exhibit reduced intestinal absorption of cholesterol and are resistant to diet-induced hypercholesterolemia (R.V. Farese, 2(X)0). Thus, the observed reduction of plasma cholesterol in response to ACAT inhibitors is probably due to decreased cholesterol absorption rather than decreased VLDL secretion. 

To put into perspective the chemistry associated with radiation pasteurization and sterilization, the basic chemical processes occurring in the constituents of irradiated meat and poultry are considered. Major constituents include the aqueous phase, the muscle and pigment proteins, the lipid (or fat) phase, and the carbohydrates. Minor constituents include salts, vitamins, and nucleic acids. The implications for assessing the wholesomeness of irradiated products, for gaining additional regulatory approvals, and for optimizing product quality and functionality are also considered. 

Foods can be classified into four major component categories carbohydrates, lipids, proteins and water. Although there are other minor components, these categories dominate the make-up of most foods. Raemy [33] has discussed these characteristics and outlined the techniques to be used, as shown in Table 1. Also of importance for foods are the thermal behaviours of minor constituents such as caffeine or vitamins. Application to reconstituted and raw food as well as microbiological study of microorganism growth in food and process safety is also discussed. 

Methyl ester derivatives of fatty acids have occasionally been found as minor constituents of animal lipids. It has now been shown that they can be formed in tissue membranes, especially those of the lung, by an enzymic reaction with... 

Other changes in frying oils take place due to transfer of lipids from foods to the frying oil. The migration of minor constituents from the foods also occurs... 

Major constituents of the nuclear membrane are proteins, lipids, minor components, carbohydrates, and sometimes nucleic acids. 

Since environmental contaminants have been a concern in the marine oil industry, in certain parts of the world, short path distillation under high vacuum or supercritical fluid extraction may be suitable to prepare pesticide-free and high quality marine oils (Breivik, 1992). Table 3 provides changes that occur in lipid composition and minor constituents of cod liver oil at different stages of processing. 

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