Free lipid definition

Free fatty acid (FFA) analysis definition of FFA, 471 lipid composition, 471 -472, 476-477 Free induction decay (FID), 22 (fig.), 23 Free radicals lipid oxidation, 535-536 lipids, 525... 

Positive cooked-beef flavor components as perceived by descriptive sensory panelists are reduced during free radical catalyzed meat flavor deterioration (MFD) while negative flavor notes with descriptor definitions of cardboard and painty intensify, as reviewed recently by Love (13). Although the cardboard and painty off-flavors correlate well with lipid oxidation products and can be measured easily by gas chromatography (1, 14, 18). much less is known about the fate of the positive cooked-beef flavors in this MFD process (13). 

Similar to the definition of free volume, the mean free surface area per lipid molecule is related to the area occupied by one phospholipid molecule, A. A0(= 40.8 A) is the area of a phospholipid molecule in the crystal and o (= A0/A) is the reduced surface density. For the surface density data see ref. 5. 

Vesely and Jakes (13) pointed out that the definition for lipides adopted in 1923 was not sufficiently precise. It included, among lipides, the fats formed of mixtures of esters and nonlipidic substances (free fatty acids, steroids, carotenoids, hydrocarbons) on the other hand, certain essential oils formed mainly of esters might be considered lipides. Vesely and Jakes advocated a more precise and concise definition for lipides natural esters nonvolatile with steam and possessing no aromatic ring in their molecule. ... 

If the classification of lipides were to be examined, some points would have to be made clear. In the first place, a definition of lipides should be made that excludes esters of mineral acids such as orthophosphoric acid. The phosphoric esters of alcohols and phenols are alkalino-stable—excluding those possessing a free carbonyl group moreover, they are not very soluble in organic solvents. The definition of lipides should therefore take into account the hydrolysis of ester linkage by heating with alkalies and the solubility of lipides in some organic solvents. 

Free radicals (R, ROO% etc.) can be defined as any chemical species having one or more unpaired electrons, a wide definition that covers hydrogen atoms, transitions metals, the oxygen molecule itself, etc. One of the major areas in which carbon free radicals and oxygen free radicals are involved is lipid oxidation that determines the quality and shelf life of foods. Oxidative rancidity leads to the production of spoiled off-flavor products and is commonly associated with the organoleptic appraisal of food products. ... 

It is the view of the present authors that a physiological role for these inhibitors cannot be disregarded on the basis of these arguments rather, the question must remain open until more definitive experiments are performed. It seems reasonable that, in the intracellular environment, the critical micelle concentration for the fatty acyl-CoA derivatives may never be achieved and that the largest fraction of these inhibitory substances is bound at hydrophobic sites of intracellular proteins and lipid structures such as membranes. In this case, the degree of inhibition would depend on the relative affinity of hydrophobic sites on the carboxylase, the concentration of free fatty acyl-CoA, and that bound at other intracellular hydrophobic sites. 

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