or propyl counterparts in the esterification methanol or ethanol are preferred although other branched or straight chain monohydric alcohols may be used the longer the aliphatic chain of the alkyl group the more lipid compatible the material becomes also the viscosity tends to increase for different types of feed or food whose consistency varies product of varying viscosity can be used to obtain the desired flow or compounding characteristics without affecting the therapeutic or nutritional properties arising from the cla moieties the theory and practice of esterification are conventional a basic explanation of the most common methods is set forth in the mccraw hill encyclopedia of science amp technology mcgraw hill book co n y 1996 5th ed the animal and human body has a variety of esterases so that the cla ester is cleaved to release the free fatty acids readily tissue uptake may have a different kinetics depending on the tissue involved and the benefit sought in the isomerization step it was found that alcoholate catalysis produced a much superior product than aqueous alkali mediated isomerization the latter process always produced undesirable isomers even under mild reaction conditions the milder conditions do give lower amounts of unwanted isomers but at the great expense of yield as shown in the examples in most systems the appearance of the c9 t11 and t10 c12 isomers dominates and they are formed in roughly equimolar amounts it has not heretofore been possible to control the isomerization of the one isomer to the exclusion of the other while it is desirable to increase the percentage of one or the other isomer depending on the physiological effect to be achieved at present this must largely be carried out by adding an enriched source of.