Sorbitan esters total fatty acid

Saponification value sorbitan esters— standard procedure, section 3.4.2 sucrose esters—allow to stand overnight in cold ethanolic 1.0 M alkali [19]. Value found includes glycerides or unreacted methyl ester. Total fatty acid saponify, evaporate off ethanol, dissolve residue in water, acidify, extract (see below). 

Table 6.1 Total fatty acid contents of pure sorbitan esters...

The saponification values of sorbitan esters do not by themselves characterise the esters very well. The total fatty acid content, however, is more useful, even when allowance is made for the fact that each nominal type contains a proportion of its neighbours, e.g. monoesters contain some diester. The total fatty acid contents of some pure compounds are shown in Table 6.1. The figures are for the esters with single homologue acids. The values for oleates are almost identical with those for stearates. 

Determination of total fatty acid followed by determination of the molecular weight and iodine value of the fatty acid serves to characterise sorbitan esters quite well. 

In practice, two types of emulsifiers are used (1) ABA triblock copolymers (e.g., Hypermer B246, HLB = 6 and B261, HLB = 8, IQ), where A is a polyester derived from 12-hydiostearic acid and B is a polyoxyethylene and (2) nonionic emulsifiers such as fatty acid esters of sorbitan and polyoxyethylene derivatives. Note also that the amount of surfactant is higher than that employed in conventional emulsion polymerization, in connection with the stability problems discussed above it lies within 2-5 wt% of the total mass. 

Stern and Shapiro (1954) incubated the intact mesenteric fat of starved rats with serum and observed a deerease in the total serum esterified fatty acid content but no decrease in the phospholipid or cholesterol ester fraction. When mesenteric adipose tissue was incubated with sodium stearate-1-C or sodium oleate, a significant uptake could be demonstrated and the fatty acids that disappeared from the medium could be recovered in good yield inside the tissue. Of the stearate absorbed, 20-30% was found in the tissue in a combined form, presumably in ester linkage. Stern and Shapiro (1954) also showed that adipose tissue can absorb fatty acids from emulsions of triolein, sorbitan-monolaurate, sorbitan-monopalmitate, and... 

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