Sorbitan ester

Chemical bleaching is never used on oils intended for edible use because it oxidizes unsaturated fatty acids to cause off-flavors. However, it does find wide usage for specialty linseed oil, for the paint industry, and fatty chemicals such as sorbitan esters of fatty acids and sodium stearoyl lactylate. Residual peroxide is destroyed by heating above its decomposition temperature. 

Polysorha.tes. Polyoxyethylene sorbitan esters [9005-63-4] are formed from the reaction of sorbitol esters with ethylene oxide. These emulsifiers are almost always employed in combination with sorbitan esters and are used in the same appHcations (36). 

Sorbitan oleate and the monolaurate are pale yeUow Hquids. Palmitates and stearates are light tan soHds. Sorbitan esters are not soluble in water but dissolve in a wide range of mineral and vegetable oils. They are lipophilic emulsifiers, solubiHzers, softeners, and fiber lubricants that find appHcation in synthetic fiber manufacture, textile processing, and cosmetic products. Sorbitan esters have been approved for human ingestion and are widely used as emulsifiers and solubiHzers in foods, beverages, and pharmaceuticals. 

Table 18. Sorbitan Esters of Fatty and Tall Oil Acids ...

Typical commercial ethoxylated sorbitan fatty acid esters are yellow Hquids, except tristearates and the 4- and 5-mol ethylene oxide adducts which are light tan soHds. These adducts, as well as the 20-mol adducts of the triesters, are insoluble but dispersible in water. The monoester 20-mol adducts are water soluble. Ethoxylated sorbitan esters are widely used as emulsifiers, antistatic agents, softeners, fiber lubricants, and solubilizers. In combination with the unethoxylated sorbitan esters or with mono- or diglycetides, these are often used as co-emulsrfiers. The ethoxylated sorbitan esters are produced by beating sorbitan esters with ethylene oxide at 130—170°C in the presence of alkaline catalysts. 

A series of sorbitol-based nonionic surfactants are used ia foods as water-ia-oil emulsifiers and defoamers. They are produced by reaction of fatty acids with sorbitol. During reaction, cycHc dehydration as well as esterification (primary hydroxyl group) occurs so that the hydrophilic portion is not only sorbitol but also its mono- and dianhydride. The product known as sorbitan monostearate [1338-41 -6] for example, is a mixture of partial stearic and palmitic acid esters (sorbitan monopalmitate [26266-57-9]) of sorbitol, 1,5-anhydro-D-glucitol [154-58-8] 1,4-sorbitan [27299-12-3] and isosorbide [652-67-5]. Sorbitan esters, such as the foregoing and also sorbitan monolaurate [1338-39-2] and sorbitan monooleate [1338-43-8], can be further modified by reaction with ethylene oxide to produce ethoxylated sorbitan esters, also nonionic detergents FDA approved for food use. 

Sorbitan esters of fatty acids are well known. Similar products can be made from ether carboxylic acids and sorbitol without an acid catalyst with a good color [39]. The advantage of these products is that the hydrophilicity can be adjusted by the polyethylene glycol content in the ether carboxylic acid. 

The reaction product with monoethanolamine acts as a thickening agent [41,101] and with alcohols as an emollient [40]. Also reaction products with amino acids and oligo- or polypeptides for use in cosmetic formulations are known [43]. Sorbitan esters from ether carboxylates are described as emulsifiers or mild surfactants in cosmetic formulations [39] and alkyl ether carboxylic acid taurides as nonirritant anionic surfactants for cosmetic cleaners in particular [44]. Using unsaturated ether carboxylates it is possible to make viscous formulations based on combinations of unsaturated and saturated ether carboxylates [111]. Highly purified alkyl ether carboxylates based on alcohol ethoxylates with low free alcohol content have also been described [112]. 

Fatty alcohol- (or alkyl-)ethoxylates, CoE, are considered to be better candidates for LLE based on their ability to induce rapid phase separation for Winsor II and III systems. (Winsor III systems consist of excess aqueous and organic phases, and a middle phase containing bicontinuous microemulsions.) However, C,E,-type surfactants alone cannot extract biomolecules, presumably because they have no net negative charge, in contrast to sorbitan esters [24,26,30,31]. But, when combined with an additional anionic surfactant such as AOT or sodium benzene dodecyl sulfonate (SDBS), or affinity surfactant, extraction readily occurs [30,31]. The second surfactant must be present beyond a minimum threshold value so that its interfacial concentration is sufficiently large to be seen by... 

SFE has been used extensively in the analysis of solid polymers. Supercritical fluid extraction of liquid samples is undertaken less widely because dissolution or entrainment of the matrix can occur. As illustrated elsewhere SFE has also been applied for the analysis of liquid poly(alkylene glycol) (PAG) lubricants and sorbitan ester formulations [370]. The analysis of PAG additives (antioxidants, biocides and anticorrosion, antiwear and antifoaming agents) is hindered by the presence of the low molecular weight PAG matrix (liquid) and therefore a method for the selective separation of additives from PAG is required. The PAG... 

Analysis by 13C NMR has shown that the 7 and 10 MPa scC02 extracts of sorbitan ester (a complex... 

Hunt et al. [354] used cSFC for the separation of extracts of poly(alkylene glycol) lubricants and sorbitan ester formulations. Doehl et al. [337] have compared the performance of cSFC-FID and pSFC-FID with both scC02 and scN20 in the analysis of the antiblocking agents oleamide and erucamide, the antistatic Armostat 400 and antioxidant Hostanox SE-10, none of which can be detected by UV absorption. By using open-tubular capillary columns, PAs as well as (un)substituted heavy carboxylic acids (> C ) can be eluted. 

A few other successful 13C 1-NMR determinations should be mentioned. Hunt et al. [28] used 13C NMR to characterise fractions of extracted analytes of PAG and sorbitan ester samples and identified Irganox 1010. H and 13C NMR have been used to identify the main organic components of a breathable diaper back-sheet as LLDPE and pentaerythritol tetra-octyl ester (PETO) [233]. The equally present AOs Irganox 1010 and Irgafos 168 were not detected without extraction. Barendswaard et al. [234] have reported fully assigned 13C solution spectra of these two antioxidants. Chimas-sorb 944 in a polyamide matrix can be determined by H or 13C 1-NMR using solvents such as formic acid, trifluoroacetic acid or trifluoroethanol [235], Both H and 13C NMR have been used to follow the chemistry of a bis-phenoxidemethylaluminum complex (reaction product of BHT and trimethylaluminum) by exposure in air. Pierre and van Bree [216] also used 13C NMR to... 

Non-ionic Alkylphenol ethoxylates, long chain alkanol ethoxylates, long chain alkylamine ethoxylates, sorbitan esters and ethoxylates, castor oil ethoxylates, EO/PO copolymers, acrylic copolymers, polysiloxane-polyether copolymers, fluorosilicones... 

Ethoxylated sorbitan ester surfactant mixtures like Tween 20 (cf. Fig. 2.9.38) were often used in biochemical applications. Detergents of this type were analysed by MALDI MS. The aim was to compare the separation results of TLC and RP-LC and to detect impurities within these ethoxylated sorbitan esters [30], Tween 20, the ethoxylated sorbitan carboxylate was ionised resulting in [M + Na]+ and [M + K]+ ions. The Tween 20 isomeric and homologue molecules contained a varying number of ethoxylate units. The number of EO units (-CH2CH2O-) was determined from 18 to 34 resulting in Am/z 44 equally spaced signals [30]. 

A mixture of sorbitan derivatives named Tween 81 specified as ethoxylated sorbitan esters containing oleic acid, was examined by APCI-FIA-MS and —LC—MS in the positive and negative modes. APCI-MS ionisation was supported by the addition of ammonium acetate resulting in equal spaced (Am/z 44) [M + NH4]+ ions which, in parallel, suppressed [M + Na]+ ions. The FIA—MS(+) spectrum contained ions with m/z between 358 and 974 while negative ionisation led to a series of ions from 399 to 971, Am/z 44 equally spaced, too. 

The ethoxylated sorbitan ester Tween 81 was examined by APCI— FIA—MS—MS(+). The compound was ionised by APCI—FIA—MS(+) under addition of ammonium acetate resulting in ions with Am/z 44 equally spaced signals. The APCI—FIA-MS—MS(+) examination of the... 

Fig. 2.9.38. General structural formula of polyethoxylated sorbitan esters. 

E 160b Annatto extracts 2.4 2.4 E 493M Sorbitan esters (2) 6.3 6.3... 

Other nonfood applications of D-sorbitol result from etherification and polycondensation reactions providing biodegradable polyetherpolyols used for soft pol5mrethane foams and melamine/formaldehyde or phenol resins. Sizable amounts of D-sorbitol also enter into the production of the sorbitan ester surfactants (cf. later in this chapter). 

The most common surfactants for analytical applications are nonionic (polyoxyethylene glycol monoethers, polyoxyethylene methyl- -alkyl ethers, t-octylphenoxy polyoxyethylene ethers, and polyoxyethylene sorbitan esters... 

Carbomer, carmellose, microcrystalline cellulose, sodium carboxymethylcellulose, povidone, sodium alginate, tragacanth, and xanthan gum Acacia and methylcellulose, glycerol esters, polysorbates and sorbitan esters, fatty acids, sodium stearate, carbomer Macrogol esters, polyvinyl alcohol, and glycerides... 

Polysorbates or sorbitan esters, acacia, and tragacanth Aluminum magnesium silicate, bentonite, carbomers, cellulose derivatives, gelatin, pectin, polyvinyl alcohol, alginates, starch, and xanthan gum Borates, citrates, acetates, and phosphates... 

Let us consider now the case of a specific ionic polysaccharide. The unique properties of complexes of the cationic chitosan with non-ionic sorbitan esters provides an interesting example. Grant and co-workers (2006) have established that mixtures of chitosan and surfactant form emulsion-like solutions and/or creams, where the surfactant component is present as droplets or micelle-like particles and the chitosan solution acts as the system s continuous phase. It was established that the length and the degree of saturation of the surfactant hydrocarbon chain have a significant impact on the development of the chitosan-surfactant complexes. Moreover, an optimal distance between the chitosan s protonated amine groups is required for effective interactions to occur between the polysaccharide and the sorbitan esters. 

According to Groot (2000), the mechanism of interaction between a polymer and surfactant may be deduced by considering parameters such as polymer size, mode of surfactant adsorption (continuous or discrete micelles), and possible sites of interaction (head group or tail). For the case of the mechanism of the interaction between chitosan and sorbitan esters, the polymer concentration (dilute, semi-dilute, concentrated) of... 

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