Starch propionate

Starch propionates, with various degrees of propionation up to the tripropionate, have been prepared by refluxing corn starch with propionic acid and propionic anhydride. The lower propionates are water-soluble, but the tripropionate is soluble only in organic solvents. Starch tripropionate and starch tributyrate are easily prepared by treating swollen starch with pyridine and the acid anhydride. These triesters are more soluble in organic solvents than the starch triacetates. 

The performance of the TPS/MMT nanocomposities using different kinds of starch have been studied. Nejad et al. [251] developed nanocomposites through the melt intercalation of nanoclays and starch esters from high amylose starch. Starch acetates (SAs) and starch propionates (SPs) were tested in combination with glycerol triacetate (triacetm) as a plasticizer for concentrations up to 30 and 20 wt %, respectively, with different types of organomodified and unmodified... 

Standard C-NMR spectra of the tosyl starch acetates and propionates are appropriate to gain information about the distribution of the functional groups by using the carbonyl signals. In contrast to a starch triacetate which possesses three separate signals at 170.5, 170.1 and 169.2 ppm in agreement to a C=0 moiety at position 2,6 and 3, the C-NMR spectrum of tosyl starch acetate (DStos = 1-02) shows only two carbonyl peaks at 169.9 and 169.4 ppm indicating that the position 6 and 3 are acetylated. Comparable results were obtained for tosyl starch propionates. ... 

The H-NMR spectra of tosyl starch acetate respectively tosyl starch propionate are suitable to calculate the DStos values (Eq. 1) from the protons both of the methyl groups or the aromatic rings of the tosylate moieties as well as from the methyl groups of the acetyl or propionyl ester function. 

Sodium propionate is also often used as an antifungal agent. Calcium is often preferable to sodium, both to reduce sodium levels in the diet and because calcium ions are necessary for the enzyme a-amylase to act on the starches in bread, making them available for the yeast, and improving the texture of the bread. Stale bread is caused by the starch amylose recrystallizing. The enzyme a-amylase converts some of this starch to sugars, which helps prevent recrystallization. 

Calcium propionate is often preferred as an antifungal agent, to reduce sodium levels in the diet, but also because calcium ions are necessary for the enzyme a-amylase to act on the starches in bread,... 

Fig. 4.—T3fpical Chromatogram for the Minor Volatile Materials from the Pyrolysis of Starch at 300°. [(1) = COa (2) = acetaldehyde (3) = 7 (4) = furan (5) = propion-aldehyde (6) = acetone (7) = acrolein (8) = 2-methylfuran (9) = butyraldehyde (10) = 2-butanone (11) = 2, 5-dimethylfuran (12) = valeraldehyde (13) 2-pentanone (14) — 3-pentanone (15) = water.] (Reproduced by permission of Die Slaerke.)...

A membrane cell recycle reactor with continuous ethanol extraction by dibutyl phthalate increased the productivity fourfold with increased conversion of glucose from 45 to 91%.249 The ethanol was then removed from the dibutyl phthalate with water. It would be better to do this second step with a membrane. In another process, microencapsulated yeast converted glucose to ethanol, which was removed by an oleic acid phase containing a lipase that formed ethyl oleate.250 This could be used as biodiesel fuel. Continuous ultrafiltration has been used to separate the propionic acid produced from glycerol by a Propionibacterium.251 Whey proteins have been hydrolyzed enzymatically and continuously in an ultrafiltration reactor, with improved yields, productivity, and elimination of peptide coproducts.252 Continuous hydrolysis of a starch slurry has been carried out with a-amylase immobilized in a hollow fiber reactor.253 Oils have been hydrolyzed by a lipase immobilized on an aromatic polyamide ultrafiltration membrane with continuous separation of one product through the membrane to shift the equilibrium toward the desired products.254 Such a process could supplant the current energy-intensive industrial one that takes 3-24 h at 150-260X. Lipases have also been used to prepare esters. A lipase-surfactant complex in hexane was used to prepare a wax ester found in whale oil, by the esterification of 1 hexadecanol with palmitic acid in a membrane reactor.255 After 1 h, the yield was 96%. The current industrial process runs at 250°C for up to 20 h. 

Propionic acid—C,H,CO,OH —74—is formed in many decompositions of organic substances By the action of caustic potassa ui>ou sugar, starch, gum. and ethyl cyanide during fermentation, vinous or acetic in the distillation of wood during the putrefaction of peas, beans, etc. by the axidation of normal propylic alcohol, etc. It is best prepared by heating elliyl cyanide with potash until the odor of the ether has disappeared the acid is then liberated from its potassium compound by H.SO, and purified. 

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