Starch acetals

Low DS starch acetates ate manufactured by treatment of native starch with acetic acid or acetic anhydride, either alone or in pyridine or aqueous alkaline solution. Dimethyl sulfoxide may be used as a cosolvent with acetic anhydride to make low DS starch acetates ketene or vinyl acetate have also been employed. Commercially, acetic anhydride-aqueous alkaU is employed at pH 7—11 and room temperature to give a DS of 0.5. High DS starch acetates ate prepared by the methods previously detailed for low DS acetates, but with longer reaction time. 

Starch acetates may have low or high DS. The industrial importance of low DS acetates results from their abiUty to stabilize aqueous polymer sols. Low DS acetates inhibit association of amylose polymers and reduce the association of the longer outer chains of amylopectin. These properties are important in food appHcations. Highly derivatized starches (DS 2—3) are useful because of their solubiHty in organic solvents and abiHty to form films and fibers. 

Low DS starch acetates have reduced gelatinization temperature ranges and reduced tendency to retrograde after pasting and cooling. Gelling may be completely inhibited if the DS is sufficiently high. Low DS starch acetate polymers also form films which are useful in textile and paper manufacture. 

Lighdy derivatized starch acetates are employed in food because of the clarity of their gels and their stabiHty. AppHcations include frozen fmit pies and gravies, baked goods, instant puddings, and pie fillings. Starch acetates are used in textiles as warp sizes and in paper to improve printabiHty, surface strength, and solvent resistance. 

Starch acetates [9045-28-7] are made by reaction of starch with acetic anhydride. Starch acetates are used in foods to provide paste clarity and viscosity stabiHty at low temperatures. A waxy maize starch acetate is most commonly used. Waxy maize starch acetates for food use are often cross-linked. Acetylated starches are also widely used in warp sizing of textiles. 

Using acetic acid, starch acetates are formed, which are used as film-forming polymers for pharmaceutical products, and as the polymer in biodegradable packing-foam peanuts. Starch acetates have a lower tendency to create gels than unmodified starch. 

SW- waxy corn starch, SWNPs- starch nanopartides. Cel- microcrystaUine cellulose, CelNPs- cellulose nanopartides, CB- carbon black, SWAcNPs- waxy starch acetate nanopartides, CelAcNPs cellulose acetate nanopartides. 

Glucose, glycerol, sucrose, starch, acetate, malate and lactate were examined for the effect of carbon sources on the hydrogen production and the effects of light intensity were also examined under the different irradiances, such as 0, 3, 7, 15, 30, 50 and 110 klux/m2, by adjusting the distance between the light source and the samples of Rb. sphaeriodes KD 131 cultures. 

Esterification Starch acetate - Esterification with acetic anhydride or vinyl acetate Acetylated distarch adipate - Esterification with acetic anhydride and adipic anhydride Starch sodium octenylsuccinate - Esterification by octenylsuccinic anhydride... 

Tuovinen, L., Peltonen, S., Jarvinen, K. (2003). Drug release from starch-acetate films. Journal of Controlled Release, 91(3), 345-354. 

Tarvainen et al. (2002) studied the film-forming ability of starch acetate (DS 2.8) and the effect of commotfly used plasticizers on the physical properties of starch acetate films. The properties were compared with ethylcellulose films. Mechanical studies, water vapor and drug permeability tests, and thermal analysis by differential scarming calorimetry (DSC) were used to characterize the film-forming ability of starch acetate and efficiency of tested plasticizers. Starch acetate films were foimd to be tougher and stronger than ethylcellulose films at the same plasticizer concentration. Also, in most cases, the water vapor permeability of starch acetate... 

Figure 16.2 Preparation of starch acetate microparticles by water-in-oil-in-water double emulsion technique.

Korhonen, O., Raatikainen, R, Harjunen, R, Nakari, J., Suihko, E., Peltonen, S., Vidgren, M., Raronen, R. (2000). Starch acetates—multifunctional direct compression excipients. Pharm.lRes., 77(9), 1138-1143. 

Tarvainen, M., Peltonen, S., Mikkonen, H., Elovaara, M., Tuunainen, M., Paronen, P, Ketolainen, J., Sutinen, R. (2004). Aqueous starch acetate dispersion as a novel coating material for controlled release products. J. Contr. Re/., 96(1), 179-191. 

Tuovinen,L.,Peltonen, S.,Liikola,M.,Hotakainen,M.,Lahtela-Kakkonen, M.,Poso, A., Jarvinen,K. (2004). Drug release from starch-acetate microparticles and films with and without ineorporated a-amylase. Biomaterials, 25(18), 4355M362. 

Starch esters are thermoplastic materials with properties that are somewhat similar to that of cellulose esters. In particular, starch acetate (DS < 0.2) is used as a coating agent for paper and as a food or detergent additive. 

N-Acetyl glucosaminidase, V, 61 Acetyl phosphate, III, 237 Acetyl propionyl. See 2,3-Propanedione. Acetyl value, determination of, for starch acetates, I, 290 Acetylation, of cellulose, I, 311 rates for various cellulosic fibers, V, 122, 123... 

Dicarbonyl sugars, III, 103 Dichroism of flow, of starch-iodine complex of A fraction, I, 266 Diffusion constants, of starch acetates, I, 295... 

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