Determination of the degree of substitution of acetylated starch by hydrolysis, 1H NMR and TGA/IR

Acetylation of banana (Musa paradisiaca L.) and maize (Zea mays L.) starches using a microwave heating procedure and iodine as catalyst: Partial characterization

“…The acetylation is the esterification of starch polymers where hydroxyl groups of the a-D-glucopyranose units are converted to acetyl (CH 3 C --O) groups [1] to produce starch acetates [2][3][4]. Acetylation alters a wide range of functional characteristics of native starches such as conferring higher peak viscosity (PV) and paste clarity, and increasing freeze-thawed stability [5].…”

“…Starch acetate shows stability and resistance to retrogradation, and impart thickening in diverse foods [6]; some applications are in fruit pies, gravies, salad dressings and filled cakes [7]. Non-food applications include wrap-sizing for textiles and surface-sizing for papers and gummed tape adhesives [4,6]; as a biodegradable material also has many potential uses in pharmaceutical applications [1].…”

“…The starch acetate is prepared commercially by reacting aqueous suspension of starch granules with acetic anhydride in the presence of alkali, such as sodium hydroxide to neutralize the acid formed [1,2,6,8,9]. Reaction times of acetylation are several hours; however, rather inefficient (À70%) due to hydrolysis of acetic anhydride by water and sodium hydroxide [8] added in large amounts to maintain pH 8-9 during reaction.…”

“…The acetylation of starches depends upon certain factors, such as starch source, reactant concentration, reaction time and pH [6]. In all applications it is important to know the degrees of substitution (DS) of acetylated starch [1]. For instance, the solubility of substituted starch depends on the extent of substitution [1].…”

“…In all applications it is important to know the degrees of substitution (DS) of acetylated starch [1]. For instance, the solubility of substituted starch depends on the extent of substitution [1]. Most starches esters currently being made commercially have low (<0.1) degree of substitution (DS); starch acetates, alkenylsuccinates, phosphates and adipates are used in the form of aqueous solution/suspensions for food applications [3,8].…”