Preparation and Characterization of Starch Acetate

Cereal Chem. 81(6):735-740Acetylation of high-amylose (70%) maize starch to high degree of substitution (DS) was studied by reacting starch with acetic anhydride using 50% aqueous NaOH as the catalyst. DS increased with increasing reaction times and increasing ratios of acetic anhydride to starch. Reaction efficiency (RE) increased with longer reaction times and decreased with increases in the ratios of acetic anhydride to starch for extended reaction times. Increasing the amount of NaOH increased both DS and RE. A series of starch acetates with DS values of 0.57-2.23 were prepared and their crystalline structures, chemical structures, thermal stability, and morphological properties were investigated. After acetylation, and as DS increased from 0.57 to 2.23, the crystalline structures of starch steadily disappeared. The carbonyl group's peak at 1,740 cm -1 appeared in the FTIR spectra. The intensity of this peak increased with a decrease in the peak intensity of the hydroxyl groups at 3,000-3,600 cm -1 , indicating that the hydroxyl groups on starch were replaced by the acetyl groups. Thermal stability of starch acetates increased. The smooth surface of the starch granules became rough with acetylation. Further acetylation led to the loss of the starch granules and the formation of beehive-and fibrouslike structures.

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“…RE (%) was calculated according to Khalil et al (1995) as DS × anhydroglucose (mol)/acetic anhydride (mol) × 100%.…”

Section: Determination Of Reaction Efficiency (Re)mentioning

confidence: 99%

Synthesis and Characterization of Starch Acetates with High Substitution

Miladinov²,

2004

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“…The overall reaction rate equation: (12) where k" is the overall reaction rate constant: (13) Equation (10) is described as follows: (14) where R is radius of anhidroglucose particle at time t (which is an unknown quantity). This can be eliminated with the help of mass of anhidroglucose and fractional conversion of anhidroglucose.…”

Section: Hydrolysis Of Starch Acetatementioning

confidence: 99%

“…Based on the starch acetate SEM analysis [10], it has been proven that the granula size of the acetylated starch is larger than the native one, thus, the fractional conversion of anhidroglucose in terms of weight of anhidroglucose is: (16) (17) Substitution Equation (17) to Equation (14), gives: (18) 3. Materials and Methods…”

Section: Hydrolysis Of Starch Acetatementioning

confidence: 99%

“…In this study, the residual acetic acid in the liquid phase decrease with the increasing reaction time, until a certain time period (40-50 minutes). The longer the reaction time, the more time is available for an acetyl group to diffuse and undergo adsorption to the surface of starch molecules [14]. The desired starch acetylation reaction is accompanied by hydrolysis reaction of the acetylated starch after 40-50 minutes acetylation, which is indicated by the decreasing value of degree of substitution and the increasing concentration of residual acetic acid in the bulk liquid.…”

Section: Effect Of the Glacial Acetic Acid/ Gadung Flourmentioning

confidence: 99%

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Mass Transfer and Chemical Reaction Approach of the Kinetics of the Acetylation of Gadung Flour using Glacial Acetic Acid

Kumoro

Amalia

2014

Bull. Chem. React. Eng. Catal.

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Acetylation is one of the common methods of modifying starch properties by introducing acetil (CH3CO) groups to starch molecules at low temperatures. While most acetylation is conducted using starch as anhidroglucose source and acetic anhydride or vinyl acetate as nucleophilic agents, this work employ reactants, namely flour and glacial acetic acid. The purpose of this work are to study the effect of pH reaction and GAA/GF mass ratio on the rate of acetylation reaction and to determine its rate constants. The acetylation of gadung flour with glacial acetic acid in the presence of sodium hydroxide as a homogenous catalyst was studied at ambient temperature with pH ranging from 8-10 and different mass ratio of acetic acid : gadung flour (1:3; 1:4; and 1:5). It was found that increasing pH, lead to increase the degree of substitution, while increasing GAA/GF mass ratio caused such decreases in the degree of substitution, due to the hydrolysis of the acetylated starch. The desired starch acetylation reaction is accompanied by undesirable hydrolysis reaction of the acetylated starch after 40-50 minutes reaction time. Investigation of kinetics of the reaction observed that the value of mass transfer rate constant (Kcs) is smaller than the surface reaction rate constant (k). Thus, it can be concluded that rate controlling step is mass transfer.

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“…Ohishi, Kasai, Shimada & Hatae (2007) reported that the swelling power and solubility indexes of starch pastes with and without acetic acid increase with increase in heating temperature from 60 ⁰C and with the swelling behaviour of starch mainly due the swelling of amylopectin (Tsai, Li & Lii, 1997). Starches can be esterified with an acid, however, according to Khalil, Hashem & Hebeish (1995), the esterification of starch also depends on the heating temperature. Starch acetates, which are very useful industrially, are known to be formed by the action of acetic acid on starch with acetyl content of starch acetate elevated with an increase in the heating temperature.…”

Section: Phmentioning

confidence: 99%

Understanding the role of water-ionic liquid mixtures on the gelatinization and dissolution of maize starches

Mateyawa¹

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The catastrophic impact of petroleum based plastics on our environment has resulted in the development of a new class of biodegradable polymers. Starch is an attractive raw material for biodegradable plastic applications due to its low cost, sustainability and its availability in large quantities. Besides, it can be transformed into thermoplastic material using conventional plastic processing techniques. Despite its attractive potential as a source of biopolymer materials, the use of starch-based plastic products has been restricted to niche markets that do not require high performance applications due to poor mechanical properties and moisture sensitivity of the materials. Starch cannot be thermally processed without water but thermoplastic starch materials developed from water are brittle due to retrogradation. Much research has been devoted to the use of plasticizers other than water. Non-volatile plasticizers such as glycerol, glycol, sorbitol, urea and ammonium derived amines have mainly been used in the plasticization of starch, but due to their high water sensitivity, recent researches have diverted to novel plasticizers, particularly the ionic liquids. Possible explanation for this behaviour is suggested.iv

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Preparation and Characterization of Starch Acetate

Cited by 72 publications

References 21 publications

Synthesis and Characterization of Starch Acetates with High Substitution

Synthesis and Characterization of Starch Acetates with High Substitution

Mass Transfer and Chemical Reaction Approach of the Kinetics of the Acetylation of Gadung Flour using Glacial Acetic Acid

Understanding the role of water-ionic liquid mixtures on the gelatinization and dissolution of maize starches

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