Modified starches properties and uses pdf
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- Applications of Modified Starch
- Modification of Cassava Starch for Industrial Uses
- Modified starches
Applications of Modified Starch
As a recyclable natural material, starch is an important raw material in food and other fields. The native starch by esterification could improve the performance of the original starch and expand its range of application. This article reviews the preparation process of acetylated distarch adipate, starch sodium octenylsuccinate, starch acetate, hydroxypropyl starch, and starch phosphate and research into the influence of starch esters on dough. At the same time, it forecasts the trend of starch esters and application prospect in the future research.
Starch is a natural, renewable, biodegradable polymer and rich in resources that are widely found in a variety of plants. Many of its unique physicochemical properties are extensively applied in food and other industries [ 1 , 2 ], but most of the native starch itself cannot be used directly [ 3 ].
After modification, the starch properties are improved and can meet the requirements of multilevel processing. Esterification is one of the effective ways of denaturation, and the starch can be modified by physical, chemical, or enzymatical methods which are effectively applied in food, textile, papermaking, petrochemical, and pharmaceutical industries depending on its different properties.
The application of starch ester in foreign countries was earlier, and large-scale industrial productions have been achieved. Some starch esters for food applications mainly include starch acetate, acetylated distarch adipate, starch sodium octenylsuccinate, monostarch phosphate, distarch phosphate, phosphated distarch phosphate, acetylated distarch phosphate, hydroxypropyl distarch phosphate, and hydroxypropyl starch in the US and EU countries [ 4 , 5 ]. Although the researches are carried out relatively late in China, the researches and development of starch esters has matured gradually in the past two decades.
At present, starch esters as food additives mainly include phosphate distarch, acetate starch, sodium starch phosphate, acetylated distarch adipate, phosphorylated distarch phosphate, acetylated distarch phosphate, and hydroxypropyl distarch phosphate in China [ 6 ]. Since many scholars had already researched the preparation process, the synthesis technology has mainly focused on increasing the degree of substitution DS which determined the application direction of esterified starch [ 7 , 8 ].
The following is a summary of common organic acid starch esters and inorganic acid starch esters Table 1. Acetylated distarch adipate ADiSP is a cross-linked composite modified starch obtained by esterification of starch with adipic acid and acetic anhydride.
The production has the characteristics of cross-linked and esterified starch and has thermal stability, high shear resistance, and acid resistance. Acetylated distarch adipate could be used as a thickener, stabilizer, and binder in the food industry [ 9 ]. Acetylated distarch phosphate is a modified starch used in some baby foods. The acetylation, cross-linking, and pregelatinization steps increased the cold viscosity, water absorption index, and gel hardness and reduced the gel cohesiveness, paste clarity, and retrogradation of the starches produced.
Acetylated tapioca distarch adipate was prepared by acetylation and cross-linking reaction using tapioca starch as a raw material and a mixture of acetic anhydride and adipic acid as acetalation and cross-linking agent, respectively, and by a wet approach. The impact of modification factors such as the amount of acetic anhydride and adipic acid, pH value, and reaction time on the esterification reactions was systematically studied. The optimum conditions required for preparation of acetylated tapioca distarch adipate were 0.
The gelatinization temperature of acetylated tapioca distarch adipate decreased, but viscosity stability was enhanced. The shearing resistance and freeze-thaw stability were much improved, but the transparency decreased [ 12 , 13 ]. Starch sodium octenylsuccinate is one of the most widely used starch esters.
It was first successfully synthesized by Caldwell and Wurzburg in the United States and was patented in [ 14 ]. Starch sodium octenylsuccinate is one of the food additives used earlier and a sort of safe and reliable emulsifier thickener. When the octenylsuccinic anhydride reacts with the starch, the ring of the anhydride is opened under alkaline conditions: one end of which combines with sodium hydroxide to form a sodium salt and the other end reacts with the starch and removes one molecule of water.
The entire reaction pH is continuously reduced as the reaction proceeds, so it is continuously neutralized with an alkaline solution to ensure pH of the entire reaction system, so that the reaction proceeds efficiently. Since the esterification reaction and the hydrolysis reaction proceed simultaneously, the esterification reaction predominates at the beginning of the reaction phase, and the reaction proceeds to the esterification reaction; when the reaction reaches a certain time, the hydrolysis reaction will be dominant due to the decrease of the substrate concentration, so the reaction time is not as long as possible, so you must control the reaction time.
There are mainly wet, dry, and physical extrusion methods for preparing starch octenylsuccinate [ 15 ]. The treated starch sodium octenylsuccinate was slowly added to the mixed solution in portions while keeping the system pH at 8. At the end of the reaction, the pH of the reaction mixture was again adjusted to 6.
Therefore, Yoshimura et al. This method allows the process to be simple, highly efficient, and low cost but nonuniform and easily leads to local violent reaction [ 17 ]. In the conventional wet method aqueous phase method , the degree of substitution and the efficiency of esterification depend on the type of starch and the reaction parameters, and they are also affected by the surface structure of the starch granules.
Due to the low solubility of starch sodium octenylsuccinate in water, the esterification reaction with starch mainly occurs on the surface of the particles, and the problems such as uneven distribution of acid anhydride and poor reaction efficiency occur easily. On the other hand, the use of sodium hydroxide, pyridine, and anhydride at high temperature often leads to the production of other by-products in the process of chemical reaction [ 18 ].
In recent years, through the improvement of traditional synthetic technology, it has sought to achieve higher efficiency and degree of substitution in a shorter time.
The main methods involved mechanical activation, microwave-assisted, and enzymatic methods. The enzymatic method can realize the reaction under mild conditions and is environmentally friendly. In addition, due to the high efficiency of the enzyme, the reaction rate can be greatly promoted and the product quality can be also improved.
Xu et al. High-speed shear attenuates the crystalline regions of starch granules without changing the type of crystallization, while the cavitation effect increases the reaction area by destroying the surface of the granules, and also promotes the reduction in droplet size and uniformity of distribution of starch sodium octenylsuccinate, making more OS groups induced into the inner regions of the starches [ 21 ]. Starch acetate is obtained by introducing an acetyl group into a hydrogen atom of the hydroxyl group on glucose.
Starch acetate could be divided into high 1. Low-substituted acetylated starch has been widely used in the food industry as a kind of thickener or stabilizer. However, the acetylated starch with medium and high degree of substitution had high solubility in acetone and chloroform and was mainly used for research and development of thermoplastic materials and biodegradable materials [ 22 ]. Preparation of starch acetate esterification agent mainly covered acetic anhydride, vinyl acetate, vinyl chloride, ketene, and so on.
Chemical synthesis generally preferred acetic anhydride and vinyl acetate as esterifying agents. In current commercial production, most of the synthesis routes chose NaOH as a catalyst to react starch and anhydride in an alkaline aqueous suspension [ 23 ].
The pH of the starch suspension was adjusted to 8. The pH was always maintained between 8. After complete addition of acetic anhydride, the reaction was allowed to continue for 15 minutes. The pH was adjusted to 4. Tupa et al. Volkert et al. Colussi et al. The results showed that rice starch with the low amylose content was more easily acetylated, and DS is higher than that of the high and medium amylose under the same circumstances at different reaction times [ 27 ]. The physical auxiliary methods for preparing starch acetate mainly include microwave-assisted synthesis and mechanical activation.
Microwave processing has achieved comprehensive researches over the past decade. Microwave heating can overcome the limitations of time-consuming and low substitution in single acetylation. Under the condition of keeping starch granules intact, it causes surface roughness and internal destruction of particles promoting the degree of acetylation [ 28 ].
The pulsed electric field PEF that regard as a new technique has been similarly applied to the acetylation process. Hong et al. This was due to the potential difference and the alterant direction of the electric field. The PEF system would accelerate the migration rate and direction of the reaction ions, and the effective collision between ions, which expedited the reaction rate and increased the DS.
The reaction of starch with the etherifying reagent, propylene oxide, results in the introduction of the hydroxypropyl group onto the polymeric chain of starch. This is termed as retrogradation and is undesirable in many food applications [ 30 ]. The etherification process is mainly done to inhibit retrogradation [ 31 ].
The reactive nature of propylene oxide is due to its highly strained three-membered epoxide ring. Alkaline reagents in this regard are excellent as catalysts. The efficiency of hydroxypropylation is greatly influenced by the reagents used. Etherification occurs mainly in the amorphous region of the starch granule. It is reported to affect the conformation of amylose molecules, and holes are known to appear at the surface of the granule [ 33 ]. The reaction efficiency is defined as the percentage of the reagent reacted or substituted upon starch.
The remaining reagent is consumed to form by-products. The efficiency depends upon the diffusion or penetration of alkali catalyst and etherifying agent into starch granules and the chances of collisions of the starch alcoholate nucleophile with the propylene oxide molecule. The elevated temperature of reaction helps in diffusion of alkaline catalyst and penetration of etherifying reagent more readily into the reaction point inside the starch granule and thus economises the reagent consumption.
Preparation of hydroxypropyl starch from a variety of cereal starch sources such as rice [ 34 ], wheat [ 35 , 36 ], corn [ 37 ], tuber starch sources like potato [ 38 ], and legume starch sources e.
A number of patented processes have been developed for the preparation of low-substituted hydroxyalkyl starch ethers in the aqueous phase. High levels of substitution can be obtained in granular starch by using nonaqueous media or in dry conditions [ 40 ]. Kim et al. After hydroxypropylation, the brittleness of the starch film decreases [ 41 ].
Hydroxypropyl gluten corn starch was prepared by using propylene oxide as an etherifying agent, and it was found that the thermal stability, acid resistance, and transparency of the starch were enhanced as the degree of substitution increased. Hydroxypropyl starch has a hydroxypropyl group attached to it, which hinders the hydrogen bond polymerization of starch molecules, which causes the starch gelatinization temperature to decrease, the stability of the paste liquid to be enhanced, the transparency to be improved, the mechanical strength of the starch film to increase, and the barrier property to be enhanced [ 42 ].
Starch phosphate is an esterified starch obtained after phosphorylation. At present, there were mainly dry, wet, and semidry methods for the preparation of starch phosphate at home and abroad. In the dry process, a certain ratio of phosphate and urea solution was adjusted to pH, and then uniformly sprayed into the dry starch to reduce the moisture in the drying oven to heat the reaction to obtain the starch phosphate.
The wet process adopted in traditional industrial production allows phosphorylating agents orthophosphate, metaphosphate, phosphorus oxychloride, etc. Landerito and Wang [ 43 ] researched that phosphorylation could increase starch viscosity and water binding capacity. Conventional phosphorylation could produce monosubstituted phosphate monoester starch or cross-linked phosphodiester starch.
The type and ratio of the product depended mainly on the phosphorylating agent used, concentration, pH, and reaction conditions. In aqueous media, phosphate monoester starch was easily formed under mild acid conditions and cross-linked phosphodiester starch was formed under alkaline conditions [ 44 , 45 ]. For wet synthesis, sodium phosphate was first dissolved in deionized water, the pH was adjusted to 6 or 8. The appropriate amount of starch is added, stirred until it was viscous, and allowed it to equilibrate for 4 hours.
Unreacted sodium phosphate was extracted with a hot aqueous ethanol solution, and the precipitated starch was collected. The distilled water was washed and dried several times to obtain phosphate monoester starch [ 46 ]. Although the wet process has continued for many years and the technology is mature, it had the disadvantages of wastewater pollution and high energy consumption and high cost in industrial production.
Modification of Cassava Starch for Industrial Uses
Overview - starch properties Why modification? To achieve many new functionalities!! Confering rheology. Retrogradation, gelling, amylose crystallisation, freeze-thaw-stability Film forming properties. Starch Convention Martin Kozich. Starches for food application native starches physically modified starches chemically modified starches. Chemically modified starches are used, because they provide functional attributes in food applications that native starches normally cannot provide.
In this article, the state of knowledge on conventional and unconventional starches and their properties, characteristics, modifications and applications are reviewed. Food starch, unmodified. Starch Ppt - Free download as Powerpoint Presentation. Aquapel polysaccharide Wheat starch, unmodified. Presentation on Starch.
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As a recyclable natural material, starch is an important raw material in food and other fields. The native starch by esterification could improve the performance of the original starch and expand its range of application. This article reviews the preparation process of acetylated distarch adipate, starch sodium octenylsuccinate, starch acetate, hydroxypropyl starch, and starch phosphate and research into the influence of starch esters on dough.
Characterization of tropical starches modified with potassium permanganate and lactic acid. General Carlos Cavalcanti, ; Campus de Uvaranas; ; demiate interponta. In the present work some tropical starches were modified by an oxidative chemical treatment with potassium permanganate and lactic acid. The native and modified samples were evaluated by mid-infrared spectroscopy, differential dyeing, pH, expansion power, solubility and swelling power, clarity of the pastes, susceptibility to syneresis, carboxyl content and reducing power. All modified samples presented dark blue color, higher expansion power except corn starch , carboxyl content and reducing power.
Если Цифровой крепости суждено стать любимой игрушкой АНБ, Стратмор хотел убедиться, что взломать ее невозможно. - Ты по-прежнему хочешь уйти. Сьюзан посмотрела на. Сидя рядом с великим Тревором Стратмором, она невольно почувствовала, что страхи ее покинули. Переделать Цифровую крепость - это шанс войти в историю, принеся громадную пользу стране, и Стратмору без ее помощи не обойтись. Хоть и не очень охотно, она все же улыбнулась: - Что будем делать. Стратмор просиял и, протянув руку, коснулся ее плеча.
Постарайтесь пройти по нему до конца. Сьюзан вздохнула: - Программа принимает ключ только в цифровой форме. Мне кажется, что тут содержится некий намек на то, что это за цифра. В тексте названы Хиросима и Нагасаки, города, разрушенные атомными бомбами. Может быть, ключ связан с количеством человеческих жертв, оценочной суммой нанесенного ущерба в долларах… - Она замолчала, снова вчитываясь в текст.
Пора переходить к решительным действиям. Немец рывком открыл дверь и собрался было закричать, но Беккер его опередил. Помахав карточкой теннисного клуба Мериленда, он рявкнул: - Полиция.