Molecular structure and physicochemical properties of potato and bean starches as affected by gamma-irradiation.

Effect of gamma irradiation on physicochemical properties of Indian Horse Chestnut (Aesculus indica Colebr.) starch

It is envisaged that there will be a considerable demand in the near future for modified starches. To meet the demand, the chemical modification of starch, including cross-linking, has been widely used to obtain desirable traits that are suitable for various food applications. Radiation processing, being a physical process, is an environmentally friendly alternative to chemical modification. It is economically viable, safe, and possesses several advantages over other conventional methods employed for modification and cross-linking. Irradiation of starch leads to the attainment of such desired functional attributes as reduction of viscosity, high water solubility, and others. This review provides insight into the impact of gamma, electron beam, and ultraviolet irradiation on the physicochemical and functional properties of starch. It also highlights the importance and the exciting new opportunities afforded by radiation treatments as a physical means for the modification of starch.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2008.00066.x

Impact of radiation processing on starch.

Publisher Summary Corn has been the staple food for countless generations of natives of North and South America. Corn has reached its present state of development through continual mutations, hybridizations, segregations and selections by random, natural processes, and by conscious selection. A number of types have developed by this process, which differ primarily in the structure of the grain. Grain sorghum (Sorghum bicolor Moench) is a cereal grain also known in some localities as milo, milo maize, or kaffir corn. The sorghum plant resembles the corn plant, but the grains, about the size and shape of No. 5 shot, are borne on a terminal, bisexual rachis (head). Mature corn or sorghum kernels are unique, well-organized entities that exist for the purpose of reproducing the species. Descriptions of their structures and compositions are helpful in understanding the process of disruption that is achieved during the wet-milling process. Grain sorghums are considered to be inferior to corn for food, feed, or industrial uses. They require less water for growth than corn and, therefore, are grown in more arid regions. The wet-milling of grain sorghum is similar to that of corn, although novel methods of extracting starch from sorghum have recently been investigated. Wet milling, as a process to recover starch, is essentially a method of disrupting the corn or sorghum kernel in such a way that the component parts can be separated in an aqueous medium into relatively pure fractions.

Corn and Sorghum Starches: Production

This article surveys methods for the enzymatic conversion of starch, involving hydrolases and nonhydrolyzing enzymes, as well as the role of microorganisms producing such enzymes. The sources of the most common enzymes are listed. These starch conversions are also presented in relation to their applications in the food, pharmaceutical, pulp, textile, and other branches of industry. Some sections are devoted to the fermentation of starch to ethanol and other products, and to the production of cyclodextrins, along with the properties of these products. Light is also shed on the enzymes involved in the digestion of starch in human and animal organisms. Enzymatic processes acting on starch are useful in structural studies of the substrates and in understanding the characteristics of digesting enzymes. One section presents the application of enzymes to these problems. The information that is included covers the period from the early 19th century up to 2009.

Enzymatic conversions of starch.

Fine flour from corn and the isolated starch were dextrinized in the presence of acid and irradiated with y-rays. Starch irradiated with high doses of y-rays was highly modified while fine flour was less affected. The irradiated starch was reduced with sodium borohydride and then hydrolysed. Erythritol and other compounds were identified in the hydrolysate. It was concluded that the C2-C3 bonds in the intermediate glucose units are probably broken by irradiation. Such hypothesis was confirmed by periodate oxidation, hydrolysis with α-amylase and ferricyanide number determination of the irradiated starch.



Modifizierung von Maisstarke und Maisfeinmehl durch Saure und Gammabestrahlung.Teil 1. Chemische Untersuchung der modifizierten Produkte.



Maisfeinmehl und die isolierte Starke wurden in Gegenwart von Saure dextriniert und mil γ-Strahlen behandelt. Mit hohen Dosen von γ-Strahlen bestrahlte Starke wurde stark modifiziert, wahrend das Feinmehl weniger stark angegriffen wurde. Die bestrahlte Starke wurde mil Natriumborhydrid reduziert und dann hydrolysiert. Erythritol und andere Verbindungen wurden in dem Hydrolysat identifiziert. Es wurde gefolgert, das die C2-C3-Bindungen in den Glucose-Einheiten wahrscheinlich durch die Bestrahlung gespalten werden. Diese Hypothese wurde durch Periodatoxidation, Hydrolyse mit α-Amylase und Bestimmung der Ferricyanidzahl bestatigt.

Modification of Corn Starch and Fine Flour by Acid and Gamma Irradiation. Part 1. Chemical Investigation of the Modified Products

It was found that the steeping of corn grains by using the usual counter-current system is more efficient for leaching protein than the continuous system. Artificial drying of corn grains at higher temperature decreases starch recovery and increases starch loss in byproducts. The scratching of presteeped corn grains reduced the steeping period by 40%. Storage of corn grains for a long period (9 months) reduced starch recovery by about 3%.



Masnahmen zur Verbesserung des Quellprozesses von Maiskornern. Teil I. Einflus von Quellprozes, kunstlicher Trocknung, Anritzen und Lagerung



Es wurde festgestellt, das die Quellung von Maiskornern bei Anwendung des ublichen Gegenstromverfahrens fur die Extraktion von Protein wesentlich wirkungsvoller ist als das kontinuierliche System. Die kunstliche Trocknung der Maiskorner bei hoherer Temperatur vermindert die Starkeausbeute und erhoht den Starkeverlust in Nebenprodukten. Das Anritzen der vorgequollenen Maiskorner verringerte die erforderliche Quellzeit um 40%. Die Lagerung von Kornermais uber einen langeren Zeitraum (9 Monate) verringerte die Starkeausbeute um etwa 3%.

Factors Improving the Steeping Process of Corn Grains. Part I. Effect of Steeping Process, Artificial Drying, Scratching and Storage

The effect of addition of proteolytic enzymes to the steeping liquor of corn grains was studied to reduce the steeping period and to obtain starch of low protein content. For this purpose the intact, scratched and broken corn grains were steeped in presence of Alcalase and Neutrase enzymes. It was found that the steeping period decreased by about 50% in case of broken grains, while steeping intact or scratched corn grains in presence of the enzymes gave no effect.



Moglichkeiten zur Verbesserung des Quellprozesses fur Maiskorner. Teil II. Wirkung von Enzymzusatzen



Die Wirkung des Zusatzes proteolytischer Enzyme zum Quellwasser fur Maiskorner zur Verkurzung der Quellzeit und zur Gewinnung von Starke mit niedrigem Proteingehalt wurde untersucht. Zu diesem Zweck wurden die intakten, angerissenen und gebrochenen Maiskorner in Gegenwart der Enzyme Alcalase und Neutrase gequollen. Es wurde gefunden, das sich die Quellzeit fur gebrochene Korner um 50% herabsetzen last, wahrend die Quellung intakter oder angerissener Maiskorner in Gegenwart der Enzyme keine Auswirkung zeigte.

Factors Improving the Steeping Process of Corn Grains. Part II. Effect of Enzyme Addition

The corn hull hemicellulose was isolated from unsteeped and for 30 and 60 h steeped grains. The hemicellulose was fractionated by Sephadex G-100 column chromatography in order to compare the fraction constituents of each hemicellulose. Also the relative percentage and molar ratio of the sugars in each fraction were determined.



Wirkung des Quellens auf die chemische Zusammensetzung der Maisschalen-Hemicellulose. Maisschalen-Hemicellulose wurde aus ungequollenen und 30 und 60 h gequollenen Maiskornern isoliert. Die Hemicellulose wurde durch Sephadex G-100-Saulenchromatographie fraktioniert, um die Bestandteile jeder Hemicellulose zu vergleichen. Auserdem wurde der relative Gehalt und das molare Verhaltnis der Zucker in jeder Fraktion ermittelt.

Effect of steeping on the chemical structure of corn hull hemicellulose

The effect of γ-irradiation and dextrinization on the chain length of the starch molecule was studied. The chain length was decreased from 30.0 to 5.4 G. U. after dextrinization in presence of hydrochlorid acid. The average chain length of the irradiated starch was affected depending on the doses. The results showed that splitting of glucosidic linkage by irradiation occured beside other transformations in the structure of the starch. The formation of little amounts of dialdehyde by irradiation has been proved. Results showed the presence of a fraction containing a monosaccharide and different amino acids. This is partial proof for the presence of a glucoprotein type. In case of irradiation of the fine flour with 700 krad, the percentages of the protein fractions were not affected. In case of acid dextrinized fine flour, there is an increase in the water-soluble fraction and a decrease in the alkali fraction. Irradiation of fine flour with 700 krad decreased the amylase activity to about half the value.

Modification of Corn Starch and Fine Flour by Acid and Gamma Irradiation. Part 2. Effect of Gamma Irradiation and Acid Treatment on the Chemical Structure of Starch and the Distribution of Protein Fractions

Y. Ghali

Papers

Modification of Corn Starch and Fine Flour by Acid and Gamma Irradiation. Part 1. Chemical Investigation of the Modified Products

Factors Improving the Steeping Process of Corn Grains. Part I. Effect of Steeping Process, Artificial Drying, Scratching and Storage

Factors Improving the Steeping Process of Corn Grains. Part II. Effect of Enzyme Addition

Effect of steeping on the chemical structure of corn hull hemicellulose

Modification of Corn Starch and Fine Flour by Acid and Gamma Irradiation. Part 2. Effect of Gamma Irradiation and Acid Treatment on the Chemical Structure of Starch and the Distribution of Protein Fractions