Gelatinization Of Wheat Starch Research Articles

Effect of Water Content on the Gelatinization of Wheat Starch

AbstractThe influence of water content on the gelatinization of wheat starch was examined by differential scanning calorimetry. Three endothermic transitions were observed when starch was heated to 140 °C with 35 to 80% (w/w) water. The temperature of the second and third endotherms and the enthalpies of the first and second endotherms vary with water content.

Application of Differential Scanning Calorimetry to Starch Gelatinization. II. Effect of Heating Rate and Moisture Level

AbstractThe influence of heating rate on the gelatinization of wheat starch and starch/water ratio on the gelatinization of wheat, maize, waxy maize and amylomaize starches was examined. More rapid heating resulted in a lowering of the onset temperature of gelatinization for wheat starch from 52 °C at 8°C/min to 46 °C at 32 °C/min. A linear relationship was observed between moisture content and gelatinization energy for starch/water ratios between 1 :2 and 2:1. This allowed calculation of the minimum level of water necessary to initiate gelatinization of each starch. These levels were in excess of the water binding capacity for each starch and were 0.45, 0.45, 0.47 and 0.52 g water/g of wheat, maize, waxy maize and amylomaize starches respectively.

Role of Starch in Bread Formation

AbstractCharacteristics of starch grains from wheat, potato, tapioca, rice, maize, waxy maize, and high‐amylose maize were assessed for their effects on the properties of a “synthetic” wheat gluten‐starch bread system. Statistically significant negative correlations existed between amylose content and fractional volume increase, crumb penetration (tenderness), and crumb hydration capacity. Significant positive correlations were found between fractional volume increase and crumb penetration and between crumb hydration capacity and crumb soluble amylose. Gelatinized wheat starch was most uniformly oriented in fibrous strands of crumb and in films about the walls of gas cells.

Influence of Monoglycerides on the Gelatinization and Enzymatic Breakdown of Wheat and Cassava Starch

AbstractThe influence of monoglycerides on the flocculation and gelatinization of suspensions of wheat starch and cassava starch was studied. The sedimentation volumes of native and gelatinized starch with and without added monoglycerides were measured and the quantity of bound monoglycerides was determined. The sediments were examined by scanning electron microscopy and the rate of enzymatic breakdown by α‐amylase was determined.

Graft copolymers of starch. III. Copolymerization of gelatinized wheat starch with acrylonitrile. Influence of chain modifiers on copolymer composition

AbstractA study was made of the influence of selected chain modifiers on both the molecular weight of grafted polyacrylonitrile and the grafting frequency of the starch–polyacrylo‐nitrile graft copolymer. Gelatinized wheat starch was used with ceric ammonium nitrate as the initiator. The organic chain modifiers investigated were ethyl mercaptan, 1‐dodecanethiol, methyl ethyl ketone, acetaldehyde, and chloroform. Sodium chromate, cupric bromide, cupric nitrate, cupric acetate, and cupric chloride were also tested as chain modifiers. In the presence of cupric chloride, there was a tenfold reduction in the molecular weight of grafted polyacrylonitrile; however, fewer chains were grafted to the starch backbone than were observed without cupric chloride.

Graft copolymers of starch. II. Copolymerization of gelatinized wheat starch with acrylonitrile: Influence of reaction conditions on copolymer composition

Graft copolymers of starch. II. Copolymerization of gelatinized wheat starch with acrylonitrile: Influence of reaction conditions on copolymer composition

An objective method for the measurement of starch gelatinization temperatures

Summary. An objective method has been devised for measuring the gelatinization temperature of granular starch under the microscope. A hot stage is used to heat the specimen, and the progress of gelatinization is followed by microphotometry of the birefringence between crossed polars. The method has been used to study the gelatinization of wheat starch in the presence of sugars, proteins and lipids, in solution or suspension.

Graft copolymers of starch. I. Copolymerization of gelatinized wheat starch with acrylonitrile. Fractionation of copolymer and effect of solvent on copolymer composition

AbstractThe starch–polyacrylonitrile graft copolymer prepared from gelatinized wheat starch with ceric ammoninm nitrate as the initiator has been freed of ungrafted polyacrylonitrile and separated into fractions by extraction with dimethylformamide, γ‐butyrolactone, and dimethyl sulfoxide. The copolymer fractions obtained differed appreciably in level of add‐on, molecular weights of grafted chains, and grafting frequency. To determiue the molecular weights of grafted chains, the starch part of the copolymer was effectively removed by hydrolysis with α‐amylase. It was necessary to dissolve or swell the polymer in dimethyl sulfoxide and freshly precipitate it by addition to water before enzymatic hydrolysis. In studying the effect of reaction medium on copolymer composition, there was less ungrafted homopolymer formed and a higher yield of graft copolymer possessing more frequent grafts with water than with aqueous dimethylformamide or aqueous ethylene glycol. Polymer solubility, the results of control polymerizations of acrylonitrile in the absence of starch, and the detection of glucose endgroups on the polyacrylonitrile liberated from the fractionated polymer by hydrolysis are presented as evidence that the copolymers obtained are true grafts rather thau intimate mixtures.

The Effects of Salts on the Gelatinization of Wheat Starch

Zusammenfassung und SchlußfolgerungEs werden die unterschiedlichen Einflüsse von Salzlösungen auf die Anfangsverkleisterungstemperatur von Weizenstärke beschrieben.Salzlösungen verändern nicht nur die Temperatur, bei der die Verkleisterung beginnt, sondern bewirken gleichzeitig auch eine beachtliche Veränderung der Merkmale des gesamten Verkleisterungsvorganges. Diese Veränderungen, die sich auf die Temperatur zu Beginn der ersten Phase, den Verkleisterungsgrad innerhalb der ersten Phase, die Länge der Übergangsperiode zwischen der ersten Phase und der zweiten Phase, die Temperatur zu Beginn der zweiten Phase und den Verkleisterungsgrad innerhalb der zweiten Phase beziehen, stehen in keiner Korrelation zueinander. So läßt beispielsweise weder eine Erniedrigung der Anfangsverkleisterungstemperatur irgendwelche Schlüsse auf diejenigen Veränderungen zu, die innerhalb der folgenden Stadien eintreten, noch stehen die Veränderungen innerhalb der folgenden Stadien in irgendeiner Beziehung zueinander. Aus diesen Feststellungen ergibt sich, daß die Veränderungen, die durch eine Salzlösung in dem Verkleisterungsbild hervorgerufen werden, nicht auf eine ganz bestimmte Eigenschaft der Salzlösung zurückzuführen sind, sondern daß jede Veränderung die Folge von unterschiedlichen Eigenschaften der Lösung ist. Die bisher erhaltenen Ergebnisse zeigen die außerordentliche Verschiedenheit der Einflüsse von Salzen auf die Verkleisterung. Sie reichen jedoch noch nicht aus, um auch die unterschiedlichen Einflüsse der einzelnen Salze vergleichend erklären zu können. Entsprechende Studien dieser Einflüsse von Salzen auf die Verkleisterung sind zur Zeit noch im Gange.AnerkennungDie Autoren danken der Corn Industries Research Foundation, Incorporated, Washington, D. C., USA., und der W. K. Kellogg Foundation, Battle Creek, Michigan, USA., für die ihnen gewährte Förderung bei der Durchführung dieser Arbeit.