CHEMICAL AND PHYSICO-CHEMICAL CHANGES INDUCED IN WHEAT AND WHEAT PRODUCTS BY ELEVATED TEMPERATURES—I

1929 ◽  
Vol 1 (6) ◽  
pp. 528-568 ◽  
Author(s):  
W. F. Geddes
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Elevated Temperatures ◽  
Temperature Limit ◽  
Heat Treatments ◽  
Loaf Volume ◽  
Fixed Temperature ◽  
Baking Quality ◽  
Wheat Products

Heat treatments of wheat and wheat products were conducted in an apparatus which made it possible to study independently the influence of time, temperature and moisture content. Straight-grade flour, milled from Western Canadian hard red spring wheat (allowed a limited amount of aging) heat treated for varying times at different temperatures and normal moisture content (13.90%) was used in most of the studies. Baking tests conducted on this flour revealed progressive improvement in baking quality, as determined without bromate, with temperature or time of heating being extended within a certain range. No well defined "region" of improvement was observed. Improvement in baking quality was reflected in a better handling quality of the dough and, in the baked loaf, by a decrease in underfermented characteristics, and by a marked improvement in crumb texture. No significant alteration in loaf volume was observed. Improvement in baking quality induced by heat was not comparable in magnitude to that obtained by the addition of 0.001%, potassium bromate to the baking formula, but induced the same general characteristics in the finished loaf. Baking tests with bromate on heated flour revealed damage to baking quality for all heat treatments. Extension of time or temperature of heating, above the range where improvement was observed, caused pronounced damage to baking quality as determined with or without bromate. The damage caused was reflected in decreased loaf volume, over-fermentation characteristics, and coarse texture. Within the range of damage, the baking quality was found to be approximately a linear function of the temperature for constant time of heating. Heat treatment resulted in a marked decrease in fermentation tolerance. This decrease could not be ascribed to lower diastatic activity, since baking tests after the addition of diastatic malt to the baking formula gave similar results. Increasing the moisture content at which heat treatments were conducted markedly reduced the temperature to which flour could be heated without damage to the baking quality. The safe temperature limit for various moisture contents has been fairly well defined. The limiting moisture content at which damage occurred for a fixed temperature and time of heating was very sharp. Heat treatment of wheats showed somewhat less damage to baking quality of the flour milled therefrom than heat treatment of flour under similar conditions.

CHEMICAL AND PHYSICO-CHEMICAL CHANGES INDUCED IN WHEAT AND WHEAT PRODUCTS BY ELEVATED TEMPERATURES—II

1930 ◽  
Vol 2 (1) ◽  
pp. 65-90 ◽  
Author(s):  
W. F. Geddes
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Loaf Volume ◽  
Potassium Sulphate ◽  
Baking Quality ◽  
Gluten Quality ◽  
Basic Procedure ◽  
Heat Treated ◽  
Diastatic Activity ◽  
Positive Correlations

Studies were conducted on heat-treated samples of unbleached straight-grade flour milled from Western Canadian hard red spring wheat with the purpose of determining the influence of time and temperature of heating flour with normal moisture content on certain biochemical properties related to "strength". Samples were selected which showed a progressive range in baking quality including some which revealed improvement as a result of heat treatment, when baked by the basic procedure. Gluten quality was impaired in all heat-treated samples, as evidenced by decreased viscosity of leached, acidulated flour suspensions, a decreased rate and extent of imbibition of the washed out gluten, and decreased gas retention of the dough. High positive correlations between viscosity, gas retention, and loaf volume were obtained. The somewhat higher correlations between these measures of gluten quality and loaf volume when determined with potassium bromate added to the formula suggest that the bromate method gives a better measure of gluten quality than the basic procedure. Decrease in viscosity was approximately a linear function of the temperature, for constant time of heating. Ease of peptization of the flour proteins by N. magnesium sulphate, N. potassium iodide, and 5% potassium sulphate solutions showed a marked and progressive decrease with increasing severity of heat treatment. The high positive correlations between the percentage of protein extractable by these salts indicate that the magnitude of these fractions is influenced by the same inherent qualities of the flour proteins. The high positive correlations between the percentage of protein peptized by these salts and viscosity, suggest that these "qualities" are the colloidal properties of the flour proteins. High positive correlations were obtained between loaf volume and percentage of protein peptized. Increasing the moisture content of the flour, with fixed time and temperature of heating, resulted in decreased peptization indicating more extensive heat denaturation of the gluten proteins. Fractionation of the flour proteins showed that the decrease in the potassium sulphate fraction with increasing severity of heat treatment contributed to both the gliadin and glutenin fraction (as determined by the direct barium hydroxide method). Diastatic activity, as determined by the modified Rumsey method and by the rate of gas production in doughs without added sugar, revealed only slight decreases with those flours which showed improvement in baking quality due to heat treatment. Marked decreases were observed with the more severe heat treatments. Susceptibility of the starch to diastatic action was unaltered until marked damage to baking quality resulted, when significant decreases were noted. Heat inactivation of diastase evidently occurred before changes in amyloclastic susceptibility. Proteolytic activity markedly decreased with heat treatment, significant decreases being noted before diastatic activity was appreciably altered. The hydrogen ion concentration of flour extracts revealed no particular trend due to heat treatment, but the buffer value was somewhat increased. The biochemical changes investigated were, for the most part, in a direction associated with decreased baking quality, and provided no adequate explanation for the improvement in baking quality observed in certain samples when baked by the basic procedure.

CHEMICAL AND PHYSICO-CHEMICAL CHANGES IN WHEAT AND WHEAT PRODUCTS INDUCED BY ELEVATED TEMPERATURES: III. THE INFLUENCE OF GERM CONSTITUENTS ON BAKING QUALITY AND THEIR RELATION TO IMPROVEMENT IN FLOUR INDUCED BY HEAT AND CHEMICAL IMPROVERS

1930 ◽  
Vol 2 (3) ◽  
pp. 195-213 ◽  
Author(s):  
W. F. Geddes
Keyword(s):  
Heat Treatment ◽  
Elevated Temperatures ◽  
Indirect Evidence ◽  
Ion Concentration ◽  
Low Grade ◽  
Loaf Volume ◽  
Hydrogen Ion Concentration ◽  
Fermentation Time ◽  
Baking Quality ◽  
Open Texture

Experiments were conducted in an effort to determine the cause of enhancement in baking quality previously observed on heat treatment of straight-grade flour not aged nor bleached. Heat treatment of straight-grade flour matured with agene (nitrogen trichloride), or of unaged fifth middlings flour (highly refined mill stream) did not result in any essential improvement in baking quality, and the unheated flours gave only a slight positive response to bromate. Similarly, ether extracted straight-grade flour gave no appreciable response to bromate and no significant improvement due to heat treatment. Germ added to fifth middlings flour markedly reduced its baking quality when determined by the basic procedure, as reflected in poorer handling qualities of the dough, and in the baked loaf by a decrease in loaf volume, underfermented characteristics, and coarse open texture. Increasing the fermentation time, addition of bromate, or heating the germ before admixture reduced the deleterious effects of the germ. The experiments indicate that response to bromate, and improvement of natural flour induced by proper heat treatment is associated with the presence of germ in the flour. Oxidation of certain germ constituents—presumably the phosphatides—is suggested as the primary change involved in such improvement. Addition of lecithin to middlings flour caused a marked response in loaf volume to the addition of bromate which is considered as indirect evidence that the phosphatides are involved. Heat treatment of germ induced a marked increase in the hydrogen ion concentration of aqueous extracts and a decrease in the iodine number of the ether extract. It is concluded from this series of investigations that heat treatment of flour is detrimental to gluten quality, but decreases the deleterious effect of germ present in the flour. Unaged flours containing low grade mill streams may show an enhancement in baking quality by heat treatment, but the improvement will not equal that induced by chemical improvers which apparently act primarily on the germ constituents.

scholarly journals The Influence of Post-Heat-Treatments on the Tensile Strength and Surface Hardness of Selective Laser Melted AlSi10Mg

2017 ◽  
Vol 370 ◽  
pp. 171-176 ◽  
Author(s):  
Leonhard Hitzler ◽  
Amandine Charles ◽  
Andreas Öchsner
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Precipitation Hardening ◽  
Elevated Temperatures ◽  
Surface Hardness ◽  
Heat Treatments ◽  
Age Hardening ◽  
Material Strength ◽  
Post Heat Treatment ◽  
Treatment Procedure

Recent investigations revealed major fluctuations in the material properties of selective laser melted AlSi10Mg, which corresponded with the varying precipitation-hardening state of the microstructure, caused by the differing dwell times at elevated temperatures. It was indicated that a subsequent heat treatment balances the age-hardening and results in a homogenized material strength. In order to further investigate this statement selective laser melted AlSi10Mg samples were subject to multiple post-heat-treatments. Subsequently, the surface hardness and tensile strength was determined and compared with the as-built results. The post-heat-treatment led to an arbitrary occurrence of rupture, indicating a successful homogenization, coupled with a remarkable improvement in ductility, but to the costs of a lowered tensile strength, which was highly dependent on the chosen heat-treatment procedure.

scholarly journals Sarawak Peat Characteristics and Heat Treatment

2014 ◽  
Vol 5 (3) ◽  
pp. 6-12 ◽  
Author(s):  
N. M. Sa’don ◽  
A. R. Abdul Karim ◽  
W. Jaol ◽  
W. H. Wan Lili
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Ph Value ◽  
Particle Density ◽  
Heat Treatments ◽  
Organic Content ◽  
Ground Subsidence ◽  
Empirical Correlations ◽  
Atterberg Limit ◽  
Ph Values

   Peat layer is extensively scattered over the land of Malaysia. In Sarawak alone, peatland represents 13 percent (about 1.66 million hectares) of Sarawak’s total land area. They are present, mostly in low-lying areas; with in some areas, peat exceeding 10 m in depth. During past few decades, the demands on development of land were expanded into the swamp and deep peat areas which cannot be avoided. Thus proper management and construction practices should be emphasized, in order to overcome consequential occurrence of ground subsidence problems. The objectives of this study are to determine the characteristics of Sarawak peat, their empirical correlations as well as the effect of heat treatment on peat. The samples were taken from Matang, Batu Kawa, and Kota Samarahan sites, in Sarawak. The characteristic tests consist of degree of humidification, loss on ignition, Atterberg limit, particle density, moisture content and pH value. The results recorded high moisture content and organic content of Sarawak peat. It is also being categorized under the hemic group with pH values ranging from 3 to 4. The heat treatments with temperatures ranging from 100°C to 400°C were used on the peat samples. Samples collected were undergoing heat treatment and changes to its physical characteristic were compared with the original Sarawak peat. It was found that the heat treatments do influence the physical properties of Sarawak peat and have shown significant reduction in the compression index determined through the empirical correlations.    

scholarly journals The Effect of Heat Treatment of Skim Milk upon the Baking Quality of the Evaporated and Dried Products

1927 ◽  
Vol 10 (4) ◽  
pp. 335-342 ◽  
Author(s):  
George R. Greenbank ◽  
Mabel C. Steinbarger ◽  
E.F. Deysher ◽  
George E. Holm
Keyword(s):  
Heat Treatment ◽  
Skim Milk ◽  
Baking Quality

scholarly journals Effect of Hydrocolloids and Emulsifiers on Baking Quality of Composite Cassava-Maize-Wheat Breads

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Maria Eduardo ◽  
Ulf Svanberg ◽  
Lilia Ahrné
Keyword(s):  
Acid Ester ◽  
Specific Volume ◽  
Quality Attributes ◽  
Bread Quality ◽  
Loaf Volume ◽  
Baking Quality ◽  
Composite Flours

Cassava is widely available worldwide but bread quality is impaired when cassava is used in the bread formulation. To overcome this problem, different improvers were tested in the preparation of composite cassava-maize-wheat (CMW) breads. Emulsifiers, diacetyl tartic acid ester of monoglycerides (DATEM), sodium stearoyl-2-lactylate (SSL), and lecithin (LC); and hydrocolloids, carboxymethylcellulose (CMC) and high-methylated pectin (HM pectin) were added during dough preparation of the composite flours (cassava-maize-wheat, 40 : 10 : 50). Each emulsifier was tested in combination with the hydrocolloids at levels of 0.1, 0.3, and 0.5% while hydrocolloids were used at a level of 3%. Bread quality attributes such as specific loaf volume, crust colour, crumb moisture, and firmness were measured. The specific volume of the fresh breads significantly improved with the addition of hydrocolloids (7.5 and 13%) and in combination with emulsifiers (from 7.9 to 27%) compared with bread produced without improvers. A significant improvement of brownness index and firmness of the composite flours breads was achieved with the addition of hydrocolloids and emulsifiers. The results show that emulsifiers and hydrocolloids can significantly improve the baking quality of CMW breads and thereby enhance the potential for using locally produced flours in bread baking.

Influence of Adopted Heat Treatments on Properties of Tri-Layer Composite AA2519 – AA1050 – Ti GR.5 Made by Explosive Cladding Method

2016 ◽  
Vol 687 ◽  
pp. 71-78
Author(s):  
Michał Najwer ◽  
Grzegorz Kwiatkowski
Keyword(s):  
Heat Treatment ◽  
Heat Treatments ◽  
Strength Test ◽  
Multilayer Material ◽  
Explosive Cladding ◽  
Tensile Strength Test ◽  
Heat Treated ◽  
Layer Composite ◽  
Structural Tests

The article shows the results of research on tri-layer composite AA2519-AA1050-Ti Gr. 5 made by explosive cladding method. Performed bond was heat treated in different conditions. Four specimens were heated in 530°C in 30 minutes, and after adopted different ways of cooling for each specimen. Used cooling in air and water. Additionally two specimens were aged at 150°C for 600 minutes. Last joint was heated at 420°C for 60 minutes and after was cooled in still air. For obtained joint were performed mechanical and technological tests. Tests included tensile strength test, yield strength test, ram strength test and bend test. Moreover performed structural tests, analysis of the chemical composition and hardness measurements. Based on the results evaluated the quality of joint, and described the influence of heat treatment on the properties of obtained multilayer material. Was found that as a result of explosive cladding, hardness in the interface increased. Heat treatments at temperature 530°C do not change properties. Only the heat treatment at temperature 420°C is decreasing hardness in the interface and in the whole cross section of the AA2519 layer.

Influence of a gene causing hardness on the milling and baking quality of two wheats

1969 ◽  
Vol 20 (6) ◽  
pp. 971 ◽  
Author(s):  
KJ Symes
Keyword(s):  
Particle Size ◽  
Genetic Background ◽  
Loaf Volume ◽  
Near Isogenic Lines ◽  
Simple Process ◽  
Hard Wheat ◽  
Baking Quality ◽  
Handling Characteristics ◽  
Size Index

Near-isogenic lines of Falcon, a hard wheat with good baking quality and high milling extraction, and Heron, a soft wheat of medium baking quality and rather low milling extraction, were produced differing only in the gene which determines hardness as measured by the particle size index. It is shown that the superiority of Falcon in milling extraction, loaf texture, and dough handling characteristics is very strongly associated with the gene which causes it to be a hard wheat. While Falcon generally has a loaf volume superior to that of Heron, if the genetic background of two wheats is identical except for hardness, soft wheats have higher loaf volumes. Because these three variables, which largely constitute total loaf score, are not all favoured by the same particle size index, total loaf score is less clearly influenced by hardness. Nevertheless hard wheats are always superior to, or not significantly different from, soft wheats of the same pedigree in this respect. This work points out the difficulty of producing really good quality soft wheats but on the other hand shows that soft wheats can easily be improved in at least some features of baking quality by the simple process of making them hard.

Dough and Breadmaking Properties of Wheat Flour Substituted by 10% with Germinated Quinoa Flour

2005 ◽  
Vol 11 (6) ◽  
pp. 471-476 ◽  
Author(s):  
S. H. Park ◽  
N. Morita
Keyword(s):  
Physical Properties ◽  
Wheat Flour ◽  
Loaf Volume ◽  
Baking Quality ◽  
Wheat Dough ◽  
The Stability ◽  
Stability Time ◽  
Quinoa Flour ◽  
Wheat Flours

Dough physical properties and baking quality of wheat flour substituted by 10% with non germinated quinoa flour (control), 24-h, 48-h and 72-h germinated quinoa flours were studied. The stability time and valorimeter value of the control and 24-h germinated quinoa flour substituted wheat flours were significantly longer and higher than those of 48-h and 72-h samples. The 10% substitution of germinated quinoa flour for wheat flour made distinctly harder dough than that of the control. The low amount of total and inner gas generations was observed for the 48-h and 72-h samples, as compared with those of the control and 24-h germinated quinoa samples. SEM observations showed that the gluten matrix of the control and 24-h germinated quinoa flour substituted wheat dough seemed to be more extended and more dispersed than those of 48-h and 72-h samples. The loaf volume of bread made from 24-h germinated quinoa flour substitution for wheat flour was the largest among the germinated samples; however, no significant differences were observed between the control and 24-h samples.

Effect of preharvest applications of glyphosate on the drying, yield and quality of wheat

1994 ◽  
Vol 74 (2) ◽  
pp. 221-230 ◽  
Author(s):  
A. L. Darwent ◽  
K. J. Kirkland ◽  
L. Townley-Smith ◽  
K. N. Harker ◽  
A. J. Cessna ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Moisture Content ◽  
Standing Crop ◽  
Seed Quality ◽  
Seed Moisture Content ◽  
Baking Quality ◽  
Moisture Contents ◽  
Seed Moisture ◽  
Direct Cutting

In experiments conducted from 1988 to 1990 at four locations in the Parkland zone of western Canada, the drydown of seed and foliage, seed yield, seed quality and baking quality of wheat (Triticum aestivum L.) following preharvest applications of glyphosate were compared with those following windrowing prior to harvest or direct cutting of the standing crop. Glyphosate was applied in late July to early September at rates of 0.45, 0.9 and 1.7 kg acid equivalent ha−1 to wheat with seed moisture contents ranging from 80 to 11%. When compared with a standing crop, all glyphosate treatments applied at seed moisture contents above 25% slightly enhanced the drydown of wheat seed and foliage. Treatments applied at seed moisture contents below 25% had no effect on either seed or foliage drydown. Seed yields were generally greater from plots to which glyphosate was applied than from windrowed control plots, although in one of five experiments the reverse trend occurred. Increasing the rate from 0.45 to 1.7 kg ha−1 had no effect on yield. Windrowing or applying glyphosate to wheat with a seed moisture content of 61% or more reduced yields more than windrowing or applying glyphosate at seed moisture contents below this level. In experiments where the wheat in both control and sprayed plots was direct cut at maturity, average yields decreased as the rate of glyphosate increased from 0 to 1.7 kg ha−1. However, applications at seed moisture of 40% or less, caused little or no yield loss. There was little or no difference in 1000-seed weight, sample density, seed germination and protein content from plots sprayed with glyphosate at seed moisture contents below 40% than from control plots windrowed at the same moisture content or direct cut at maturity. Baking quality was not affected by any of the glyphosate treatments in experiments where the wheat was harvested by direct cutting. Key words: Glyphosate, wheat, desiccation, wheat quality, Triticum aestivum

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