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 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.

gluten quality involves the addition of low levels of gluten, ied typically are compared to results obtained by some about 2%, to a standard test flour, which often is of a type of baking test. McDermott [85] compared baking "weak" type, and observing the effects on bread quality. (Chorleywood bake test) and other properties of 30 com-Water absorption is adjusted as appropriate for the gluten mercial glutens, mostly of European origin (Table 8), and levels added [23]. A stressed gluten-enriched baking test found that under his test conditions six samples were of was identified [31], which assumes that gluten is added to relatively poor quality; correlation between baking perfor-enable production of specialty breads using substantial mance and other measured properties was not high. levels of non-gluten-containing ingredients such as rye Weegels and Hamer [130] studied a group of 32 European flour, dietary fiber, bran and germ, or raisins [49]. Czucha-commercial glutens. These workers devised a test involv-j owska and Pomeranz [31] described a simple, repro-ing protein content, denaturation index (based on a series ducible method for baking undiluted gluten, highly corre-of sodium dodecyl sulfate sedimentation measurements), lated with the gluten-enrichment baking test. and extensigraph resistance; a model utilizing these tests A prime reason for performing end-use tests of func-was able to predict 59% of the baking quality variation of tionality, of course, is to monitor variations in the quality the glutens. Bushuk and Wadhawan [20] examined 27 of commercial wheat glutens that can occur. Differences commercial gluten samples, although only 8 were subject-among commercial gluten are usually attributable to varia-ed to extensive end-use testing; the highest correlation co-tions in the starting material, wheat or flour, and/or efficients were between loaf volume and acetic acid-solu-changes caused by production processing conditions. Dur-ble protein (r = 0.88) and between loaf volume and ing processing, the drying of gluten is critical, as noted fluorescence of acetic acid extract (r = 0.98). above, and investigators have shown that less than opti-mum heat treatment can lower the baking quality of gluten (b) Nonbaking Tests. Considerable efforts have been [14,49,98,111,130]. However, McDermott [85] reported expended in developing nonbaking tests to evaluate the no definite relationship between manufacturing variables quality or vitality of wheat gluten for baking purposes. The and gluten quality in a group of 30 commercial glutens. baking test is often cited as being labor intensive, relative-Dreese et al. [38] studied commercial and hand-washed ly expensive, requiring skilled workers, and not effectively lyophilized gluten and found that differences were more differentiating gluten quality [86]. The farinograph has attributable to washing procedures than to drying proce-been used to evaluate gluten for many years. The usual ap-dures. proach has been to test the gluten as a gluten-flour mixture Results obtained by other methods that have been stud-(e.g., Refs. 5, 18, 36, and 49), while an alternative method TABLE 8 Properties of 30 Commercial Glutens Baking performance Property Average Range Poor Average Good Increase in loaf volume, %a 10 7.7-12.2 8.3 10.2 11.8 Protein, %b 77.4 66.4-84.3 76.2 77.4 81.1 Moisture, % 7.55.3-10.2 8.877.7 Particle size, % <160 p.m 88.8 55.8-98 80.5 91 90.3 Color 68.3 56.5-75 65.2 68.9 69.5 Lipid, % 5.84.2-7.65.86.15.1 Ash, % 0.69 0.44-0.94 0.71 0.74 0.6 Chloride, %` 0.08 0.01-0.28 0.10.08 0.08 Water absorption, mug protein 2.37 1.84-2.93 2.26 2.45 2.29 SDS sedimentation volume, ml/g protein 99 55-159 70 107 127 Lactic acid sedimentation, % reduction in turbidity 18 2-68 49 11 7 Hydration time, min 0.90.2-10 2.72.40.6 Extensibility, units/min 3.80.7-9.33.23.93.9 Viscosity, cP 117 73-222 159 109 101 '2% gluten protein. Dry matter basis. `As NaCl. Source: Ref. 85.

2000 ◽  
pp. 779-792
Keyword(s):  
Acetic Acid ◽  
Water Absorption ◽  
Wheat Gluten ◽  
Sodium Dodecyl ◽  
Standard Test ◽  
Loaf Volume ◽  
Performance Property ◽  
Baking Quality ◽  
Gluten Quality ◽  
End Use

Effect of Heat Treatment on Decay Resistance of Chinese Fir and Pine

2012 ◽  
Vol 468-471 ◽  
pp. 1118-1122
Author(s):  
Yan Jun Li ◽  
Lan Xing Du ◽  
Gou Ying Hu ◽  
Xing Xia Ma
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Treatment Time ◽  
Brown Rot ◽  
Decay Resistance ◽  
Chinese Fir ◽  
Heat Treatment Time ◽  
White Rot ◽  
Heat Treated ◽  
Brown Rot Fungus

To enhance decay resistance, the effect of heat treatment and the variation of chemical composition on Chinese Fir and Pine were investigated in this study — heat treatment temperature was 170°C, 190°C and 210°C, respectively, heat treatment time was 2, 3 and 4hours, respectively. Both of them were subsequently exposed to white-rot fungus and brown-rot fungus. The results showed that:(1) With the increasing of the heat treatment, decay resistance of Chinese Fir and Pine were improved, anti-corrosion of Pine after being heat treated at 190°C which were exposed to write-rot fungus can reach I, anti-corrosion of Chinese Fir after being heat treated at 170°C treated which were exposed to brown-rot fungus could reach I yet, After being heat treated at 210°C for 3 hours , the Chinese fir samples had no measurable weight loss when exposed to the write-rot fungus.(2) There was no remarkable influence on both Chinese Fir and Pine by heat treatment time.(3) The moisture content of Chinese Fir and Pine were lower than the moisture content that the rot fungus need, macromolecule chains such as cellulose and hemicellulose broke down, their contents decreased, and the hemicellulose decomposed into acetic acid, they prevented the growth of rot fungus.

scholarly journals Modeling the influence of thermal modification on the electrical conductivity of wood

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Christian Brischke ◽  
Kathrin A. Sachse ◽  
Christian R. Welzbacher
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Moisture Content ◽  
Electrical Resistance ◽  
Specific Resistance ◽  
Thermal Modification ◽  
Heat Treated ◽  
Wood Temperature ◽  
Color Data

Abstract A model has been developed aiming at the description of the effect of thermal modification on the electrical conductivity of wood. The intention was to calculate the moisture content (MC) of thermally modified timber (TMT) through the parameters electrical resistance R, wood temperature T, and CIE L*a*b* color data, which are known to correlate well with the intensity of a heat treatment. Samples of Norway spruce (Picea abies Karst.) and beech (Fagus sylvatica L.) samples were thermally modified in laboratory scale at 11 different heat treatment intensities and the resistance characteristics of the samples were determined. Within the hygroscopic range, a linear relationship between the resistance characteristics and the mass loss (ML) through the heat treatment was established. Based on this, a model was developed to calculate MC from R, T, and ML. To validate this model, color values of 15 different TMTs from industrial production were determined for estimation of their ML and fed into the model. MC of the 15 arbitrarily heat-treated TMTs was calculated with an accuracy of ±3.5% within the hygroscopic range. The material-specific resistance characteristics based on experimental data led to an accuracy of ±2.5%.

scholarly journals Haptic and Aesthetic Properties of Heat-Treated Modified Birch Wood

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1081
Author(s):  
Vlastimil Borůvka ◽  
Přemysl Šedivka ◽  
David Novák ◽  
Tomáš Holeček ◽  
Jiří Turek
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Heat Capacity ◽  
Moisture Content ◽  
Thermal Characteristics ◽  
Treated Wood ◽  
Treatment Temperature ◽  
Birch Wood ◽  
Positive Perception ◽  
Heat Treated

This paper deals with the effect of heat treatment on the selected physical properties of birch wood. Five stages of heat treatment were used, ranging from 160 °C to 200 °C, in 10 °C increments, having a peak treatment duration of 3 h for each level. Primarily, changes in thermal characteristics, namely conductivity, diffusivity, effusivity, volume heat capacity, changes in colour and gloss parameters, mass loss due to modification and different moisture content in wood under given equilibrium climatic conditions, were monitored. The ISOMET 2114 analyser was used to measure the thermal characteristics. The measurement principle of this analyser is based on the analysis of the thermal response of the analysed material to pulses of heat flow. Measurements of colour, gloss, density and moisture content were carried out according to harmonised EN standards. The aim was to experimentally verify the more or less generally known more positive perception of heat-treated wood, both by touch and sight, i.e., the warmer perception of darker brown shades of wood. In terms of thermal characteristics, the most interesting result is that they gradually decrease with increasing treatment temperature. For example, at the highest treatment temperature of 200 °C, there is a decrease in thermal conductivity by 20.2%, a decrease in volume heat capacity by 15.0%, and a decrease in effusivity by 17.7%. The decrease in thermal conductivity is nearly constant at all treatment levels, specifically at this treatment temperature, by 6.0%. The fact mentioned above is positive in terms of the tactile perception of such treated wood, which can have a positive effect, for example, in furniture with surface application of heat-treated veneers, which are perceived positively by the majority of the human population visually or as a cladding material in saunas. In this context, it has been found that the thermal modification at the above-mentioned treatment temperature of 200 °C results in a decrease in brightness by 44.0%, a decrease in total colour difference by 38.4%, and a decrease in gloss (at an angle of 60°) by 18.2%. The decrease in gloss is only one essential negative aspect that can be addressed by subsequent surface treatment. During the heat treatment, there is also a loss of mass in volume, e.g., at a treatment temperature of 200 °C and subsequent conditioning to an equilibrium moisture content in a conditioning chamber with an air temperature of 20 ± 2 °C and relative humidity of 65 % ± 5%, there was a decrease by 7.9%. In conclusion, the experiments clearly confirmed the hypothesis of a positive perception of heat-treated wood in terms of haptics and aesthetics.

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 Heat Treatment on the Static and Dynamic Sorptive Behavior of Moso Bamboo (Phyllostachys pubescens)

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Yuxiang Huang ◽  
Ru Liu ◽  
Fandan Meng ◽  
Yanglun Yu ◽  
Wenji Yu
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Moisture Sorption ◽  
Moso Bamboo ◽  
Chemical Components ◽  
Sorption Behavior ◽  
Phyllostachys Pubescens ◽  
Phase Lag ◽  
Heat Treated ◽  
Hemicellulose Removal

The influence of heat treatment on moisture sorption behavior of moso bamboo (Phyllostachys pubescens), especially under dynamic sorption conditions, was investigated. Moso bamboo was heated to 180 and 200°C for 8 h to investigate the chemical components and sorptive behavior at sinusoidal relative humidity (RH) and constant humidity. The results of chemical components revealed that the content of holocellulose,α-cellulose, and hemicellulose decreased while that of lignin increased slightly with increasing treatment temperatures. The results of static adsorption at constant RH showed that 200°C treated bamboo exhibited the lowest moisture content and moisture sorption coefficient. The results of dynamic sorptive behavior indicated that the moisture content changed sinusoidally but lagged behind the triggering sinusoidal RH changes. Heat-treated bamboo presented greater phase lag and smaller amplitudes of moisture content and sorption hysteresis due to the hemicellulose removal.

scholarly journals Chemical and Sensory Parameters of Heat-treated Vacuum-packaged Broiler and Hen Fillet Products

2012 ◽  
Vol 27 (1) ◽  
pp. 54-58 ◽  
Author(s):  
Kristine Ramane ◽  
Envija Strautniece ◽  
Ruta Galoburda
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Protein Content ◽  
Meat Products ◽  
Fat Content ◽  
Sensory Properties ◽  
Poultry Meat ◽  
Heat Treated ◽  
Sensory Parameters ◽  
And Storage

Chemical and Sensory Parameters of Heat-treated Vacuum-packaged Broiler and Hen Fillet Products The heat treatment of vacuum-packaged products - Sous vide processing method - that offers convenience and storage stability, combined with poultry meat marinating was used in the current study. The aim of this research was to evaluate the effect of a fruit-vegetable additive on chemical and sensory parameters of heat-treated vacuum-packaged poultry meat products made from broiler or hen fillets. The skinless fillets and other ingredients were packaged in polyamide/polyethylene (PA/PE) pouches, vacuum sealed, marinated, heat treated, and chilled rapidly. The following parameters were evaluated: moisture content (LVS ISO 1442:197), protein content (LVS ISO 937:1978), fat content (LVS ISO 1443:1973), ash content (ISO 936:996), degree of liking, and intensity of sensory properties (ISO 4121: 2003). The smallest changes in moisture content among the studied samples were observed in those prepared with the fruit-vegetable additive if compared to a raw fillet. In the process of heat treatment, the protein content in dry matter of broiler and hen fillet decreased (p<0.05), whereas fat content decreased in broiler fillet but increased in hen fillet (p<0.05). Sensory evaluation results showed that panellists preferred broiler fillet (6.6) and hen fillet (5.8) products which were prepared without the fruit-vegetable additive. Evaluation of the intensity of sensory properties showed that there do not exist significant differences in aroma, colour, flavour, and aftertaste of heat-treated vacuum-packaged hen and broiler fillet (p>0.05), but texture of broiler fillet products is more tender than texture of samples made from hen fillet.

Effect of a Complex Heat Treatment on the Structure of 300M Steel

1981 ◽  
Vol 39 ◽  
pp. 312-313
Author(s):  
R. Padmanabhan ◽  
W. E. Wood
Keyword(s):  
Heat Treatment ◽  
Metal Carbides ◽  
Austenite Grain Size ◽  
300M Steel ◽  
Heat Treated ◽  
Strain Fracture ◽  
Prior Austenite Grain Size ◽  
Short Time ◽  
Final Tempering ◽  
Similar Yield

Intermediate high temperature tempering prior to subsequent reaustenitization has been shown to double the plane strain fracture toughness as compared to conventionally heat treated UHSLA steels, at similar yield strength levels. The precipitation (during tempering) of metal carbides and their subsequent partial redissolution and refinement (during reaustenitization), in addition to the reduction in the prior austenite grain size during the cycling operation have all been suggested to contribute to the observed improvement in the mechanical properties. In this investigation, 300M steel was initially austenitized at 1143°K and then subjected to intermediate tempering at 923°K for 1 hr. before reaustenitizing at 1123°K for a short time and final tempering at 583°K. The changes in the microstructure responsible for the improvement in the properties have been studied and compared with conventionally heat treated steel. Fig. 1 shows interlath films of retained austenite produced during conventionally heat treatment.

“In vitro” and in Animal Model Studies on a Double Virus- Inactivated Factor VIII Concentrate

1995 ◽  
Vol 74 (03) ◽  
pp. 868-873 ◽  
Author(s):  
Silvana Arrighi ◽  
Roberta Rossi ◽  
Maria Giuseppina Borri ◽  
Vladimir Lesnikov ◽  
Marina Lesnikov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Animal Model ◽  
Factor Viii ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Virus Inactivation ◽  
Enveloped Viruses ◽  
Model Studies ◽  
Heat Treated

SummaryTo improve the safety of plasma derived factor VIII (FVIII) concentrate, we introduced a final super heat treatment (100° C for 30 min) as additional virus inactivation step applied to a lyophilized, highly purified FVIII concentrate (100 IU/mg of proteins) already virus inactivated using the solvent/detergent (SID) method during the manufacturing process.The efficiency of the super heat treatment was demonstrated in inactivating two non-lipid enveloped viruses (Hepatitis A virus and Poliovirus 1). The loss of FVIII procoagulant activity during the super heat treatment was of about 15%, estimated both by clotting and chromogenic assays. No substantial changes were observed in physical, biochemical and immunological characteristics of the heat treated FVIII concentrate in comparison with those of the FVIII before heat treatment.

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