Improvement Of Baking Quality Research Articles

An investigation on the effect of heat-moisture treatment on baking quality of wheat by using response surface methodology

Effect of heat-moisture treatment on quality properties of two bread wheats (cvs. Tosunbey and Bayraktar) were investigated by using response surface methodology (RSM). Temperature and moisture conditions in the experimental design were in the range of 55–95 °C and 13–19%. Heat-moisture treated grains were milled into flour and quality properties were determined. The optimum moisture-temperature combination for the highest dry gluten, Zeleny sedimentation, Alveograph W and bread volume values were estimated as 14%-63 °C for Tosunbey and 19%-55 °C for Bayraktar samples. Alveograph W seems to be a good indicator of baking quality for wheats treated at higher temperatures. In order to describe the relationship between the dependent and independent variables (moisture, temperature), the response values were fitted by second order polynomial models. Significance analysis showed that the effect of both moisture and temperature on dry gluten content, sedimentation and falling number values for Tosunbey; falling number and damaged starch values for Bayraktar were significant (p < 0.05). The effect of temperature on Farinograph water absorption, W and P/G, bread volume and firmness values were significant for both cultivars (p < 0.05). It can be concluded that improvement in baking quality can be achieved and flours with different properties can be produced by heat-moisture treatments on wheat.

Breeding progress, environmental variation and correlation of winter wheat yield and quality traits in German official variety trials and on-farm during 1983\u20132014

Key messageOver the last 32 years, a large gain in grain yield (24%) was achieved in official German variety trials, and despite considerable loss in protein concentration (−7.9%), winter wheat baking quality was partially improved over the last 32 years. On-farm gain in grain yield (32%) exceeded gain in trials, but at yield level about 25 dt ha−1lower. Breeding progress was very successfully transferred into both progress in grain yield and on-farm baking quality.Long-term gains in grain yield and baking quality of 316 winter wheat varieties from German official trials were evaluated. We dissected progress into a genetic and a non-genetic part to quantify the contribution of genetic improvement. We further investigated the influence of genotype and environment on total variation by estimating variance components. We also estimated genetic and phenotypic correlation between quality traits. For trial data, we found a large gain in grain yield (24%), but a strong decline in protein concentration (−8.0%) and loaf volume (−8.5%) relative to 1983. Improvement of baking quality could be achieved for falling number (5.8%), sedimentation value (7.9%), hardness (13.4%), water absorption (1.2%) and milling yield (2.4%). Grain yield, falling number and protein concentration were highly influenced by environment, whereas for sedimentation value, hardness, water absorption and loaf volume genotypes accounted for more than 60% of total variation. Strong to very strong relations exist among protein concentration, sedimentation value, and loaf volume. On-farm yields were obtained from national statistics, and grain quality data from samples collected by national harvest survey. These on-farm data were compared with trial results. On-farm gain in grain yield was 31.6%, but at a mean level about 25 dt ha−1 lower. Improvement of on-farm quality exceeded trial results considerably. A shift to varieties with improved baking quality can be considered as the main reason for this remarkable improvement of on-farm baking quality.

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

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.

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

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

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.