V.F. Rasper

The ability of chlorine and chlorine-related oxidants to induce oxidative gelation in wheat flour pentosans

Aqueous solutions of water-soluble non-starch polysaccharides (WSNP) were extracted from untreated wheat flours and subjected to various oxidant systems (H2O2,-peroxidase, sodium chlorite, gaseous chlorine, chlorine dioxide, chlorine dioxide/peroxidase and ferric chloride). The increase in viscosity of the solutions, as a result of the oxidative gelation of the WSNP, was dependent on both the type of WSNP (cake, cookie and bread flour WSNP) and on the oxidising agent. Bread flour WSNP underwent more extensive gelation with the H2O2, and ferric chloride systems than did the other WSNP. Bread flour WSNP were the only ones which responded with an increased viscosity to chlorine dioxide in the absence of exogenous peroxidase. With cake and cookie flour WSNP, the presence of the enzyme was necessary to induce gelation. Treatment of cake flour WSNP with gaseous chlorine resulted in the largest increase in flow time recorded for the tested WSNP solutions. The increase in viscosity of the cookie and bread flour WSNP solutions was less pronounced. Treatment of the WSNP solutions with H2O2/peroxidase or C1O2/peroxidase lowered their ferulic acid content. However, no such decrease in ferulic acid content was observed when WSNP solutions were treated with gaseous chlorine.

Measurement of Corn Kernel Hardness

Abstract A Strong-Scott barley pearler and a disc grinding mill were modified and electromechanical sensors were installed so that torque and energy during pearling and grinding could be recorded. These instruments were used to study the effect of moisture content on corn hardness. The results are in agreement with other hardness indices: compression resistance, stiffness, pearling index, breakage index and percentage of grits larger than 1.70 mm produced by grinding (called grinding index). Corn endosperm becomes softer with increasing moisture content; corn bran becomes more plastic. The relationship between grinding energy and grinding index was found to be linear and inverse. The possibility of differentiation between hard and soft corn was satisfactory with the grinding test, pearling test and breakage test; whereas that of the compression test was unsatisfactory. The value calculated from the grinding index divided by grinding energy appears to improve the sensitivity of corn hardness measurements.

Composition of Ontario Soybeans and Soymilk

Abstract Proximate analysis was performed on 55 samples representing varieties of Ontario grown soybeans. All of the samples were made into soymilk and composition of the milk determined. In addition to gross composition, the content of phosphorus, calcium and magnesium was measured. The soymilk was subjected to ultrafiltration and the diffusate analyzed for soluble constituents. All results are presented in the form of frequency distribution charts. Correlations of variables indicated that an increased protein level in soybeans was accompanied by a decrease in fat. Soluble carbohydrates in the diffusate were determined by gas-liquid chromatography of the TMS derivatives. Sucrose was the predominant sugar.

Functionality of Soy Proteins in Wheat Flour/Soy Isolate Doughs. II. Rheological Properties and Bread Making Potential

Abstract The dough and baking performance of wheat flour supplemented with soy protein isolates prepared under different conditions of extraction, precipitation and drying was evaluated in an attempt to relate it to the physical and physico-chemical properties of the supplementing material. Expectedly, the isolates differed most in their hydration capacity and solubility (dispersibility), but there was an ambiguity in the relationship of these properties to the baking performance, displayed most noticeably in the loaf volume depression effect. The involvement of a mechanism other than hydration (e.g., complexing effect of polyvalent calcium, the presence of reactive SH and SS groups) was best demonstrated by the comparison of the isoelectric protein and Ca proteinate. While they both were characterized by a very low hydration and solubility, they were found among the test isolates to exhibit the highest and lowest loaf depressing effect, respectively. Rheological tests (farinography, angiography, extensigraphy), performed on supplemented flour or dough, provided a closer assessment of the suitability of the supplement for bread making. The ranking of the isolates in this respect was not changed by the addition of any surfactant used in the study.

Effect of Polyphosphate Addition in Spaghetti

Abstract The influence of sodium phosphates on the quality of spaghetti was investigated. Appearance and transverse strength of uncooked spaghetti, cooking behavior and cohesion of the cooked spaghetti were monitored. Various phosphates, in levels of 0.5 to 5.0%, were added to a control spaghetti sample. As the level of phosphate increased, colour and appearance deteriorated and transverse breaking strength decreased. Phosphates accelerated the cooking rates and reduced optimum cooking times. Cooking properties were affected detrimentally. There was a reduced volumetric increase, decreased water absorption and an increased loss of cooking solids. Phosphates also reduced the cohesion of the cooked product. The phosphates caused a retraction of the protein matrix; and the starch granules were left exposed to severe cooking conditions. The amide groups of the wheat protein were probably masked. Thus, H-bonding sites were lessened and product cohesion reduced. The addition of sodium phosphates was thus detrimental to spaghetti quality.

Functional Properties of Non-Wheat Flour Substitutes in Composite Flours. I. The Effect of Non-Wheat Starches in Composite Doughs

Abstract Some functional properties relative to breadmaking of starches and flours prepared from tubers of yam (Dioscorea rotundata Poir., Dioscorea alata L., Dioscorea cayenensis Lam.), cormels of cocoyam (Xanthosoma sagittifolium Schott.), roots of cassava (Manihot utilissima Pohl.), fruits of plantain (Musa paradisiaca L.), and grains of sorghum and millet were studied and compared with those of a starch and a typical bread flour of Canadian HRS wheat origin. All materials were tested for gelatinization temperature, pasting characteristics and diastatic activity and an attempt was made to correlate these properties with the results of baking tests performed with mixtures in which 15% of wheat flour was replaced by the tested material. Though considerable differences were found between the starches, the results indicate that in the replacement of wheat flour by any non-wheat flour, the functionalities of other components than starch may play a more significant role than the variations in starch properties. When wheat flour was partially replaced by pure starches, the best baking performance was achieved with blends containing cassava starch. When non-wheat flours were used instead of pure starches, the best loaf volumes were obtained with blends containing yam flours.

An Improved Dough Extensigraph

Abstract An improved dough Extensigraph is described. An electronic system has replaced the standard mechanical sensing system. Forces generated during dough extension are recorded on a rectilinear chart. Cradle depression effects on the measurements are eliminated. Modifications of the Extensigraph increased the precision of measurement and its operational flexibility. The improved Extensigraph readings were correlated with standard Brabender Extensigraph results. Stress relaxation and effects of hook speed were studied. The application of this instrument for the study of the transverse breaking strength of spaghetti demonstrated its operational flexibility.

Pregelatinized rice flours in composite blends for breadmaking

Abstract Rice flours milled from grits pregelatinized to a different degree by extrusion under varying conditions of feed moisture and extrusion temperature, were tested for their dough-making and bread baking potential in mixtures with an untreated strong wheat flour. Although none of the composite mixtures was fully comparable in its functionality to the plain wheat flour control, a noticeable improvement in performance was achieved when rice flours of higher degree of pregelatinization (DG) were used in place of the unex-truded material. Such mixtures were characterized by higher baking absorptions and a potential to give loaves with a less-reduced volume and a markedly lower tendency to firm during storage. An acceptable loaf was obtained with mixtures in which up to 25% wheat flour was substituted with an equal amount of rice flour of DG over 70%.

Functionality of Soy Proteins in Wheat Flour/Soy Isolate Doughs. I. Characterization of Isolates Prepared Using Different Isolation Procedures

Abstract Soy proteins prepared under laboratory conditions using different extraction media (water and alkali), different treatment in the separation of the isolated proteins (isoelectric precipitation and neutralization to form Ca, K and Na proteinates) and drying (freeze-, spray and drum drying) were subjected to chemical and physico-chemical testing in order to establish quantitatively the differences between their nature and their functional behaviour in protein supplemented wheat doughs. (Results of functionality tests will be reported in Part II.) Apart from chemical analysis (including reactive and total SH and SS groups) and N solubility tests, the isolates were compared on the basis of their gel filtration profiles and electrophoretic as well as ultracentrifugation patterns of their major globulin fraction. The tests revealed some consistent differences between the test proteins (e.g., higher SH and SS content in isoelectric protein than in proteinates, minor but consistent differences in the gel filtration profiles of the alkali and water extracted isolates, higher loose bulk density of the former); but water solubility and hydration capacity, measured in terms of both water absorption and retention, gave expectedly the most marked indication of sufficient variability in the nature of the isolated samples for further testing of their functionality.

Bread Baking Potential of UHT-Milk

Abstract The effects of UHT-treated liquid milk on the physical quality of milk-supplemented bread doughs were evaluated by farinography, extensigraphy, maturography and test baking. In comparison with pasteurized milk and scalded milk, the UHT-treated milk tended to give doughs with farinograph absorptions lower than those recorded with the other tested milk doughs, but the doughs appeared stronger and gave better baking results. In addition to lower loaf volume depression, the UHT-treated milk seemed to exhibit a more favourable effect on the crumb firming during storage than the other two heat-treated milks.