Yeast Dough Research Articles

Behavior of Surface Membrane of Yeasted Dough during Expansion in a Cylinder.

Expansion of yeasted dough in a glass cylinder with time was followed by measuring the dough height with a cathetometer. The gassing power of the dough was estimated by collecting the expelled air and the released carbon dioxide. The volume of dough at which CO2 began to escape from the dough, estimated from the gassing power and dough expansion curves, was higher for rapidly-expanding and oxidized doughs than for slowly-expanding, reduced and control doughs.The doughs which showed higher volumes at the point of CO2 leakage had higher tension of the surface membrane. The top surface of yeasted doughs in the glass cylinder, determined from the measured volume of the dough meniscus, appeared to have the shape of a revolving parabola rather than that of a revolving ellipsoid. In the comparison of these results obtained from the behavior of the dough surface membrane with the results of test baking the former data were found to be applicable to the basic research on baking properties of dough.

Effect of chromosome loss on the leavening ability of Saccharomyces cerevisiae in dough

To investigate the leavening ability of yeast in dough, chromosome loss was induced by benomyl treatment in YOY1037, a diploid between a baking strain and a laboratory strain, and its effect on the leavening ability was studied. When benomyl-treated cells were spread on plates with a dye indicator for ploidy, about 20% of the visible colonies were stained dark blue or dark purple; the rest stained pale blue, similar to the diploid YOY1037. Strains showing the MATα phenotype, and non-galactose fermenting strains, apparently having lost particular chromosomes, were observed only in those with darkcoloured colonies. Strains with dark-coloured colonies showed a wider range of leavening ability than did those with pale-coloured colonies.

Effect of invertase activity on the leavening ability of yeast in sweet dough

Leavening ability of yeast in dough and invertase activity were determined in 32 strains of Saccharomyces cerevisiae. By the regression analysis of the data obtained, participation of invertase in sweet dough leavening was less than the osmotolerance of yeast cells. Four representative strains were selected and further investigation was conducted in these strains. Along with the concentration ofNaCl added to the growth medium, sweet dough leavening increased but invertase activity changed independently. Acid treatment of the cells with diluted HCl deprived the yeast cells of invertase activity in the four strains, and elevated leavening ability was observed in sweet dough in the two strains but not in the other two strains. Addition of purified invertase to the dough gave a limited effect on the sweet dough leavening. These observations suggested that invertase activity was not obligately related to the leavening ability o f sweet dough.

Principal-Component Analysis of the Characteristics Desirable in Baker's Yeasts

Twenty-seven properties considered to be required for good bakery products were examined in 56 industrial and 2 laboratory yeast strains. The data obtained were applied to principal-component analysis, one of the multivariate statistical analyses. The first and second principal components together were extracted, and these accounted for 77.7% of the variance. The first principal component was interpreted as the glycolytic activity of yeast in dough, and the second one was interpreted as the balance of leavening abilities in sweet and flour doughs from the factor loadings. The scattergram on the two principal components was effective in grouping the 58 yeast strains used.

Fate of phytic acid during bread making

AbstractThe effect of malt addition and yeast concentration on the hydrolysis of phytic acid during different stages of bread making has been reported. There was a considerable hydrolysis of phytic acid with the addition of yeast and malt. In the breads of S‐308 and WL‐711 wheat varieties, the loss of phytic phosphorus was 6.6. 8,1; 24.6, 23.0 and 26.6, 27.7% in case of nonyeasted, 1.5% and 3% yeasted dough of whole wheat flour (Atta) respectively. However in white bread, the loss of phytic phosphorus was 14.0 and 18.4; 46.2 and 41.5; 51.7 and 49.4%, in non‐yeasted, 1.5% and 3% yeasted doughs of S‐308 and WL‐711 wheat varieties respectively. A significant loss of phytic acid was observed at a yeast level of 1.5 and 3% and with 0.4% malt addition as compared with the control. Most of the phytic acid was hydrolysed during the fermentation and proofing stages in both types of bread samples.

Technical note: A small‐scale yeasted dough expansion test for the evaluation of breadmaking flours and other bakery ingredients

Technical note: A small‐scale yeasted dough expansion test for the evaluation of breadmaking flours and other bakery ingredients

Hybrid yeast strains capable of raising an extraordinarily broad range of dough types

Over 200 hybrid yeast strains were screened and 11 of these found to have versatile fermentation characteristics. This paper reports the results obtained with these 11 strains compared with a commercially available strain of baker's yeast used for bread making and marketed as “instant active dry yeast”. In contrast to bakers yeast, the hybrid strains fermented very well in yeast, hard biscuit, shortcake and heavy cake dough without prior sponge formation. The fermentation kinetics were investigated and the technical potential of such hybrid strains discussed on the basis of the fermentation kinetics.

LITERATURE ABSTRACTS

LITERATURE ABSTRACTS

ROUTINE METHOD FOR DETERMINATION OF THE ACTIVITY OF BAKER'S YEAST

The baking-strength test, which estimates the fermentative activity of yeast in dough by measuring the time for a standard amount of dough to reach a fixed height under standardized conditions, is subject to a random error of about 2.0 min. In 70 min. In addition, systematic errors associated with days, operators and testing stations are appreciable. These errors are mainly due to atmospheric pressure variations and to difficulties of temperature control during mixing, handling and incubation of large volumes of dough. A critical examination of published methods based on the measurement, at constant pressure or constant volume, of carbon dioxide formation, showed that none of these was entirely suitable for routine use in yeast factories. A new method, which has been called the fermentometer test, is described. This test is based on the measurement of gas evolution from a small volume of thin dough which is under constant temperature conditions throughout test. Many thousands of determinations have been carried out by the new test, which has now been adopted by us as the standard method for determination of the fermentative activity of yeast in dough. The average standard deviation of the fermentometer test is 1.0 ml. in 100.0 ml., and systematic errors are small.

Flour testing. II.—An Alternative Method of Using the Brabender Farinograph and Extensograph for Testing Bread Flours

AbstractA method is described for measuring the water absorption of flour, using a yeasted dough 3 hours after mixing, by determining the minimum mobility on remixing in the Brabender Farinograph. This enables a correction to be applied to derive the water necessary for the dough subsequently stretched on the Extensograph. A yeasted dough is given 3 hours rest before moulding and then a further 30 minutes before stretching. The advantage over the standard method is that untreated and variously treated bread flours are shown in a more correct relation to each other in close agreement with their placings in baking practice.