http://encarta.msn.co.uk/find/Concise.asp?z=1&pg=2&ti=761556236
http://homecooking.about.com/library/weekly/aa072197b.htm
Biology for AQA separate award by Ann Fullick
I have performed the experiment using the method mentioned previously. I have paid attention to the precautions carefully, and tried to do it correctly and as precise as possible and have obtained the following results:
The results shown in the table prove that the higher the temperature, the further the dough will rise, supporting my hypothesis. To support my hypothesis further I had to research, I found the following sites and books helpful:
http://encarta.msn.co.uk/find/Concise.asp?z=1&pg=2&ti=761556236
http://homecooking.about.com/library/weekly/aa072197b.htm
Biology for AQA separate award by Ann Fullick
The graph, on the next page, shows that when dough is heated at a higher temperature it will rise faster. However, if heated in a glass-measuring cylinder, it would have perhaps risen further than it did. This can be seen by comparing the dough at 32˚C in the plastic measuring cylinder (A) and the dough at 22˚C in the glass-measuring cylinder (B). Although A is 10˚C above B for the first fourteen minutes, they are constantly crossing temperatures. A’s line of best fit, starts lower than B, its intercept being 23 and B’s being 32.
From the graph, the differences between the lines can be seen easily, at 37˚C, it had risen the most and at 22˚C, it had risen the least, the difference between the two being 46 cm3. At 22˚C, it raised 28cm3, at 32˚C it raised 44cm3, and at 37˚C it raised 74cm3, and the graph showed this.
From the line of best fit, the lines can be compared by their intercepts and gradients easily. However, the line which each set of results form is more important. Each of them show a steady rise, but the steadiest is the dough at 37˚C, this suggest that perhaps this is an ideal temperature for rising dough, not too high as to kill the yeast and not too low, so it wont grow as fast and as steady. This also helps me to understand why a change in material will help the dough rise faster or slower. If in a glass container, the heat can pass through easily, and so it will rise faster, but because plastic is an insulator, the heat cannot pass through as easily.
In conclusion, I can form the opinion that dough will expand more rapidly when at a higher temperature, perhaps ranging between 30˚and 40˚, and in a container that is not heat resistant, and the graph shows this in a simpler form. I think this because yeast multiplies at a faster rate in a high heat, however, if too high, it will die. Also, the graph shows the dough rising at a steady rate at 37˚C, and so at 40˚C it would perhaps rise faster, and it raises relatively well at 32˚C. Although the yeast would probably rise faster in a higher heat, within bread the carbon dioxide gas given off would probably create pockets within the bread, or the yeast would begin to die. The results have turned out as expected, supporting my prediction.
My method gave evidence that was reliable, and so would be counted on as correct. I believe this because it showed how yeast can be useful and expands dough in higher temperatures. By producing dough and exposing it to the conditions in which I wanted to test it, I could produce reliable results. This was done by measuring the dough carefully and fairly, using the same ingredients as a precaution, making the investigation fair; and then heating it at a steady temperature. By recording it throughout, I was able to produce a graph, to show my results in a clear and precise way.
I think that I have given enough evidence to draw a conclusion. However, I think that this investigation could be advanced, by heating dough at a lower temperature, such as 15˚C, in two different materials, and then the same again at a higher temperature, such as 50˚C, also at a middle temperature, such as 18˚C. By comparing two extremes and an intermediate, we can see if yeast will rise any more rapidly and steadily at the different temperatures and more importantly, if the materials in which they are heated make a difference. This would help support my earlier conclusion, that dough will expand more rapidly when at a higher temperature, perhaps ranging between 30˚and 40˚, and in a container that is not heat resistant.
