Hard Bread and Soft Cookies
One evening we neglected to do the usual kitchen clean-up. I discovered in the morning that although a bread stick had become so hard I could use it as a hammer, our cookies had become soft and unappetizing.
Cookies and bread differ in both composition and texture. Cookies are denser, and contain much more sugar than bread does. Cookies become soft because finely powdered sugar is what we call hydroscopic: that is, it soaks up moisture from the atmosphere. The dense texture of the cookie helps retain and distribute that adsorbed moisture by capillary action. The denser the cookie is, and the more sugar it contains, the more likely it is to go soggy.
Bread has little or no sugar to attract water vapour. Bread also has a more open structure, and so there is little capillary action. However, there is a much greater surface from which moisture can be lost. The reason bread becomes harder when it goes stale is because the starch molecules move together in a tighter more ordered arrangement when the moisture which separates them is removed.
You can try your own experiments by putting some open textured biscotti, which is not very sweet, with some crispy sweet cookies in a sealed container. The cookies with high sugar content will gain weight by adsorbing water, whereas the biscotti with no sweetener will lose weight.
So next time you want crisp cookies and soft bread remember to store them properly.
It’s great to be able to do simple experiments and see for ourselves that what we’ve been told is true. In some cases, the experiments simply confirm what we’ve already observed. In others, we can learn something new. I don’t suppose I’ll do the cookie/biscotti experiment because I’ve already seen the expected results in everyday life. What is helpful is the scientific explanation for why cookies soften and breads harden as they get stale. That allows me to make good storage plans for baked goods in the future.
While kitchen chemistry is fairly easy to experiment with, there are some experiments that are totally beyond the resources of any individual. Some would require handling dangerous materials. Some would require advanced technological devices to carry out. The fact is that few of us will do very many experiments at all. We are usually quite willing to accept someone else’s word for what they have observed in the laboratory.
If someone we trust, even if we don’t know them personally, relates an observation related to an experience they have had, we generally accept the account. If several others corroborate it independently, we trust it even further. We’re often willing to stake our lives on these things which we learn only from others who, we believe, know what they are talking about.
To be acceptable to scientists, experiments have to be repeatable. This is because they don’t always accept the observations of others and need to test them for themselves. This strengthens the accuracy of scientific theories and laws. The most well established facts of science are accepted widely because every experiment produces the same results.
There are some things, however, which cannot be tested by experimentation. Specifically, things that happened in the past, or relating to people who lived in the past. Some dispute the historical validity of Jesus and the details of His life. Others accept the life and actions of Jesus as fact. Why the difference?
The Bible (and other sources) give several independent accounts of the historical Jesus and the most significant events of His life. While there is some variation in the stories, enough of the details overlap to render a fairly complete biography. The question now is: “Are we prepared to accept the evidence of those who were witnesses of His life?”
David Humphreys and Ron Hughes
© August 2004
