It seems that the stars are aligned or something for me to continue my discussion on water and material science. Not only did Dario comment on my Water Activity post asking me to discuss the relationship between glass transitions and water activity, but in a recent Friday Sprog post on Janet’s blog, she discussed phases of matter and a commenter talked about materials that was both solid and liquid. These materials are known as amorphous materials – there seems to confusion as to whether they are solid or liquid because they can have the behavior of both phases. Amorphous materials do not have the regular, ordered pattern of crystalline solids and they typically have more structure than a liquid.
Many foods are amorphous. In fact, very few foods are true crystalline solids or true liquids. Those that are; salt, sucrose, oils; are generally pure compounds. In most foods, water is present with solutes; salts and sugars; and polymers; proteins, complex carbohydrates, and lipids. These interfere with the standard behavior of pure water.
To get you started Janet has a great post about the typical three phases of matter that you meet in high school chemistry class, namely solid, liquid and gas. In that post she represents a great phase diagram:
This is a great representation for materials such as water that have a crystalline solid, ice, and when pure easily convert into a liquid. The point of change between ice and water is the melting point if you increase the temperature or the freezing point if you decrease the temperature.
As you add solutes to water the temperature of freezing/melting changes. Freezing occurs at a lower temperature. This is one of the colligative properties and is the reason why, as long as you don’t live anywhere really cold like Minnesota, a dilute solution of salt can be used as an antifreeze, as it freezes at a lower temperature than pure water. Here is a phase diagram from Spark Notes showing both the pure solution and the solution with dissolved solutes:
This is true of whatever solute you use, so sugar would have a similar influence on the freezing temperature. Thus, food freezes at a lower temperature than pure water. If you have ever seen the Alton Brown episode on Thanksgiving the turkey guy talks about the different temperatures and definitions of fresh, hard chilled and frozen turkey. They are also given here. For instance:
Any turkey labeled “fresh” in a food store has never been cooled to a temperature lower than 26°F, which is the point that turkey meat begins to freeze.
[…]in order to be considered “frozen” a turkey must be cooled to a temperature of 0°F or below.
Obviously, hard chilled turkeys are stored between 0 and 26F.
So where does that get us?
Pure water has three phases: ice, water and steam (or solid, liquid and gas for other materials) and the phase change temperatures are influenced by the presence of solutes and polymers present in the liquid. Additionally, as a food freezes, the water typically freezes out, leaving behind a more and more concentrated solute liquid phase. This can result in an change in pH, viscosity amongst other properties. In some instances, the solute-liquid phase might never solidify. If a food is rapidly cooled to below the freezing temperature, a glass may be formed. A glass is an amorphous solid that has a disordered structure while behaving like a highly viscous solid. In some frozen foods, water will freeze to from crystalline ice and the solute-liquid phase will form a glass.
Out on Friday night with friends going blueberry and sour cherry picking near the Conowingo Dam. On the way home we stopped on the way to walk along the Susquehanna river near Port Deposit MD, when we saw this Great Blue Heron. It was so still, I thought it was a statue at first. Herons are very cool.
Encouraged by the commentators on Magical Water Part 2, I am revisiting a year old New Scientist article on the wonders of water. When I read it last April (I actually subscribe to NS, having read it for over twenty years it is hard to give it up) I was disturbed as the article seemed to concentrate a lot on Massru Emoto’s work on how emotion alters water crystal shape. His work was used in that weird movie “what the bleep!?” which left me very uncomfortable. I was also left feeling uncomfortable after reading the New Scientist article. Amongst the new age woo, there were statements by scientists, such as Dr Felix Frank who did research on the role of water in food shelf life and stability. I even had the opportunity to meet Dr Frank as I was asked to co-chair a session on the “Role of Water Functionality” at one of the Institute of Food Technologists’ annual meetings. I just have assume that Dr Frank has either joined the ranks of great scientists tripping over the great wonders of woo. The greatest member of that group being Dr Linus Pauling with his ideas about Vitamin C. Or he has been misused by New Scientist. Admittedly his comments are not too far out but it is the company that he is keeping that bothered me.
I digress. One of the reasons I didn’t get round to writing this article last April, other than day to day distractions, is that Orac chose Massru Emoto and his studies for one of his Friday Doses of Woo. All covered, I thought, by Orac. Additionally while searching for information on water and, in particular the zero point energy, I found this great site on water which is going to save me a lot of time, but also discouraged me from writing on water for a while.
The New Scientist article strongly implied that there might be something in the new age theories by using scientific studies, and talking about the quantum effects of water and the fact that water is necessary for many proteins and even DNA (gosh, the molecule of life) to function correctly. I also got discouraged because they talked about the zero-point vibration* properties of water as if this was really important and I had never heard of it before and couldn’t find anything out about it that I understood. I even asked people for help on my last magical water posts and it was confirmed that zero point energy is obviously serious woo. They even mention hydrogen bonding and the unique behavior of frozen water in hushed terms as if it was something new that no one understood.
We have known for a long time that many molecules need water as part of their structure. Known as the water of hydration, this water cannot be removed without chemical compounds losing their structure, and in the case of proteins, function.
Considering how little is known about the chemistry of water – it was disappointing to see how much space was wasted on new age theories.
I do actually believe water is amazing. See my scientific posts on water to find out how truly amazing water is without needing to add woo.
* I am sure this definition helps:
(′zir·ō ¦pöint vī′brā·shən) (statistical mechanics) The vibrational motion which molecules in a crystal lattice, or particles in any oscillator potential, retain at a temperature of absolute zero; it is quantum-mechanical in origin. Also known as residual vibration.