Science Buddies: "Ask an Expert"

My science experiment proved that keeping a home made chocolate chip cookie in the refrigerator kept it fresher than in a closet or on a counter. I am looking for research to back up my results. All the sites I have found are not scientific but are baking sites. Is there any research that I can use for this?

Erin - Not a real expert here, so this is just some common sense theory. Refrigeration of food is an important part of slowing food spoilage. This mechanism is based on the slowing of the rate of bacteria growth at lower temperatures to preserve the freshness of the food. You are asking a slightly different question about the "freshness" of a chocolate chip cookie. I think you are referring to the effect that moisture evaporation can have on a fresh, moist cookie. If a fresh cookie is left in a room temperature environment with relatively dry air, it would lose some of it's moisture content and 'dry out' or get 'hard' in a few days, a condition we would associate with losing it's freshness.

There is a definite correlation between water evaporation and temperature that can be researched. The environment of your refrigerator is probably about 5-8 degrees Celsius. This low temperature also means that the refrigerator air is probably pretty close to being saturated by water emanating from other exposed foods and vegetables already in the fridge. That alone limits the rate that a cookie would give up it's moisture in the refrigerator, as the air is already happily 'saturated'. There is also the 'vapor pressure' of water that changes with temperature and pressure. At refrigerator temperatures, it is very low, slowing the rate of evaporation. There is a link attached concerning evaporation that will give you some more insight into this effect. Good luck.

http://en.wikipedia.org/wiki/Evaporation

Rick Marz