Class: BE210
Group: W7
Members:
Reidich
Wang
Lee
Kuchinskas
Costello
Date: April 2004
Abstract:
The yeast medium used in lab is made up of three constituents:
dextrose, peptone, and yeast extract. Using the Parr Oxygen
Calorimeter, the caloric value of these three components can be
measured. Dextrose is a form of glucose, peptone is essentially a
combination of amino acids, and yeast extract is primarily dried
protein. Literature values for dextrose give its heat of combustion as
3694 cal/gram. Due to their complex structures, heat of combustion
values could not be attained for peptone and yeast extract. In order to
determine caloric content, careful calibration of the calorimeter is
required. This is done using benzoic acid (which has a heat of
combustion of 6318 cal/gram), to determine W (the energy equivalent of
the calorimeter). It is also necessary to determine if W is constant,
and a property of the calorimeter, or if it depends on the caloric
value of the sample, and if so, what the nature of the dependence is.
Once the calorimeter is calibrated, caloric values can be attained for
each yeast medium constituent. Furthermore, these caloric values may be
correlated with yeast growth, since calories can be converted to energy
by organisms.