Graduation date: 2007
The primary purpose of this study was to try to (1) provide information on the chemical nature, including turbidity formation, of polygalacturonic acid in different concentrations of NaCl solution. (2) use turbidity formation characteristics to develop an assay for determining the activities polygalacturonic acid depolymerases by using a polyelectrolyte. (3) provide information on the chemical nature, including protein aggregation, of egg albumen in different temperatures of incubation. (4) develop a series of egg experiment to demonstrate the chemical nature of eggs.
The initial phase of the study tested the solubility characteristics of polygalacturonic acid in different NaCl concentrations and different temperature incubations, in order to find the optimum incubation temperature and NaCl concentration which form the turbidity suitable for activity determination of polygalacturonic acid depolymerases. The results demonstrate that the commercial polygalacturonic acid product tested has the stable turbidity formation when incubation temperature is 60oC and higher, and has the critical turbidity concentration of 0.25M NaCl which needs more time to form a stable turbidity. This observation has the potential to develop a new turbidity assay to determine the activity for polygalacturonic acid depolymerase.
To develop another turbidity assay for polygalacturonic acid depolymerase, poly(diallyldimethylammonium chloride) (PDADMAC) is used as the polycation to react with the polygalacturonic acid. The flocculation will form a quantitatively determinable turbidity which is proportional to the polygalacturonic acid concentration. The assay developed has been successfully used for the comparison of fresh tomato and molded tomato polygalacturonic acid depolymerase activities and can be used for quality control laboratories to monitor polygalacturonic acid depolymerase activities.
Egg white protein behavior in different NaCl concentrations and different incubation temperatures as studied in the present study, is important for different egg products. The results revealed that high NaCl concentrations (2M and higher) stabilize the major protein of egg white – ovalbumin. This will provide additional basic protein information to the egg industries.