Digestive proteases were isolated from the pancreas of the stomachless cunner fish (Tautogolabrus adspersus) and characterized in terms of their physicochemical properties, their ability to hydrolyze native pectin methylesterase (PME) from orange and polyphenol oxidases (PPO) from mushroom and the ability of the cunner enzyme(s) to maintain the stability of orange juice cloud. / The cunner trypsin fraction exhibited exceptional capacity to hydrolyze native proteins versus the bovine trypsin. Incubation of native PME with cunner or bovine trypsin resulted in a loss of 75% or 35% in PME activity respectively. Similarly, a 75% or 55% loss in PPO activity was observed after treatment with cunner and bovine trypsin respectively. Bovine trypsin, however, hydrolyzed the heat-denatured PME and PPO better than the cunner trypsin. Also, there was no reactivation of both PME and PPO activity after treatment with either the cunner or bovine enzyme during storage at 4$ sp circ$C for 3 weeks. However, PPO retained up to 20% or 50% of the initial activity after treatment with cunner or bovine trypsin, respectively. / A 3 x 3 factorial design involving the factors of temperature, enzyme concentration and incubation time carried out gave an r$ sp2$ of 0.92 and 0.95 for cunner and bovine trypsin treated PME respectively. On the other hand, an r$ sp2$ of 0.91 and 0.94 was obtained for the combined effects using cunner and bovine trypsin for PPO inactivation. Validation of the model of PME inactivation measured as the % cloud remaining revealed that the cunner trypsin fraction upheld the cloud stability of cloud juice better than bovine trypsin, with cunner trypsin retaining more than 90% of the cloud whereas the juice treated with bovine trypsin only resulted in a 70% retention of the juice cloud. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28033 |
| Date | January 1997 |
| Creators | Kyei, Mary Abena. |
| Contributors | Simpson, B. K. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Food Science and Agricultural Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001642420, proquestno: MQ37309, Theses scanned by UMI/ProQuest. |
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