Enzymic systems able to hydrolyze the compounds forming
the supporting structure of plant tissues have a major effect upon
the texture of fruit products.
The objective of this thesis was the development of a theory
to explain the textural changes in fresh and processed strawberries.
The presence of pectinolytic enzymes and the substrates upon which
they act were studied. In addition the activity of cellulase was
investigated.
The following conclusions were made:
1. An endopolymethylgalacturonase exists in Northwest
strawberries which catalyzes the hydrolysis of pectins, pectates
and protopectins.
2. The strawberry endopolymethylgalacturonase indicated a
maximum activity at pH values between 4.5 and 5.5.
3. The degree of methylation of the substrate did not appear
to have an influence upon the activity of the enzymes. This enzyme
demonstrated the same rate of action upon Na pectate and citrus
pectin.
4. Sodium chloride solutions at concentrations up to 0.50 M
and calcium ion at concentration 0.01 M did not show any effect on
the activity of the strawberry endopolymethylgalacturonase in citrate
buffer at pH 5.0.
5. The strawberry endopolymethylgalacturonase was inactivated
after heating at 212°F for approximately 35 minutes in citrate
buffer at pH 5.0.
6. Non-enzymic hydrolysis of the strawberry pectic substances
occurs and hydrolysis is more pronounced at lower pH values.
7. The pectinesterase activity in Northwest strawberry is
low in comparison with tomato fruits. The optimum activity of strawberry
P.E. occurred at pH 7.5.
8. While cellulase activity existed in Northwest strawberries,
the strawberry cellulase did not hydrolyze the insoluble strawberry
cellulose. / Graduation date: 1964
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26686 |
| Date | 20 December 1963 |
| Creators | Gizis, Evangelos John |
| Contributors | Dietz, James H. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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