Two series of tests were performed in summer 1993 and repeated in summer 1994 to investigate effects of potassium, calcium and water table depth on mechanical properties of tomato fruit. In the first group of tests five mechanical properties stress, strain, ER (ratio of stress to strain at break), energy and toughness were calculated from the force-deformation curve obtained by compression of pericarp disks taken from tomato fruits (cv New Yorker) at the breaker stage. In the second group of tests force, deformation and energy were obtained from puncture tests on whole tomato fruit. The textural parameters were used to compare the effects of the potassium, calcium and water level depths on the mechanical properties of tomatoes. Results showed the effects of calcium and water table depths on the mechanical properties were significant. Tomato fruits exposed to increasing moisture stress levels by increasing water table depth exhibited increased firmness. Increased application of calcium also resulted in increased firmness. Application of different potassium levels had in general no significant effect on breaking stress, strain, ER, energy and toughness of tomato fruit pericarp. / A new method of measuring skin strength of tomatoes is described. The method, refered to as loop method, overcame the problems with the existing method using mechanical grips. Further, the loop method was applied to measure the effect of potassium and calcium on skin strength of tomato. Using the loop method, data were collected on relaxation of tomato skin (epidermis). A computer program was written to model th tensile stress relaxation behaviour of tomato skin. The program was employed to calculate linear and non-linear coefficients of a relaxation model. The fitted values were in a very good agreement with experimental data (R$ sp2>$0.99).
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.39984 |
| Date | January 1995 |
| Creators | Rajabipour, Ali |
| Contributors | Norris, E. R. (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 | Doctor of Philosophy (Department of Agricultural and Biosystems Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001487466, proquestno: NN12464, Theses scanned by UMI/ProQuest. |
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