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UBC Theses and Dissertations

Effect of maturity and variety on the textural quality of green snap beans Martens, Victor Jake


Rheological measurements on intact fresh snap beans (Phaseolus vulgaris v.) and purees made from raw beans were used to assess the effect of variety and sieve size on the textural characteristics of green snap beans. Seed length, percentage dry matter and physical fiber measurements were used as textural quality indicators. Four varieties of green snap beans (Tendercrop, Rainier, Harvester and BBL 290) were tested in 1971 and 1972. Each variety was harvested five times in each year. Adverse environmental conditions in 1971 caused bean textural quality to be higher in 1972 than in 1971. The four varieties tested showed significant differences with Rainier exhibiting the best textural quality while Harvester generally showed the poorest quality. Tests involving the resistance to shearing of intact bean pods were carried out using the Ottawa Texture Measuring System and the Food Technology Corporation's Texture Test System (formerly the Kramer shear press). Viscosity tests were performed on purees composed of macerated raw green bean tissue and water. Results were obtained from spread test using a simplified Adams-type consistometer and from rotating coaxial cylinder tests using a Brookfield RVT Synchro-Lectric Viscometer fitted with a small sample adapter. The Brookfield data were then fitted to the power-law equation. Rheological parameters showed highly significant interrelationships in most instances. Viscous properties of purees (spread, m, n and yield stress) were highly correlated with percentage dry matter of the beans. Peak force readings of the Kramer shear press and the Ottawa Texture Measuring System were significantly correlated with all textural quality and viscometric parameters.

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