compaction and impaction forces from loading mechanisms for separation of stigmas from dried saffron flowers

the separation of saffron stigmas from fresh flowers is the most important and the most difficult stage of saffron harvesting. saffron production costs are high because this harvesting stage is done by hand and is very time-consuming. one way of preserving the saffron flower is to dry it. the separating of the stigma from dried saffron flowers can then be done at an appropriate time. this study investigated the separation of the stigmas from dried flowers. the compaction and impaction forces of the loading mechanisms were evaluated. the dried flowers were loaded using pressure rollers and finger drums to test compaction and impaction forces, respectively. the effect of feed rate (2.6, 6, 8.7 g/s), roller drum speed (80, 200, 300 rpm), finger drum speed (500, 700, 900 rpm) and stage of flower development (buds, partially-opened, fully-opened) were investigated on the percentage (wt) of stigmas separated and the percentage (wt) of broken stigmas. the results showed that the percentage of separated stigma in the fully-opened and partially-opened flowers was higher than in flower buds. the percentage of broken stigmas in the buds was 30% lower than for fully-opened flowers. the percentage of broken stigmas increased as the roller speed increased. the results suggested that the performance of finger drums was not satisfactory and that the percentage of separated stigmas was 50%. a pressure roller speed of 200 rpm and a feed rate of 6 g/s were the most favorable conditions for separation of stigmas from partially-opened flowers (99.48%).