Efficient fluidised bed drying of high quality seeds


High quality seeds are the starting point for successful agricultural crop production and have major impact on the sustainability of our food production system. Vegetable production is an important industry, facilitating the trend towards more vegetarian and healthy diets. For the Netherlands, being worldwide the biggest vegetable seed exporting country, vegetable seeds are of huge economic importance. Suboptimal seed drying and storage conditions lead to significant seed loss and can affect seed quality. Seed breeding companies are challenged by producing high quality seeds for farmers and keeping the quality of different batches constant to assure healthy plants and high yields. Therefore, throughout the seed production process, many dedicated treatments and drying steps are applied. Convective drying systems are most commonly used, with a shift from static air dryers to drum dryers and, more recently, fluidised bed dryers. While hydrating treatments are well investigated, drying treatments have not yet been intensively studied. In particular, the specific effects of drying on seed properties, storability and germination, as well as optimal drying routes for different input batches, are largely unknown. Furthermore, drying is an energy- and space-intensive step where energy and floor-space can still be saved. Therefore, in this project seed drying will be investigated to further understand its influence on physical parameters and seed quality and models will be employed to optimise seed drying regarding quality and efficiency.

Schematic process of cabbage production from seed to plant and focus points of research.
Schematic process of cabbage production from seed to plant and focus points of research.


In this project the drying of seeds is investigated by modelling the drying kinetics as well as the moisture and temperature gradients within seeds and linking them to predictions of quality. First, this research will focus on a single seed level of simple and complex shaped seeds before investigating bulk seeds in fluid bed drying. For validation of the model different small-scale seed dryers will be used in combination with in-line measurements. In addition, seed material characteristics like seed integrity are analysed and linked to the model. These physical characteristics will be taken as constraints for process conditions regarding germination and storage quality. In drying studies optimal seed quality will be investigated and modelled. Finally, the efficiency of fluid bed dryers will be analysed and optimal drying conditions regarding high quality and high efficiency determined, which might lead to new best practices in industrial seed drying and hence more sustainable and long-lasting high quality seeds.

The project is supported by seed experts of Bejo Zaden B.V. and Rijk Zwaan B.V.