Diffusion of water inside legume seeds

Introduction:

Previously we observed the diffusion of water inside two types of legume seeds(white speckled beans, red kidney beans) and the conclusion was that despite having higher initial moisture content inside white speckled beans, the rate of diffusion of water inside these legume seeds is more as compared to red kidney beans. This was clear from the water diffusivity values calculated from the mathematical modeling based on Ficks first and second law of diffusion. This variation can be attributed to the varied composition(chemical) of the seeds or different physical structure.

Present Work:

This time we studied the factors on which water diffusivity inside legume seeds depends in addition to the chemical composition and physical structure. We also determined whether the seed coat plays a role in determination of diffusion rate or not. On comparing the previous data of diffusion inside coated seeds with the present data of diffusion inside peeled off seeds, it is inferred that seed coating offers a significant resistance to water diffusion through seeds. Diffusion of salted water is also seen. It has been observed that rate of diffusion is decreased in presence of NaCl but overall water absorbed(after long period of time) increases with increasing concentration of NaCl in the solution(water+NaCl).The decreased rate of diffusion can be due to the decrease in water activity of the solution (due to the presence of solute) and hence decreasing the driving force of concentration gradient and thus the reduced diffusion rate.

Future Work:

In future we will be determining the diffusion rate dependence on the following factors:

Water activity of the legume seeds

Protein content

pH of diffusing solution

temperature

We will also investigate the role of water activity of food products in their spoilage by microorganisms, physical change and chemical change.

Submitted by: Supervisor:

Vinita Kumari Prof. Sudip Pattanayek

2011ch70188