From raw material to mildly refined ingredient – Linking structure to composition to understand fractionation processes

The relation between the structure of yellow pea and its optimal fractionation process was investigated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Different fractionations obtained by milling and various methods were investigated and compared to pea flour. Milling resulted in structure break-up and a distinction of particles in shape and size. Different particles were identified using the mapping of the elements (EDS), carbon, oxygen and nitrogen, indicating the presence of starch, protein and other carbohydrates, in the form of protein bodies, starch granules and cell wall fragments. It was further observed that not only protein bodies contained protein, but also particles that were presumed to be cell wall material contained protein, although in considerably lower concentrations. With both fractionation methods protein and starch could be partly separated, but wet fractionation resulted in a higher purity in both the soluble and non-soluble protein fractions.