Processes have been developed and commercialized for the concentration and isolation of starch from field pea and other pulses using dry and wet (aqueous) technologies, respectively.

Production of starch concentrates, a.k.a. starch-rich flours or air-classified starches, utilizes fine grinding and air classification technology, which requires milling of whole, dehulled or coarsely ground pulses to a sub-cellular level (less than approximately 50 µm) and separation into coarse (starch-rich) and fine (protein-rich) fractions in a carefully controlled centrifugal airstream. The technology takes advantage of the particulate nature of both starch and protein in pulses, the larger size of starch granules relative to protein particles, and, to some extent, the greater particle density of starch granules in comparison to protein particles. Ideally, the fine grinding process employed (impact milling is preferred) results in minimal damage (breakage or abrasion) to starch granules, as otherwise the fine fraction will contain an excessive amount of starch. The fine grinding process also must be capable of disintegrating aggregates of protein bodies, thereby enabling their recovery in the fine fraction. Coarse and fine fraction yield and composition are dependent on milling efficiency, raw material composition, the cut-size used in the separation, and the number of millings and classifications employed. Production of starch-rich fractions containing 85% or more of starch, and less than 5% of protein, has been reported.

Starches of higher purity may be prepared from pulses using wet milling technology. Typically, dehulled seed, which may be pre-ground, is finely milled in water, usually at alkaline pH. Cell wall fibre is separated from insoluble material (mainly starch) and dissolved/dispersed constituents (mainly protein) by screening. Starch is then separated from the protein extract by centrifugation and/or hydrocycloning. The starch fraction is washed to enhance its purity further and then dispersion dried, with or without prior modification. Production of starch isolates containing 98% or more of starch, and less than 1% of protein, has been reported. Challenges associated with the wet milling process include difficulty in separating starch from cell wall fibre, and loss of protein and other solubles in a voluminous effluent stream. A highly purified starch also may be obtained from pulses by alkaline washing and screening of air-classified starch. The functionality of starches prepared by the two wet methods differs slightly, due to the higher level of damaged starch in the product prepared by washing of air-classified starch.