Peas belong to a legume family. Moreover, peas along with beans, lentils and other pea types (chickpea, cowpea, etc.) are also known as pulses. Pulses are edible seeds of leguminous plants classified from oilseeds as soybean and peanut and fresh peas/beans.
Peas usually contain 20-30% protein, 40-50% starch, and 10-15% of fiber as the main components. Despite rather moderate levels of mainly protein and starch components that can be used as a meal for livestock (it is assumed that peas are de-hulled beforehand) today`s trends go towards protein enrichment. Protein enrichment can be obtained by different processing techniques depending mainly on the final desired protein level. Thus, a simple protein enrichment starts with simple cleaning (de-hulling) process, continues with protein shifting obtained by dry classification (includes fine grinding and air classifying), further with wet processing in order to obtain even higher protein level. As the last step in a protein enrichment, it can be purification applied (e.g. ultra-filtration). Any steps involved in this protein enrichment chain will consequently bring certain capital investment level, energy/water input, processing requirements but, at the same time, it will create an additional value for a given product.
Aiming for different protein levels and their functional properties (e.g. (in)soluble protein, etc.) will different commercially available processes be taken into consideration and applied.
Figure 1. The figure below, why Vestkorn process can be declared as 100% natural. Difference between Vestkorn process and wet processing.
The major driven factor is an end-application followed by production costs and functional properties that certain actor on the market wants to achieve. For instance, the same type of product (e.g. protein isolate) can be achieved by starting with different raw materials (e.g. using the de-hulled material or any of the dry fractions (mainly protein).
Choosing different processing techniques may bring to some processing challenges:
Mechanical shifting (dry process) will mainly maintain functionality as only physical modification was applied due to the molecular weight difference between the two major components (protein and starch). However, applying this protein enrichment method brings certain limitations due to the impossibility to separate efficiently and entirely one component from another.
On the other hand, a wet process often involves adjusting pH (iso-electric precipitation) with addition of acids and salts which may cause some undesired protein structural change; loss of ordered structure, hydrophobic groups become exposed and thus reduce solubility, decreased ability to crystallise (Wet processing methods for protein and starch, Nienke Lindeboom, POS, Bio-Sciences, 2016, presentation). Moreover, in applying a wet process as such can come to a microbial growth and a waste of water from a sustainability point of view is a challenge.
Based on a final requirement and from an end-user standpoint all these previously aspects need to be considered.