The peas are spherical when harvested, with an outer skin. The peas are dried and the dull-coloured outer skin of the pea removed, then split in half by hand or by machine at the natural split in the seed’s cotyledon.
There are green and yellow varieties of split pea. Gregor Mendel studied the inheritance of seed colour in peas; the green phenotype is recessive to the yellow one. Traditionally, the genotype of purebred yellow is “YY” and that of green is “yy”, and hybrids of the two, “Yy”, have a yellow (dominant) phenotype.
Split peas are high in protein and low in fat, with one gram of fat per 350 calories (1,500 kJ) serving. Most of the calories come from protein and complex carbohydrates. The split pea is known to be a natural food source that contains some of the highest amounts of dietary fibre, containing 26 grams of fibre per 100 gram portion (104% DV based on a 2,000 calories (8,400 kJ) diet).
The Indian toor dal (split pigeon peas) and chana dal (split yellow gram, desi chickpeas) are commonly also referred to as peas, although from other legume species than Pisum sativum.