Milling Energy Impacts the Co-Extraction of Globulins, Albumins, and Anti-Nutritional Factors of Peas

Abstract

Pea protein ingredients are typically produced through alkaline solubilization and isoelectric point precipitation. This work evaluated the influence of milling and the resulting flour particle sizes on the recovery of protein fractions and antinutrient contents via this extraction method. Milling energy inputs of 2.39 to 260 kJ/kg were applied to yellow and green peas. An energy input of 180 kJ/kg yielded a d₉₀ of ~ 2.2 μm. No further significant difference was found when the input was increased further. Increasing the milling energy input increased the release of globulins, albumins, and phytic acid from both pea cultivars. The protein yield of the globulin-rich fraction increased up to 52.1 ± 1.3% using yellow peas and up to 54.2 ± 0.6% using green peas. The resulting protein extracts had protein contents of 77.0 ± 1.9% and 78.5 ± 0.9%, respectively. Similarly, the protein yield of albumin-rich fractions also significantly increased up to around 17.5% when using both cultivars. The albumin-rich fractions represented the largest mass yielded in the extraction process from both pea types. With increasing milling energy input, phytic acid solubilization increased as well and its yield rose to around 40% in both protein fractions. However, trypsin inhibitor yields were relatively low in them. Overall, a milling energy input at 130 kJ/kg resulted in particle sizes that yielded optimum protein solubilization but simultaneously increased solubilization of phytic acid. This indicates that adjusting the energy input and particle size of the pea protein raw material can customize the composition of the resulting protein ingredient.