Protein from camelina seed is a valuable co-product that can be derived
from the meal remaining after oil extraction. The current study
describes the types and physicochemical properties of the major proteins
present in camelina meal. Seed coat mucilage, which interferes with
protein extraction, was removed from whole seeds by digestion with
Viscozyme® and lipids were removed with hexane to obtain
demucilaged/defatted meal. Protein comprised 51.3% of meal dry matter
and the eight essential amino acids comprised 40.8% of total amino
acids. The meal polypeptide profile showed bands originating from
cruciferin (~44.1 and 51.7 kDa), napin
(~14 kDa) and oil body proteins (OBP;
~15-20 kDa) resembling that of other crucifers.
Cruciferins (11 isoforms) were the predominant proteins, while vicilins
(6 isoforms) also were identified among the proteins soluble at pH 8.5.
Among the proteins soluble at pH 3, napins (5 isoforms) comprised the
majority, though late embryogenesis abundant proteins also were found.
Camelina cruciferin and napin were confirmed to possess predominantly
β-sheet and α-helix secondary structures, respectively. Camelina
cruciferin structure was highly sensitive to changes in medium pH and
underwent acid-induced denaturation at pH 3, but exhibited high thermal
stability (>80°C) at neutral and alkaline pHs. The
structure of camelina napins was less sensitive to pH. The major
proteins associated with oil bodies were oleosins (6 isoforms).
Identification and characterization of the properties of camelina meal
proteins will enable strategic paths for co-product valorization.