Investigation on physicochemical, structural, and functional properties of protein from pecan (Carya illinoinensis (wangenh.) K. Koch) treated by three different peeling methods

The removal of endocarp, which has great effects on protein properties, is indispensable during developing pecan kernel protein. The effect of different removal methods, namely alkaline peeling (AP), enzymatic peeling (EP), and mechanical peeling (MP), on the physicochemical, structural, and functional properties of pecan kernel protein was investigated. The obtained proteins by three peeling methods had similar molecular weight (14–66 kDa) and amino acids (18 in all) composition. The average particle size of obtained protein samples in series of EP, AP, MP were 0.89, 0.74, and 0.80 μm respectively, the protein contents were 70.34%, 74.72%, and 73.12% respectively, and the L* values (representative of lightness) were 49.21, 65.18, 59.78 respectively. The protein structure of AP and EP samples was greatly changed, behaving as the reduction of the α-helix and β-sheet in secondary structure and the red-shift of the maximum wavelength in the endogenous fluorescence, while the MP was beneficial to maintain the structure. The AP sample presented better solubility, oil absorption capacity, and emulsification; The MP sample showed the best foaming property. These results confirmed that different peeling methods could greatly influence the physicochemical, structural, and functional properties of pecan protein. This research would provide a useful guideline for the production and applications of pecan protein.