Physico-chemical and functional characteristics of neem seed protein isolate

Abstract

The demands for plant-based proteins have increased, hence, the search for alternative sources for beneficial purposes. The physico-chemical and functional characteristics of protein isolated from neem seed were ascertained in this work. Neem seed protein isolate (NSPI) contained 86.33% protein rich in charged amino acids. Gel electrophoresis revealed that NSPI consists of polypeptides ranging from 97 to 21 kDa with 28–23 kDa components being prominent. Secondary structure data showed that β–sheets (45.83%) and α–helices (20.42%) were predominant in NSPI. The intrinsic fluorescence emission and surface hydrophobicity data indicated that at pH 3.0, NSPI was highly denatured and has less folded conformation. At pH 3.0 and 9.0, NSPI exhibited the highest protein solubility. NSPI had significantly (p<0.05) higher foaming and emulsifying capacities at pH 3.0. The oil and water holding abilities of NSPI were 3.17±0.09 and 1.72±0.17 g/g protein, respectively. Thus, NSPI could be considered a potentially good protein source for food formulations. Practical applications: The knowledge of the structure and function of a protein gives an insight into its potential applications in nutrition and wellness. The biochemical, physical, and functional properties of neem seed protein isolate such as the rich abundance of glutamic and aspartic amino acids and legumins, high arginine/lysine ratio, high solubility in acidic and alkaline conditions, and relatively high water and oil holding capacities make it a good protein source for food formulation and nutraceutical.

Keywords

• Neem seed
• Fourier transform infrared, Surface hydrophobicity
• Intrinsic fluorescence
• Foaming stability