Functional properties of pumpkin (Cucurbita pepo) seed protein isolate and hydrolysate

Abstract

Pumpkin seed protein isolate (PSPI) was enzymatically hydrolysed by pepsin to obtain pumpkin seed protein hydrolysate, PSPH. Investigation of the solubility, interfacial and emulsifying properties of both PSPI and PSPH was conducted under different conditions of pH (3-8) and ionic strength (0-1 mol dm-3 NaCl). PSPI had the lowest solubility, i.e., isoelectric point (pI) at pH 5. PSPH had higher solubility than PSPI over the whole range of tested pH and ionic strength values. The decreases in the surface and interfacial tension evidenced that both PSPI and PSPH adsorb at the air/protein solution and oil/ /protein interfaces of the solution. Emulsions (20 % oil in water) stabilized by 10 g dm-3 PSPI or PSPH solution were prepared at pH 3, 5 and 8 and ionic strength of 0 and 0.5 mol dm-3 NaCl. PSPH stabilized emulsions from coalescence at all tested pH and ionic strength values. PSPI was able to stabilize emulsions at pH 3 and 0 mol dm-3 NaCl, and at pH 8 regardless of ionic strength, while emulsions at pH 5 and both 0 and 0.5 mol dm-3 NaCl and at pH 3 when the ionic strength was increased separated into an oil and a serum layer immediately after preparation. All emulsions were susceptible to creaming instability.

Proteomic analysis of oilseed cake: a comparative study of species‐specific proteins and peptides extracted from ten seed species

“…Moreover, it is difficult to compare results, even within the seeds of one species, if the authors use different raw materials, extraction methods, and electrophoresis conditions. We obtained SDS‐PAGE profiles similar to those that have been described previously for coconut meal, 19,20 flaxseed meal, 21 hemp seed meal and hemp protein isolate, 22,23 milk thistle seed protein isolate, 24 black cumin flour obtained from Nigella damascena , 25 pumpkin seed protein extract, 11,26 rapeseed meal, 27–29 sesame protein isolate and seed flour, 30,31 and finally, from sunflower flour and protein concentrate 32,33 …”

“…When protein powders from coconut oil and coconut milk cakes were compared, milk cake presented higher water and oil absorption capacities but oil cake powder exhibited better foaming capacity and emulsifying activity 10 . Differences in solubility, interfacial activity and emulsifying properties of pumpkin seed protein isolate under different environmental conditions were described by Bučko et al 11 …”

Effect of Acetylation on Physicochemical and Functional Properties of Commercial Pumpkin Protein Concentrate

“…As we can see on the electropherogram, proteins of about 18–22 kDa·MW accompanied this main protein. According to previous research studies, cucurbitin, the major storage protein in pumpkin seed, is a hexamer with a molecular size of about 325 kDa, consisting of two major bands (MW d 22 kDa) corresponding to acidic and basic polypeptides [ 38 , 39 , 40 , 41 ]. The vast majority of cucurbitins are salt-soluble globulins with a sedimentation index of about 11–12S [ 42 ].…”

“…The solubility profile of native PPC indicates that PS reduced as the pH increased from 2 to 4 (from 10.16% to 6.48%), which corresponds to its isoelectric point, after which an increase in pH increased PS progressively (to 62.55%). This solubility profile of pumpkin proteins is U-shaped, common for oil seeds [ 40 , 41 ]. Other authors [ 46 , 47 , 48 , 49 ] have emphasized that the solubility of the proteins is strongly influenced by pH and ionic strength, with higher values in the alkaline pH regions, and by the type of solvent used to degrease the seeds during preparation of the raw material.…”

Pumpkin seed oil cake/polyethylene film as new food packaging material, with perspective for packing under modified atmosphere

“…Considering that surface tension of pumpkin seed protein isolate (main fraction of FFS) under similar conditions was reported to amount approximately 50 mN/m 28 and that best adhesion to a substrate is obtained when the surface energy of the substrate is 7–10 mN/m higher than the surface tension of the coating being applied, more intense surface treatment of PE layer should result in higher values of adhesion force 29 . The other approach would be to reduce FFS surface tension values by addition of surfactants or other FFS modifications, like concentration, pH, ionic strength 28 . These modifications should be approached with caution because they would probably induce changes in functional properties of biopolymer layer.…”