An investigation on the influence of pH and ionic strength on the adsorption and interfacial dilatational properties at the oil-water interface of pumpkin (Cucurbita pepo) seed protein hydrolysate

Pumpkin (Cucurbita pepo) seed protein hydrolysate (PSPH) was obtained by enzymatic hydrolysis of pumpkin seed protein isolate using pepsin. Influence of pH (3, 5 and 8) and ionic strength, Ic (0?1 mol dm-3), on the adsorption kinetics of PSPH (diffusion rate constant, kdiff, and adsorption rate constant, kads), interfacial pressure (?) and interfacial dilatational properties (dilatational elasticity, E?, and viscosity, E?) of the oil?PSPH solution interfaces was investigated at different PSPH concentrations (c = 0.0014?14 g dm-3). It was found that PSPH adsorbs to the interface at c ? 0.0014 g dm-3, regardless of pH and ionic strength, as evidenced by the increase in interfacial pressure. The kdiff and kads value were found to be the highest at pH 3 and the lowest at pH 5 at the corresponding concentrations. The dilatational properties of the interfaces, which were investigated at different oscillation frequencies, ?, 0.01?0.2 Hz, showed that the E? of the oil?PSPH solution interfaces is much higher than its E?. Moreover, E? increases with increasing PSPH concentration at pH 5 and 8, and with increasing Ic, regardless of the pH, while E? changes only minimally.

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

Journal of the Serbian Chemical Society ◽

10.2298/jsc150615081b ◽

2016 ◽

Vol 81 (1) ◽

pp. 35-46 ◽

Cited By ~ 6

Author(s):

Sandra Bucko ◽

Jaroslav Katona ◽

Ljiljana Popovic ◽

Zuzana Vastag ◽

Lidija Petrovic

Keyword(s):

Ionic Strength ◽

Cucurbita Pepo ◽

Seed Protein ◽

Protein Hydrolysate ◽

Protein Isolate ◽

Emulsifying Properties ◽

Protein Solution ◽

Pumpkin Seed ◽

Solution Interface ◽

Oil In Water

Pumpkin seed protein isolate (PSPI) was enzymatically hydrolysed by pepsin to obtain pumpkin seed protein hydrolysate, PSPH. Investigation on 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/dm3 NaCl). PSPI had the lowest solubility, i.e. isoelectric point (pI), at pH 5. PSPH had higher solubility than PSPI over whole range of pH and ionic strengths tested. Decrease in surface and interfacial tension evidenced that both PSPI and PSPH adsorb at air/protein solution and oil/protein solution interface. Emulsions (20 % oil in water) stabilized by 1 g/100cm3 PSPI or PSPH solution were prepared at pH 3, 5 and 8 and ionic strength of 0 and 0.5 mol/dm3 NaCl. PSPH stabilized emulsions from coalescence at all pH and ionic strengths tested. PSPI was able to stabilize emulsions at pH 3 and 0 mol/dm3 NaCl, and at pH 8 regardless of ionic strength, while emulsions at pH 5 and both 0 and 0.5 mol/dm3 NaCl and at pH 3 when ionic strength was increased separated to oil and serum layer immediately after preparation. All emulsions were susceptible to creaming instability.

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Emulsion stabilization by tomato seed protein isolate: Influence of pH, ionic strength and thermal treatment

Food Hydrocolloids ◽

10.1016/j.foodhyd.2016.01.014 ◽

2016 ◽

Vol 57 ◽

pp. 160-168 ◽

Cited By ~ 34

Author(s):

Anwesha Sarkar ◽

Hannah Kamaruddin ◽

Annie Bentley ◽

Shikai Wang

Keyword(s):

Ionic Strength ◽

Thermal Treatment ◽

Seed Protein ◽

Protein Isolate ◽

Tomato Seed ◽

Emulsion Stabilization ◽

Influence Of Ph

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Effect of Xanthan and Arabic Gums on Foaming Properties of Pumpkin (Cucurbita pepo) Seed Protein Isolate

Journal of Food Research ◽

10.5539/jfr.v3n1p87 ◽

2013 ◽

Vol 3 (1) ◽

pp. 87 ◽

Cited By ~ 1

Author(s):

Quirino Dawa ◽

Yufei Hua ◽

Moses Vernonxious Madalitso Chamba ◽

Kingsley George Masamba ◽

Caimeng Zhang

Keyword(s):

Sodium Chloride ◽

Salt Concentration ◽

Seed Protein ◽

Foam Stability ◽

Chloride Concentration ◽

Egg White ◽

Protein Isolate ◽

Foaming Properties ◽

Ph Optimum ◽

Pumpkin Seed

Understanding how foaming properties of proteins are affected by factors such as pH, salt concentration and temperature is essential in predicting their performance and utilisation. In this study, the effects of pH and salt concentration were studied on the foaming properties of pumpkin seed protein isolate (PSPI) and PSPI- xanthan (XG)/Arabic (GA) gum blends. The foaming properties of the PSPI-GA/XG blends were also compared with egg white. Foam stability (FS) was significantly affected by pH with PSPI: GA (25:4) and PSPI: XG (25:1) having a significantly higher stability at pH 2 with the lowest foam stability at pH 4. Sodium chloride (0.2-1.0 M) did not significantly affect foaming properties although PSPI: GA (25:4) had the highest FC (89.33 ± 3.24%) and FS (76.83 ± 1.53 min) at 0.2 M sodium chloride concentration. The foaming capacity (FC) of PSPI: GA (25:4) blend (128.00 ± 0.91%) was significantly higher (p < 0.05) than that of egg white (74.00 ± 1.33%) but its FS was significantly lower. It was further revealed that the FC of egg white (74.00 ± 1.33%) was comparable to the PSPI:XG (25:1) blend (74.00 ± 1.46%) but the FS for egg white (480.00 ± 2.67 min) was significantly higher (p < 0.05) than the FS (116.21 ± 0.86 min) of PSPI:XG (25:1). The foaming properties of PSPI and PSPI-xanthan (XG)/Arabic (GA) blends were significantly affected by pH. Optimum foaming properties, PSPI:XG (25:1) and PSPI:GA (25:4) were observed at pH 2 and heat treatment temperature of 80 ºC.

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