Note: Influence of pH on the Extraction Yield and Functional Properties of Macadamia (Macadamia Integrofolia) Protein Isolates

2004 ◽  
Vol 10 (4) ◽  
pp. 263-267 ◽  
Author(s):  
P. S. Bora ◽  
D. Ribeiro
Keyword(s):  
Functional Properties ◽  
Extraction Yield ◽  
Emulsifying Properties ◽  
Alkaline Ph ◽  
Protein Isolates ◽  
Ph Values ◽  
Macadamia Nut ◽  
Isoelectric Ph ◽  
Ph Range ◽  
Influence Of Ph

Three protein isolates from de-fatted macadamia nut kernel flour were prepared by extraction at acidic (pH2.0), neutral (pH7.2 with 0.2M phosphate buffer containing 0.5MNaCl) and alkaline (pH12.0) conditions. Extraction at pH2.0 solubilised nearly 52.0% of the proteins present in defatted macadamia flour, while extraction with buffer (pH7.2) and alkaline pH (12.0) solubilised about 83.0% of proteins. The yield of isoelectrically precipitated protein from acidic extract (pH2.0, isolate A) was about 65.2% and from neutral (isolate B) and alkaline extracts (isolate C) was slightly over 83.0% which accounted for 33.7, 69.1 and 69.4% of the proteins present in defatted flour. The protein content of the isolates was 80.1, 92.1 and 92.0% in A, B and C isolates respectively. The functional properties of these isolates were significantly different. Isolate A presented better solubility at pH below isoelectric pH, isolate C at pH above isoelectric pH and isolate B intermediate solubility at the pH range studied. Isolate B showed best water and oil absorption capacities followed by isolate C and least by isolate A. For each isolate, the emulsifying properties were also significantly different at different pH values.

scholarly journals Functional Properties of Lupinus angustifolius Seed Protein Isolates

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Antonio Hilario Lara-Rivera ◽  
Pedro García-Alamilla ◽  
Laura Mercedes Lagunes-Gálvez ◽  
Ramón Rodríguez Macias ◽  
Pedro M. García López ◽  
...  
Keyword(s):  
Functional Properties ◽  
Foam Stability ◽  
Nitrogen Solubility ◽  
Activity Index ◽  
Stability Index ◽  
Lupinus Angustifolius ◽  
Minimum Concentration ◽  
Protein Isolates ◽  
Isoelectric Ph ◽  
Ph Range

Protein isolates prepared by alkaline solubilization followed by isoelectric precipitation and freeze-drying from six varieties of Lupinus angustifolius (Haags Blaue, Sonate, Probor, Borlu, Boregine, and Boruta) grown in Mexico were evaluated for functional properties: nitrogen solubility, water-holding capacity (WHC), oil holding capacity (OHC), emulsion activity index (EAI), emulsion stability index (ESI), foaming capacity (FC), foam stability (FS), and gelling minimum concentration (GMC). The nitrogen solubility values, WHC, OHC, and FC did not show significant differences between the protein isolates. The solubility of the isolates was minimal at pH of 4.0 and 5.0 while the regions of maximum solubility were found at pH of 2.0 and 10.0. There were significant differences in EAI and ESI depending on the varieties used. The isolates of the Boregine and Borlu varieties showed the highest EAI with 29.3 and 28.3 m2 g−1, respectively, while the lowest index was recorded in the isolate obtained from the Sonate variety (24.6 m2 g−1). Like solubility, these indices also increased at both extremes of pH evaluated; both properties were minimal in the isoelectric pH range (4.0 to 5.0).

Functional properties of ?cotton protein.? II. Emulsifying properties of cotton protein isolates obtained by extraction with acid

1986 ◽  
Vol 22 (3) ◽  
pp. 331-333
Author(s):  
A. L. Li ◽  
A. N. Gurov ◽  
T. S. Yunusov ◽  
M. T. Turakhozhaev ◽  
T. T. Shakirov ◽  
...  
Keyword(s):  
Functional Properties ◽  
Emulsifying Properties ◽  
Protein Isolates

scholarly journals Organic/Inorganic Superabsorbent Hydrogels Based on Xylan and Montmorillonite

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shuang Zhang ◽  
Ying Guan ◽  
Gen-Que Fu ◽  
Bo-Yang Chen ◽  
Feng Peng ◽  
...  
Keyword(s):  
Compressive Modulus ◽  
Cross Linking ◽  
Swelling Properties ◽  
Ph Values ◽  
Swelling Capacity ◽  
Wide Ph Range ◽  
Grafting Copolymerization ◽  
Ph Range ◽  
Influence Of Ph ◽  
Superabsorbent Hydrogels

The unique organic/inorganic superabsorbent hydrogels based on xylan and inorganic clay montmorillonite (MMT) were prepared via grafting copolymerization of acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) withN,N-methylenebisacrylamide (MBA) as a cross-linking agent and potassium persulfate (KPS) as an initiator. The effect of variables on the swelling capacity of the hydrogels, such as the weight ratios of MMT/xylan, MBA/xylan, and AMPS/AA, was systematically optimized. The results indicated that the superabsorbent hydrogels comprised a porous cross-linking structure of MMT and xylan with side chains that carry carboxylate, carboxamide, and sulfate. The hydrogels exhibit the high compressive modulus (E), about 35–55 KPa, and the compression strength of the hydrogels increased with an increment of the MMT content. The effect of various cationic salt solutions (LiCl, CaCl2, and FeCl3) on the swelling has the following order: Li+> Ca2+> Fe3+. Furthermore, the influence of pH values on swelling behaviors showed that the superabsorbent composites retained around 1000 g g−1over a wide pH range of 6.0–10.0. The xylan-based hydrogels with the high mechanical and swelling properties are promising for the applications in the biomaterials area.

Influence of pH on hexavalent chromium reduction by Fe(II) and sulfide compounds

2015 ◽  
Vol 72 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Juan Chen ◽  
Ri Chen ◽  
Mei Hong
Keyword(s):  
Reduction Process ◽  
Single Species ◽  
Batch Experiments ◽  
Chromium Reduction ◽  
Promoting Effect ◽  
Ph Values ◽  
Ph Dependent ◽  
Ph Range ◽  
Influence Of Ph ◽  
Sulfide Species

Abstract Batch experiments were conducted to investigate the influence of pH on Cr(VI) reduction with Fe(II), sulfide and mixtures of Fe(II) and sulfide at pH 3.0–12.0. The results showed that Fe(II) could reduce Cr(VI) with a high removal of nearly 100% in the pH range of 3.0–9.0, while the reduction of Cr(VI) decreased to approximately 60% considering the oxygenation of Fe(II) at pH 12.0. The reaction between Cr(VI) and sulfide, however, was largely pH dependent. H2S was the main sulfide species with the Cr(VI) removal of ∼80% at pH < 7.0, while sulfide mainly existed in the forms as HS− or S2− at pH ≥ 7.0, which had very limited removal of Cr(VI) (no more than 10%). The Cr(VI) removal by the mixtures of Fe(II) and sulfide was also compared with the sum of separate ones at different pH values. The sum of Cr(VI) removal by single Fe(II) and S(-II) was similar to that by the mixtures at pH 3.0–5.0 and pH 12.0, while the removal of Cr(VI) by the mixtures was observed to be more effective than the sum of the single-species removals at pH 7.0–9.0; the promoting effect was primarily attributed to the catalysis of ferric ion generated during the reduction process.

scholarly journals The action of trialkyltin compounds on mitochondrial respiration. The effect of pH

1974 ◽  
Vol 138 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Alan P. Dawson ◽  
Michael J. Selwyn
Keyword(s):  
Maximum Rate ◽  
Ph Dependence ◽  
Acid Value ◽  
Alkaline Ph ◽  
Free Medium ◽  
Succinate Oxidation ◽  
Ph Values ◽  
Acid Ph ◽  
Internal Ph ◽  
Ph Range

1. Inhibition of 2,4-dinitrophenol-stimulated respiration by trialkyltins is dependent on the presence of Cl− in the assay medium and is only apparent at acid pH values. It appears to be a result of the Cl−–OH− exchange mediated by trialkyltins. 2. In a KCl medium at alkaline pH values, the maximum rate of respiration produced by uncouplers is further increased by the presence of trialkyltins. 3. The inhibition of uncoupled succinate oxidation at acid pH values is not reversed by increasing the external substrate concentration, suggesting that depletion of intramitochondrial succinate is not an important factor in the inhibition. 4. It is suggested that the probable explanation for these observations is that in the presence of Cl− trialkyltins alter the internal pH to a more acid value and this directly affects the activity of one or more steps in succinate oxidation. 5. The oligomycin-like action of trialkyltins in a Cl−-free medium shows considerable pH-dependence over the pH range 6.6–7.6 in the presence of 10mm-phosphate, but very much less pH-dependence in the presence of 1mm-phosphate. 6. The binding of triethyltin to mitochondria shows a pK at pH6.3 and does not change greatly over the pH range 6.6–7.6. 7. It is suggested that the pH-dependence of the oligomycin-like action described by Coleman & Palmer (1971) is the result of the pH-dependence of the formation of a hydrophilic complex between trialkyltins and Pi.

scholarly journals Comparative Study of the Structural and Functional Properties of Membrane-Isolated and Isoelectric pH Precipitated Green Lentil Seed Protein Isolates

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 694
Author(s):  
Etinosa C. Osemwota ◽  
Adeola M. Alashi ◽  
Rotimi E. Aluko
Keyword(s):  
Functional Properties ◽  
Food Systems ◽  
Protein Extraction ◽  
Seed Proteins ◽  
Protein Digestibility ◽  
Protein Isolates ◽  
Structural And Functional Properties ◽  
Lentil Flour ◽  
Droplet Sizes ◽  
Isoelectric Ph

The demand for isolated seed proteins continues to increase but functionality in food systems can be greatly dependent on the extraction method. In this work, we report the physicochemical and functional properties of lentil seed proteins isolated using various protocols. Lentil flour was defatted followed by protein extraction using isoelectric pH precipitation (ISO) as well as NaOH (MEM_NaOH) and NaCl (MEM_NaCl) extractions coupled with membrane ultrafiltration. The MEM_NaCl had significantly (p < 0.05) higher protein content (90.28%) than the ISO (86.13%) and MEM_NaOH (82.55%). At pH 3–5, the ISO was less soluble (2.26–11.84%) when compared to the MEM_NaOH (25.74–27.22%) and MEM_NaCl (27.78–40.98%). However, the ISO had higher yield and protein digestibility (48.45% and 89.82%) than MEM_NaOH (35.05% and 77.87%) and MEM_NaCl (13.35% and 77.61%), respectively. Near-UV circular dichroism spectra showed that the MEM_NaOH had loose tertiary conformation at pH 3, 5, 7 and 9 while ISO and MEM_NaCl had more compact structures at pH 7 and 9. The three protein isolates formed better emulsions (lower oil droplet sizes) at pH 7 and 9 when compared to pH 3 and 5. In contrast, foaming capacity was better at pH 5 than pH 3, 7, and 9.

Magnetite Sorption Capacity for Strontium as a Function of pH

2008 ◽  
Vol 1107 ◽  
Author(s):  
Joan de Pablo ◽  
Miquel Rovira ◽  
Javier Giménez ◽  
Ignasi Casas ◽  
Frederic Clarens
Keyword(s):  
Spent Nuclear Fuel ◽  
Surface Complexation ◽  
Retardation Factor ◽  
Alkaline Ph ◽  
Layer Model ◽  
Surface Complexation Model ◽  
Ph Values ◽  
End Products ◽  
Diffuse Layer Model ◽  
Ph Range

AbstractThe ubiquity of iron oxide minerals and their ability to retain metals on their surface can represent an important retardation factor to the mobility of radionuclides. In a deep repository for the spent nuclear fuel, the intrusion of the groundwater might produce the anoxic corrosion of the iron, with magnetite as one of the end-products. In this study, as expected considering the strontium speciation in solution, strontium is sorbed onto magnetite at alkaline pH values while at acidic pH the sorption is negligible. Magnetite is able to sorb more than the 50% of the strontium from a 8·10-6 mol·dm-3 solution at the pH range representative of most groundwater (7-9). A surface complexation model has been applied to the experimental data, allowing to explain the results using the Diffuse Layer Model (DLM) and considering the formation of the inner-sphere complex >FeOHSr2+ (with a calculated logK=2.7±0.3). Considering these data, the magnetite capacity to retain strontium and other radionuclides is discussed

Emulsifying properties of chickpea protein isolates: Influence of pH and NaCl

2009 ◽  
Vol 23 (1) ◽  
pp. 146-152 ◽  
Author(s):  
Tao Zhang ◽  
Bo Jiang ◽  
Wanmeng Mu ◽  
Zhang Wang
Keyword(s):  
Emulsifying Properties ◽  
Protein Isolates ◽  
Influence Of Ph

scholarly journals ANALYSIS OF INFLUENCE OF PH AND TEMPERATURE IN ADSORPTION METHYLENE BLUE FOR PSEUDOSTEM FIBER BANANA

2013 ◽  
Vol 12 (24) ◽  
pp. 34-41
Author(s):  
Caroline CASTANHETTI ◽  
Ana Paula FIGUEIREDO ◽  
Lucas DOMINGUINI
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Carboxylic Acid ◽  
High Efficiency ◽  
Hydroxyl Groups ◽  
Alkaline Ph ◽  
Banana Fiber ◽  
Ph Values ◽  
Ft Ir ◽  
Influence Of Ph

This study examined the potential for adsorption of methylene blue, in solution of 50 mg.L-1, by banana fiber spray, to 2 g/L of solution. We carried out variations in temperature and pH of the solution. The results indicate that it is possible to use the banana fiber as adsorbent methylene blue in ambient temperature and alkaline pH values with high efficiency. The FT-IR spectrum showed the presence of carboxylic acid and hydroxyl groups on the fiber. Such groups are capable of forming hydrogen bonds with methylene blue and removing it from the aqueous solution. It was concluded that for the conditions tested, the best temperature for adsorption was 25 °C and pH to better efficiency of better temperature was 11.

scholarly journals Functional properties of proteins isolated from industrially produced sunflower meal

2014 ◽  
Vol 3 (2) ◽  
Author(s):  
Petia Ivanova ◽  
Vesela Ivanova Chalova ◽  
Lidia Koleva
Keyword(s):  
Food Industry ◽  
Foam Stability ◽  
Protein Isolate ◽  
Absorption Capacity ◽  
Sunflower Meal ◽  
Protein Isolates ◽  
Ph Values ◽  
Meal Protein ◽  
Future Potential ◽  
Influence Of Ph

Protein isolate 1 (PI1) and protein isolate 2 (PI2) were prepared from industrially produced sunflower meal by using isoelectric and ethanol precipitation respectively. The water absorption capacity of PI1 was 6 times higher than that of PI2 and was significantly reduced by the presence of 0.03 M and 0.25 M NaCl. Oil absorption capacity of both protein isolates was not influenced by NaCl supplementation. Foam capacity of PI1 and PI2 was pH-dependent. While the foam capacity of both isolates was improved by either 0.03 M or 0.25 M NaCl, the foam stability was negatively influenced by the addition of NaCl at all pH values with except for pH 4. Emulsifying activity of PI1 and PI2 was lowest at pH 4. The emulsions exhibited relatively high stability (> 90%) under all studied conditions. Knowledge of the influence of pH and boundary concentrations of NaCl on the functionality of sunflower meal protein isolates could be beneficial for their future potential application in food industry.

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