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

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.

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Na Thi Ty Ngo ◽  
Fereidoon Shahidi

AbstractCamelina and flixweed (sophia) seed protein isolates were prepared using both the conventional extraction and ultrasonic-assisted extraction methods at 40 kHz for 20 min, and their functional properties investigated. SDS-PAGE showed that both ultrasound-assisted and conventional extractions resulted in a similar protein profile of the extract. The application of ultrasound significantly improved protein extraction/content and functional properties (water holding capacity, oil absorption capacity, emulsifying foaming properties, and protein solubility) of camelina protein isolate and sophia protein isolate. The water-holding and oil absorption capacities of sophia protein isolate were markedly higher than those of camelina protein isolate. These results suggest that camelina protein isolate and sophia protein isolate may serve as natural functional ingredients in the food industry. Graphical Abstract


2004 ◽  
Vol 10 (4) ◽  
pp. 263-267 ◽  
Author(s):  
P. S. Bora ◽  
D. Ribeiro

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.


2021 ◽  
Author(s):  
Darius Sargautis ◽  
◽  
Tatjana Kince ◽  
Vanda Sargautiene ◽  

Oat protein itself, as a substance, has extensively been studied providing information on its nutritional value, some functional properties and possible applicability in food systems. Chosen protein isolation methods and technological aspects define final composition of obtained oat protein product, its concentration, nutrition value and its functionality in food industry. Scientific data on oat protein recovery methods, typically relying on protein solubility or dry fractionation, provides an insufficient knowledge about the success in commercialization of oat protein recovery technologies and their derivatives in form of oat protein. The aim of the study was to analyse and summarize the research findings on oat protein extraction methods and functional properties of oat protein. Semi-systematic, monographic methods were used to analyse the oat protein isolation techniques, functional properties of oat protein in aqueous food systems, covering the latest information on oat protein extraction methods. Wet and dry isolation methods were demonstrated as main methods in oat protein extraction. Functional properties of oat protein, such as thermal stability, solubility, emulsification, water hydration capacity and foaming were reviewed and evaluated, identifying limitations and protein alterations which occur through the oat protein extraction process. The study provides recent trends in oat protein recovery technologies, along with an overview of current and potential oat protein utilization in food systems.


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 ◽  
...  

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).


Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3265 ◽  
Author(s):  
Wenjun Ma ◽  
Fengying Xie ◽  
Shuang Zhang ◽  
Huan Wang ◽  
Miao Hu ◽  
...  

The soy protein isolates (SPI) extracted from different extruded full-fat soybean flakes (FFSF), and their conformational and functional properties were characterized. Overall, the free thiol (SH) content of SPI increased when the extrusion temperature was below 80 °C and decreased at higher temperatures. Soy glycinin (11S) showed higher stability than β-conglycinin (7S) during extrusion. Results also indicated that the increase in some hydrophobic groups was due to the movement of hydrophobic groups from the interior to the surface of the SPI molecules at extrusion temperatures from 60 to 80 °C. However, the aggregation of SPI molecules occurred at extrusion temperatures of 90 and 100 °C, with decreasing levels of hydrophobic groups. The extrusion temperature negatively affected the emulsifying activity index (EAI); on the other side, it positively affected the emulsifying stability index (ESI), compared to unextruded SPI.


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