Characterization of soluble and insoluble fractions obtained from a commercial pea protein isolate
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Abstract:
In this study, the characteristics of pea protein isolates after aqueous fractionization into water-soluble and water-insoluble fractions by centrifugation, decantation, and lyophilization were studied. Chemical composition and physicochemical properties upon pH changes were determined. The overall protein compositions of both soluble and insoluble pea protein fractions were similar containing albumins, globulins, and lipoxygenases, but amino acid compositions slightly varied. Distinct differences were observed in their charge properties, particle sizes, and voluminosities. The soluble pea protein fraction was free of measurable particles at pH 7, whereas the insoluble proteins contained particles with sizes of > 80 µm. Close to their respective isoelectric points, the soluble (pI = 3.9) and insoluble pea proteins (pI = 4.9) had very similar sizes of 40–50 µm. At pH 3, the particle sizes of soluble proteins did not change, however, the insoluble pea proteins had again sizes of > 80 µm. Voluminosity of the insoluble fraction was pH-dependent and had its highest voluminosity at pH 3 and 7, indicating changes in water binding as a function of pH. In contrast, the voluminosity of the soluble pea protein fraction did not change with pH. Taken together, this study showed that water-soluble and insoluble pea protein fractions of a commercial isolate may differ substantially with respect to their physicochemical properties. Observed inconsistencies in technofunctionality of various commercial preparations could thus be promoted by varying ratios between the two fractions.Keywords:
Pea protein
Fraction (chemistry)
Water soluble
Decantation
Decantation
Centrifuge
Settling
Sedimentation
Centrifugal force
Elutriation
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Coratina monocultivar extra virgin olive oil (EVOO) is known for its level of bitterness, which, if too high, can cause consumer acceptance problems. The aim of this study was to modulate the bitter taste of freshly produced olive oil through endogenous enzymatic activity and microbiota during the decantation phase. The opalescent appearance of the newly produced EVOO was substantially reduced during the first three months of decantation due to the deposition of more than 90% of suspended material, consisting of vegetation water and suspended solid particles. The high content of biophenols and the reduction in water concentration in the oil samples negatively affected the survival of yeasts, which were absent in the oil samples at the end of the third month of decantation. The oleuropeinolytic activity was very intense during the first month of decantation, whereas the reduction in the bitter taste associated with the aglycons was consistent only in the second and third months of decantation. At the end of decantation, the sensory notes of bitterness in the Coratina EVOO were reduced by 33%, lowering the position on the value scale without altering the other qualitative parameters whose values fell within the limits of the commercial EVOO class.
Decantation
Bitter Taste
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Decantation is a simple and traditional process, but it can be performed in innovative ways in the kitchen. In falfisication of true precipitates, the water clarified by rest & separated by decantation is usually useless. Decantation has been frequently used in the kitchen, for example for decanting drinkable water or for defatting meat stocks, or for the clarification of wines (see later), but since the beginning of the 20th century, the need to concentrate ores in large facilities has triggered the design of systems for separating large quantities of solids and liquids in continuous processes. Decantation is based simply on the sedimentation of particles in liquids. An important method for improving decantation is centrifugation, which can greatly increase the rate of separation by simulating a great increase in the force of gravity.
Decantation
Sedimentation
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Creaming
Pea protein
Thermal Stability
Denaturation (fissile materials)
Coalescence (physics)
Protein isolate
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Proteins are widely used as emulsifiers in food formulations. However, emulsifying properties of proteins are weak at pH values close to their isoelectric point resulting in destabilization. Protein-polysaccharide interactions have been proposed to improve the emulsification behaviour of proteins in such conditions. In this work, two different polysaccharides (pectin and gum Arabic) with a range of surface charges were chosen to investigate their interactions with pea proteins. The initial aim was to investigate the effect of heat treatment on the complexation of pea protein isolate (PPI) and the polysaccharide with the ultimate purpose of using them as effective emulsifiers at various pH values for beverage application. The emulsions were prepared, and the emulsification ability was determined with the selected protein-polysaccharide complexes at both basic (pH 8.0) and isoelectric pH (pH 4.5) conditions. Turbidity graphs of gum Arabic-PPI and or pectin-PPI complexes at 1:1 mixing ratio revealed an increase in the pH range of the soluble complexes upon heat treatment of the mixture to 75ºC. The soluble complexes of the protein and polysaccharide were able to stabilize oil-in-water beverage emulsions at the isoelectric pH of the protein. The stabilization effect of soluble pectin-PPI complexes was better than gum Arabic-PPI complexes at pH 4.5. At pH 8, although droplet sizes were similar, pectin-PPI complexes caused depletion flocculation leading to a higher accelerated creaming velocity of the emulsion than the gum Arabic-PPI complexes. The emulsions stabilized by pectin-PPI complexes at pH 4.5 had the highest emulsion stability in terms of lower instability index, lower accelerated creaming velocity and the lowest droplet diameter than all other emulsions. The findings of this study will provide beneficial information on the effect of processing conditions on biopolymer interactions and the emulsification ability of protein-polysaccharide complexes for the application in beverage emulsions.
Pectin
Pea protein
Gum arabic
Creaming
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Laboratory conditions were first investigated to determine are optimum processing parameters for the preparation of a protein isolate from the ground, defatted, commercial flakes of Lupinus mutabilis. The extraction variables were: pH (2-10); solvent to lupine ratio (5:1 to 40:1); temperature (28 degrees C - 60 degrees C) and time (10-50 min). The isoelectric point of the lupine protein was found to be pH 4.5 with a protein solubility higher than 80% above pH 8.0. Using 70-100 mesh, ground defatted flakes, and extracting at pH 8.7 for 60 min, a protein isolate was obtained on acidification to pH 4.5 which was 99.8 protein (dry basis), compared to 55.25% protein for the original material. This protein isolate represented 32% of the initial material and 57.6% of the initial nitrogen. When making pilot plant assays we found that the yield of protein isolate decreased to 20.4% of the original material and 36.4% of the initial nitrogen. The protein efficiency ratio for the protein isolate was 2.15 when supplemented with methionine, and had a digestibility of 89.33
Lupinus
Pea protein
Protein isolate
Plant protein
Protein purification
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Pea protein
Enzymatic Hydrolysis
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Abstract The decanted surfaces of a crystal grown from the melt show various kinds of solidification markings formed either during growth or decantation. Some of the special features which are peculiar to decantation were discriminated from the real solid‐liquid interface morphology by in situ observation of salol crystals under the microscope.
Decantation
Morphology
Crystal (programming language)
Polarized light microscopy
Interface (matter)
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Fraction (chemistry)
Decantation
Pellet
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