Electrostatic complexes of whey protein and pectin as foaming and emulsifying agents (original) (raw)
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Improved emulsion stabilizing properties of whey protein isolate by conjugation with pectins
Functional properties of glyco-protein conjugates of the anionic polysaccharide pectin with whey protein isolate, obtained by dry heat treatment at 60 8C for 14 days, have been investigated in O/W emulsions containing 20% (w/w) soybean oil and 0.4% (w/w) protein both at pH 4.0 and 5.5. Emulsion stabilizing properties of mixtures and conjugates were compared at five protein to pectin weight ratios by determining changes in droplet size distribution and extent of serum separation with time. The results indicated that the dry heat-induced covalent binding of low methoxyl pectin to whey protein, as shown by SDS-PAGE, led to a substantial improvement in the emulsifying behaviour at pH 5.5, which is near the isoelectric pH of the main protein b-lactoglobulin. At pH 4.0, however, a deterioration of the emulsifying properties of whey protein was observed using either mixtures of protein and pectin or conjugates.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007
Combining total carbon (TC) and total nitrogen (TN) measurements, the solubility of both protein and pectin in mixtures of 0.5% whey protein isolate and non-amidated high methoxyl sugar beet pectin was determined at pH 4.0, as well as pH 5.5. The experimental results indicated that insoluble complexes with a protein to pectin ratio of 3.84 ± 0.88 were formed at pH 4.0 at protein to pectin ratios ranging from 5 to 0.5. At pH 5.5, the protein solubility was independent from the amount of pectin added, indicating that at these pH conditions, located above the whey protein's iso-electric point, either soluble complex formation or cosolubility occurred. Light microscopic analysis of the corresponding emulsions revealed that the large droplet sizes at a protein-pectin ratio of 5 at pH 4.0 were due to the low amount of soluble protein left due to complexation with pectin. Comparing the residual dissolved protein and pectin concentrations in the absence and presence of oil droplets indicated that not only the protein, but also the pectin was accumulated at the O/W interface both below and above the protein's iso-electric point. Electrophoretic mobility measurements clearly indicated that pectin adsorption to the whey proteins induced a charge reversal at pH 4.0 at higher pectin concentrations, giving rise to smaller droplet sizes. At pH 5.5, on the other hand, the electrophoretic mobility of the whey protein stabilised emulsion droplets became gradually more negative upon pectin addition, which not only resulted in a smaller droplet size, but also in a significant increase of the creaming stability. From the experimental results, it follows that pectin has an emulsion stabilising effect on protein stabilised emulsions both below and above the protein's iso-electric point, provided that electrostatic protein precipitation is prevented.
Colloids and Surfaces, 2016
Whereas Whey Protein Isolate may be used as effective emulsifier, it suffers from limited stability upon heating. In this research, the effect of combining Whey Protein Isolate (WPI) with Low Methoxyl Pectin (LMP) on the heat stability of WPI was investigated. This was accomplished either by simple mixing or by conjugate formation by dry heat treatment. WPI-LMP mixtures and conjugates were prepared at a WPI to LMP ratio of 1:0, 4:1, 2:1, and 1:1. Conjugates were prepared by means of dry heat treatment at a temperature of 60 o C and 74% relative humidity by incubation for up to 16 days. The pH effect and brown color development of the WPI-LMP conjugates upon incubation was monitored. SDS-Page, free amino group determination, as well as diffusion coefficient analysis, all confirmed the formation of new compounds with high molecular weight. The heat stability of the conjugates was then tested and compared to the native WPI. Upon 2 minutes of heating at 80 o C and pH 6.5, the solubility of WPI was reduced by approximately 50% due to thermal denaturation and subsequent aggregation. However, dry heat treatment of the WPI-LMP mixtures highly improved the heat stability of WPI: as the incubation time was increased, the residual protein solubility upon heating of the WPI became higher. Upon 16 days of incubation, the protein solubility of the heated WPI-LMP conjugates was comparable to that of the conjugates before heating. Considering the emulsifying properties, it was found that WPI-LMP conjugates produced smaller oil droplet compared to either native WPI, dry heated WPI, or mixtures of WPI-LMP which were not subjected to conjugation by dry heat treatment. Heating the emulsions at 80 o C for 10 and 20 minutes revealed that WPI-LMP conjugates stabilized emulsions exhibited excellent stability towards heat: whereas pronounced aggregation and gelation occurred in emulsions stabilized by WPI or mixtures with LMP, the conjugate stabilized emulsions retained their original viscosity and particle size.
Emulsifying Properties of Whey Protein-Carboxymethylcellulose Complexes
Journal of Food Science, 2002
Proteins/polysaccharides complexes could improve emulsifying properties of proteins by thickening the layer at the interface of the oil droplets. Emulsifying properties of whey protein-carboxymethylcellulose complexes (WPI/CMC) were compared with those of a whey protein isolate (WPI). Ingredients were incorporated into oilin-water emulsions with various protein and oil contents. Visual observations, protein load, protein distribution and rheological measurements were used to evaluate emulsion stability. Protein load up to 26.1 and 48.9 mg protein/g oil were obtained for WPI and WPI/CMC emulsions, respectively. The higher protein load of WPI/CMC emulsions and visual observations indicated that WPI/CMC complexes had greater emulsifying properties against coalescence than whey proteins. However, complexes enhanced flocculation of oil droplets.
Food Structure, 2020
In this study, we have investigated the interfacial and emulsion stabilizing properties of heat-induced whey protein isolate (WPI) aggregates prepared in the presence or absence of low-methoxy pectin (LMP). Sub-micron complex particles were formed by heating of oppositely charged WPI and LMP at different WPI:LMP mass ratios. The Quartz Crystal Microbalance with Dissipation (QCM-D) technique was used to better understand the adsorption properties of these biopolymeric particles at a model hydrophobic surface. Clear correlations were observed between the interfacial properties of WPI and WPI:LMP aggregates and the resulting emulsion characteristics. Compared to WPI aggregates (which led to emulsions containing larger flocculated droplets), the heated complexes (formed at a higher ratio of LMP to WPI) were highly efficient as Pickering stabilizers leading to emulsions with smaller droplets (5.5-6.8 μm). Cryo-SEM analysis clearly revealed the manipulation of the emulsions' interfacial microstructure due to the adsorption of a WPI:LMP inter-polymeric film onto the surface of the droplets. The effectiveness of the colloidal particles in stabilizing emulsions depended largely on the formation of a sufficiently 'dense layer' of particles at the oil-water interface where these properties were controlled by the composition of WPI and LMP at the oil droplet surface. Moreover, the emulsion physical stability was greatly influenced by the formation of an interconnected film at the oil droplet interface, whereby these viscoelastic films increased the steric hindrance against coalescence of emulsion droplets. This work provides the mechanism of emulsion stabilization by WPI particles formed by heating in the absence or presence of pectin.
Foods
Whey protein pectin complexes can be applied to replace fat in food products, e.g., pudding and yogurt, contributing to creaminess while adding a source of protein and fiber. Production of these complexes is usually conducted on the laboratory scale in small batches. Recently, a process using a scraped-surface heat exchanger (SSHE) has been employed; however, dispersion preparation time, feasibility of using different whey protein sources and enrichment of the complexes for subsequent drying have not been assessed. Preparing whey protein pectin dispersions by solid mixing of pectin and whey protein powders resulted in larger complexes than powders dispersed separately and subsequently mixed after a hydration time. Dispersions without hydration of the mixed dispersions before thermomechanical treatment had the largest particle sizes. The targeted particle size of d90,3 < 10 µm, an important predictor for creaminess, was obtained for five of the six tested whey protein sources. Dis...
Protein-polysaccharide interactions and aggregates in food formulations
Current Opinion in Colloid & Interface Science, 2020
The protein-polysaccharide combinations that lead to electrostatic complex and coacervates formation are the object of extensive research using both layer-by-layer and mixed emulsion approaches. The protein-polysaccharide conjugates demonstrated interesting physico-chemical properties as stabilizers and emulsifiers as well as texture modifiers in food products. Furthermore, they are potential optimal nutrient delivery systems. Their complex behavior due to several factors such as pH, ionic strength, concentration, heat, and mechanical treatments is the main reason behind the continuous growth of the research field. The review is reporting same recent advances on the topic, along with an overview on the possible interactions between protein and polysaccharide, from Maillard reaction to enzymatic crosslinking passing through coacervates.
Comprehensive Reviews in Food Science and Food Safety, 2018
Whey proteins are obtained from dairy industry waste. Studies involving the analysis of the bioactive compounds in whey show health benefits, as it is an excellent source of indispensable amino acids. Milk whey contains principally β‐lactoglobulin, α‐lactoglobulin, bovine serum albumin, and lactoferrin, proteins with innumerable functional and technological properties. One application of these proteins in food is the formation of interpolymer complexes, along with other proteins or anionic polysaccharides. The formation of complexes occurs mainly through electrostatic interactions between a negatively charged biopolymer and a positively charged biopolymer. This formation is influenced by factors such as pH, ionic strength, and biopolymer ratio. Because they do not use high temperatures and chemical reagents and have additional nutritional and functional value, these complexes have been used as encapsulating agents for bioactive ingredients. Recent studies on their training and appli...
Stabilization of Whey Protein Isolate−Pectin Complexes by Heat
Journal of Agricultural and Food Chemistry, 2010
Protein-polysaccharide complexes formed under electrostatic associative conditions could have interesting functional properties. However, their stability over a wide range of pH limits their widespread application. The aim of this work was to determine the time-temperature combination required to stabilize whey protein isolate (WPI) and pectin (LMP) complexes formed at pH 4.5 to a further pH adjustment to 7. The effect of storage for 28 days at 4°C was also evaluated. Stability was confirmed by quantification of sugar and nitrogen in each phase after centrifugation. Three heat treatments were performed: 73°C/5 min, 85°C/15 min, and 90°C/2 min. At 73°C/5 min, adjustment to neutral pH led to disruption of WPI-LMP complexes. The most severe heating conditions (85 and 90°C) allowed the stabilization of WPI-LMP complexes. Heated complexes (90°C) could be preserved for up to 28 days of storage at 4°C without affecting their stability.
Food Chemistry, 2020
We investigated changes in the chemical composition of WPI as a result of heating (60°C, 72 h) with SBP in solution (pH 6.75). The concentration of WPI was kept at a constant (3%), whereas the level of SBP was varied at 1, 1.5, and 3%. The reaction products were examined using the Ellman's reagent, ninhydrin assay, and gel electrophoresis. The results demonstrated that the losses of the free sulfhydryl (-SH) and primary amine (-NH 2) contents in WPI were less severe compared to those occurring in the dry-state at similar conditions (mass ratio, temperature, and reaction duration). The mixtures were used as emulsifiers in an O/W emulsion system at pH 3.20 and 6.75 and showed an improved ability to stabilize the average size of the droplets than WPI alone at acidic pH. The mixtures at higher levels of SBP, ≥ 1.5%, however, adversely affected the emulsion stability at neutral pH.