As interaction between proteins and polysaccharides is expected to change the average diffusion coefficient and the distribution width, it is believed that NMR diffusometry can be a useful tool to ...study and quantify the interaction between whey protein isolate (WPI) and low methoxyl pectin (LMP). For this purpose, the influence of pH, dry‐heat‐treatment duration, and WPI to LMP ratio on WPI and LMP interaction was evaluated using pulsed field gradient NMR. At pH 5.0 and 5.5, approximately 40–50% of the WPI present in the mixture interacted with LMP through electrostatic interaction. Hence, it is important to measure the degree of covalent interaction at a pH where electrostatic interaction between WPI and LMP is limited. The diffusion coefficient of WPI gradually decreased as the mixtures of WPI and LMP were incubated for 1, 2, 8, and 16 days, which was accompanied by an increase in the distribution width. With regard to the LMP concentration, the higher the LMP concentration, the higher the amount of WPI bound to LMP and the smaller the diffusion coefficient of WPI. Overall, the results indicate that NMR diffusometry enables the quantification of the interaction in biopolymer mixtures. Whereas the results showed a similar trend as that obtained via chemical analysis, pulsed field gradient NMR does not require any sample pretreatment.
In our research, NMR diffusometry was used to study the interaction between whey protein isolate and low methoxyl pectin in function of pH, dry‐heat‐treatment duration, and whey protein isolate to low methoxyl pectin ratio. Our results indicate that NMR diffusometry enables the quantification of the interaction in biopolymer mixtures. The obtained results are comparable with those from chemical analysis.
Polysaccharide protein conjugate is usually prepared by electrostatic interactions or Maillard reaction. In this study, coconut protein concentrate (CPC)-pectin conjugate was synthesized by a ...combination between the electrostatic and early stage Maillard reaction. The objective was to evaluate the effect of CPC-pectin ratio, temperature, and pH on emulsion stability index (ESI) and emulsion activity index (EAI). Furthermore, the obtained conjugate was used to stabilize the red palm oil emulsion. The conjugate was prepared by mixing CPC and pectin solution, and dried in a cabinet dryer. Factors, such as CPC-pectin ratio (1:3, 1:2, 1:1, 2:1, 3:1), incubation temperature (50, 60, 70, 80, 90 °C), and pH (3; 3.5; 4; 4.5; 5) were evaluated. The result show that CPC contained 67.40% ± 0.93 protein. ESI and EAI of CPC was not detected. CPC-pectin ratio, temperature, and pH had a significant effect on ESI and EAI, except temperature was not significant effect on EAI. Early stage Maillard reaction was confirmed by FTIR analysis since the peak intensity of amida I increased and amida II decreased. The best CPC-pectin conjugate was found at CPC-pectin ratio of 1:2 (w/w), incubation temperature of 80 °C, and pH of 4. ESI, EAI, droplet size and zeta potential of red palm oil emulsion were 165.263 min; 72.314 m2/g; 553.4 nm and −45.5 mV, respectively. The emulsion droplets were uniform in size and equally dispersed. In summary, drying of conjugate on cabinet dryer induced early stage Maillard reaction and the conjugate can be used to stabilize red palm oil emulsion.
As the demand for “clean label emulsions” and natural emulsifiers is increasing, whey proteins have a big potency to be used as an emulsifier in food emulsions. However, in order to enable their ...application, whey proteins should withstand high temperature processing. Hence, the limited heat stability of whey proteins is a major drawback: they are highly heat labile and thus prone to heat induced protein denaturation and aggregation. As this phenomenon highly impacts their functionality, it is of utmost importance to increase the heat stability of whey proteins to broaden their application in the food industry, which requires a thorough knowledge of the heat stability properties of whey proteins.
To better understand the heat stabilizing activity of whey protein-polysaccharides conjugates, studies on the heat stability of whey proteins and whey protein stabilized emulsions, as well as approaches to improve their heat stability, especially using the dry heat treatment method are reviewed.
Chemical modification by combining whey proteins and polysaccharides has been reported to successfully improve the heat stability of the obtained conjugates. Hence, this new whey protein-polysaccharide material is promising to be used as a natural emulsifier.
•Whey proteins and whey protein stabilized emulsions are heat labile.•Heat stability is crucial for the broader industrial application of whey proteins.•Whey protein-polysaccharide conjugation largely increases the heat stability of whey proteins.•This is attributed to electrosteric stabilization provided by the attached polysaccharides.
Cold cocoa (chocolate) drink is highly in demand in tropical countries, especially in the cocoa-producing regions. Due to a relatively high fat content and a strong structure of cocoa powder ...particle, the solubility of cocoa powder in a relatively low temperature of water is low. A method that can create easily dissolved powder in relatively low temperature of water is highly desired by cocoa beverage producers. The objective of this study was to investigate the performance of a laboratory-scale steam jet agglomerator that was used to produce instanised cocoa drink powder with a higher solubility. In this study, two experimental variables, namely drying duration and stabiliser/sweetener addition, were used. Three drying durations, namely 4, 6 and 8 h, were applied. Cocoa powder (60%) was mixed with maltodextrin (40%). For other samples, cocoa powder (55%) was mixed with a sweetener (45%). Sucrose, coconut sugar and mixture of sucrose and coconut sugar was used as sweeteners. The results showed that the solubility of the cocoa powder mixed with coconut sugar was the highest. All samples exhibited good flowability and cohesiveness. The fineness modulus of the agglomerated samples was higher than that of the raw ingredients. The colour of the cocoa drink powders formulated with maltodextrin had propensity to be the brightest. In addition, samples with maltodextrin exhibited significantly low moisture content. The results presented that steam jet agglomerator has potential to improve the most important quality parameters of the cocoa drink powder.
Spirulina (Arthrospira platensis) is an intriguing but underutilized protein source in the food industry. This study aims to investigate the effect of electrostatic complexation and conjugation on ...the techno-functional properties of the protein spirulina and its benefits as an emulsifier in oil-in-water (O/W) emulsion in order to broaden its application as food ingridients. The Spirulina protein concentrate (SPC) interacted with carrageenan via electrostatic and conjugation (Maillard reactions). The properties of the complexes and conjugates were then evaluated. The results showed that the turbidity, browning index, and thermal stability of the solution were influenced by the protein: polysaccharides ratios and pH conditions. The best conjugates (MR) were obtained at a ratio of 2:1 with a pH of 7.0 based on confirmation of the degree of glycation, browning index value, emulsion activity index (EAI) value, and emulsion stability index (ESI). The best electrostatic complexes (EI) were obtained at a ratio of 2:1 with a pH of 2. SPC-carrageenan conjugates and complexes exhibited different functional properties based on conformation structure by FTIR and thermal properties by DSC. Conjugation and Electrostatic Interaction increased the denaturation temperature of SPC, which were reflected in the emulsions stabilized by maillard reaction (MR), electrostatic interaction (EI), and simple mixed (SM) SPC-carrageenan. The emulsion stabilized by MR had smaller droplet sizes, was more evenly distributed, and had better stability towards heating than those stabilized by Native SPC, SM, and EI. This study provides valuable basic information for the development of spirulina protein as a green emulsifier and other type of novel food.
•Spirulina protein was modified through electrostatic complexation and conjugation•pH and ratio influenced the emulsifyng activity of conjugates and complexes•Conjugated spirulina protein produced better emulsion
In this study, Whey Protein Isolate (WPI) was conjugated with Low Methoxyl Pectin (LMP) as a means to improve the heat stability of whey protein stabilized oil in water (o/w) emulsions. Hereby, the ...emulsifying activity and heat stability of the emulsions (10% w/w of oil) stabilized by 0.5% WPI-LMP conjugates were compared to the stability of emulsions stabilized by either 0.5% WPI, 0.5% of a mixture of WPI-LMP, or 0.5% dry heated WPI. The influence of LMP concentration, pH (i.e. 6.5 versus 5), and ionic strength (i.e. 0 and 30 mM of NaCl) on the stability of the emulsions was studied. It was found that unheated emulsions stabilized by WPI-LMP conjugates had a relatively small droplet size and were stable against creaming, irrespective of the pH and ionic strength of the emulsions. Results also showed that not only the pH sensitivity, but also the heat-sensitivity of WPI-stabilized emulsions could be significantly improved by application of pectin. Upon heating at 80 °C and 120 °C up to 20 min, there was almost no change in the particle size distribution of the conjugate-stabilized emulsions after heating. Viscosity measurements showed a similar trend; heat treated emulsions stabilized by conjugates did not show any change in consistency. This pronounced heat stabilizing effect of LMP, however, was not observed in emulsions stabilized by a mixture of WPI-LMP. With regard to the dry heat incubation time, a 2 days incubation period was sufficient to produce a WPI-derived emulsifier with superior stability towards both pH and heat treatment.
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•Conjugation significantly improved the heat stability of WPI stabilized emulsions.•LMP concentration did not influence the heat stabilizing activity of conjugates.•WPI-LMP conjugates exhibited better emulsifying activity than mixture of WPI-LMP.•Incubation time influenced the emulsifying activity of the WPI-LMP conjugates.•The nature of the interaction between WPI and LMP was important.
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•Low methoxyl (LM) and high methoxyl (HM) pectin are used.•Dialysis is performed on pectin prior to dry heat treatment.•Degree of methoxylation does not have effect on the emulsifying ...activity of the conjugates.•Heat stability of the emulsions is not affected by the degree of methoxylation.•The heated and unheated emulsions have better creaming stability in the presence of HMP.
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•QCM-D was used to study the adsorption of WPI and LMP.•pH influenced the adsorbed layer characteristics in a reversible way.•LMP interaction with WPI was studied by sequential ...adsorption.•The presence of bound LMP produced a thick and highly viscoelastic layer.
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