In this research, gum Arabic (GA) and whey protein nanofibrils (WPN) were employed for the encapsulation of curcumin as a bioactive compound with low water solubility through the complex coacervation ...method. The optimum conditions for the formation of complex coacervates were found at WPN/GA weight ratio of 1:1 and pH value of 3.0. The resulting complexes showed a high ability for loading of curcumin as a bioactive cargo. Fluorescence spectroscopy showed that the curcumin was loaded in the hydrophobic core of WPN/GA coacervates. The characteristics of curcumin-loaded coacervates were also evaluated by XRD and FT-IR analysis. The curcumin-loaded complex coacervates dispersions showed a shear thinning behavior. They also showed a good surface activity which makes them excellent candidates to fabricate new functional food emulsions and beverages. The results indicated that the antioxidant activity and photo-stability of curcumin were significantly improved by encapsulation into WPN/GA complexes. A sustained-release profile also was investigated for curcumin from WPN/GA complexes in the simulated gastrointestinal conditions. This study suggested that the WPN/GA electrostatic-driven complexes can be used as efficient carriers for curcumin delivery.
A significant barrier to using plant proteins in food formulation is their low solubility and inferior functionality compared to animal proteins. In the current study, alkaline electro-activation ...(EA) was employed to graft whey proteins with canola proteins to create new composite soluble proteins with superior functionality. Sweet whey was used as a low-price source of animal protein to modify the canola proteins. It was found that the alkaline EA treatment was very effective in functionality improvement of both canola protein alone solution and their mixtures. Furthermore, the results suggested the presence of whey during the alkaline EA treatment of canola protein solution caused the structural alteration of canola proteins, and formation of protein particle with smaller size and higher surface charge. It resulted in the creation of novel composites proteins with superior solubility and emulsifying properties compared to the EA-treated canola alone sample. This enhanced solubility and emulsifying properties was concluded to be a result of lactose grating on the protein backbone of canola proteins. The overrun of canola protein alone solution increase from 100% to more than 500% after EA-treatment. However, the presence of whey in the EA-treated whey/canola protein solution slightly decreased the foam overrun of the sample compared to EA-treated canola alone sample, possibly due to grafting lactose onto the surface of the proteins, resulting in a lower protein surface hydrophobicity. This study showed that the alkaline EA treatment was an effective process to enhance the solubility and functionality of canola proteins and their mixture with whey.
Display omitted
•Alkaline electro-activation (EA) improved protein solubility of canola proteins.•EA in the presence of whey showed a superior impact on canola proteins functionality.•EA-treated canola/whey solution had higher solubility than EA-treated canola alone solution.•The EA-treated canola/whey samples produced emulsions with the highest stability.
Thistle flowers are traditional coagulants that have been used for many years in southern Europe and northern Africa for cheese production. The flowers contain aspartic proteases (APs) with high ...milk-clotting and cheeses produced with the vegetable coagulants tend to have a creamier and softer texture and more intense odour and flavour compared with those made with commercial chymosin or calf rennet. This review provides an overview of structural characteristics of the APs and their functional properties such as pH and temperature-dependence of their enzyme activity, substrate specificities, and technological applications, with a focus on cheese manufacturing. The review also refers to recent achievements on in vitro production of the APs present in thistle flowers using recombinant enzyme technologies. These techniques could be considered as promising strategies to scale up the production of plant APs to strengthen the industrial applications of the vegetable enzymes.
Background.
The shifts in global eating patterns towards greater consumption of protein-based foods encourages research to recover protein from sustainable sources and valorization of existing ...proteins. However, some proteins show poor functionalities in food systems. The application of alkaline-aided treatments to modify these proteins for converting them into functional ingredients has attracted prominent interest. A review on this subject is of demanding to fill the knowledge gap in exploiting the benefits of the alkaline-aided treatments.
Scope and approach.
This review studied the recent developments in alkaline-mediated treatments for extraction and functional modification of proteins. The most important parameters in alkaline-assisted extraction of proteins from animal and plant sources were surveyed. The combination of alkaline-assisted extraction with other technologies was investigated. The effects of the alkaline-mediated treatment alone or in combination with other novel technologies for the functional modification of proteins and their co-assembling to produce soluble hybrid proteins are reviewed. Finally, the electro-activation approach as a reagentless technology for generation in place alkaline medium and its applications in the extraction and functional modification of protein is discussed.
Key findings and conclusions.
This review reveals that alkaline medium, particularly when combined with other treatments such as heating and ultrasound, can significantly affect the conformation and structure of protein due to their irreversible unfolding, leading to significant enhancement of their solubility, emulsifying, foaming, gelation, and bioactive compound binding properties. Furthermore, alkaline treatment can be used for co-assembling a low soluble compact protein with a highly soluble protein, leading to the fabrication of the soluble hybrid nanoparticles through structural interactions. It is evident from the findings that a combination of novel techniques is proven to be more efficient for protein recovery and functional modification of proteins, so innovating combination of the novel technologies with alkaline treatments can be interesting topics to help to decipher the key challenges faced by food processing industries to valorize the food protein resources.
•Alkali-aided treatments to extract and modify proteins are outlined in the review.•Protein yield and functionality are influenced by pH levels used during extraction.•Novel techniques assisted-alkaline extraction can increase protein extractability and improve their functionality.•Alkaline-induced hybridization can fabricate highly soluble and function proteins.•Electro-activation as a reagentless method to generate in place alkaline medium discussed.
Casein is an excellent carrier for curcumin, but it is susceptible to hydrolysis in gastrointestinal digestion. This study intended to design a tailored nano-carrier composed of camel casein/bovine ...whey protein to protect casein and curcumin during digestion. After loading curcumin to the casein, whey protein was added to solution followed by heating at 80°C for 10 min in order to form casein/whey protein aggregations. Binding of curcumin to the solution was assayed by fluorescence. The results showed that in the existence of aggregated whey proteins, stability of curcumin against gastrointestinal condition significantly improved. These results attributed to the protective effect of the aggregated whey proteins during the gastric digestion and denaturation in the accessibility of pepsin to the casein. It was demonstrated that this method might be a good design to combat susceptibility of casein without the use of any synthetic material.
In the present study, whey protein nanofibrils (WPN) were used as carriers to improve the aqueous solubility of curcumin at acidic conditions (pH 3.2) for expanding its applications in functional ...beverages and drinks. Nanofibrils with nanometric diameter (less than 15 nm) and micrometric length were produced by 5 h heating (85 °C) of whey protein isolate (WPI) solution at pH 2.0. WPN showed a higher surface hydrophobicity compared to the native parental proteins which improved its ability to form a soluble complex with curcumin. The water solubility of curcumin was increased by about 1200-folds through the complexation with WPN, whereas the complexation with WPI increased its solubility by approximately 180-folds. Fluorescence measurements and Fourier transform infra-red spectroscopy indicated that the hydrogen bonding and hydrophobic interactions were mainly contributed to the formation of curcumin-WPN complexes. Circular dichroism spectroscopy revealed that the secondary structures of WPN were not significantly affected by binding to curcumin. The structural phase of nanocomplexes also was studied using X-ray diffraction analysis. Complexation of whey protein nanofibrils with curcumin improved their apparent viscosity and surface activity which makes them appropriate candidates to design new functional food emulsions and beverages. The results of antioxidant activity measurements (DPPH radical scavenging activity and reducing power) also showed that the antioxidant capacity of curcumin was drastically improved through the complexation with WPN. Generally, this study suggests that the whey protein nanofibril could be employed as a material to enhance the food applications of curcumin as a water-insoluble bioactive compound.
Display omitted
•Whey protein nanofibrils (WPN) with high surface hydrophobicity were produced.•Binding of curcumin to WPN drastically increased its aqueous solubility at pH 3.2.•Curcumin was bound to WPN mainly by hydrophobic interactions and hydrogen bonds.•Curcumin-WPN nanocomplexes showed a good antioxidant activity and high viscosity.
•Alkaline electro-activation (EA) efficiently improved protein solubility of whey.•EA-treated whey produced emulsions with smaller size and superior stability.•A significant enhancement in foaming ...properties was achieved by EA-treated whey.
The impact of alkaline electro-activation (EA) on the protein solubility, foaming, and emulsifying characteristics of whey was investigated. EA caused protein aggregation and conjugation. At low electric current and holding time, proteins aggregation through disulfide bonds was observed, whereas increasing currents and holding times caused proteins to conjugate with sugars such as lactose, lactulose and galactose. The EA process improved the protein solubility at the pH range of 4.0–7.0. Compared to untreated whey, which produced micron-sized and unstable emulsions at pH 3, whey samples treated under 750 mA and 24–48 h holding time formed nano-sized and stable emulsions at this pH. Furthermore, although both untreated and EA-whey produced stable emulsions at pH 7, those emulsions prepared with EA-whey had smaller particle size and were more stable against droplet flocculation. EA-treated whey tended to generate foams with significantly higher overrun and stability. The present study demonstrated that EA can enhance the functionality of whey.
The objective of this study was to investigate the effect of cathodic alkaline electro-activation (EA) treatment on the flow behavior and gelling properties of canola proteins and the mixture of ...sweet whey/canola proteins. Canola proteins alone (C) and whey/canola proteins mixed suspensions (CW) were treated in an alkalinizing electro-activation reactor and then naturalized to neutral pH. The alkaline EA treatment resulted in the production of small aggregates crosslinked by disulfide and covalent bonds. The gelation experiments showed that the EA-treated canola proteins and whey/canola protein samples had a superior capacity to develop an integrated gel structure with higher mechanical and rheological properties and improved water holding capacity compared to the untreated samples. Characterization of interactions involved in the gel network structure suggested that the strong covalent interactions played a prominent role in the network of these EA-treated samples. The SDS-PAGE pattern of the gels made from EA-treated canola proteins and EA whey/canola proteins samples confirmed the presence of intensive protein polymerization through covalent crosslinking in these gels. The results of this study suggest that the alkaline EA treatment is an effective tool for improving the gelation properties of canola proteins and producing whey/canola proteins composite gels with improved functionality.
Display omitted
•Impact of EA on gelation capacity of canola and whey/canola protein were studied.•EA enhanced gelation capacity of canola and whey/canola protein solutions.•Gels made from EA-treated samples showed higher elasticity and mechanical strength.•Gels made from EA-treated samples had more uniform and integrated microstructure.•WHC of the gels prepared from EA-treated samples was higher.
This study aimed to design mixed hydrogels composed of whey protein aggregates (WPA)/k-carrageenan with a tailored microstructure to protect curcumin within the upper gastrointestinal tract and ...deliver it to the colon. Curcumin was loaded in WPA and followed by cold gelation of the aggregates in the presence of k-carrageenan. The Microstructure of the hydrogels varied from homogenous to protein continuous or k-carrageenan continuous depending on the k-carrageenan concentration (0.0, 0.1 and 0.55%, w/w). The physical stability of curcumin toward precipitation during gelation of curcumin-loaded WPA was significantly improved after k-carrageenan addition. The higher capacity of k-carrageenan containing gels to curcumin entrapment was attributed to curcumin embedment inside of the rich-protein microdomains (called microgels), higher viscosity of the gel pre-solutions contained k-carrageenan and the shorter gelation time of the corresponding gels. Moreover, it was found about 31% of the loaded curcumin was released in the simulated gastrointestinal tract for pure WPA gels, while after addition of 0.55% k-carrageenan to WPA gels, more than 87% of loaded curcumin were delivered to the colon. Besides, 33% of curcumin degraded after the gastrointestinal digestion, while for WPA gels containing 0.1% and 0.55% k-carrageenan it was only 9.6% and 3.5%, respectively. The results were attributed to the protective effect of k-carrageenan to protein during in vitro digestion so that the access of digestive enzymes into the hydrogels was limited resulting in a reduction of gel matrix erosion and curcumin release. Therefore, curcumin remained bound to the protein and was not damaged during digestion until it reaches the colon.
Display omitted
•Microstructure of WPI gels varied from homogenous to protein continuous or k-carrageenan continuous.•Curcumin entrapment capacity of WPI gels improved after k-carrageenan addition.•Formation of curcumin loaded microgels made the k-carrageenan/WPI gels suitable for colon specific delivery.•Curcumin remained bound to the protein during digestion in the k-carrageenan/WPI gels.
This study investigated the impact of free radical-induced aggregation by a redox pair (ascorbic acid + H2O2) on physicochemical characteristics, structure, and rheology as well as the emulsifying ...and foaming capacity of egg white protein (EWP). In general, this treatment led to oxidize the free SH groups, a little change in secondary structure, increasing surface hydrophobic (H0) and ζ-potential as well induce aggregation of egg white protein through disulfide cross-linking. The pH at which the oxidative aggregation reaction was performed had a significant effect on the functionality of the EWP. The EWP aggregated at pH 11 had a very high apparent viscosity, which justified by its greater H0, higher aggregation yield and larger aggregates with high effective volume, as confirmed by SDS-PAGE and AFM. Furthermore, emulsions prepared by aggregated EWP samples, particularly the EWP aggregated at pH 11, showed higher stability against droplet flocculation and phase separation during storage for 30 days at various pH (4–7) and salt concentration (0–200 mM) as compared to emulsions made with native EWP, presumably due to create a more viscoelastic film with promoted steric hindrance on oil droplets. Moreover, a dramatically enhanced foam stability was obtained by the EWP aggregated at pH 11. This study suggested that radical induced aggregation has a potential to improve the interface-related properties of egg white protein.
Display omitted
•Egg white proteins (EWP) were aggregated by a radical cross-linking method.•The treatment led to oxidize the free SH groups and form disulfide bridges.•The EWP aggregated at pH 11 (11-AEWP) have the highest aggregation yield.•Emulsions stabilized with aggregated EWP (AEWP) showed enhanced stability.•Foams prepared by 11-AEWP have dramatically enhanced foam stability.
PDF
