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1.
Food Chem ; 351: 129356, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-33647693

RESUMO

Nanoemulsions are currently of interest in the functional food sector because their small droplet size (100-500 nm) provides a number of potential advantages over conventional emulsions. This study concerned the behavior of nanoemulsions stabilized with whey proteins and two synthetic emulsifiers (Tween 80 and Croduret), and exposed to conditions simulating the human upper gastrointestinal tract. In particular, the effect of synthetic emulsifiers (food additives) on the interfacial composition and digestion rate of milk proteins at the interface of nanoemulsions was determined. The results indicate that the protein was partially co-absorbed with only one synthetic emulsifier (Croduret) at the interface, which made protein more resistant to digestion in the nanoemulsion system. This suggests that the degree of protein digestion can be controlled by appropriate selection of synthetic emulsifiers and presenting the protein in nanoemulsion system.


Assuntos
Emulsificantes/química , Nanoestruturas/química , Proteólise , Proteínas do Soro do Leite/química , Humanos , Tamanho da Partícula , Polissorbatos/química
2.
Food Chem ; 352: 129267, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-33691207

RESUMO

In this study, a soluble complex formed between 0.5% (w/v) heated whey protein isolate (HWPI) and 5% (w/v) octenyl succinic anhydride (OSA)-modified starch at pH 4.5 was used to encapsulate ß-carotene for improving its solubility and stability. The apparent aqueous solubility of ß-carotene was increased markedly (264.05 ± 72.53 µg/mL) after encapsulation in the soluble complex. Transmission electron microscopy and scanning electron microscopy were used to evaluate the effect of the encapsulation of ß-carotene on the structure of the soluble complex. Fourier transform infrared spectroscopy showed that the characteristic peaks of ß-carotene disappeared in the soluble complex, suggesting that ß-carotene may have been encapsulated into the soluble complex via hydrophobic interactions. X-ray diffraction indicated that the ß-carotene was in an amorphous form within the soluble complex. An accelerated stability test showed that the soluble complex could effectively improve the chemical stability of ß-carotene during long-term storage under low pH conditions.


Assuntos
Amido/análogos & derivados , Proteínas do Soro do Leite/química , beta Caroteno/química , Cápsulas , Interações Hidrofóbicas e Hidrofílicas , Solubilidade , Amido/química
3.
Carbohydr Polym ; 260: 117843, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712117

RESUMO

In this study, trehalose (TRE) was added to prepare whey protein concentrate (WPC)/pullulan (PUL)/TRE hydrogel and the hydrogel was used as the wall material to improve the viability of encapsulated L. plantarum during freeze drying and storage. The optimum conditions were 5.0 % TRE concentration and 1:4 (v:v) of the ratio of L. plantarum suspension to the hydrogel. Under these conditions, the survival rates of L. plantarum were 94.36 ± 1.06 % after freeze drying and 97.02 ± 0.30 % after storage for 240 d at 4 °C. Interactions and rheological properties of WPC/PUL/TRE hydrogel were also studied. The results showed TRE reduced storage modulus (G') of the hydrogel and weakened hydrophobic interactions, disulfide and hydrogen bonds between proteins and polysaccharides, which was not conducive to hydrogel formation. In addition, the excellent water-holding capacity of WPC/PUL/TRE hydrogel was found by the drying kinetic experiment.


Assuntos
Glucanos/química , Hidrogéis/química , Lactobacillus plantarum/fisiologia , Trealose/química , Proteínas do Soro do Leite/química , Liofilização , Hidrogéis/farmacologia , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Viabilidade Microbiana/efeitos dos fármacos , Reologia , Compostos de Sulfidrila/química
4.
Food Funct ; 12(5): 2090-2101, 2021 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-33554990

RESUMO

Plant-based polyphenols are increasingly being explored as functional ingredients in emulsified food systems. In this study, the effects of sesamol on the physical and chemical stability of flaxseed oil-in-water emulsions stabilized by either phospholipids (sunflower) or proteins (whey or pea) were investigated. In the absence of sesamol, the protein-based emulsions displayed better physical stability than the phospholipid-based ones, which was related to their smaller particle diameter and higher particle charge. For the phospholipid-based emulsions, sesamol addition did not improve their physical stability, but it did inhibit lipid oxidation. In particular, it decreased the formation of secondary oxidation products, with a 65% reduction in TBAR formation compared to the control after 8 days of storage. For the protein-based emulsions, sesamol addition reduced particle aggregation and inhibited lipid oxidation, reducing the secondary oxidation products by around 85% after 19 days of storage. The inhibitory efficiency of sesamol in the pea protein-based emulsions was comparable to that in the whey protein-based ones. The effects of sesamol on the physical and chemical stability of the emulsions were related to its partitioning between the oil, water, and interfacial layers. This study suggests that adding sesamol to plant-based emulsions may improve their physical and chemical stability, thereby extending their shelf life.


Assuntos
Benzodioxóis/farmacologia , Emulsões/química , Óleo de Semente do Linho/química , Fenóis/farmacologia , Fosfolipídeos/química , Proteínas/química , Água/química , Antioxidantes/farmacologia , Fenômenos Químicos , Estabilidade de Medicamentos , Peroxidação de Lipídeos/efeitos dos fármacos , Oxirredução , Proteínas de Ervilha/química , Proteínas do Soro do Leite/química
5.
Food Funct ; 12(5): 2112-2125, 2021 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-33564805

RESUMO

Breakdown of solid foods during gastric digestion plays a major role in the release and absorption of nutrients in the gastrointestinal tract. The breakdown mechanisms of foods during gastric digestion may be influenced by composition, particle geometry, and the resulting moisture uptake and gastric emptying. The extent of breakdown may have implications on the pH, pepsin activity, and subsequent protein hydrolysis. This study aims to identify the influence of particle geometry on pH, buffering capacity, and breakdown mechanisms during in vitro dynamic gastric digestion. Whey protein gels made in different geometries (small, medium, and large cubes with side lengths of 3.1, 5.2, and 10.3 mm, respectively, and spheres with a diameter of 6.5 mm) were subjected to gastric digestion using the Human Gastric Simulator (HGS) over a 180 min period. Particle size in the bulk digesta showed the breakdown mechanism of spheres was primarily by erosion, whereas breakdown of cubes was by fragmentation at the beginning of digestion, followed by erosion. Moisture uptake and gastric emptying of dry matter were significantly influenced by digestion time, particle geometry, and their interaction (p < 0.001). Initial buffering capacity of the gels was highest in small cubes and lowest in large cubes, causing the pH to decrease faster in large cubes. There was a higher pepsin activity in the liquid phase of the digesta in large cubes compared to the rest of the treatments, which was hypothesized to be due to a diffusion limitation of pepsin, resulting in less diffusion into large cubes due to their lower total specific surface area. Further work is needed to develop quantitative connections between food initial properties, breakdown mechanisms, and their implications on pH, pepsin activity, and nutrient digestibility for future food design.


Assuntos
Digestão , Proteínas do Soro do Leite/metabolismo , Tampões (Química) , Esvaziamento Gástrico , Suco Gástrico/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Modelos Biológicos , Tamanho da Partícula , Pepsina A/metabolismo , Saliva/metabolismo , Água/metabolismo , Proteínas do Soro do Leite/química , alfa-Amilases/metabolismo
6.
Food Chem ; 347: 129079, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33493834

RESUMO

This study aimed to examine the effect of whey protein isolate-low acyl gellan gum (WPI-GG) conjugate on the physicochemical properties and digestibility of ß-carotene-loaded oil-in-water emulsions. The WPI-GG conjugate-stabilized emulsions had lower droplet sizes with more homogenous distribution, more negative surface charge, and higher interfacial protein concentration and viscosity, compared to those stabilized by WPI-GG mixture and WPI. The emulsion droplets coated by the conjugate were also generally more stable to environmental stresses (i.e., storage, pH changes, ionic strength, freeze-thaw cycles, and thermal treatment) along with higher ß-carotene retention than other systems. The stability to droplet aggregation during in vitro digestion was remarkably increased for the conjugate-stabilized emulsion. However, the ß-carotene bioaccessibility was significantly affected when the conjugate was used to stabilize the emulsions, likely due to the thick interfacial layer, high viscosity, and negative charge of the corresponding emulsions that could inhibit droplet digestion and mixed micelle formation.


Assuntos
Emulsões/química , Polissacarídeos Bacterianos/química , Proteínas do Soro do Leite/química , beta Caroteno/química , Digestão , Armazenamento de Alimentos/métodos , Concentração de Íons de Hidrogênio , Óleos/química , Concentração Osmolar , Temperatura , Raios Ultravioleta , Viscosidade , Água/química , beta Caroteno/metabolismo
7.
Food Chem ; 348: 129102, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33508599

RESUMO

The present study aimed to fabricate whey protein isolate (WPI)-sodium alginate (ALG) nanocomplexes for curcumin (CUR) stabilization in a model fat-free beverage. Mass ratio of 5:1 at pH 5.0 in the absence of NaCl was optimized for WPI-ALG nanocomplex fabrication. Mean particle size and zeta-potential of CUR-WPI-ALG nanocomplex was 209.9 nm and -39.1 mV at pH 5.0, respectively. Highest loading amount (LA) of CUR in CUR-WPI-ALG nanocomplex were 15.26 µg/mg. No obvious precipitates were observed for CUR-WPI-ALG nanocomplex under simulated food processing and storage conditions including high sucrose, high NaCl, and thermal treatment at 90 °C for 2 h. Fluorescence results confirmed that the spontaneous interaction between CUR and WPI-ALG nanocomplex was primarily motivated by hydrophobic interaction and hydrogen bonding. Compared with CUR (free), chemical stability (UV light, and heat), and DPPH scavenging capacities of CUR in CUR-WPI-ALG nanocomplex were strikingly improved.


Assuntos
Alginatos/química , Bebidas/análise , Curcumina/química , Proteínas do Soro do Leite/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Solubilidade
8.
Food Chem ; 347: 129006, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33472117

RESUMO

Multilayer bottles consisting of chitosan (CS), microcrystalline cellulose (MCC), whey protein isolate (WPI), and polyethylene terephthalate (PET) were tested as novel materials for packaging and extending shelf life of rosebud beverages. We studied the storage stability at 4 °C, 25 °C, 37 °C, and 55 °C by assessing the physical and biochemical parameters. The results show that multilayer PET bottles had better barrier performance and improved soluble solids content, pH, polyphenol content, color indices, and browning degree in rosebud beverages over the control at all studied temperatures. A shelf life model was established based on the Arrhenius equation, and the number of days when polyphenol contents dropped to <50% of the initial content was defined as the shelf life. Our results highlight the reliability of the prediction model, and we conclude that packaging rosebud beverages in multilayer PET bottles significantly extends the product shelf life, and this benefit was further extended at low temperatures.


Assuntos
Bebidas/análise , Celulose/química , Quitosana/química , Embalagem de Alimentos/métodos , Polietilenotereftalatos/química , Proteínas do Soro do Leite/química , Cor , Armazenamento de Alimentos , Concentração de Íons de Hidrogênio , Polifenóis/química , Temperatura
9.
J Agric Food Chem ; 69(4): 1348-1358, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33492149

RESUMO

Low-environment-sensitive nanoparticles were prepared by enzymatic cross-linking of electrostatic complexes of dextran-grafted whey protein isolate (WPI-Dextran) and chondroitin sulfate (ChS). The effect of transglutaminase (TG) and laccase cross-linking on nanoparticle stability was investigated. Covalent TG cross-linking and grafted dextran cooperatively contributed to the stability of nanoparticles against dissociation and aggregation under various harsh environmental conditions (sharply varying pH, high ionic strength, high temperature, and their combined effects). However, fragmentation induced by laccase treatment did not promote nanoparticle stability. Structural characterization showed that the compact structure promoted by TG-induced covalent isopeptide bonds repressed dissociation against varying environmental conditions and thermal-induced aggregation. Furthermore, the increasing α-helix and decreasing random coil contents benefited the formation of disulfide bonds, further contributing to the enhanced stability of nanoparticles cross-linked by TG, whereas weak hydrophobic interactions and hydrogen bonding as evidenced by the increase in ß-sheet and microenvironmental changes were not able to maintain the stability of nanoparticles treated with laccase. Encapsulated cinnamaldehyde presented sustained release from TG-cross-linked nanoparticles, and the bioaccessibility was considerably enhanced to 50.7%. This research developed a novel mild strategy to enhance nanoparticle stability in harsh environments and digestive conditions, which could be an effective delivery vehicle for hydrophobic nutrients and drug applications in food and pharmaceutical industries.


Assuntos
Lacase/química , Nanopartículas/química , Transglutaminases/química , Sulfatos de Condroitina/química , Reagentes para Ligações Cruzadas/química , Géis/química , Temperatura Alta , Interações Hidrofóbicas e Hidrofílicas , Concentração Osmolar , Eletricidade Estática , Proteínas do Soro do Leite/química
10.
Food Chem ; 346: 128963, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33422917

RESUMO

ß-Carotene (BC) exhibits several bioactive properties, but its application is restrained due to the unstability and low biological availability. In this study, protein fibrils were prepared from whey protein isolate fibrils (WPIF), which were used as carriers to protect and deliver BC. With the extension of heating time, the molecular weight of WPI decreased gradually. WPI was hydrolyzed into peptides which self-assembled into WPIF, resulting in significant changes in secondary structure, zeta-potential, viscosity and, antioxidant capacity. The main interactions between WPIF and BC were hydrogen bonding and hydrophobic interaction. The encapsulation efficiency of WPIF24 was increased from 76.55% to 92.11% compared to that of untreated WPI. Moreover, the simulated gastrointestinal release showed that the cumulative release of BC encapsulated by WPIF24 reached the maximum in the simulated intestine. Therefore, WPIF could be a potential delivery system for water-insoluble bioactive compounds with enhanced encapsulation efficiency and protection effect.


Assuntos
Proteínas do Soro do Leite/química , beta Caroteno/química , Antioxidantes/química , Química Farmacêutica , Dicroísmo Circular , Cor , Portadores de Fármacos/química , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Estrutura Secundária de Proteína , Reologia , Espectroscopia de Infravermelho com Transformada de Fourier , beta Caroteno/metabolismo
11.
Food Chem ; 346: 128900, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33418409

RESUMO

Curcumin is a bioactive food component, with poor bioaccessibility due to low water solubility and stability. Spray drying retained and in fact enhanced curcumin-whey protein isolate (WPI) complexation via desolvation, lowering the amount of unbound curcumin to <5% wt after drying, forming microparticles with better water solubility, stability, and bioaccessibility than raw curcumin. The desolvated microparticles encapsulated 3.47 ± 0.05 mg/g curcumin, almost one order of magnitude higher than the un-desolvated sample 0.37 ± 0.03 mg/g. After incorporation into yogurt, the rapid-release formula liberated 87% curcumin, whereas the targeted-release one discharged 44% before entering the simulated intestinal condition. Most of the yogurt sensory properties were not adversely affected, except for colour and curcumin flavour. This study proposed a strategy in which food ingredients containing hydrophobic bioactive small molecules can be incorporated into a food matrix to improve bioaccessibility and targeted release, without affecting their sensory properties.


Assuntos
Curcumina/química , Microesferas , Proteínas do Soro do Leite/química , Antioxidantes/química , Cor , Interações Hidrofóbicas e Hidrofílicas , Limiar Sensorial , Solubilidade , Iogurte/análise
12.
Food Chem ; 346: 128886, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33422921

RESUMO

This study examined the release of vitamin B6 from a hydrogel made of whey protein isolate (WPI). Work was carried out at ambient temperature without preheating the whey protein. Native-state macromolecules were crosslinked with a nontoxic compound, genipin. Experimentation included a ninhydrin assay with UV-vis absorbance, FTIR, 13C NMR, compression testing, SEM imaging, WPI matrix swelling and vitamin release protocols. It was confirmed that geninin crosslinked effectively the protein chains whose network strength was reinforced with increasing crosslinker concentrations. The modified Flory-Rehner theory predicted the molecular weight between crosslinks, network mesh size and crosslinking density in the swollen WPI gels as a function of added crosslinker. Transport patterns of vitamin B6 through the polymeric matrix were monitored over prolonged periods of observation. These were examined with the generalised Fick's equation and the Peppas-Sahlin equation to unveil the interplay between diffusion and relaxation dynamics in the anomalous transport of the bioactive compound.


Assuntos
Iridoides/química , Vitamina B 6/metabolismo , Proteínas do Soro do Leite/química , Força Compressiva , Difusão , Portadores de Fármacos/química , Liberação Controlada de Fármacos , Hidrogéis/química , Vitamina B 6/química
13.
Int J Biol Macromol ; 172: 429-438, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33454333

RESUMO

In the present study, the effect of transglutaminase (TGase) concentration on the physical and oxidative stabilities of filled hydrogel particles created by biopolymer phase separation was investigated. The results showed that filled hydrogels had relatively smaller particle sizes, higher absolute zeta-potentials, higher interfacial layer thicknesses and lightness values with the increasing of TGase concentration (P < 0.05), as evidenced by the apparent viscosity and viscoelasticity behavior. However, the relatively higher TGase concentration promoted the protein aggregation, which weakens the protection of the surface protein layer, having the negatively impacted the physical stability of filled hydrogels. Microstructural images which obtained via cryo-scanning electron microscopy also verified the above results. In particular, it is noted that filled hydrogels displayed the lowest degrees of lipid and protein oxidation during 10 days of storage (P < 0.05) at TGase concentration of 10 U/g. Prevention against oxidation was attributed mainly to TGase crosslinking of protein molecules on the surface of droplets, which likely provided a denser interface around lipid droplets. Our results indicated that TGase was a favourable agent to crosslink protein on the surface of lipid and improve the physical and oxidative stability of filled hydrogel particles.


Assuntos
Hidrogéis/química , Gotículas Lipídicas/química , Pectinas/química , Transglutaminases/química , Proteínas do Soro do Leite/química , Portadores de Fármacos , Estabilidade de Medicamentos , Elasticidade , Humanos , Concentração de Íons de Hidrogênio , Oxirredução , Tamanho da Partícula , Reologia , Soluções , Viscosidade
14.
Food Chem ; 336: 127707, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32763737

RESUMO

Anthocyanins (ACNs) are naturally derived colorants and antioxidants added to manufactured foods. ACNs were encapsulated in nanocomplexes with chitosan hydrochloride (CHC), carboxymethyl chitosan (CMC) and whey protein isolate (WPI). The ACN-loaded CHC/CMC-WPI nanocomplexes (ACN-CHC/CMC-WPI) showed a preferred particle size (332.20 nm) and zeta potential (+23.65 mV) and a high encapsulation efficiency (60.70%). ACN-CHC/CMC-WPI nanocomplexes exhibited a smooth spherical shape by transmission electron microscopy. Fourier transform infrared (FT-IR) and Raman spectroscopy confirmed interactions between the ACNs and the encapsulation materials (CHC/CMC-WPI). The nanocomplexes or the nanocomplexes incorporated into coffee beverage better protected ACNs at high temperature compared to the unencapsulated ACNs. In simulated gastrointestinal fluids, the ACNs in the ACN-CHC/CMC-WPI were more stable and more slower released over time. The nanocomplexes maintained high DPPH and hydroxyl free radical scavenging activities. This study indicated that CHC/CMC-WPI nanocomplexes can improve the thermal stability and slow the release of ACNs added to food products.


Assuntos
Antocianinas/farmacocinética , Quitosana/química , Café/química , Nanoestruturas/química , Proteínas do Soro do Leite/química , Antioxidantes/química , Quitosana/análogos & derivados , Digestão , Humanos , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Temperatura
15.
Food Chem ; 336: 127700, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32768906

RESUMO

The processing stability and antioxidant capacity of blueberry anthocyanins (ANs) in the presence of whey protein isolate (WPI) were examined. WPI was found to enhance both the stability and antioxidant activity of ANs during processing and simulated in vitro digestion, especially at a concentration of 0.15 mg·mL-1. Fluorescence and ultraviolet-visible absorption spectroscopy showed that ANs were primarily stabilized by hydrophobic forces between WPI and malvidin-3-O-galactoside (M3G), the major anthocyanin monomer. Circular dichroism and Fourier-transform infrared spectroscopy confirmed that the structure of WPI changed and the microenvironments of certain amino acid residues were modulated by non-covalent binding to M3G; furthermore, fewer α-helices and more ß-sheets were formed. Molecular docking studies revealed that WPI, especially immunoglobulin (IgG), contributed the most to ANs stability via hydrogen bonds and hydrophobic forces according to molecular docking scores (-141.30 kcal/mol). These results provided an important fundamental basis for improving the stabilities of ANs in milk systems.


Assuntos
Antocianinas/química , Antioxidantes/química , Mirtilos Azuis (Planta)/química , Simulação de Acoplamento Molecular , Proteínas do Soro do Leite/química , Animais , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas
16.
Food Chem ; 337: 127682, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32795852

RESUMO

Consumers are increasingly interested in low-fat meat products. Therefore, there is demand for new fat replacers that improve the quality of low-fat meat products. Whey protein isolate (WPI; 10% (w/v)) and sodium dodecyl sulfate (SDS; 0-0.09% (w/v)) were used to produce WPI-SDS gel as a fat replacer of low-fat meat products. Characteristics of WPI-SDS gel were evaluated using SDS-PAGE, FT-IR, viscometer, and texture analyzer. Addition of SDS to WPI increased gelation while reducing aggregation. Addition of 0.06% SDS to WPI-SDS gel has the highest viscosity and hardness, while 0.09% SDS decreased the heat stability of WPI. Quality characteristics including cooking loss, emulsion stability, hardness, and chewiness were significantly improved in WPI-SDS gel-supplemented low-fat sausages. Particularly, the highest hardness and chewiness were obtained in the low-fat sausage added with WPI-SDS gel containing 0.06% SDS. Our results suggest that WPI-SDS gel can be used as a fat replacer in low-fat meat products.


Assuntos
Culinária , Produtos da Carne/análise , Dodecilsulfato de Sódio/química , Proteínas do Soro do Leite/química , Géis , Dureza , Viscosidade
17.
Food Chem ; 338: 127819, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32810812

RESUMO

Impacts of citric acid (CA) treatment under non-acidic conditions (pH 7.0, 8.0 and 9.0) on whey protein isolate (WPI) were examined in this study. Size exclusion chromatography and SDS-PAGE indicated that molecular size and weight of WPI-CA became larger at pH 7.0, 8.0 and 9.0 with CA ranged from 0 to 15 mg/mL, but the protein aggregates disappeared after ß-mercaptoethanol was added. The free SH groups of WPI-CA gradually decreased. This could be deduced that CA could promote disulfide bond formation of WPI at the non-acidic pH values. Furthermore, fourier transform infra-red (FTIR) spectroscopy and fluorescence spectroscopy data confirmed the conformational changes of secondary and tertiary structures of CA-modified WPI, respectively. Therefore, these results suggested that disulfide bond formation of WPI occurred at citric acid treatment under non-acidic conditions, being contributed to production of its larger molecular size substances and alteration of its structural characteristics.


Assuntos
Ácido Cítrico/química , Dissulfetos/química , Proteínas do Soro do Leite/química , Cromatografia em Gel , Reagentes para Ligações Cruzadas/química , Eletroforese em Gel de Poliacrilamida , Concentração de Íons de Hidrogênio , Mercaptoetanol/química , Conformação Proteica , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , Água/química
18.
Food Chem ; 337: 127973, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32927224

RESUMO

To establish the effect of the presence of milk serum proteins on heat-induced changes to lactoferrin, lactoferrin alone, and lactoferrin mixed with either milk serum or ß-lactoglobulin was heated at 65 °C, 70 °C and 75 °C for 30 min. After heating, the effect of milk serum proteins on aggregation of lactoferrin was characterized, after which the effect of such aggregation on digestion and bacteriostatic capacity of lactoferrin were determined. The presence of milk serum proteins accelerated the aggregation of lactoferrin during heating through thiol/disulphide interchange. Lactoferrin also formed disulphide-linked aggregates when it was heated with ß-lactoglobulin. Protein aggregates formed at 75 °C were much more resistant to infant digestion, causing decreased peptide release from lactoferrin. Heating lactoferrin and milk serum proteins together accelerated the loss of bacteriostatic activity upon heating. In conclusion, heat-induced aggregation of lactoferrin with milk serum proteins affected both its digestion and its bacteriostatic activity.


Assuntos
Lactoferrina/química , Lactoferrina/farmacocinética , Proteínas do Leite/química , Animais , Antibacterianos/farmacologia , Digestão , Suco Gástrico , Temperatura Alta , Humanos , Lactoglobulinas/química , Leite/química , Tamanho da Partícula , Proteínas do Soro do Leite/química
19.
J Sci Food Agric ; 101(1): 120-130, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32613628

RESUMO

BACKGROUND: An ultrasonic spray nozzle was evaluated for the production of powders and microcapsules, using blueberry extract, modified starch (HI-CAP 100), and whey protein isolate (WPI). The effects of ultrasonic power and the concentration of coating materials on the characteristics of the resulting samples - such as viscosity, particle size, microencapsulation efficiency, color, glass transition temperature, Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and morphology - were also studied. RESULTS: The apparent viscosity was primarily affected by the self-heating of the ultrasonic nozzle as the power increased. The largest mean particle size of samples was observed under conditions of 30% coating concentration at 10 W. Glass transition temperatures (Tg ) of the samples were affected by all atomization parameters significantly (P < 0.05) and the highest Tg values of all samples were determined when the coating concentration was maximum (30%) and power level was minimum (5 W). The FTIR and XRD results indicate that the power of the ultrasonic nozzle did not cause any change in WPI structure and led to only a small change in the structure of HI-CAP 100 at 10 W. The short atomization time preserved, to some extent, the properties of the coating materials and the blueberry extract. With regard to the morphological properties, it was observed that the samples obtained with WPI showed less shrinkage than HI-CAP 100. CONCLUSION: The results indicated that an ultrasonic nozzle could be used successfully to prepare the blueberry microcapsule with HI-CAP 100 and WPI as coating materials. This study may contribute to the development of ultrasonic nozzle applications using different coatings for the microencapsulation of high-quality functional materials. © 2020 Society of Chemical Industry.


Assuntos
Mirtilos Azuis (Planta)/química , Carboidratos/química , Tecnologia de Alimentos/métodos , Extratos Vegetais/química , Ultrassom/métodos , Proteínas do Soro do Leite/química , Cápsulas/química , Frutas/química , Tamanho da Partícula , Pós/química , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/química , Temperatura , Ultrassom/instrumentação , Viscosidade , Difração de Raios X
20.
J Sci Food Agric ; 101(1): 262-271, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32627183

RESUMO

BACKGROUND: The adsorption of proteins at oil/water interfaces can reduce interfacial tension and increase emulsion stability. However, emulsions stabilized by soy protein isolate (SPI) are not sufficiently stable. Using SPI as a control, a theoretical basis for the adsorption behavior of mixed SPI and whey protein isolate (WPI) at the oil/water interface was established and the effects of the protein ratio and content on the emulsion stability were studied. RESULTS: Compared to SPI solution, SPI-WPI mixed solutions were found to reduce the size distribution of emulsion droplets and significantly improve the emulsion stability. Among the studied protein contents and ratios, the protein content of 0.2 g kg-1 and SPI/WPI mass ratio of 1:9 offered the lowest creaming stability index (15%), the smallest droplet size (278 nm), and the largest absolute value ζ-potential (35 mV), i.e. the emulsion stability was excellent. The largest dilatational modulus (10.08 mN m-1 ), dilatational elasticity (10.01 mN m-1 ), and dilatational viscosity (1.18 mN m-1 ), were observed with a protein content of 0.15 g kg-1 (SPI/WPI ratio of 1:9), along with a high interfacial protein adsorption capacity (47.33%). SPI-WPI complexes form a thick adsorption layer around oil droplets, resulting in an increase of the expansion modulus of the interfacial layer. CONCLUSION: SPI-WPI complexes can form a thick adsorption layer around oil droplets, resulting in increased expansion modulus of the interfacial layer, which improves emulsion stability. © 2020 Society of Chemical Industry.


Assuntos
Óleos/química , Proteínas de Soja/química , Água/química , Proteínas do Soro do Leite/química , Elasticidade , Emulsões/química , Estabilidade Proteica , Viscosidade
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