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1.
Food Chem ; 336: 127624, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32768901

RESUMO

Recently, there is a growing interest in developing protein-enriched beverages with improved nutritional and functional properties. However, this is challenged by heat-induced aggregation and gelation of edible proteins, which limits their practical applications in high protein systems. In this study, soy protein particles (SPPs) with tunable heat stability were prepared by simply preheating soy proteins suspensions (pH 6.4 and 1% (w/v) concentration) at different temperatures and times. Results showed that heat-stabled SPPs were successfully obtained at high preheating temperatures with prolonged time. The SPPs structures were found to be highly unfolded, denatured, and compact. In addition, these particles exhibited lower viscosities and higher flow behavior index without gelation, whereas those prepared at lower preheating temperatures were found to readily gel after reheating. These results provide useful insights on how heat stable SPPs can be prepared, which extends their further application in protein-enriched beverages and relevant products.


Assuntos
Proteínas de Soja/química , Géis/química , Temperatura Alta , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Agregados Proteicos , Desnaturação Proteica , Estabilidade Proteica , Reologia , Compostos de Sulfidrila/química , Viscosidade
2.
J Oleo Sci ; 69(11): 1417-1426, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33132279

RESUMO

In this paper, the effects of homogenization at low pressure (1~40 MPa) on structural and functional properties of soy protein isolates (SPI) are investigated. Homogenization at low pressure increase solubility, surface hydrophobicity, emulsification activity and foaming capacity of SPIs, these all functional properties increases and then decreases with the homogenization pressure. Whereas, emulsion stability and foaming stability of SPIs treated by homogenization initially decrease and then increase with homogenization pressure. There is a dramatic decrease in hardness, springiness and cohesiveness of homogenized SPI gels. Generally, homogenization at low pressure do not change the subunit composition of SPIs. It is observed that, when the homogenization pressure is lower than 10 MPa than there is no significant impact on structural change. The content of ß-sheet decreased, while unordered structure significantly increased, when the homogenization pressure increased from 10 MPa to 20 MPa. Furthermore, the content of ß-sheet increases, when the content of the other structures decreases with the increasing homogenization pressure. The maximum emission wavelength (λmax) for SPIs increases with homogenization pressure increases from 10 Mpa to 20 Mpa, which is attributed to the gradual structural unfolding exposing more hydrophobic residues in protein surface. While, the decreased λmax of SPIs treated with 20 Mpa to 40 Mpa homogenization corresponds to the protein aggregation. It can be deduced that appropriate selection of homogenization pressure is important for improving the functional properties of SPIs.


Assuntos
Pasteurização , Pressão , Proteínas de Soja/química , Emulsões , Interações Hidrofóbicas e Hidrofílicas , Agregados Proteicos , Solubilidade
3.
Int J Food Microbiol ; 335: 108890, 2020 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-32971300

RESUMO

The bioactivity of essential oils applied in foods to act as natural preservatives can be reduced due to interactions with other components of the food matrix. Microencapsulation can help to increase the functionality of these compounds. In addition, the electrostatic interaction between proteins and polysaccharides can result in double-layered encapsulating structures, ensuring greater protection to essential oils than using only protein as surface active agent. In this work, pink pepper essential oil was microencapsulated by spray drying of single-layer emulsions, stabilized by soy protein isolate (SPI), and of double-layer emulsions, stabilized by soy protein isolate/high methoxyl pectin (SPI/HMP). Pink pepper essential oil showed predominance of α-pinene, ß-pinene, ß-mircene, δ-3-carene, d-limonene, and germacrene D. Compared to SPI microcapsules, SPI/HMP microcapsules better preserved the total volatile content identified in pure oil, showed less water adsorption during storage at relative humidity ≥75% and improved antimicrobial properties. When stored for 20 days (25 °C/RH = 52.8%), both microcapsules allowed more gradual release of volatiles compared with non-encapsulated oil. Microencapsulation by spray drying did not have negative effects on the antioxidant activity of the encapsulated oil, as the microcapsules showed similar results to the non-encapsulated oil, around 11 µg Trolox/mg of oil. After storage, however, the non-encapsulated oil showed greater losses of its antioxidant activity due to higher rates of volatile release. In the in vitro antimicrobial activity assay, both microcapsules inhibited growth of Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes and Listeria innocua, although no inhibition was observed against Gram-negative bacteria. When added in milk, both microcapsules reduced bacterial growth, whereas non-encapsulated oil showed no satisfactory inhibition. Faster reduction of microbial growth in milk was observed for SPI/HMP microcapsules. Inhibition results were better for skim milk than for whole milk, suggesting that the interaction of essential oil with other lipids present in milk decreased its bioactivity. Microencapsulation positively affected the functionality of pink pepper essential oil, highlighting its potential for application as a natural preservative in food products.


Assuntos
Anacardiaceae/química , Antibacterianos/química , Conservantes de Alimentos/química , Óleos Voláteis/química , Antibacterianos/farmacologia , Cápsulas/química , Cápsulas/farmacologia , Dessecação , Emulsões/química , Emulsões/farmacologia , Conservantes de Alimentos/farmacologia , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/crescimento & desenvolvimento , Óleos Voláteis/farmacologia , Pectinas/química , Proteínas de Soja/química , Terebintina/química , Terebintina/farmacologia
4.
PLoS One ; 15(9): e0239080, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32956384

RESUMO

Two commercial proteases (subtilisin-typed FNA from Bacillus amyloliquefaciens, and chymotrypsin-like NPP from Nocardiopsis prasina), porcine pepsin, porcine pancreatin having protease activity and their combinations were studied in vitro by LC-MS for their ability to digest soy protein isolate (SPI) under conditions close to those found in the stomach (pH 3.7) and small intestine (pH 6.5). The total number of peptides generated, and their size distribution were obtained under each set of the digestion conditions. These peptides were grouped according to their C-terminal amino acid (AA) residue (P1) and mass, based on which two concepts were proposed, i.e., Normalized Peptide Bond Cleavage Frequency (NPBCF) and Protease Substrate Broadness Index (PSBI). At pH 3.7, FNA+pepsin increased PSBI vs. pepsin alone by 2.7 and 4.9 percentage points (p.p.) at a SPI:protease ratio of 20:1 and 100:1, respectively. At pH 6.5, FNA+pancreatin improved PSBI by 9.1 and 10.2 p.p. at SPI:protease 20:1 and 100:1, respectively, vs. pancreatin alone. NPP generated 38% more peptides than FNA when administered with pancreatin at SPI:protease 200:1:1 and pH 6.5, but FNA alone (28.9) or FNA+pancreatin (29.1) gave a higher PSBI than pancreatin (22.2), NPP (20.3) and NPP+pancreatin (22.0). At pH 3.7 FNA generated 59% and 39% of peptides of pepsin at SPI:protease of 20:1 and 100:1, respectively, and both groups of peptides had similar size distribution. At pH 6.5 more small sized peptides were generated by FNA or FNA+pancreatin than pancreatin and NPP alone or pancreatin+NPP. In conclusion, FNA showed complementary effects with pepsin and pancreatin in terms of PSBI and generated more small sized peptides compared to NPP.


Assuntos
Peptídeo Hidrolases/metabolismo , Peptídeos/metabolismo , Proteínas de Soja/metabolismo , Actinobacteria/enzimologia , Animais , Bacillus amyloliquefaciens/enzimologia , Digestão , Concentração de Íons de Hidrogênio , Hidrólise , Peptídeos/química , Proteínas de Soja/química , Especificidade por Substrato , Suínos
5.
Food Chem ; 333: 127530, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32683264

RESUMO

Soybean protein isolate (SPI) was incubated with flaxseed gum (FG) at 60 °C for 3 days under high hydrostatic pressure (HHP 0.1-300 MPa). Results showed improvement in solubility of SPI upon glycation with FG. The maximum solubility reached 86.84% when SPI-FG was treated at pH 8.0 and 200 MPa. The occurrence, degrees and sites of SPI-FG glycation suggested that moderate pressure (100 MPa) significantly promoted Maillard reactions, but higher pressures (greater than 200 MPa) suppressed these reactions. The secondary structure of the glycated proteins varied greatly with respect to α-helix and random coil contents and vibrations of the amide II band at 200 MPa. These microstructural changes increased the solubility over a broad pH range. The conformational changes in the glycated SPI supported the improved solubility of SPI-FG. Overall, HHP represents a potential method of controlling glycation to improve protein processability and expand their applicability in the food industry.


Assuntos
Linho/química , Gomas Vegetais/química , Proteínas de Soja/química , Glicosilação , Pressão Hidrostática , Reação de Maillard , Estrutura Secundária de Proteína , Solubilidade
6.
Food Chem ; 333: 127400, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32673949

RESUMO

The conjugate prepared from (-)-epigallocatechin gallate (EGCG) and soy protein isolate (SPI) under alkaline and aerobic conditions was analyzed using a Nano-LC-Q-Orbitrap-MS/MS technique. The sulfhydryl and free amino groups of SPI were involved in covalent binding. Fifty-one peptides were conjugated with EGCG. Fifty-nine modified sites were identified, located on Cys, His, Arg, and Lys, respectively. It is the first time to confirm that each of the two phenolic rings of EGCG contained a reactive site that bound to an amino acid residue. The amino acid residue reactivity, amino acid sequence and composition affected the EGCG binding site in SPI. Lys and Arg residues are the most likely sites for modification, and modification appears to reduce IgE binding. This study is helpful to elucidate the pattern of covalent binding of polyphenols to proteins in food systems and provides a theoretical basis for the directional modification of soy proteins with polyphenols.


Assuntos
Catequina/análogos & derivados , Imunoglobulina E/metabolismo , Proteínas de Soja/química , Proteínas de Soja/metabolismo , Aminoácidos/metabolismo , Sítios de Ligação , Catequina/química , Polifenóis/metabolismo , Ligação Proteica
7.
Food Chem ; 329: 127148, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32485647

RESUMO

The performance of a whey protein hydrolysate (WPH) for producing physically and chemically stable omega-3 emulsions was compared to hydrolysates obtained from other sustainable protein sources such as soy (SPH) and blue whiting (BPH). The oxidative stability of hydrolysate-stabilized emulsions was greatly influenced by their physical stability. Emulsion stabilized with BPH suffered a constant increase in droplet size and BPH was not able to prevent omega-3 oxidation, showing high concentration of volatiles. The peroxide value of SPH emulsion increased after the first day of storage, but it had a lower concentration of volatiles. In contrast, WPH-stabilized emulsion, which did not had any change in droplet size during storage, showed the highest oxidative stability. Therefore, our results confirmed that WPH is an interesting option for physical and oxidative stabilization of omega-3 emulsions, while SPH could be used in emulsions with shorter storage time such as pre-emulsions for microencapsulation of omega-3 oils.


Assuntos
Antioxidantes/química , Emulsificantes/química , Proteínas do Soro do Leite/química , Animais , Emulsões , Gadiformes , Oxirredução , Proteínas de Soja/química , Soja/química
8.
Food Chem ; 331: 127374, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32593796

RESUMO

Effects of a novel slit divergent ultrasound (SDU) treatment on soybean protein isolate (SPI)-lentinan conjugates via Maillard reaction was investigated. Besides, the stability of emulsions prepared by SPI and SPI-lentinan conjugates (ultrasound and un-ultrasound) as emulsifiers was compared. The results showed that ultrasonic treatment (40 min) markedly increased the degree of grafting (26.48%) by 1.91 times comparing with traditional heating method (2 h, 13.89%). In addition, structural analysis showed that the conjugates obtained by SDU treatment changed the secondary structure and had higher surface hydrophobicity and fluorescence intensity than those obtained by traditional heating method. Apart from this, SDU treatment could significantly improve the functional properties (solubility, foaming, emulsifying capacity, thermal stability, and viscosity) of conjugates. Furthermore, the emulsions prepared by the SPI-lentinan conjugates (ultrasound) as emulsifiers possessed the highest stability against environmental stresses. Taken together, SDU-assisted heating could be an excellent method to improve the functional properties of conjugates.


Assuntos
Emulsões/química , Lentinano/química , Reação de Maillard , Proteínas de Soja/química , Dicroísmo Circular , Emulsificantes/química , Fluorescência , Indústria de Processamento de Alimentos/métodos , Glicosilação , Calefação , Interações Hidrofóbicas e Hidrofílicas , Estabilidade Proteica , Estrutura Secundária de Proteína , Solubilidade , Proteínas de Soja/isolamento & purificação , Ultrassom , Viscosidade , Água/química
9.
Biochim Biophys Acta Proteins Proteom ; 1868(8): 140440, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32376479

RESUMO

Lunasin is a 43-amino acid peptide from seeds and grains with bioavailability in humans and potent chemotherapeutic action against several cancer cell lines. Here, we investigate new information about the physicochemical and structural properties of lunasin using circular dichroism (CD), fluorescence spectroscopy, electrospray ionization-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS), size exclusion chromatography (SEC), molecular dynamics (MD), and bioinformatics. CD analysis and disorder prediction obtained by PONDR indicate that lunasin has a mostly unordered structure. Double wavelength [θ]222nm x [θ]200nm plot data suggests that lunasin is an intrinsically disordered peptide (IDP) in a pre-molten globule-like (PMG-like) state, while CD spectrum deconvolution and MD simulation indicate small ß-strand content. The presence of residual structure was supported by loss of CD signal at 222 nm after treatment with urea and by increasing fluorescence emission upon bis-ANS binding. Lunasin also demonstrated stability to heating up to the temperature of 100 °C, as verified by CD. MD and CD analyses in the presence of TFE and MoRFpred prediction indicated the helix propensity of lunasin. ESI-IMS-MS data revealed that lunasin shows a propensity to form disulfide bonds at the conditions used. MD data also indicated that disulfide bond formation affects the adopted structure, showing a possible role of aspartyl-end in structure stabilization and compaction. In conclusion, our data support a characterization of lunasin as a peptide with an intrinsic disorder in a PMG-like state and reveal new aspects about its structural stability and plasticity, as well as the effects of disulfide bond formation and electrostatic attractions.


Assuntos
Antineoplásicos Fitogênicos/química , Proteínas Intrinsicamente Desordenadas/química , Proteínas de Soja/química , Sequência de Aminoácidos , Antineoplásicos Fitogênicos/isolamento & purificação , Dissulfetos , Humanos , Proteínas Intrinsicamente Desordenadas/isolamento & purificação , Simulação de Dinâmica Molecular , Dobramento de Proteína , Estabilidade Proteica , Estrutura Secundária de Proteína , Proteínas de Soja/isolamento & purificação , Soja/química , Espectrometria de Fluorescência , Espectrometria de Massas por Ionização por Electrospray , Temperatura , Ureia/química
10.
Pharm Res ; 37(6): 91, 2020 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-32385723

RESUMO

PURPOSE: Bevacizumab (BCZ) is a recombinant monoclonal antibody that inhibits the biological activity of the vascular endothelial growth factor, which has an important role in angiogenesis for tumoral growth and progression. In this way, our objective was to develop chitosan-coated lipid-core nanocapsules functionalized with BCZ by an organometallic complex using gold-III. METHODS: The formulation was produced and characterized in relation to physicochemical characteristics. Furthermore, the antitumoral and antiangiogenic activities were evaluated against C6 glioma cell line and chicken embryo chorioallantoic membrane (CAM), respectively. RESULTS: Final formulation showed nanometric size, narrow polydispersity, positive zeta potential and gold clusters size lower than 2 nm. BCZ in aqueous solution (0.01-0.10 µmol L-1) did not show cytotoxic activity in vitro against C6 glioma cell line; although, MLNC-Au-BCZ showed cytotoxicity with a median inhibition concentration of 30 nmol L-1 of BCZ. Moreover, MLNC-Au-BCZ demonstrated cellular internalization dependent on incubation time and BCZ concentration. BCZ solution did not induce significant apoptosis as compared to MLNC-Au-BCZ within 24 h of treatment. CAM assay evidenced potent antiangiogenic activity for MLNC-Au-BCZ, representing a decrease of 5.6 times in BCZ dose comparing to BCZ solution. CONCLUSION: MLNC-Au-BCZ is a promising product for the treatment of solid tumors.


Assuntos
Inibidores da Angiogênese/química , Bevacizumab/química , Quitosana/química , Glioma/tratamento farmacológico , Ouro/química , Lipídeos/química , Nanocápsulas/química , Inibidores da Angiogênese/farmacologia , Animais , Apoptose/efeitos dos fármacos , Bevacizumab/metabolismo , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular , Embrião de Galinha , Membrana Corioalantoide/efeitos dos fármacos , Complexos de Coordenação/química , Relação Dose-Resposta a Droga , Composição de Medicamentos/métodos , Hexoses/química , Humanos , Lectinas de Plantas/química , Polissorbatos/química , Proteínas de Soja/química , Propriedades de Superfície , Fator A de Crescimento do Endotélio Vascular/metabolismo
11.
Food Chem ; 324: 126876, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32361092

RESUMO

The effect and mechanism of wheat bran cellulose (WBC) on the gelling characteristics of soy protein isolate (SPI) were evaluated. It was found that the water holding capacity, gel strength, and viscoelasticity of SPI gel were improved with the increase of WBC concentration. The addition of WBC (0.5-2.0%, w/v) stabilized the moisture phase and induced the construction of the regular and homogenous three-dimensional gel network. The Raman spectroscopy revealed that WBC addition caused a significant reduction in α-helix percentage (28.92-63.08%) (p < 0.05) with a concomitant increase in ß-sheet (16.92-34.37%) (p < 0.05) and ß-turn (8.09-13.54%) (p > 0.05) percentages of the pure SPI gel. Additionally, hydrogen-bonding interaction between SPI and WBC and the enhanced thermal stability were proposed in the composite gels. Overall, WBC is effective in improving the gel properties of SPI, suggesting its potential application as novel gel modifier in the food industry.


Assuntos
Celulose/química , Géis/química , Proteínas de Soja/química , Fibras na Dieta/análise , Géis/metabolismo , Ligação de Hidrogênio , Reologia , Análise Espectral Raman , Termogravimetria , Viscosidade , Água/química
12.
Food Chem ; 327: 127062, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32454279

RESUMO

Soy glycinin (11S) was mixed with soyasaponin (Ssa) to elucidate the mechanism(s) involved in the stabilization of emulsions by mixed systems based on dynamic interfacial tension and dilatational rheology at the oil-water interface. The short/long-term properties of oil-in-water emulsions stabilized by 11S-Ssa mixtures included droplet-size distribution, droplet ζ-potential, microstructure, and Turbiscan stability index. The combination of Ssa (0.05%) with 11S significantly affected the interfacial dilatational and emulsion properties although the interfacial properties were still dominated by the protein. Higher concentrations (0.1% and 0.2%) of Ssa combined with 11S synergistically decreased the interfacial tension, which was attributed to the interaction between 11S and Ssa. Using high Ssa concentrations (0.25%-0.5%) enhanced the long-term stability of emulsions (in response to external deformations) after 42 d. These results will aid the basic understanding of protein-Ssa interfacial adsorption during emulsion formation and can help prepare natural food additives for designing emulsions.


Assuntos
Globulinas/química , Saponinas/química , Proteínas de Soja/química , Soja/química , Adsorção , Óleo de Milho/química , Emulsões/química , Tensão Superficial , Água/química
13.
Food Chem ; 322: 126638, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32283365

RESUMO

This study investigated the effects of adding different polysaccharides (Arabic Gum (GA), Sodium Alginate (SA) and Soy-soluble polysaccharides (SSPS)) on the embedding properties and physical stability of soybean protein isolate (SPI). 1-Octacosanol (1-Octa) was encapsulated in SPI nanoparticles. The addition of GA, SA, SSPS not only increased the encapsulation efficiency of 1-Octa from 90.38% to 96.65%, 95.49%, 94.74%, respectively, but also increased the ζ-potential of nanoparticles from -29.05 mV to -38.77 mV, -41.50 mV, -38.00 mV, respectively. Through the changes of ζ-potential and the Fourier transform infrared spectroscopy (FT-IR), it can be known that anionic polysaccharides can also combine with positive charges of SPI by the electrostatic interaction under neutral conditions. The thermal stability of nanoparticles has been greatly improved, and SA has the best effect on denaturation temperature of nanoparticles in aqueous phase. Overall, The nanoparticles of SPI, 1-Octa and polysaccharides have the potential to be used in drinks.


Assuntos
Álcoois Graxos/química , Aditivos Alimentares/química , Polissacarídeos/química , Proteínas de Soja/química , Soja/química , Alginatos/química , Temperatura Alta , Nanopartículas/química , Estabilidade Proteica , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Food Chem ; 320: 126655, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32224423

RESUMO

The effects of ß-cyclodextrin (ß-CD), whey protein (WP), and soy protein (SP) on the color loss and degradation of anthocyanins in purple-fleshed sweet potato anthocyanin extracts (PFSPAEs) during thermal treatment and shelf-life storage in model beverage systems by performing chromaticity, degradation kinetics, and principal component analysis. Results showed that WP and SP improved the thermal stability of the PFSPAE, but WP accelerated the color loss of the extract. However, the addition of 25 mg/L SP improved the color and thermal stability of the anthocyanins when heated at 100 °C for 30 min. With regard to the shelf-life storage, the addition of SP and WP showed non-significant effect on the storage stability of the PFSPAE. However, the addition of 2500 mg/L ß-CD significantly improved the storage stability of the PFSPAE. In summary, our findings provide useful information on improving the thermal and storage stability of PFSPAEs in beverage systems using food biopolymers.


Assuntos
Antocianinas/química , Ipomoea batatas/química , Proteínas de Soja/química , Proteínas do Soro do Leite/química , beta-Ciclodextrinas/química , Antocianinas/análise , Bebidas , Armazenamento de Alimentos , Temperatura Alta
15.
Food Chem ; 318: 126421, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32126461

RESUMO

The objective of this study was to determine the effects of pre-heating soybean protein isolate (SPI) and transglutaminase (TG) induced cross-linking on egg-SPI composite gels. Solubility, surface hydrophobicity, electrophoresis and rheology of the prepared solutions were determined, whereas texture, water-holding capacity and microstructure of the composite gels were evaluated. SPI pre-heating improved solutions' solubility and protein's surface hydrophobicity; thus enhancing TG cross-linking evidenced by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). When only TG was used, solubility and surface hydrophobicity of the composites remained unchanged or decreased, forming strong gels but with low springiness and water-holding capacity. When SPI pre-heating and TG action were combined, a denser and finer gel network was obtained that exhibited improved mechanical properties and better water-holding capacity. The results of this research demonstrate that the combination of pre-heating SPI and TG treatment is a reliable method to improve the gelling properties of egg-SPI composite gels.


Assuntos
Proteínas do Ovo/química , Géis/química , Proteínas de Soja/química , Soja/metabolismo , Transglutaminases/metabolismo , Proteínas do Ovo/metabolismo , Eletroforese em Gel de Poliacrilamida , Interações Hidrofóbicas e Hidrofílicas , Reologia , Solubilidade , Proteínas de Soja/metabolismo , Propriedades de Superfície , Temperatura
16.
Food Chem ; 318: 126494, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32126470

RESUMO

The object of this research was to compare the influence of different soy protein products on wheat dough and its gluten characteristics, including soy protein isolate (SPI), texturized soy protein (TSP) and hydrolyzed soy proteins (SPH), all of which with similar protein content. Addition of TSP could increase dough stability and gluten content, but gluten could not be detected when flour was fortified with SPH. During mixing, SPI tended to interact with SDS soluble wheat proteins, SPH tended to interact with SDS soluble and alcohol soluble wheat proteins, and TSP tended to interact with SDS soluble wheat proteins and TSP. A new protein component was observed from TSP fortified dough by SDS-PAGE. Disulfide bonds change confirmed the new linkage formation in blend dough. CLSM micrographs revealed that effect of SPI, SPH and TSP was different, and this difference was responsible for the change of gluten and dough characteristics.


Assuntos
Glutens/química , Proteínas de Soja/química , Triticum/química , Pão/análise , Farinha/análise , Alimentos Fortificados , Hidrólise
17.
Food Chem ; 318: 126499, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32143134

RESUMO

The production of soy protein-based foods requires multiple-step, intensive processing and storage of soy ingredients, which can increase the product's susceptibility to oxidation. Therefore, we investigated the oxidative stability of soy protein-based products subjected to different relevant conditions or treatments: over storage of soy flours, over fractionation to yield soy protein isolate (SPI), and over subsequent thermomechanical processing to yield a model structured product. Soy flours were stable to lipid and protein oxidation over 250 days storage in chilled or ambient conditions. The fractionation process applied to make SPI did not increase substantially protein carbonylation, but increased surface-exposed hydrophobicity and decreased free thiols, compared to the starting defatted flour. Subsequent processing of hydrated SPI powder at 140 °C further increased protein carbonylation to a high extent. Therefore, we conclude that soy flours can be stable over long storage times, but processing to yield structured foods products promote protein oxidation.


Assuntos
Alimentos de Soja/análise , Proteínas de Soja/química , Soja/química , Farinha/análise , Manipulação de Alimentos , Interações Hidrofóbicas e Hidrofílicas , Oxirredução
18.
Enzyme Microb Technol ; 135: 109498, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32146931

RESUMO

Whole-cell biocatalysts could be used in wide-ranging applications. In this study, a new kind of whole-cell biocatalyst was successfully constructed by genetically immobilizing soybean seed coat peroxidase (SBP) on the cell surface of Yarrowia lipolytica Po1h, using a new integrative surface display expression vector (pMIZY05). The coding sequence of SBP was optimized and chemically synthesized, then inserted into pMIZY05 to generate expression plasmid pMIZY05-oEp. A DNA fragment corresponding to SBP and selection marker expression cassettes, without bacterial sequences, was released from pMIZY05-oEp by enzyme digestion and used to transform host yeast cells. A transformant (CM11) with a high recombinant SBP activity of 1571.9 U/mL was obtained, and recombinant SBP was proved to be successfully anchored on cell surface by testing the activities of different cellular fractions. After optimization of culture conditions, the recombinant SBP activity of CM11 was increased to 4187.8 U/mL. Afterwards, biochemical properties of the recombinant SBP were determined: optimum catalytic conditions were 37.5℃ at pH 3.5, and recombinant SBP exhibited high stability during thermal or acidic treatment. Recombinant activity of cell-displayed SBP was re-examined at optimum temperature and pH, which promoted an increase up to 4432.5 U/mL. To our knowledge, this represents the highest activity ever reported for heterologous expression of SBP. This study also provides a useful strategy for heterologous expression of proteins which could be toxic to intracellular content of host cells.


Assuntos
Peroxidases/genética , Proteínas de Soja/genética , Yarrowia/genética , Biocatálise , Clonagem Molecular , Estabilidade Enzimática , Expressão Gênica , Peroxidases/química , Peroxidases/metabolismo , Plasmídeos/genética , Plasmídeos/metabolismo , Proteínas de Soja/química , Proteínas de Soja/metabolismo , Yarrowia/metabolismo
19.
Food Funct ; 11(2): 1635-1646, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32025672

RESUMO

At present, there are few reports on the glycosylation modification of soybean proteins under irradiation. In this paper, a soybean protein isolate and maltose were used as raw materials to prepare a glycosylated soybean protein under gamma-ray treatment to improve the functional properties and evaluate the changes in the structure. The results of analysis of the graft degree, browning index, polyacrylamide gel electrophoresis, infrared spectrum, fluorescence spectrum and ultraviolet spectrum of the modified product showed that the Maillard reaction between the soybean protein isolate and maltose occurred and the structure of the reaction product changed. When the irradiation dose was 7.5 kGy, the solubility of modified products increased by 23 ± 0.21% compared with that of the control group. The foaming property and foam stability increased by 62.5 ± 0.34% and 41 ± 0.47%, respectively. Emulsification, water absorption capacity and fat absorption capacity of glycosylated compounds also increased significantly. Compared with other modification methods, irradiation technology had the advantages of short action time, high efficiency and low cost, and more importantly, its industrial production was easy to implement. This experiment combined irradiation technology with the glycosylation modification method. It was proved that irradiation could promote the Maillard reaction between the soybean protein isolate and maltose, and significantly improve the functional properties of the modified protein, providing theoretical and technical support for expanding the application of the soy protein isolate in the food industry.


Assuntos
Raios gama , Proteínas de Soja , Manipulação de Alimentos , Glicosilação , Interações Hidrofóbicas e Hidrofílicas , Reação de Maillard , Maltose/química , Solubilidade , Proteínas de Soja/análise , Proteínas de Soja/química , Proteínas de Soja/efeitos da radiação
20.
J Sci Food Agric ; 100(6): 2732-2741, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32003461

RESUMO

BACKGROUND: Recombinant plant-based whipping cream (RSWC) has been widely studied in recent years. The present study investigated the effects of soybean protein and its hydrolysates on the stability and physical properties of the RSWC. The RSWC was made with 28% soybean oil bodies and 4% additional soy proteins or its hydrolysates. The proteins used were soy protein isolate, 7S, 11S, oil body protein, soybean proteins isolate hydrolyzed by pepsin (SPHPe) and soybean protein isolate hydrolyzed by papain (SPHPa). RESULTS: RSWC made with SPHPa containing a large amount of small-molecule polypeptide had the lowest apparent viscosity, shortest whipping time, best overrun and worst whipping stability, whereas RSWC made with SPHPe containing the α, ß subunit and small-molecule polypeptides exhibited the second highest overrun and best whipping stability. The partial coalescence of fat and confocal micrographs of cream emulsions suggested that oil body protein was displaced by the small peptides from the interface, which led to partial destabilization and sufficient coalescence of fat globules after aging and whipping. CONCLUSION: Selectively hydrolyzed soy protein, such as SPHPe, can be used for the production of RSWC with sufficient overrun and whipping stability. This research is of great significance and opens a route to production of the recombinant plant-based cream in the future. © 2020 Society of Chemical Industry.


Assuntos
Emulsões/química , Tecnologia de Alimentos/métodos , Proteínas de Soja/química , Fenômenos Físicos , Óleo de Soja/química , Viscosidade
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