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1.
A number of attempts have been made to improve the functional properties of milk proteins by chemical modifications. One of such modifications is glycosylation which was carried out to determine the effect of covalent binding of glucose molecules to beta-casein (beta CN) on its emulsifying properties. It was found that up to six molecules of glucose were bound to one molecule of beta CN. Glycosylated beta CN produced smaller emulsion droplets than the intact beta CN. Increases in emulsion-forming and -stabilizing properties were observed. A prerequisite of proteins to form emulsions is their adsorption onto oil/water interface. Therefore the secondary structure of intact and glycosylated beta CN, both in solution and adsorbed onto a hydrophobic teflon/water interface also were studied by far-ultra violet circular dichroism (CD). It appeared, that after glycosylation the degree of helicity of intact beta CN decreased and the incorporation of glucose moieties most likely resulted in a type beta-turn formation after adsorption onto the interface. 相似文献
2.
Limited hydrolysis of β‐casein by cell wall proteinase and its effect on hydrolysates's conformational and structural properties
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Xiaofen Ren Daodong Pan Zhen Wu Xiaoqun Zeng Yangying Sun Jinxuan Cao Yuxing Guo 《International Journal of Food Science & Technology》2015,50(1):55-61
Optimisation of enzymatic hydrolysis of β‐casein with cell envelope proteinase (CEP) from Lactobacillus acidophilus JQ‐1 to produce the angiotensin‐I‐converting enzyme (ACE) inhibitory peptides using response surface methodology (RSM). Under optimal conditions (enzyme‐to‐substrate ([E]/[S]) ratio (w/w) of 0.132 and pH of 8.00 at 38.8 °C), the ACE inhibitory activity of hydrolysates was 72.06% and the total peptides was 11.75 mg mL?1. Scanning electron microscopy (SEM) micrographs indicated that the tightness of the β‐casein surface structure was gradually weakened and small holes appeared after enzymatic treatment, while Fourier transform infrared spectroscopy (FTIR) spectra indicated remarkable changes in the chemical composition and macromolecular conformation of β‐casein after enzymatic hydrolysis. Differential scanning calorimetry (DSC) analysis indicated that the corresponding hydrolysates had higher thermal stability. The enzymatic hydrolysis also led to an increase in the free sulfhydryl content of β‐casein hydrolysates compared with raw β‐casein, which led to the increase in the antioxidant activity of β‐casein hydrolysates. 相似文献
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Study on microwave‐accelerated casein protein grafted with glucose and β‐cyclodextrin to improve the gel properties
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Weiwei Bi Weili Zhao Xiaodong Li Wei Ge Zafarullah Muhammad Haixia Wang Lingling Du 《International Journal of Food Science & Technology》2015,50(6):1429-1435
The effect of glycosylation treatment coupled with microwave heating (MH) on gel properties and structure change of casein were investigated. Conjugation was confirmed by electrophoresis. Protein disulphide bonds were broken by microwave irradiation to create an increase first and a decrease later in free sulfhydryl contents with time, thereby inducing subunit disaggregation. Also, the exposure of hydrophobic core residues was increased in MH‐treated casein, which brings about protein disaggregation and unfolding. It showed that graft reactions by MH had much faster than those by water bath heating (WH). The content of disulphide bonds is 7.2% and 6.0% in the casein–glucose and casein–β‐cyclodextrin, respectively, treated by MH which was reduced significantly than that of treated by WH. Moreover, MH can increase the hardness of the gel. Consequently, MH could improve the efficiency of the reaction and gel properties. 相似文献
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Anna M. Sulewska Karsten Olsen Jens C. Sørensen Lars H. Øgendal 《International Journal of Food Science & Technology》2014,49(12):2538-2545
In this study, the residual activity horseradish peroxidase was used as a novel marker of chaperone‐like activity of β‐casein under elevated temperature. It was shown that β‐casein does affect residual activity of horseradish peroxidase (HRP) depending on the concentration and molar ratio between proteins. Incubating HRP (0.1 mg mL?1) for 10 min at 72 °C resulted in residual activity of 59 ± 5%, while addition of 1 mg mL?1 β‐casein resulted in increase in residual activity up to 85 ± 1%. Increased residual activity is not merely attributed to an effect of higher total protein concentration, as similar experiment with bovine serum albumin resulted in residual activity of horseradish peroxidase that was significantly lower than without any addition. The effect of β‐casein on HRP disappears when pH is below the isoelectric point of β‐casein. It was also proven by light scattering studies that β‐casein interacts with horseradish peroxidase when the temperature was increased from 25 to 70 °C whereas interactions seem to cease when temperature was lowered back to 25 °C. This study highlights how specific proteins can influence enzyme activity, which is of potential importance for various industries such as enzyme manufacturers and food industry. 相似文献
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Zhiyong He Jie Chen Sydney E. Moser Owen G. Jones Mario G. Ferruzzi 《International Journal of Food Science & Technology》2016,51(2):342-348
The interactions between the flavan‐3‐ol (?)‐epigallocatechin‐3‐gallate (EGCG) and bovine β‐casein in phosphate‐buffered saline (PBS) of pH 6.5 subjected to thermal processing at various temperatures (25–100 °C) were investigated using fluorescence quenching. The results indicated that different temperatures had different effects on the structural changes and EGCG‐binding ability of β‐casein. At temperatures below 60 °C, the β‐casein–EGCG interaction changed little (P > 0.05) with increasing temperature. At temperatures above 80 °C, native assemblies of β‐casein in solution dissociated into individual β‐casein molecules and unfolded, as demonstrated by a red shift of the maximum fluorescence emission wavelength (λmax) of up to 8.8 nm. The highest quenching constant (Kq) and the number of binding sites (n) were 0.92 (±0.01) × 1013 m ?1 s?1 and 0.73 (±0.02) (100 °C), respectively. These results provide insight into the potential of interactions between β‐casein–EGCG that may modulate bioactivity or bioavailability to be altered during thermal process. 相似文献
6.
ANTONIE E POST HANNA SAMPELS ALINE HOLDER JÖRG HINRICHS 《International Journal of Dairy Technology》2012,65(4):482-489
For the application of functional peptides in innovative products, these peptides have to be individually available. This may be accomplished by a well‐considered combination of a pure protein precursor, a selective cleaving enzyme, and an advanced separation technology. In this proof‐of‐principle approach, micellar casein and β‐casein were subjected to tryptic hydrolysis and the generated casein peptides were identified and characterised. The basic target peptides, β‐casein f(177‐183) and β‐casein f(170‐176), were then enriched. A permeate containing 35% of the target peptides was produced after two‐stage ultrafiltration of micellar casein tryptic hydrolysate. In comparison, enrichment up to 58% was achieved starting from β‐casein tryptic hydrolysate. 相似文献
7.
Cai‐ hong Xu Shu‐ juan Yu Xiao‐quan Yang Jun‐ru Qi Hua Lin Zhen‐gang Zhao 《International Journal of Food Science & Technology》2010,45(5):995-1001
The purpose of this study was to characterise the Maillard reaction in a pressurised liquid system containing β‐conglycinin and dextran. The rate of browning and the free amino content in this liquid system, with an initial pH of 7.2, were measured after reaction under atmospheric pressure and at 10 MPa. The secondary and tertiary structures of the conjugates were analysed by circular dichroism, showing that the increased pressure accelerated the reaction rate of the free amino groups and reduced the rate of browning. Significant structural changes occurred in the tertiary structure of the conjugates. Additionally, the emulsifying properties of the β‐conglycinin–dextran conjugates produced were studied. The emulsifying properties of the conjugates produced at 10 MPa were higher than those made at atmospheric pressure. 相似文献
8.
V. Sedmerov H. Heleicov V. Pokorný V. Podrazký 《Molecular nutrition & food research》1977,21(2):139-147
By means of spectroscopy in visible light, the interaction was followed between artificial casein micelles and β-lactoglobulin at 20 °C and after heating to 80 °C for IO min. The micelles consisted of either αs1-casein-χ-casein or β-casein-χ-casein. In the presence of β-lactoglobulin, the micelles of the αs1-casein-χ-casein type were found to be of spherical shape. On heating, they dissociated to particles of a smaller size and this dissociation was followed by reassociation to aggregates of a larger size than that of micelles in the absence of β-lactoglobulin. The aggregates formed in the system of β-casein-χ-casein in the presence of β-lactoglobulin were also of spherical shape but of a smaller size. 相似文献
9.
Henrike Moeller Dierk Martin Katrin Schrader Wolfgang Hoffmann Peter Chr. Lorenzen 《International Journal of Food Science & Technology》2017,52(5):1122-1130
To apply native casein micelles (CM) as nanocarriers for lipophilic substances in non‐ or low‐fat food products, they have to be conditioned before loading. In this study, an experimental set‐up for the production and loading of CM was developed. Microfiltration was used to separate CM from skimmed milk. To identify optimal loading conditions temperatures (2, 20, 40 °C), pH values (6.8 and 5.5) and holding times (5, 15, 30, 60 min) were varied. The release of calcium, phosphate and protein from the micellar phase as well as static light scattering and transmission electron microscopy showed that CM were optimally primed at 2 °C and a pH of 5.5 for 5 min. Therefore, loading with β‐carotene was performed under those conditions. After the back‐extraction of β‐carotene, the photometrical analyses revealed total recovery rates of >79% whereby 94% of it was associated with the native CM. 相似文献
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R. Wüstneck J. Krgel R. Miller V.B. Fainerman P.J. Wilde D.K. Sarker D.C. Clark 《Food Hydrocolloids》1996,10(4):395-405
The adsorption kinetic behaviour of β-lactoglobulin and β-casein solutions studied by dynamic surface tension measurements was interpreted by diffusion-controlled models. Approximate solutions of the model led to diffusion coefficients for short and long adsorption times. The coefficients associated with the short time region were found to be unexpectedly high. From the long time approximation, the coefficients reflect a slower process in the adsorption layer which is possibly superimposed by rearrangement processes. 相似文献
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Ali Rafe Seyed M. A. Razavi 《International Journal of Food Science & Technology》2013,48(9):1924-1931
Effect of pH (4.5–7.5) and Ca2+ (0.01–0.5 m ) on gelation of single and mixed systems of 10% β‐lactoglobulin (BLG) and 1% basil seed gum (BSG) was investigated. The gelling point of BLG and BSG gels was strongly pH‐dependent, and stiffer gels formed at higher pH. The BLG gels were formed upon heating to 90 °C and reinforced on cooling to 20 °C; however, the gelation of BSG occurred at temperatures below 70 °C. By increasing Ca2+ concentration, storage modulus of BLG and BSG gels were increased, although pH had a greater effect than Ca2+. In contrast, mixed systems showed two distinct types of behaviour: BLG gel formation and BSG network, suggesting that phase‐separated gels were formed. In addition, higher strength was obtained for BLG‐BSG mixture at higher Ca2+ concentration. 相似文献
15.
Cheng‐Bin Zhao Fei Wu Yong‐Ping Li Xiao‐Ling Liu 《International Journal of Food Science & Technology》2015,50(2):347-355
The effects of concentration and molecular weight of oat β‐glucans on properties of soya bean protein isolate (SPI) thermal gels prepared by heating at 90℃for 30 min were investigated. Compared with control (free of β‐glucan) formulations, the presence of β‐glucans (0.5–1.5%, w/v) largely enhanced storage modulus (G′) and texture properties of SPI (12%, w/v) thermal gels measured by dynamic oscillatory rheometry and texture profile analysis, which were developed as increasing β‐glucan concentration and molecular weight. It is possible that β‐glucans could cause the formation of protein aggregates to produce gels through hydrophobic interactions. Mixed gel systems at low ionic strength showed higher G′ resulting from the lower denaturation temperature of SPI, which was beneficial to the formation of gel structure. In addition, although adding a certain amount of β‐glucan into SPI reduced water‐holding capacity of mixed gels, high molecular weight of β‐glucan improved their water‐holding capacity compared to control formulations attributed to the improvement of the structural integrity of the mixed gel network. 相似文献
16.
The effect of glycosylation on the interfacial properties of bovine caseinomacropeptide 总被引:1,自引:0,他引:1
The two major fractions of bovine caseinomacropeptide (CMP), the glycosylated gCMP and non-glycosylated aCMP, were studied for their emulsifying properties. The main finding was that aCMP showed significantly better emulsifying properties than gCMP. While aCMP showed an emulsifying activity index (EAI) of 150.7 g/m2, gCMP achieved a value of 98.5 g/m2. Stability of emulsions was 1.4 times higher for aCMP as compared to gCMP. Droplet size measurements and creaming studies showed a strong influence of pH on both fractions with minimal emulsion stabilities at pH 4.1 (gCMP) and 4.9 (aCMP). Investigation of the flocculation behaviour and variations of the ionic strength indicate that the glycan side chains induce a combination of electric, steric and hydrophilic effects, preventing an ordered adsorption of gCMP molecules at the oil/water interface, while aCMP builds a stable network at the surface. For further elucidation, zeta potential measurements for both fractions were performed, resulting in isoelectric points of 3.15 for gCMP and 4.15 for aCMP in bulk solution. Finally, a hypothesis of surface adsorption of CMP is presented as a function of glycosylation and pH based on experimental data supported by an approach using protein modelling techniques. 相似文献
17.
Bo Young Byun Su‐Jin Lee Jae‐Hyung Mah 《International Journal of Food Science & Technology》2014,49(1):238-245
The objective of this study was to investigate the antibacterial activity of levan compounds, including high‐molecular‐weight levan, low‐molecular‐weight levan and difructose dianhydride IV (DFA IV). The levans exhibited broad antibacterial spectra against foodborne pathogenic bacteria, in a concentration‐dependent manner. From comparison with simple saccharides, often regarded as by‐products of levan production, it turned out that the antibacterial activity of levans was primarily caused by themselves. The strongest effect was observed with low‐molecular‐weight levan as compared to the others, and oligosaccharides as well. The low‐molecular‐weight levan was therefore applied to bread making. The bread samples inoculated with pathogenic bacteria were divided into two groups: bread with sugar alone (control) and bread with both sugar and levan (treatment). It was found from the in situ test that the viability of pathogenic bacteria in bread was reduced by the addition of low‐molecular‐weight levan. Therefore, levan compounds have potential as alternative sweeteners for reduction in pathogenic contamination. 相似文献
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Gang Fan Yongxia Xu Xiaomin Zhang Shengjiao Lei Shuzhen Yang Siyi Pan 《International Journal of Food Science & Technology》2011,46(11):2312-2320
In this study, bound volatile compounds were isolated and extracted with Amberlite XAD‐2 resin and then hydrolysed by free or immobilised β‐glucosidase. The released bound volatiles were analysed by GC‐MS. In addition, the optimisation of immobilisation method on sodium alginate and the characteristics of immobilised β‐glucosidase were studied. The results showed that crosslinking‐entrapment was the best method. The optimal conditions of this method were as follows: sodium alginate concentration 3.5%, glutaraldehyde concentration 1%, crosslinking time 3 h, immobilisation time 2 h and CaCl2 concentration 3%. The optimum temperature for β‐glucosidase (65 °C) was decreased by 10 °C after immobilisation, while the optimum pH values for free and immobilised β‐glucosidase were both at pH 5.0. The Km values of free and immobilised β‐glucosidase were 14.89 and 0.59 m , respectively. In total, thirteen and six bound volatile compounds were detected in orange juice hydrolysed by free and immobilised β‐glucosidase, including benzenic compounds, terpenic compounds, hydroxy esters, C13‐norisoprenoids and alcohols. 相似文献
20.
Kairy Dharali Pujols Luis Osorio Elsy Paola Carrillo Wisdom Wardy Damir Dennis Torrico Hong Kyoon No José Andrés Herrera Corredor Witoon Prinyawiwatkul 《International Journal of Food Science & Technology》2014,49(5):1383-1390
Effects of α‐ and β‐chitosan (CH), soybean oil (SO) and their emulsions (CH:SO = 2:3) as coating materials on selected internal quality and sensory properties of eggs were evaluated during 5 weeks storage at 25 °C. After 3 weeks of storage, α‐ and β‐CH‐coated eggs changed to B grade, while SO‐ and emulsion‐coated eggs preserved grade A quality. Weight loss of eggs coated with SO and CH:SO emulsions was <2.0% vs. 5.3–5.8% for noncoated and CH‐coated eggs after 5 weeks of storage. β‐CH (0.9%) maintained lower weight loss of eggs than α‐CH (1.2%) only at 1‐week storage. Albumen pH of eggs coated with SO and CH:SO emulsions decreased progressively throughout storage. Eggs coated with β‐CH:SO emulsion and SO were significantly glossier than noncoated eggs. Consumers indicated positive purchase intent (69.17–76.67%) for all coated eggs. Overall, α‐CH:SO and β‐CH:SO emulsions extended egg shelf life by at least 3 weeks during room temperature storage. 相似文献