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1.
Myofibrils, oxidized with FeCl3/H2O2/ascorbate, exhibited an increase in carbonyls and amines, SH→SS conversion, peptide scission, myosin polymerization, and a decrease in thermal stability and gel‐formation ability. Amino‐acid side chains of whey‐protein isolates (WPI) and soy‐protein isolates (SPI) were also modified during oxidation, but the thermal stability of WPI or SPI was not significantly altered. Oxidation increased elasticity of SPI gel but not that of WPI gel. Similarly, oxidation promoted interactions of myofibrils with SPI but not with WPI, resulting in > 30% increases in elasticity of the myofibril/SPI composite gel over its nonoxidized control. Hence, in processed meats where oxidation occurs, the presence of soy proteins may enhance the functionality of myofibrillar proteins.  相似文献   

2.
Lipid‐soluble vitamin E (VE) and water‐soluble vitamin B2 (VB2) can be encapsulated together in the same water–oil–water emulsion system. The ability of whey protein isolate (WPI)–polysaccharide complexes to synergistically control the release rates in such a system was investigated. The complexes studied were WPI–low methoxyl pectin (LMP) and WPI–κ‐carrageenan (KCG). The encapsulation efficiency of VE and VB2 of the WPI system is 66% and 64% and increases by about 1.4‐ and 1.2‐fold in the WPI–LMP and WPI–KCG complexes, respectively, which serve as selective non‐pH‐dependent barriers against enzyme attack. These complexes also greatly ameliorate the controlled release rates of both vitamins. The low‐charge LMP, with its multiple protein‐ and oil‐binding abilities, exhibits greater synergistic effects than the high‐charge KCG.  相似文献   

3.
Oxidative Stability of Anhydrous Milkfat Microencapsulated in Whey Proteins   总被引:2,自引:0,他引:2  
The chemical stability was studied on anhydrous milkfat (AMF) encapsulated in whey protein isolate (WPI) and WPI combined with lactose (1:1 w/w WPI/L). AMF-containing microcapsules, as well as bulk milkfat, were stored at 20°C with light, 40°C without light, and 50°C with and without light for up to 12 mo. Milkfat oxidation was monitored by oxygen uptake in headspace and hexanal accumulation. In all cases, AMF oxidation was significantly limited by microencapsulation in WPI or WPI/L. Whey proteins are effective microencapsulating agents.  相似文献   

4.
为了提高益生菌在人体胃液中的存活率,本研究以大豆蛋白(SPI)、乳清蛋白(WPI)、酪蛋白(Casein)、明胶(Gelatin)为壁材,采用转谷氨酰胺酶交联的乳化凝胶方法,将Lactobacillus gasseri和Bifidobacterium bifidum包埋于蛋白质胶囊中,通过测定这两种益生菌在人体模拟胃液中的存活率,结果表明:相比于未经过包埋处理的细胞,包埋于蛋白质微胶囊中的细胞具有较高的存活率,并且还发现大豆蛋白微胶囊对菌的保护效果最好,明胶微胶囊最差。对于Lactobacillus gasseri,在加和未加胃蛋白酶的模拟胃液中,菌在这四种蛋白质微胶囊中的D值分别为:73.1、59.7、63.9、47.3min及246.6、240.5、220.0、90.2min。对于Bifidobacterium bifidum,在加和未加胃蛋白酶的模拟胃液中,菌在这四种蛋白质微胶囊中的D值分别为:31.7、24.2、22.7、18.7min和124.3、103.5、97.6、47.8min。除此之外,还比较了蛋白质的四种理化特性(乳化能力,凝胶强度,乳化稳定性、渗透性),其结果:乳化能力大小为SPI>Casein>WPI>Gelatin,凝胶强度大小为Gelatin>SPI>Casein>WPI,模拟胃液的渗透性大小为Gelatin>SPI=Casein>WPI,缓冲能力大小为Casein>WPI=SPI>Gelatin。通过上述结果可以推测蛋白质的缓冲能力与保护效果有很大的相关性,但缓冲能力并不是唯一决定因素,蛋白质其它的理化性质都有可能影响其保护效果。  相似文献   

5.
The effectiveness of two drying agents, namely whey protein isolate (WPI) and maltodextrin (MD), was evaluated during spray-drying of strawberry puree. With the increase of WPI substitution in the feed material, the surface tension of strawberry puree decreased, and powder recovery increased. Powder recovery (Rp) increased from 39.2 ± 2.3% (S:MD:WPI = 60:40:0) to 56.5 ± 2.8% when MD was replaced by WPI (S:MD:WPI = 60:39:1). Surface morphology of powders showed that the addition of WPI resulted in shrunken particle surface, which gave rise to smaller DB and particle size. The particles were not spherical, and even with the addition of 0.5% WPI, the particle morphology was altered. The surface shrinkage of strawberry powder increased with increase in WPI from 0.5% to 10%. The production efficiency of strawberry powder could be greatly improved when MD was replaced by 1% WPI.  相似文献   

6.
Scope: Metabolic phenotyping promises to be a useful tool in human intervention studies. This study examined whether metabolic phenotyping could identify responders to vitamin D supplementation in terms of the metabolic syndrome. Methods and results: In a double‐blind, randomised placebo‐controlled dietary intervention subjects were assigned to receive 15 μg vitamin D3 or placebo daily. Serum 25‐hydroxyvitamin D (25(OH)D) and biochemical markers of the metabolic syndrome were measured at baseline and following the 4‐wk intervention. k‐means clustering and 1H‐NMR metabolomic analysis were used to explore responsive phenotypes. Vitamin D supplementation significantly increased serum 25(OH)D to an endpoint concentration of 78.1±20.0 nmol/L (p<0.001). There was no effect of supplementation on the measured markers of the metabolic syndrome. k‐means cluster analysis based on 13 biochemical markers of the metabolic syndrome and 25(OH)D concentrations revealed five discrete biomarker clusters. One of these clusters, characterised by lower serum 25(OH)D and higher levels of adipokines, showed significant responses in insulin (15% decrease), homestatic model assessment scores (19% decrease) and c‐reactive protein (54% decrease). Metabolomic analysis revealed further changes and the extent of change in serum vitamin D correlated negatively with changes in glucose. Conclusion: Overall, metabolic phenotyping revealed a phenotype that was responsive to vitamin D supplementation.  相似文献   

7.
To improve the quality of modified atmosphere (60% CO2/15% O2/25% N2)-packaged or vacuum-packaged bigeye tuna (Thunnus obesus) chunks, an edible film containing whey protein isolates (WPI) were added. During storage at 2 °C, the samples coated with WPI prior to packaging exhibited slower microbial growth, thiobarbituric acid (TBA), and total volatile basic-nitrogen (TVB-N) values than did those without films. On comparing the two formulations of WPI with 4 and 8% (v/v) glycerol, it was observed that WPI containing 8% glycerol induced more severe weight loss but retarded the lipid oxidation more effectively. The usage of WPI films with 8% glycerol is proved to be helpful to enhance the effect of modified atmosphere packaging on the quality of tuna, as the samples (MAP-2) displayed the lowest bacterial counts (3.63 log CFU/g) and TBA (0.349 mg malondialdehyde (MDA)/kg) and TVB-N (12.94 mg N/100 g) contents.  相似文献   

8.
Mixtures of proso millet starch with zein (15%, w/v), soy protein isolate (SPI, 15%, w/v) and whey protein isolate (WPI, 10%, w/v) as starch–protein composites were prepared through heat–moisture treatment, and the effects of protein addition on the physicochemical, structural and digestibility properties of starch were investigated. Rapid Visco Analysis showed that the addition of zein, SPI and WPI gave significantly decreased setback values to 240.7cp, 192.0cp and 83.0cp, respectively, and setback values decreased reflected the excellent cold paste properties. Thermal analysis showed that each protein reduced the enthalpy, but especially WPI (reduced by 94.7%), suggesting that the double helices of the starch granules were decreased. X-ray diffraction showed that starch crystallinity was decreased after protein addition. The digestibility studies revealed that the addition of zein, SPI and WPI decreased the content of rapidly digestible starch and increased the resistant starch content to 8.4%, 14.6% and 17.5%, respectively. The whey protein displayed a more obvious impact on the digestibility of proso millet starch. These results will help guide the production and processing of starchy foods with desirable properties.  相似文献   

9.
《Journal of dairy science》2023,106(2):954-973
The objectives of the experiment were to determine the effects of supplementing 2 amounts of 25-hydroxyvitamin D3 (calcidiol; CAL) compared with equal amounts of vitamin D3 (cholecalciferol; CHOL) on serum concentrations, absorptions, and retentions of Ca, Mg, and P in periparturient dairy cows. One hundred seventy-seven (133 parous and 44 nulliparous) pregnant Holstein cows were enrolled in the experiment. Cows were blocked by parity and previous lactation milk yield (parous) or genetic merit for energy-corrected milk yield (nulliparous) and assigned randomly to receive 1 or 3 mg/d of CAL or CHOL in a 2 × 2 factorial arrangement of treatments. Treatments were provided to individual cows as a top-dress to the prepartum diet from 250 d gestation until parturition. The prepartum diet had a dietary cation-anion difference of ?128 mEq/kg of dry matter. All cows were fed a common postpartum diet containing 46 μg of vitamin D3/kg of dry matter without further supplementation of treatments. Concentrations of vitamin D metabolites, Ca, Mg, and P in serum were measured pre- and postpartum, in addition to total-tract digestibility and urinary excretion of Ca, Mg, and P in the prepartum period. Feeding 3 mg compared with 1 mg of CAL increased serum 25-hydroxyvitamin D3 (CAL1 = 94 vs. CAL3 = 173 ± 3 ng/mL). In comparison, the increment in serum 25-hydroxyvitamin D3 from feeding 3 mg compared with 1 mg of CHOL was small (CHOL1 = 58 vs. CHOL3 = 64 ± 3 ng/mL). Feeding CAL increased prepartum concentration of P in serum compared with CHOL (CHOL = 1.87 vs. CAL = 2.01 ± 0.02 mM), regardless of the amount fed, but neither source nor amount affected prepartum Ca or Mg in serum. Feeding CAL increased serum Ca and P for the first 11 d postpartum compared with CHOL (CHOL = 2.12 vs. CAL = 2.16 ± 0.01 mM serum Ca; CHOL = 1.70 vs. CAL = 1.78 ± 0.02 mM serum P) but the amount of vitamin D did not affect postpartum concentrations of Ca, Mg, and P in serum. Feeding CAL increased prepartum apparent digestibility of Ca compared with CHOL (CHOL = 26.6 vs. CAL = 33.5 ± 2.8%) but treatments did not affect Ca retention prepartum. Neither source nor amount of vitamin D affected Mg and P apparent digestibility, but CAL decreased the concentration of P excreted in urine during the prepartum period (CHOL = 1.8 vs. CAL = 0.8 ± 0.3 g/d). Calcidiol tended to increase the amount of Ca secreted in colostrum (CHOL = 9.1 vs. CAL = 11.2 ± 0.9 g/d) and Ca excreted in urine postpartum (CHOL = 0.4 vs. CAL = 0.6 ± 0.1 g/d) compared with CHOL. Collectively, feeding CAL at 1 or 3 mg/d compared with CHOL in the last 24 d of gestation is an effective way to increase periparturient serum P concentration and postpartum serum Ca of dairy cows fed a prepartum diet with negative DCAD.  相似文献   

10.
Studies conducted among populations of tropical countries have reported high prevalences of vitamin D deficiency and insufficiency. Information resulting from meta-analyses on the spatial distribution of vitamin D deficiency and insufficiency in tropical countries is still rare. The aim of this review was investigated the prevalence of vitamin D deficiency and insufficiency among the Brazilian population. Observational studies were searched in eight electronically databases. Additionally, theses and dissertations and abstracts were screened. Details on study design, methods, population, mean and data on serum concentrations of vitamin D in different age groups in Brazil were extracted. Data were pooled using a random-effects model and choropleth maps were created based on the geopolitical regions of the country. 72 published paper met the inclusion criteria. The mean vitamin D concentration among the Brazilian population between 2000 and 2017 of 67.65 nmol/L (95% CI: 65.91, 69.38 nmol/L).The prevalences of vitamin D deficiency and insufficiency were 28.16% (95% CI: 23.90, 32.40) and 45.26% (95% CI: 35.82, 54.71), respectively, for the Brazilian population. The highest prevalence of deficiency were observed in the southern and southeastern regions and the highest occurrence of vitamin D insufficiency was among the populations of the southeastern and northeastern regions. Finally, there are high prevalence of inadequate vitamin D concentrations among the population, regardless of age group in Brazil. The development of vitamin D food fortification policies in needs to be cautious and carefully planned.  相似文献   

11.
《Journal of dairy science》2019,102(12):10760-10771
Over the past decades, several studies investigated the health-promoting functions of milk peptides. However, to date many hurdles still exist regarding the widespread use of milk-derived bioactive peptides, as they may be degraded during gastrointestinal digestion. Thus, the aim of our study was to in vitro digest intact whey protein isolate (WPI) and casein proteins (CNP), mimicking in vivo digestion, to investigate their bioactive effects and to identify the potential peptides involved. Whey protein isolate and CNP were digested using a pepsin–pancreatin protocol and ultra-filtered (3-kDa cutoff membrane). A permeate (<3 kDa) and a retentate (>3 kDa) were obtained. Soy protein was included as a control (CTR). Angiotensin-1-converting enzyme inhibitory (ACE1-I) and antioxidant activity (AOX) were assessed and compared with those observed in undigested proteins and CTR. Furthermore, the permeate was characterized by nano-liquid chromatography electrospray ionization tandem mass spectrometry (LC-nano ESI MS/MS) using a shotgun peptidomic approach, and retentate was further digested with trypsin and analyzed by MS using a shotgun proteomic approach to identify potentially bioactive peptides. Further, the effects of WPI, CNP, and CTR retentate on cell metabolic activity and on mucus production (MUC5AC and MUC2 gene expression) were assessed in intestinal goblet HT29-MTX-E12 cells. Results showed that WPI permeate induced a significant ACE1-I inhibitory effect [49.2 ± 0.64% (SEM)] compared with undigested WPI, CNP permeate, and retentate or CTR permeate (10.40 ± 1.07%). A significant increase in AOX (1.58 ± 0.04 and 1.61 ± 0.02 µmol of trolox AOX equivalents per mg of protein, respectively) upon digestion was found in WPI. Potentially bioactive peptides associated with ACE1-I and antihypertensive effects were identified in WPI permeate and CNP retentate. At specific concentrations, WPI, CNP, and CTR retentate were able to stimulate metabolic activity in HT29-MTX-E12 cells. Expression of MUC5AC was increased by CNP retentate and unaltered by WPI retentate; MUC2 expression was significantly increased by 0.33 mg/g of CNP and reduced by 1.33 mg/g of CNP. Our results confirm that milk proteins may be rich sources of bioactive compounds, with the greatest beneficial potential of CNP at the intestinal goblet cell level.  相似文献   

12.
Butyric acid is an important short‐chain fatty acid for intestinal health and has been shown to improve certain intestinal disease states. A triglyceride containing 3 butyric acid esters, tributyrin (TB) can serve as a source of butyric acid; however, the need to target intestinal delivery and mitigate unpleasant sensory qualities has limited its use in food. Microencapsulation, the entrapment of one or more cores within a matrix, may provide a solution to the aforementioned challenge. This research primarily focused on the influence of (1) wall material: whey and soy protein isolate (WPI and SPI, respectively) and gamma‐cyclodextrin (GCD), (2) wall additives: inulin of varying chain length, and (3) processing method: spray or oven drying (SD or OD, respectively) on the morphological properties and volatile retention of TB within microcapsules. SPI‐based microcapsules retained significantly less (P < 0.001) TB compared to WPI‐based microcapsules as measured by gas chromatography. The inclusion of inulin in the SD WPI‐based microcapsules increased (P < 0.001) TB retention over WPI‐based microcapsules without inulin. Inulin inclusion into WPI‐based microcapsules resulted in a smoother, minimally‐dented, circular morphology as compared to noninulin containing WPI‐based microcapsules as shown by scanning electron microscopy. GCD and TB OD microcapsules retained more (P < 0.001) TB (94.5% ± 1.10%) than all other WPI, WPI‐inulin, and GCD TB SD microcapsules. When spray dried, the GCD‐based microcapsules exhibited (P < 0.001) TB retention than all other microcapsules, indicating the GCD may be unsuitable for spray drying. These findings demonstrate that microencapsulated TB in GCD can lead to minimal TB losses during processing that could be utilized in functional food applications for intestinal health.  相似文献   

13.
The effect of limited hydrolysis was investigated on the physico‐chemical properties of soy protein isolate–maltodextrin (SPI‐Md) conjugate. The hydrolysates at a degree of hydrolysis (DH) of 1.8% showed much higher surface hydrophobicity (H0; 71.39 ± 3.60) than that of the SPI control (42.09 ± 2.17) and SPI‐Md conjugates (53.46 ± 2.74). Intrinsic fluorescence analysis demonstrated the unfolding of protein molecule and exposure of hydrophobic groups of SPI‐Md conjugate hydrolysates. As evidenced by far‐UV circular dichroism (CD) spectroscopy, the limited hydrolysis increased the unordered secondary structures of SPI‐Md conjugates. The denaturation temperature (Td) of SPI‐Md conjugate was significantly increased by subsequent limited hydrolysis from 102.53 ± 0.60 °C to 108.11 ± 0.61 °C at DH 1.8%. In particular, the emulsifying activity index (EAI) was improved notably after limited hydrolysis of DH 1.8% (147.76 ± 4.39 m2 g?1) compared with that of native SPI (88.90 ± 1.44 m2 g?1) and SPI‐Md conjugate (108.97 ± 1.45 m2 g?1).  相似文献   

14.
ABSTRACT

This review provides an overview of microchannel emulsification (MCE) for production of functional monodispersed emulsion droplets. The main emphasis has been put on functional bioactives encapsulation using grooved-type and straight-through microchannel array plates. MCE successfully encapsulates the bioactives like β-carotene, oleuropein, γ-oryzanol, β-sitosterol, L-ascorbic acid and ascorbic acid derivatives, vitamin D and quercetin. These bioactives were encapsulated in a variety of delivery systems like simple and multiple emulsions, polymeric particles, microgels, solid lipid particles and functional vesicles. The droplet generation process in MCE is based upon spontaneous transformation of interfaces rather than high energy shear stress systems. The scale-up of MCE can increase the productivity of monodispersed droplets >100 L h?1 and makes it a promising tool at industrial level.  相似文献   

15.
Proteinase activities for Alcalase® 2.4L (EC 3.4.21.62), Flavourzyme® (EC 3.4.11.1), Protease A (EC 3.4.24.39) and Protease N (IUB 3.4.24.28) were determined using 2% whey protein isolate (WPI) and 2% casein. The optimum substrate and enzyme concentrations and temperature were determined by the pH-stat method. Residual enzyme activity, hydrolysate molecular weight and free amino acid (FAA) content were determined. Protease N and Alcalase® 2.4L had the highest proteinase activities on casein and WPI, respectively. Alcalase® 2.4L was more stable in the presence of WPI while Protease N was inhibited by hydrolysates, and like Protease A which released high FAAs, they produced shorter peptides. Flavourzyme® hydrolysed WPI poorly and released the highest FAAs. Short peptides were removed by 5% trichloroacetic acid (TCA) and 3.5% 5-sulphosalicylic acid before FAA analysis by reversed phase high-performance liquid chromatography (RP-HPLC) of Flavourzyme® and Protease A hydrolysates, but were detected in Alcalase® 2.4L and Protease N hydrolysates. The enzyme activities for WPI hydrolysis in an enzymatic membrane reactor were Flavourzyme®<Protease A<Alcalase® 2.4L⩽Protease N.  相似文献   

16.
The following study explored how the addition of various proteins (gelatin, soy protein isolate (SPI) and heated/unheated whey protein isolate (WPI)), at two different concentration levels (1% and 2%), affected the mechanical, microstructural and optical properties of calcium cross-linked ‘wet’ alginate films. Additionally, the water holding capacity and textural profile analysis (TPA) properties were determined for the alginate–protein gels. Adding all types of protein significantly (P < 0.05) decreased the force to puncture the ‘wet’ alginate–protein composite films compared to the control alginate film. The tensile test showed significant differences in tensile strength between the various films but interestingly there was no significant difference in the percent elongation at breaks between any of the films. Micrograph images showed that the SPI and heated WPI formed relatively larger protein clumps/regions in the alginate films whereas the gelatin and unheated WPI appeared to be more integrated into the alginate film. The heated WPI films were the least transparent of all the films, followed by the SPI films. Few TPA differences existed between the alginate–protein gels. However, the alginate–gelatin gels did have significantly less water loss than the other alginate–protein gels suggesting that alginate and gelatin may be the most compatible of all the alginate–protein combinations tested.  相似文献   

17.
Coalescence Index of Protein-Stabilized Emulsions   总被引:1,自引:0,他引:1  
A simple method is proposed to estimate coalescence stability of protein-stabilized emulsions. Coalescence was accelerated through agitation and measured by change in emulsion turbidity over time. A coalescence index (CI) was determined and used to compare emulsions stabilized with casein, whey (WPI) and soy protein isolates (SPI). CI increased when stirring rate increased. Casein produced more stable emulsions, followed by WPI and SPI. High homogenization pressure increased coalescence stability of WPI and SPI-stabilized emulsions and decreased coalescence stability of casein-stabilized emulsions. Microscopic examination, showed agitation of the emulsion had clearly induced formation of large oil droplets which acted as coalescence nuclei.  相似文献   

18.
Pork patties containing 1.5% NaCl and 2% hydrolyzed whey protein isolate (WPI, 1 h with flavourzyme or 6 h with protamex) or soy protein isolate (SPI, 0.5 h with chymotrypsin or flavourzyme) were cooked to 70?°C and subsequently stored at 4?°C up to 7 days. Lipid oxidation in patties during storage was analyzed by measuring the concentration of conjugated dienes (CD) and thiobarbituric acid-reactive substances (TBARS). Intact WPI and SPI, and their hydrolysates, were all inhibitory of oxidation (P <0.05) in cooked patties, with SPI being slightly more effective than WPI. Hydrolysis with protamex augmented the antioxidative activity (CD, TBARS) of WPI. Hydrolysis with either chymotrypsin or flavourzyme improved the ability of SPI to retard CD formation but did not delay the production of TBARS in stored pork patties.  相似文献   

19.
本试验分别研究了在乳清蛋白-葡萄糖和牛血清白蛋白-葡萄糖模拟生理体系中,荔枝果皮原花青素(Litchi pericarp procyanidins,LPPC)对美拉德反应和晚期糖基化终末产物(advanced glycation end products,AGEs)的抑制作用,以荧光性AGEs的强度为表征依据。结果表明,在乳清蛋白-葡萄糖模拟体系中孵育35 d时,LPPC对AGEs的抑制效果最强,达60.21±1.34%。LPPC浓度为1 mg/m L时,相对抑制率最大可达85.33±9.02%(显著高于维生素C(Vc),p0.05)。在牛血清白蛋白-葡萄糖体系中,孵育35 d后LPPC对AGEs的相对抑制率最高达70.01±1.32%,且与LPPC浓度呈现正相关。当LPPC浓度为0.5 mg/m L时,抑制率最大为95.46±10.12%(显著高于氨基胍(AG),p0.05)。不同p H值下蛋白质的稳定性研究表明,乳清蛋白在与LPPC长期孵育后,其热稳定性明显降低,再次提示了LPPC对美拉德反应的抑制作用。LPPC可作为一种天然的食品基质的AGEs抑制剂深度开发。  相似文献   

20.
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