共查询到20条相似文献,搜索用时 15 毫秒
1.
Timely monitoring of changes in the type and quantity of aromatic compounds throughout the must fermentation process provides useful information for wine makers. This paper aimed to use headspace solid phase micro-extraction coupled with gas chromatography (HS-SPME/GC–MS) to analyse aromatic compounds produced during must alcoholic fermentation. The results showed that both qualitatively and quantitatively, the PDMS/CAR/DVB fibre was suitable for extracting aromatic compounds in wine. The amount of alcohols, esters, acids and monoterpenes absorbed on the SPME fibre were influenced by the ethanol content. Calibration curves with a high correlation (R2 > 0.900) obtained in seven ethanol contents (2%, 4%, 6%, 8%, 10%, 12% and 14%) were established to quantitatively determine the amount of aromatic compounds during alcoholic fermentation. A validated HS-SPME method for determining aromatic compounds was used to monitor aromatic compounds during Syrah alcoholic fermentation. This modified HS-SPME method was proved to be useful for controlling the oenological process. 相似文献
2.
The stipe of shiitake, a disposable byproduct in mushroom industry, was applied as a nitrogen source in alcoholic fermentation. Four yeast strains were screened by evaluating their fermentative efficiency and ethanol tolerance. The results showed that shiitake stipe extract could enable yeast cell proliferation and be sequent to good performance of sugar utilization and ethanol production, depended on strains. The ethanol production (mL/100 mL) of 13.7 ± 0.8, 14.1 ± 0.9, 11.9 ± 0.1 and 10.9 ± 0.3 was obtained from strains 20262, 22236, 21686 and 21992, respectively, at the end of fermentation. Ethanol tolerance of strain in term of glucose utilization rate was more consistent with the extent of ethanol production during fermentation than that of survival rate. Therefore, the evaluation of glucose utilization rate in external ethanol condition might help establish a simple and quick method to screen the strains capable of high ethanol production. The shiitake stipe alcoholic beverage would also provide comparable consumer acceptances with a commercial Taiwanese white wine. 相似文献
3.
Multifactorial analysis of acetaldehyde kinetics during alcoholic fermentation by Saccharomyces cerevisiae 总被引:1,自引:0,他引:1
J.N. JackowetzS. Dierschke R. Mira de Orduña 《Food research international (Ottawa, Ont.)》2011,44(1):310-316
Acetaldehyde is the terminal electron acceptor in the alcoholic fermentation by Saccharomyces cerevisiae. Quantitatively the most important carbonyl by-product, it has relevance for ethanol production yields as well as product stabilization and toxicology. The aim of this study was to investigate the effect of various enological parameters on acetaldehyde kinetics during alcoholic fermentations. Two commercial yeast strains were tested in two grape musts and the pH, temperature, SO2 and nutrient addition were varied. All incubations had uniform kinetics where acetaldehyde reached an initial peak value followed by partial reutilization. Peak acetaldehyde concentrations and residual concentrations after 15 days of fermentations ranged from 62 to 119 mg l− 1 and 22 to 49 mg l− 1, respectively. A positive linear relationship was found between peak and final acetaldehyde levels in Gewürztraminer, but not Sauvignon Blanc fermentations, where sluggish fermentations were observed. Several factors had a significant effect on peak and/or final acetaldehyde levels. SO2 addition, grape cultivar and fermentation nutrition were important regulators of peak acetaldehyde production, while final acetaldehyde concentrations were correlated with SO2 addition, grape cultivar and temperature. The results allowed to estimate the acetaldehyde increase caused by SO2 addition to 366 ??g of acetaldehyde per mg of SO2 added to the must. The course of the final fermentation phase was shown to determine acetaldehyde residues. Comparison of acetaldehyde and hexose kinetics revealed a possible relationship between the time of occurrence of peak acetaldehyde concentrations and the divergence of glucose and fructose degradation rates. 相似文献
4.
Interaction of milk α- and β-caseins with tea polyphenols 总被引:1,自引:0,他引:1
Imed Hasni Philippe BourassaSaber Hamdani Guy SamsonRobert Carpentier Heidar-Ali Tajmir-Riahi 《Food chemistry》2011
The interaction of α- and β-caseins with tea polyphenols (+)-catechin (C), (−)-epicatechin (EC), (−)-epigallocatechin (EGC) and (−)-epigallocatechin gallate (EGCG) was examined at a molecular level, using FTIR, UV–visible, CD and fluorescence spectroscopic methods as well as molecular modelling. The polyphenol binding mode, the binding constant and the effects of polyphenol complexation on casein stability and conformation were determined. Structural analysis showed that polyphenols bind casein via both hydrophilic and hydrophobic interactions with overall binding constants of KC–α-cas = 1.8 (±0.8) × 103 M−1, KEC–α-cas = 1.8 (±0.6) × 103 M−1, KEGC–α-cas = 2.4 (±1.1) × 103 M−1 and KEGCG–α-cas = 7.4 (±0.4) × 103 M−1, KC–β-cas = 2.9 (±0.3) × 103 M−1, KEC–β-cas = 2.5 (±0.6) × 103 M−1, KEGC–β-cas = 3.5 (±0.7) × 103 M−1 and KEGCG–β-cas = 1.59 (±0.2) × 104 M−1. The number of polyphenol bound per protein molecule (n) was 1.1 (C), 0.9 (EC), 1.1 (EGC), 1.5 (EGCG) for α-casien and 1.0 (C), 1.0 (EC), 1.1 (EGC) and 1.5 (EGCG) for β-casein. Structural modelling showed the participation of several amino acid residues in polyphenol–protein complexation with extended H-bonding network. Casein conformation was altered by polyphenol with a major reduction of α-helix and β-sheet and increase of random coil and turn structure suggesting further protein unfolding. These data can be used to explain the mechanism by which the antioxidant activity of tea compounds is affected by the addition of milk. 相似文献
5.
Morán-Marroquín GA Córdova J Valle-Rodríguez JO Estarrón-Espinosa M Díaz-Montaño DM 《International journal of food microbiology》2011,151(1):87-92
Knowledge of physiological behavior of indigenous tequila yeast used in fermentation process is still limited. Yeasts have significant impact on the productivity fermentation process as well as the sensorial characteristics of the alcoholic beverage. For these reasons a better knowledge of the physiological and metabolic features of these yeasts is required. The effects of dilution rate, nitrogen and phosphorus source addition and micro-aeration on growth, fermentation and synthesis of volatile compounds of two native Saccharomyces cerevisiae strains, cultured in continuous fed with Agave tequilana juice were studied. For S1 and S2 strains, maximal concentrations of biomass, ethanol, consumed sugars, alcohols and esters were obtained at 0.04 h−1. Those concentrations quickly decreased as D increased. For S. cerevisiae S1 cultures (at D = 0.08 h−1) supplemented with ammonium phosphate (AP) from 1 to 4 g/L, concentrations of residual sugars decreased from 29.42 to 17.60 g/L and ethanol increased from 29.63 to 40.08 g/L, respectively. The S1 culture supplemented with AP was then micro-aerated from 0 to 0.02 vvm, improving all the kinetics parameters: biomass, ethanol and glycerol concentrations increased from 5.66, 40.08 and 3.11 g/L to 8.04, 45.91 and 4.88 g/L; residual sugars decreased from 17.67 g/L to 4.48 g/L; and rates of productions of biomass and ethanol, and consumption of sugars increased from 0.45, 3.21 and 7.33 g/L·h to 0.64, 3.67 and 8.38 g/L·h, respectively. Concentrations of volatile compounds were also influenced by the micro-aeration rate. Ester and alcohol concentrations were higher, in none aerated and in aerated cultures respectively. 相似文献
6.
K.I. Popov N. Sultanova H. Rönkkömäki M. Hannu-Kuure J. Jalonen L.H.J. Lajunen I.F. Bugaenko V.I. Tuzhilkin 《Food chemistry》2006
The 13C NMR technique is used for the measurement of the first dissociation constant of sucrose (HL) in highly alkaline solutions. In 1.0 M NaCl/NaOH medium and for 25 °C, the concentration dissociation constant (pK1) was 13.1 ± 0.3; and, for 60 °C, pK1 = 12.30 ± 0.05. The β-d-fructofuranosyl ring was found to be responsible for dissociation. The NMR data reveal no clear evidence of the second dissociation step below pH 14, either at 25 °C or at 60 °C. In the solutions with 4–10 mol dm−3 NaOH content the 13C NMR technique indicated the chemical shift changes, treated as the second dissociation step of sucrose and a sodium complex formation. A very rough estimation, for variable ionic strength, gives the value: pK2 ∼ 15.8 ± 0.8. The anionic species L− and NaH−1L− have been registered by electrospray ionization time-of-flight mass spectrometry (ESI-ToF MS) for 0.01 M sucrose solutions with initial pH 13. 相似文献
7.
Luciano Manfroi Paulo H.A. Silva Luiz A. Rizzon Priscila S. Sabaini M. Beatriz A. Glória 《Food chemistry》2009
The influence of alcoholic and malolactic fermentations on the levels of amines in Merlot wines was investigated. Saccharomyces bayanus, S. cerevisiae, Lactobacillus plantarum, Oenococcus oeni (DSM 7008 and 12923) and spontaneous fermentations were used. Four of the 10 amines investigated were detected: spermidine, serotonin, putrescine and cadaverine. When considering the factors independently, the malolactic bacteria significantly affected the levels of serotonin and total amines, whereas the fermentation yeasts significantly affected the levels of spermidine (two way Kruskal–Wallis, p ? 0.05). Spermidine levels were significantly higher in wines produced with S. cerevisiae. Significantly higher serotonin levels were found in wines made with L. plantarum. Putrescine and cadaverine were not detected in wines produced by spontaneous alcoholic fermentation or by L. plantarum. There were significant differences in alcohol content, total and volatile acidity, sulphite levels and taste quality among wines (Tukey test, p ? 0.05). 相似文献
8.
M.M. Gvozdenović B.Z. Jugović D.I. Bezbradica M.G. Antov Z.D. Knežević-Jugović B.N. Grgur 《Food chemistry》2011
Polyaniline (PANI) enzyme electrode was formed by immobilisation of Glucose oxidase (GOx) via glutaraldehyde into electrochemically polymerised PANI on graphite electrode. Electrochemical polymerisation of PANI on graphite was performed from aqueous solution of 1.0 mol dm−3 HCl and 0.25 mol dm−3 aniline at constant current density of 2.0 mA cm−2. Hronopotentiometric curves of the PANI enzyme electrode obtained at current density of 10 μA cm−2 were recorded in different glucose concentrations. The linearity response range was between 1.0 and 5.0 mmol dm−3 of glucose concentration. The estimated apparent Michaelis–Menten constant, was Km′ = 0.30 mmol dm−3, which is significantly lower than that of free enzyme. 相似文献
9.
Invertase was immobilized into polyacrylamide–gelatin carrier system by chemical cross-linking with chromium (III) acetate, chromium (III) sulphate, and potassium chromium (III) sulphate. The optimum conditions, namely substrate concentration, temperature, and pH were determined. The effect of polyacrylamide–gelatin ratio and cross-linker concentration on immobilized enzyme activity were analysed. Maximum immobilized enzyme activities were obtained with chromium (III) acetate (0.01 mol dm−3), chromium (III) sulphate (0.004 mol dm−3) and potassium chromium (III) sulphate (0.001 mol dm−3) for 0.177 (w/w) polyacrylamide–gelatin carrier ratio as 79%, 72% and 79%, respectively. The Km values were 86 and 166 mM for free and immobilized enzyme, respectively. All immobilized samples were used 20 times over a period of 2 months without a considerable loss of activity. 相似文献
10.
Methanolic extracts of six cultivars of Portulaca oleracea were analyzed for their total phenol content (TPC) using the Folin–Ciocalteu method. The antioxidant activity was measured using the 1,1-diphenyl-2-picrylhydrazyl, ferric-reducing antioxidant power (FRAP) and β-carotene bleaching (BCB) assays. The iodine titration method was used to determine the ascorbic acid content (AAC). The TPC of the cultivars of P. oleracea ranged from 127 ± 13 to 478 ± 45 mg GAE/100 g of fresh weight of plant. There was good correlation between the TPC value and its AEAC, IC50 and FRAP values (r2 > 0.9) for all the cultivars. The AAC for the cultivars ranged from 38.5 ± 0.6 to 73.0 ± 17.5 mg/100 g. The TPC value of the common variety PO1, was the lowest compared to the ornamental cultivars (PO2–PO6). The BCB assay showed that all cultivars were capable of inhibiting lipid peroxidation and the inhibition power did not correlate with TPC value. 相似文献
11.
C.D. Kanakis Imed Hasni Philippe Bourassa P.A. Tarantilis M.G. Polissiou Heidar-Ali Tajmir-Riahi 《Food chemistry》2011
The effect of milk on the antioxidant capacity of tea polyphenols is not fully understood. The complexation of tea polyphenols with milk proteins can alter the antioxidant activity of tea compounds and the protein secondary structure. This study was designed to examine the interaction of β-lactogolobulin (β-LG) with tea polyphenols (+)-catechin (C), (−)-epicatechin (EC), (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG) at molecular level, using FTIR, CD and fluorescence spectroscopic methods as well as molecular modelling. The polyphenol binding mode, the binding constant and the effects of polyphenol complexation on β-LG stability and secondary structure were determined. Structural analysis showed that polyphenols bind β-LG via both hydrophilic and hydrophobic interactions with overall binding constants of KC–β-LG = 2.2 (±0.8) × 103 M−1, KEC–β-LG = 3.2 (±1) × 103 M−1, KECG–β-LG = 1.1 (±0.6) × 104 M−1 and KEGCG–β-LG = 1.3 (±0.8) × 104 M−1. The number of polyphenols bound per protein molecule (n) was 1.1 (C), 0.9 (EC), 0.9 (ECG) and 1.3 (EGCG). Molecular modelling showed the participation of several amino acid residues in polyphenol–protein complexation with extended H-bonding network. The β-LG conformation was altered in the presence of polyphenols with an increase in β-sheet and α-helix suggesting protein structural stabilisation. These data can be used to explain the mechanism by which the antioxidant activity of tea compounds is affected by the addition of milk. 相似文献
12.
Gelatinised waxy maize starch and low-methoxy pectin mixtures were solubilised/dispersed in water and cross-linked with sodium trimetaphosphate (STMP). The polysaccharides were subjected to α-amylase, β-amylase or amyloglucosidase (AMG) hydrolysis for different times, and at two starch to pectin combination ratios (3:2 and 2:3). The extent of hydrolysis by porcine pancreatic α-amylase of the cross-linked (gelatinised) starch was 54.8–58.9% in comparison with gelatinised starch (for different incubation times), corresponding to 52.3–58.9% and 51.3–55.3% of the starch in the uncross-linked (UL) 3:2 and 2:3 starch to pectin ratios (for the same hydrolysis times). Blends of individually cross-linked starch to pectin ratios (3:2 and 2:3) were hydrolysed to 66.2–67.0% and 65.4–71.8%, respectively, compared with the corresponding UL counterparts. When the gelatinised starch was incubated for 0.5–36 h with β-amylase, hydrolysis ranged from 9.2% to 26.2%, and from 5.4% to 12.2% when the starch was cross-linked (corresponding to 40.0–58.7% of the gelatinised starch). For starch to pectin ratios of 3:2 or 2:3 blended after cross-linking, or by simultaneous cross-linking, hydrolysis represented 2.3–3.4% and 0.3–0.6% for the 3:2 ratio but only 1.2–2.0% and 0–0.3% for the 2:3 ratio. Hydrolysis with AMG using a 0.1 mg ml−1 enzyme concentration caused 51.8% hydrolysis of gelatinised starch, which was lowered to 35.2% (i.e. by 68%) after cross-linking. At a higher enzyme concentration (1 mg ml−1), the comparable figures were 91.7% and 71.9% (a reduction of 78.4%). For the UL 3:2 starch to pectin ratio and 0.1 and 1 mg ml−1 enzyme concentrations, there was 27.8% and 56.5% hydrolysis of the polysaccharide which translated to 24.3% (87.4%) and 45.8% (81.1%), respectively, after cross-linking. Comparable figures for the 2:3 ratio (for the 0.1 and 1 mg ml−1 enzyme concentrations) were 20.2% and 36.5% hydrolysis of the UL samples and 18.2% (90.1%) and 32.5% (89.0%) hydrolysis, respectively, after cross-linking. 相似文献
13.
Rheology, micro-DSC and confocal microscopy were used to study the effect of potassium ion on the viscoelastic behavior, disorder–order transition and microstructure, respectively, of κ-carrageenan in solution under different conformations at 60, 25 and 9 °C. At 60 and 25 °C the rheological behavior of 0.5% κ-carrageenan with 0–80 mmol/dm3 and 0–5 mmol/dm3 KCl, respectively, was typical of viscoelastic solutions of random coiled polymers. At 9 °C and below a critical ionic concentration of about 7.0 mmol/dm3, κ-carrageenan adopted an ordered conformation in which helical structures did not aggregate and hence did not form self-supporting gels. Changes in polysaccharide stiffness were estimated from intrinsic viscosity variations as a function of ionic content. In the ordered state, the stiffness was higher than in the disordered state, whereas a liquid-like viscoelastic behavior was still exhibited. In 0.5% κ-carrageenan at 25 °C, increasing KCl from 0 to 300 mmol/dm3 produced gels of increasing rigidity. However, above 100 mmol/dm3 such increase was marginal. Confocal images evidenced a three-dimensional network whose continuity depends on polysaccharide and salt concentrations. These observations are consistent with the rheological behavior of the self-supporting gels obtained with κ-carrageenan concentrations in the range of 0.05–1%. 相似文献
14.
Biodegradable three-layer gelatin film was obtained by heat – compression of piled dialdehyde starch (DAS) – cross-linked and plasticized-gelatin films (Ge-10DAS) outer layers and sodium montmorillonite (MMt) – plasticized – gelatin film (Ge-5MMt) inner layer. Multilayer film displayed a compact and uniform microstructure due to the highly compatible individual layers which could interact by strong hydrogen bonding. Lamination reduced moisture absorption and total soluble matter compared to the single layers while keeping transparency. Tensile strength and elastic modulus of the multilayer were 8.0 ± 1.3 MPa and 14.7 ± 2.4 MPa, which were significantly higher than values obtained for Ge-10DAS due to the contribution of the of the bio-nanocomposite inner layer. Elongation at break was not affected by lamination meanwhile it had a beneficial effect on barrier properties. Water vapor permeability (WVP) of the multilayer was 0.8 ± 0.1 × 10−13 kg m Pa−1 s−1 m−2 which was lower than those of the individual components whereas oxygen permeability was similar to that of Ge-5MMt (10.5 ± 0.4 cm3(O2) mm m−2 day−1) and lower than that of Ge-10DAS film. 相似文献
15.
Valeria E. Fernandez Gonzalo G. Palazolo Natalia A. Bosisio Luis M. Martínez Jorge R. Wagner 《Journal of food engineering》2012
The aim of present study was to investigate the feasibility of application high-pressure homogenized (HPH) yeast aqueous dispersions with low nucleic acid content for the formulation of low-in-fat dressings. The HPH treatment (1500 bar, 3 passes) in alkaline medium improved the protein dispersibility (>50%). Emulsions were prepared using sunflower oil (12.0% or 25% w/w oil), xhantan/guar gums (0.5% w/w), modified starch (0–4.0% w/w), salt, sucrose, acidulants, EDTA, and antimicrobial agents. All emulsions (pH 3.97 ± 0.27; aw = 0.97 ± 0.01), whatever the starch content, behaved clearly as pseudoplastic fluids in steady flow measurements. Moreover, as the frequency sweep measurements were made they also exhibited a weak gel behavior. Although the presence of starch produced an increase of mean particle size (D3,2 values), the rheological parameters (consistency index, proportionality coefficient and coordination number) also increased, so that the starch contributes to reinforce the three-dimensional network formed by oil droplets, protein aggregates and other polysaccharides. Yeast dressings were stable to coalescence after 28 days of quiescent storage (7.0 ± 0.5 °C) and only the highest starch concentration at 25% w/w oil was sufficient to maintain the stability of network. 相似文献
16.
Starches were isolated and characterised from 10 potato cultivars grown under the same conditions (with a commercial starch for reference). The chemical composition revealed some differences amongst the starches with protein ranging from 0.30% to 0.34%, amylose 25.2% to 29.1% and phosphorus 52.6–66.2 mg 100 g−1. High performance size-exclusion chromatography (HPSEC) fractionation of isoamylase debranched amylopectin showed that the amylopectin molecules were less branched and consisted of more B1, but less A-chains, than cereal starches. Gelatinisation onset (To), peak (Tp) and conclusion (Tc) temperatures of the native potato starches ranged from 58.7 to 62.5 °C, 62.5 to 66.1 °C and 68.7 to 72.3 °C, respectively, whilst the gelatinisation enthalpies ranged from 15.1 to 18.4 J g−1. The gelatinisation temperatures of the starches increased in common with the amounts of short and intermediate sized amylopectin chains. The 13C magic angle spinning nuclear magnetic resonance (13C CP-MAS NMR) and wide angle X-ray diffraction (XRD) data (30.6% ± 0.22% crystallinity on average) showed little variance amongst the samples. Particle sizing results, however, revealed more variance (20.6–30.9 μm mean diameter). Overall, these data reveal the subtleties of cultivar specific variation against a background of constant environmental conditions. 相似文献
17.
A.T. Mata C. Proença A.R. Ferreira M.L.M. Serralheiro J.M.F. Nogueira M.E.M. Araújo 《Food chemistry》2007,103(3):778-786
In the present work, we report the results of a study aimed at evaluating the antiradical activity, the antioxidant activity and the acetylcholinesterase (E.C. 3.1.1.7.) inhibitory capacity of essential oils, ethanol and boiling water extracts from five aromatic herbs growing wild in Portugal and used in traditional food preparations: fennel (Foeniculum vulgare), mint (Mentha spicata), pennyroyal (Mentha pulegium), rosemary (Rosmarinus officinalis) and wild thyme (Thymus serpyllum). The water extracts of M. spicata and M. pulegium showed the highest radical-scavenging activity (DPPH test) values (IC50 = 5.7 ± 0.4 and 8.9 ± 0.2 μg ml−1 respectively). This activity was higher than that found with the standard antioxidant BHT. The ethanol extracts of M. spicata, T. serpyllum and F. vulgare showed the highest antioxidant activities measured by the β-carotene/linoleic acid assay, IC50 = 36.9 ± 0.1, 41.2 ± 0.1 and 68.7 ± 0.1 μg ml−1, respectively. The inhibition of AChE was higher in the essential oil fraction. The highest activity was found for R. officinalis with an IC50 = 69.8 ± 0.1 μg ml−1. 相似文献
18.
Yingming Pan Zhiren Zhu Zhili Huang Hengshan Wang Ying Liang Kai Wang Qian Lei Min Liang 《Food chemistry》2009
A novel red pigment (RP) was isolated from Osmanthus fragrans ’ seeds. The optimised experimental parameters of extraction obtained with a four-factor at three-level orthogonal array experimental design L9(34) were ethanol concentration, temperature, pH and extraction time as 90%, 78 °C, 2.5 and 40 min, respectively. A yield of 34.6 ± 2.2 g/100 g was obtained under optimised conditions. The red pigment directly from O. fragrans’ seeds can be dissolved in alkaline, acidic waters solutions and hydrophilic organic solvents in common use. The colour of a water solution of RP changed with pH. RP was stable to heat in the temperature range of 25–100 °C. Physical and chemical properties of RP revealed that the red pigment was also stable in the presence of Na2SO3, NaCl, amino acid, organic acid, sugar, starch or metal-ions (such as Ca2+, Cu2+, Fe3+, Zn2+, Al3+, Mg2+ and Na+), but was bleached by strong oxidants (KMnO4, K2Cr2O7 and NaOCl). Subsequently, free radical scavenging activities of RP were assessed using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals using a new resonance scattering spectral method. RP showed an excellent DPPH radical scavenging activity and was superior to butylated hydroxytoluene (BHT), and exhibited quite a strong concentration-dependent inhibition of hydroxyl radical at low concentrations compared with ascorbic acid and quercetin. When the concentration of RP was 0.03 μg/ml, the scavenging percentage of hydroxyl radical reached 92.3%. Salidroside was isolated as an active principle. 相似文献
19.
Vilbett Briones-Labarca Gabriela Venegas-Cubillos Susana Ortiz-Portilla Marcelo Chacana-Ojeda Hector Maureira 《Food chemistry》2011
The aim of this work was to study the effect of high hydrostatic pressure on the bioaccessibility of specific nutrients (antioxidant, minerals and starch) in apple and to establish processing conditions that maximise the health benefits. The apple was pressurised at 500 MPa during 2, 4, 8 and 10 min. The antioxidant activity, mineral and starch content and bioaccessibility of apple samples were significantly affected by the processing and digestion conditions. Therefore, these results indicated that in vitro digestion has a noticeable effect on the antioxidant concentration, IC50, with much lower values (a smaller IC50 value corresponds to a higher antioxidant activity) of apple samples compared with those untreated and non-digestion. Apple has the highest calcium content (30.33 ± 1.94 mg/100 g), iron (14.46 ± 3.49 mg/100 g) and zinc (6.22 ± 0.91 mg/100 g). High hydrostatic pressure increased the mineral contents availability by 2.11–303.00% for calcium, 4.63–10.93% for iron and 8.68–28.93% for zinc. The dialysability and solubility of calcium, iron and zinc with respect to the values for the untreated sample were reduced by this high pressure technique. Consumption of apple under high hydrostatic pressure may supply substantial antioxidants, mineral and starch, which may provide health promoting and disease preventing effects. 相似文献
20.
A modified indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method was developed using a highly sensitive and specific monoclonal antibody (McAb) to determine doxycycline (DC) residues in chicken tissues and egg. The McAb against DC was produced by hybridoma technique and a modified ic-ELISA was characterised in terms of sensitivity, specificity, precision and accuracy. At optimal experimental conditions, the standard curve was constructed at concentrations ranged from 0.01 to 100 ng/ml. The IC50 value was 1.32 ± 0.18 ng/ml. The limit of detection was 0.14 ± 0.02 ng/g. The recoveries of DC from spiked chicken liver, muscle, and egg at levels of 50–600 ng/g were 84.6–85.5%, 88.2–89.1%, and 84.4–89.3%, respectively. The coefficient variations (CVs) were 5.1–9.3%, 3.7–11.3%, and 4.7–9.8%, respectively. Linear regression analysis showed good correlation, with r2 values 0.9909 for chicken liver and 0.9916 for chicken muscle. 相似文献