共查询到20条相似文献,搜索用时 31 毫秒
1.
Ali Ganjloo Russly Abdul Rahman Jamilah Bakar Azizah Osman Mandana Bimakr 《Food and Bioprocess Technology》2012,5(6):2151-2159
Peleg’s equation was used to study the effect of process parameters on kinetics of mass transfer in terms of solids gain and water loss during osmotic dehydration using 30–50% (w/w) sucrose solution at 30, 40 and 50 °C. The experimental data were successfully fitted employing Peleg’s equation with the coefficient of determination (R 2) higher than 0.88, the root mean square error, and the mean relative percentage deviation modulus (E) of less than 0.003% and 6.40% for all treatments, respectively. In all cases, initial mass transfer rate parameter (K 1) decreased significantly (p < 0.05) as the solution concentration and solution temperature increased suggesting a corresponding increase in the initial mass transfer rate. Initial mass transfer rate followed an Arrhenius relationship which showed that solids gain had the highest temperature sensitivity (E a = 21.93–33.84 kJ mol−1) during osmotic dehydration. Equilibrium mass transfer parameter (K 2) decreased significantly (p < 0.05) as solution concentration increased demonstrating that the equilibrium solid and water contents increased with increase in solution concentration. The equilibrium solid and water contents were also estimated adequately using Peleg’s equation (R 2 > 0.78). The results of this work allow estimating the kinetics of mass transfer during osmotic dehydration in order to obtain products with determined solid and water contents. 相似文献
2.
Six racemic δ-lactone (C7–C12) flavors were successfully resolved in less than 14 min each by packed column super critical CO2 fluid chromatography (pSFC). Baseline resolution was achieved for δ-C7–δ-C10. Chiralcel OB column and modifier isopropanol were selected. The chromatographic conditions including column temperature,
column pressure, content of isopropanol in mobile phase and flow rate of mobile phase were optimized while their influences
on capacity factor (k), enantioselectivity factor (α) and resolution factor (R
s
) were discussed. The present work indicated that preparative resolution of the δ-lactone racemates by the pSFC method was
potential. 相似文献
3.
Javier I. Enrione Carlos Sáez Daniel López Olivier Skurtys Cristian Acevedo Fernando Osorio William MacNaughtan Sandra Hill 《Food and Bioprocess Technology》2012,5(6):2446-2453
Mechanical relaxation of glassy carbohydrates has been reported extensively in the literature; however, little work is available on protein-based systems. This study deals with the structural relaxation of salmon (Salmo salar) gelatin in the glassy state. Skin gelatin was obtained by an acid–alkaline extraction method. Molecular weight (M w) was determined by capillary viscometry. Films prepared by casting (7% w/v) were equilibrated to a moisture content of ~18.4% (db). The glass transition temperature (T g) and enthalpic relaxation were determined by differential scanning calorimetry (DSC). Mechanical properties were assessed using a texture analyzer at constant temperature and moisture content. DSC showed a T g ~34°C, and the selected storage temperature (T a ) was 29°C (T g − T a = 5°C). The films were aged for 0, 4, 8, 16, and 40 h. Viscometry produced values of M w ~90.2 kDa. The stress relaxation was modeled by the Kohlrausch–Wlliams–Watts (KWW) equation, reporting an increase in relaxation time (τ 0) as the ageing time increased (τ 0 ~6.41E + 03 s for 0 h; τ 0 ~9.01E + 05 s for 40 h). β parameter was smaller for the aged films, indicating a spread of relaxation times. The derivative of KWW equation (dφ/dt) indicated a more rapid relaxation in a fresh sample compared with aged films. DSC showed an excess in enthalpy (ΔH) on the aged samples due to the non-equilibrium state of the matrix. ΔH increased with ageing time with values of ΔH ~2.42 J/g for the films aged for 40 h. This work demonstrated molecular relaxation process of gelatin in the glassy state, which must be taken into account if this material is used as a structure forming matrix. 相似文献
4.
The distribution of 15 aroma constituents, including the (R)- and (S)-enantiomers of ethyl 2-methylbutanoate, in 30 commercially available and laboratory prepared apple juices was evaluated
by multivariate statistical methods. Principal component analysis and cluster analysis revealed ethyl 3-methylbutanoate, 3-methylbutyl
acetate and (R)-ethyl 2-methylbutanoate as key components for the differentiation of apple juices. In freshly pressed and some commercial
juices ethyl 3-methylbutanoate and 3-methylbutyl acetate were not present, and the (S):(R) ratio of ethyl 2-methylbutanoate was found to be >99 : 1%. Another group of commercial products was separated in which the
amounts of ethyl 3-methylbutanoate and 3-methylbutyl acetate exceeded 1 μg/l and 180 μg/l, respectively, and in which the
(S):(R) ratio of ethyl 2-methylbutanoate was <97 : 3%. The statistical data confirmed the high selectivity of apple fruit tissue
in biosynthesizing 2-methylbutyl and 2-methylbutanoate esters, and could also be used to extend the results of enantio-multidimensional
gas chromatography and other authenticity analyses.
Received: 20 April 1998 / Revised version: 23 June 1998 相似文献
5.
Mohd Hazim Mohd Yusop Shuhaimi Mustafa Yaakob B. Che Man Abdul Rahman Omar Nur Fadhilah Khairil Mokhtar 《Food Analytical Methods》2012,5(3):422-429
Pork identification in raw meat using real-time polymerase chain reaction (PCR) was developed. Total DNA from meat samples
were successfully extracted and found to be of high quality and produced clear PCR products. Porcine-specific molecular beacon
probe and primers that amplifies 119 bp of the cytochrome b gene fragment of swine (Sus scrofa domestica) was used. Analysis of data showed that the C
q (quantification cycle) from 10 ng/μl porcine DNA is (18.70 ± 0.12 to 19.08 ± 0.06). Meanwhile, the other samples exhibited
negative result, which confirmed the specificity of the primers. The method also showed that the limit of detection of pork
was 0.0001 ng. Based on the regression analysis of the standard curve, the 96% efficiency of real-time PCR was achieved with
high correlation coefficient (r
2 = 0.9989). Sensitivity of the assay in discriminating pork as low as 0.1% (w/w) pork in pork–beef mixtures was also obtained. Reproducibility of the assay was successfully validated by applying sample
and experimental replicates in every assay being conducted. Thus, this methodology could serve as a fast and sensitive method
for detection of pork for meat species verification. 相似文献
6.
The moisture sorption isotherms of grain and kernel of barnyard millet (Echinochloa frumentacea) were determined at 20, 30, 40, and 50 °C. A gravimetric static method was used under 0.112–0.964 water activity (a
w) range for the determination of sorption isotherms. The models were compared using the coefficient of determination (r
2), reduced chi-square (χ
2) values, and on the basis of residual plots. In grain, modified Chung–Pfost (r
2 > 0.99; χ
2 < 0.7) and modified Oswin (r
2 > 0.99; χ
2 < 0.55) models were found suitable for predicting the M
e
–a
w relationship for adsorption and desorption, respectively. Modified Henderson model was found to give the best fit (r
2 > 0.99 and χ
2 < 0.55) for describing the adsorption and desorption of the kernel. The isosteric heat, calculated using Clausius–Clapeyron
equation, was varied between 46.76 and 61.71 kJ g−1 mol−1 at moisture levels 7–21% (d.b.) for grain and 47.11–63.52 kJ g−1 mol−1 at moisture level between 4% and 20% (d.b.) for kernel. The monolayer moisture content values ranged from 4.3% to 6% d.b.
in the case of adsorption of barnyard millet grain and 5.2–6.6% d.b. in the case of desorption at the temperature ranges of
50–20 °C. The monolayer moisture values of barnyard millet kernel ranged from 4.4% to 6.67% d.b. in adsorption and 4.6% to
7.3% d.b. in desorption in the temperature ranges of 50–20 °C. 相似文献
7.
Péter Molnár József Deli Zoltán Matus G. Tóth Andrea Steck Hanspeter Pfander 《European Food Research and Technology》2000,211(6):396-399
(3S,5R,8R,3′R)- and (3S,5R,8S,3′R)-mutatoxanthin were isolated from red spice paprika (Capsicum annuum) and characterized by their UV-VIS, CD, 1H-NMR, 13C-NMR and mass spectra.
Received: 22 November 1999 / Revised version: 11 February 2000 相似文献
8.
Simultaneous Determination of Sodium, Potassium, Manganese and Bromine in Tea by Standard Addition Neutron Activation Analysis 总被引:1,自引:0,他引:1
Standard addition method was applied for neutron activation analysis of tea leaves. Four brands of tea leaves were analyzed
for its Na, K, Mn, and Br contents by this method. The Na, K, Mn, and Br concentrations were found to be in the 90–120 μg/g,
1.8–2.1% w/w, 150–500 and 3–7 μg/g ranges, respectively. The extraction efficiency of these elements, during the infusion, was calculated
by analysis of tea leaves before and after the infusion process. It was observed that about 90% of the Na, K, and Br elements
were extracted to water during the infusion process. The drinking tea is a rich source of Mn (despite of an extraction efficiency
of 50% for this element). 相似文献
9.
B. K. Tiwari C. P. O’ Donnell K. Muthukumarappan P. J. Cullen 《Food and Bioprocess Technology》2009,2(1):109-114
Freshly squeezed orange juice samples were sonicated at a constant frequency of 20 kHz for a range of processing temperatures
(10–30 °C), amplitude levels (40–100%) and time (2–10 min) with pulse durations of 5 s on and 5 s off. Hunter colour values
(L*, a* and b*), pH, oBrix, titratable acidity, cloud, non-enzymatic browning and ascorbic acid content were measured. Response surface methodology
(RSM) based upon a three-factor, three-level Box–Behnken experimental design was used to determine the effect of independent
variables. Under process conditions used in this study, no significant difference (p < 0.05) in pH, oBrix or titratable acidity was observed. Model predictions developed for Hunter colour values, cloud value, non-enzymatic
browning and ascorbic acid content were closely correlated (R
2 > 0.92) to experimental data. Box–Behnken design and RSM was demonstrated to be an effective technique to model the effect
of sonication on juice quality while minimising the number of experiments required. 相似文献
10.
Changes on Dough Rheological Characteristics and Bread Quality as a Result of the Addition of Germinated and Non-Germinated Soybean Flour 总被引:1,自引:0,他引:1
Maribel Rosales-Juárez Beatriz González-Mendoza Emigdio C. López-Guel Flora Lozano-Bautista Jorge Chanona-Pérez Gustavo Gutiérrez-López Reynold Farrera-Rebollo Georgina Calderón-Domínguez 《Food and Bioprocess Technology》2008,1(2):152-160
The increasing interest in functional and healthy food products has promoted the use of germinated soybean flour in the manufacture
of foods for human consumption. Considering the beneficial effects of soy and its germination, farinograph and extensograph
were used to study the effect of adding defatted flour of germinated (32 °C, 72 h) or non-germinated soybean—at different
dry protein ratios (0, 0.5, 1.0, 1.5%)—to wheat flour on: water absorption (WA), maximum consistency time (MCT), dough stability
(S), maximum resistance to extension (R
max), and dough extensibility (L). Baking tests (straight-dough procedure) were also performed to evaluate the effect of this addition on bread characteristics:
loaf volume, texture (firmness, compression force, resilience), color (L*, a*, b*), crumb–grain structure (cell density, mean cell area, shape factor), and consumer acceptance (sensory analysis). Addition
of both kinds of soybean flours increased the values of farinographic parameters (WA, MCT, S), although they did not have
significant effects (p > 0.05) on extensographic properties (R
max, L). Loaf volume and crumb color were improved as soy flour addition was increased, whereas crust color was not affected (p > 0.05). Texture analysis showed that the addition of soy flour produced breads similar or better than the control, whereas
the addition of GSF produced a coarser crumb grain. No detectable differences were found among samples during the sensorial
analysis. Germinated soybean flour was better to improve dough breadmaking properties. 相似文献
11.
Terenzio Bertuzzi Silvia Rastelli Annalisa Mulazzi Amedeo Pietri 《Food Analytical Methods》2012,5(3):512-519
The extraction procedure for aflatoxin determination in maize is based on a methanol–water (8 + 2 v/v) or an acetone–water (85 + 15 v/v) mixture. Initially, the extraction efficiency of two solvents was evaluated for each aflatoxin. Different results were obtained
for highly contaminated maize: significantly higher levels of aflatoxin B1 were obtained by acetone–water, on the contrary higher levels of aflatoxin G2 were achieved by methanol–water. Then, acetone–water mixtures in different proportions (7 + 3, 6 + 4 and 5 + 5 v/v) were tested to improve the extraction of aflatoxin G2. Applying these extraction mixtures, the values both of aflatoxin B1 and of other aflatoxins were generally higher compared to those obtained by acetone–water 85 + 15; moreover, acetone–water
(6 + 4) and (7 + 3) showed the best extraction efficiency for all aflatoxins. 相似文献
12.
Emma S. Sánchez Susana Simal Antoni Femenia José Benedito C. Rosselló 《European Food Research and Technology》1999,209(3-4):215-219
The effect of ultrasound on mass transfer during cheese brining has been investigated. The rate of water removal and NaCl
gain increased when ultrasound was applied in comparison with brining performed under static or dynamic conditions, suggesting
that ultrasound improves both external and internal mass transfer. A simple diffusional model was developed to simulate mass
transport during acoustic brining. Model parameters were estimated using experimental data from acoustic brining experiments
carried out on cheese cylinders of 1.7×10–2 m radius and 3×10–2 m height at different temperatures (5, 15 and 20 °C). Effective water (D
W) and NaCl (D
S) diffusivities estimated using the proposed model ranged from 5.0×10–10 m2/s and 8.0×10–10 m2/s at 5 °C to 1.3×10–9 m2/s and 1.2×10–9 m2/s at 20 °C. Both D
W and D
S varied with temperature according to the Arrhenius equation. Through the proposed model, water losses and NaCl gains of the
experiments used in the parameter identification were accurately simulated (average %var=98.2%) and also of two additional
acoustic experiments carried out under different conditions of temperature (10 °C) and sample size and geometry [parallelepiped
of (6×2.5×1.25)×10–2 m] to those used in the parameter identification (average %var=98.4%).
Received: 22 September 1998 / Revised version: 20 November 1998 相似文献
13.
Kar Lin Nyam Chin Ping Tan Oi Ming Lai Kamariah Long Yaakob B. Che Man 《Food and Bioprocess Technology》2011,4(8):1432-1441
Supercritical carbon dioxide (SC-CO2) extraction of oil from Kalahari melon seeds was investigated in this study. Response surface methodology was applied to
model and optimize the extraction, namely pressure (200–400 bar), temperature (40–80 °C), and supercritical fluid flow rate
(10–20 mL/min). Well-fitting models were successfully established for oil recovery (R
2 = 0.9672) and phytosterol concentration (milligrams per 100 g; R
2 = 0.8150) through multiple linear regressions with backward elimination. The effect of supercritical fluid flow rate was
the most significant (P < 0.05) factor that affected oil recovery but this factor had no significant (P > 0.05) effect on phytosterol concentration. The optimal processing conditions for oil recovery and phytosterol concentration
were pressure of 300 bar, temperature at 40 °C, and supercritical fluid flow rate of 12 mL/min. These optimal conditions yielded
a 76.3% oil recovery and 836.5 mg/100 g of phytosterol concentration. The oil content in the Kalahari melon seeds as estimated
by Soxhlet extraction was around 30.5/100 g. The phytosterol concentration in the oil extracted with SC-CO2 extraction was 94% higher than that obtained with solvent extraction. 相似文献
14.
G. Buchbauer J. H?finghoff E. M. Hoffmann 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1999,45(7):305-307
The structure-flavour relationships of some Schiff bases are discussed. The carbonyl part – (S)-(+)-/(R)-(–)-carvone – showed a greater impact on the aroma of the imine than the amine part. The different aromas of the two enantiomeric Schiff bases could clearly be distinguished. No flavours similar to Maillard products were detected in aromatic or heteroaromatic compounds with a structurally related imine unit. Some new and interesting aroma notes were discerned. 相似文献
15.
Qing Kong Feng Chen Xi Wang Jing Li Bin Guan Xingqiu Lou 《Food and Bioprocess Technology》2011,4(7):1205-1211
Enzymatic condition for producing angiotensin I-converting enzyme (ACE) inhibitory peptides from collagen was optimized with
the aid of response surface methodology, which also derived a statistical model for experimental validation. The results showed
that the optimal condition for the hydrolysis by pepsin was at pH 2, temperature 37 °C, and in enzyme to substrate ratio (E/S) of 2 when 8.23% collagen (w/v) and 3.82 h of hydrolysis time were applied. Through the single-enzyme hydrolysis, the ACE inhibitory activity could reach
an average of 78.06%. In contrast, when a combination of pepsin and trypsin was used for a multiple-proteases hydrolysis,
the ACE inhibitory activity could be significantly improved to an average of 88.25%. Furthermore, the IC50 (μg/mL) value of the enzyme combination by pepsin and trypsin (141.64 ± 22.11) was significantly lower than that of the combinations
of pepsin and papain (438.59 ± 84.37) or pepsin and protease M (336.76 ± 87.88; p<0.05). Our results have shown that collagen can be used for enzyme-mediated production of ACE inhibitory peptides. 相似文献
16.
Ali Ganjloo Russly Abdul Rahman Azizah Osman Jamilah Bakar Mandana Bimakr 《Food and Bioprocess Technology》2011,4(8):1442-1449
Thermal treatment of seedless guava (Psidium guajava L.) cubes was carried out in the temperature range of 80–95 °C. The kinetics of peroxidase inactivation and color changes
due to thermal treatments were determined. Peroxidase inactivation followed a first-order kinetic model, where the activation
energy was 96.39 ± 4 kJ mol−1. Color was quantified in terms of L, a, and b values in the Hunter system. The color changes during processing were described by a first-order kinetic model, except total
color difference which followed a zero-order kinetic model. The temperature dependence of the degradation followed the Arrhenius
relation. The activation energies (E
a) for L, a, b, and total color difference (ΔE) were 122.68 ± 3, 88.47 ± 5, 104.86 ± 5, and 112.65 ± 5 kJ mol−1, respectively. The results of this work are a good tool to further optimize seedless guava thermal treatment conditions. 相似文献
17.
Coriander leaves are widely used in cooking throughout the world. Thermal degradation kinetics of chlorophyll a, b, and total
chlorophyll in coriander leaf puree was investigated at varying levels of pH (4.5–8.5) and processing temperature (80–145°C).
Coriander puree at pH 4.5 was processed at 80° to 100°C, whereas that at pH 5.5 to 8.5 was processed at 105° to 145°C. Chlorophyll
degradation followed first-order reaction kinetics. Good agreement was found between estimated and experimental chlorophyll
retention in all cases (R
2 > 0.80). Activation energies ranged from 6.57 to 96.00 kJ/mol. Reaction rate and activation energy data indicated that chlorophylls
were more stable at alkaline pH. Transition state theory was applied to estimate the enthalpy, entropy, and Gibbs free energy
of activation. Enthalpy of activation (ΔH
#) ranged from 3.46 to 91.99 kJ/mol, whereas entropy of activation (ΔS#) ranged from −0.265 to −0.047 kJ/(mol K). The overall free energy change was 107.55 kJ/mol. Results indicated that, the compensation
effect did not exist for chlorophyll degradation in coriander puree during thermal processing. 相似文献
18.
Fengjie Cui Caixia Wan Yebo Li Zhe Liu Gireesh Rajashekara 《Food and Bioprocess Technology》2012,5(4):1278-1286
Lactic acid and cell production from whey permeate by Lactobacillus rhamnosus with different nutrient supplements were investigated in this study. Yeast extract was identified as the most effective nutrient
affecting lactic acid production. Increase in inoculum size from 0.05% to 1% (v/v) resulted in a substantial increase in lactic acid productivity from 0.66 to 0.83 g L−1 h−1 (P < 0.001). The optimal temperature for lactic acid production was 37 °C, while the highest cell production was obtained at
42 °C. When whey permeate and yeast extract concentrations were 6.8% (w/v) and 3 g L−1, respectively, lactic acid productivity reached 0.85 g L−1 h−1 after 48-h cultivation, which is 3.40 times of those without nutrient supplements. 相似文献
19.
Caglar Ozdemir Ozlet Akca E. Ilker Medine Dilek Odaci Demirkol Perihan Unak Suna Timur 《Food Analytical Methods》2012,5(4):731-736
Fe3O4 magnetic nanoparticles (MNPs) were synthesized and silanized to form a core–shell (Fe3O4–SiO2) structure. Afterwards, surface modification with amino silane was carried out to produce amino groups on the MNPs for the
biomolecule immobilization. In order to test the performance of amino functional MNPs as immobilization platform in biosensing
applications, glucose oxidase was immobilized on the surface via glutaraldehyde. Obtained Bio-MNPs were then fixed onto the
carbon paste electrode by the aid of magnetic force and used as the working electrode during the amperometric measurements
at −0.7 V versus Ag/AgCl. After optimization of some parameters affecting the biosensor performance, analytical characterization
was carried out. Linearity was found in the range of 0.25–2.0 mM glucose and defined by the equation of y = 8.366x + 1.819, (R
2 = 0.996). Proposed biosensor was then applied for the glucose analysis in various beverages. Finally, data were compared
with a commercial enzyme assay kit based on spectrophotometric Trinder reaction as a reference method. 相似文献
20.
M. Xie A. von Bohlen R. Klockenk?mper X. Jian K. Günther 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1998,207(1):31-38
Total-reflection X–ray fluorescence (TXRF) was used for the simultaneous determination of 15 elements in tea samples which
were produced either by acid digestion or acidified infusion of tea leaves (Camellia sinensis). The accuracy and precision of the method were checked by its application to a certified reference material (GBW 08505 : tea).
A variety of 39 tea samples of different kinds and/or qualities produced in different regions of China were analysed. The
range and mean of the concentrations of elements in the tea leaves (0.1–30.000 μg g–1) and their solubility in infusions (0.5–85%) were determined and the influence of the origin, type and quality of the tea
samples was studied. In some tea leaves produced in a Se-rich region, the content of Se was found to be very high (up to 7.5 μg g–1), in contrast to a concentration of only about 0.1 μg g–1 Se in most of the tea leaves examined.
Received: 27 January 1998 相似文献