共查询到20条相似文献,搜索用时 406 毫秒
1.
Ahmet Yemenicioğlu Mehmet Özkan Sedat Velioğlu B. Cemeroğlu 《European Food Research and Technology》1998,206(4):294-296
Thermal inactivation kinetics of crude peroxidase (POX) and lipoxygenase (LOX) in fresh pinto beans were studied over the
temperature range of 55–90°C. The inactivation of both enzymes followed first-order kinetics. The biphasic inactivation curves
for POX indicate the existence of several isoenzymes of varying heat stability. In the temperature range of 55–70°C, the activation
energies (E
a) of POX were 46.5 kcal·mol–1 for the heat-labile portion and 37.6 kcal·mol–1 for the heat-stable portion. On the other hand, the LOX enzyme had an E
a value of 42.26 kcal·mol–1 at 55–75°C and 49.1 kcal·mol–1 at 55–90°C.
Received: 28 July 1997 / Revised version: 16 October 1997 相似文献
2.
M. José Esteve A. Frígola L. Martorell Carmen Rodrigo 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1999,208(2):144-147
Thermal degradation of green asparagus ascorbic acid in high-temperature short-time conditions was studied by heating in
a five-channel computer-controlled thermoresistometer. Ascorbic acid was heated to between 110 °C and 140 °C and the degradation
kinetics were analyzed assuming that two different inactivation mechanisms were occurring, one aerobic and the other anaerobic.
The two reactions followed first-order kinetics, with E
a=12.3(2.0) kcal/mol and k
125 °C=47.0(3.0)×10–3 s–1 for the aerobic oxidation, and E
a=6.1(1.4) kcal/mol and k
125 °C=4.1(0.2)×10–3 s–1 for the anaerobic degradation.
Received: 30 January 1998 / Revised version: 11 June 1998 相似文献
3.
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
4.
Thermal inactivation of quality-related enzymes in both cauliflower crude enzyme extracts and fresh tissue samples was studied
in temperature range 50–100 °C. For crude enzyme extracts, several parameters, reaction rate constants (k) and activation energy (E
a) as well as decimal reduction time (D) and (z) values, were used to characterize the thermal stability. The rates of inactivation were found to follow first-order inactivation
kinetics. Activation energies varied between 101.18 and 208.42 kJ mol−1 with z values of 10.59–24.09 °C. The examined kinetics indicated that lipoxygenase was the most heat resistant followed by peroxidase,
polyphenol oxidase, pectin methyl esterase and ascorbic acid oxidase. Furthermore, the obtained results from the blanched
fresh tissues indicated that inactivation of lipoxygenase secured disappearing of any other enzyme activities. Therefore,
this study recommends using lipoxygenase as an indicator enzyme to optimize the thermal treatments of cauliflower products. 相似文献
5.
Polyphenol oxidase inactivation and vitamin C degradation kinetics of Fuji apple quarters by high humidity air impingement blanching 总被引:1,自引:0,他引:1
Jun‐Wen Bai Zhen‐Jiang Gao Hong‐Wei Xiao Xiao‐Tuo Wang Qian Zhang 《International Journal of Food Science & Technology》2013,48(6):1135-1141
In this study, polyphenol oxidase (PPO) and vitamin C were used as the indicators of enzymes and nutrients to evaluate the apple quality during high humidity air impingement blanching (HHAIB) process. The PPO can be completely inactivated within 7 min at 90–120 °C and can retain relatively more vitamin C in the case of PPO fully inactivation. PPO inactivation followed zero‐order kinetics model at 90 and 100 °C, and followed first‐order fraction model at 110 and 120 °C. Activation energy (Ea) of PPO inactivation was between 11.61 and 13.66 kJ mol?1 by Arrhenius equation. Vitamin C degradation under all processing temperatures was well described by first‐order model and its Ea value was 26.69 kJ mol?1. Therefore, the HHAIB process was proved to be an effective pretreatment for Fuji apple quarters to inactivate PPO fast and meanwhile to maintain produce quality. 相似文献
6.
Dolores Rodrigo Ruben Jolie Ann Van Loey Marc Hendrickx 《European Food Research and Technology》2006,222(5-6):636-642
The combined isothermal (10–60 °C) and isobaric (0.1–650 MPa) inactivation kinetics of lipoxygenase (LOX) extracted from tomatoes
and reconstituted in a tomato purée were studied. Thermal inactivation of LOX at atmospheric pressure proceeded in the temperature
range of 45–65 °C. LOX inactivation did not follow first order kinetics; the data could be fitted assuming that the two isoforms
of LOX with different thermostability were present. Combined thermal and high pressure inactivation occurs at pressures in
the range of 100–650 MPa combined with temperatures from 10–60 °C, and followed first-order kinetics. In the high-temperature/low-pressure
range, (T≥50 °C and P≤300 MPa) an antagonistic effect is observed, therefore, the Arrhenius and Eyring equation cannot be used over the entire
temperature and pressure range. Small temperature dependence is found in the low-temperature/high pressure range. A third
degree polynomial model was successfully applied to describe the temperature–pressure dependence of the inactivation rate
constants, which can be useful to predict inactivation rate constants of tomato LOX reconstituted in tomato purée in the temperature–pressure
range studied. 相似文献
7.
Wilfrido Torres‐Arreola Josafat Marina Ezquerra‐Brauer Ramón Pacheco‐Aguilar Elisa M. Valenzuela‐Soto Ofelia Rouzaud‐Sandez Maria E. Lugo‐Sanchez Gisela Carvallo‐Ruiz 《International Journal of Food Science & Technology》2012,47(5):947-953
Lysyl oxidase (LOX; E.C.1.4.3.13) was purified from jumbo squid muscle (Dosidicus gigas) with 1900‐fold and yield 1.9%, and characterized for the first time. The purification procedure consisted of fractionation with urea and a combination of size‐exclusion and anion‐exchange chromatography. The enzyme had a molecular weight of 32 kDa, as estimated by SDS‐PAGE. Using a specific LOX substrate (1,5‐diaminopentane), its optimum activity was determined at pH 8.2 and 65 °C. Activation energy (Ea) of the enzyme was 69.94 kJ K?1 mol?1. The enzyme was strongly inhibited by β‐aminopropionitrile fumarate (BAPN), a specific LOX inhibitor. Moreover, purified LOX was able to work at different temperatures (20–90 °C) at pH 8.2. Although further research is needed, the results from this work suggest that based on LOX activity, this enzyme may be of practical use in preventing textural changes in jumbo squid during storage or processing. 相似文献
8.
In order to better understand inactivation of cells during a drying process, the inactivation kinetics of concentrated Lactobacillus paracasei ssp. paracasei (F19) was measured under stationary conditions for different combinations of water activities and temperatures in a water activity range of a w = 0.23–a w = 0.75 and temperatures between 4°C and 50°C. It was shown that the inactivation kinetics of the probiotic bacterium L. paracasei at moderate temperatures could, for all conditions, be formally described by a first-order reaction with activation energies that are much lower than for thermal inactivation (E a = 61 kJ/mol). With regard to the water activity, the reaction rate constants exhibit a maximum inactivation rate at intermediate water activity a w = 0.52. As this behavior has direct implications for the stability of cells in a drying process, the stationary data were used to model the inactivation during test vacuum drying processes, where both temperature and water activity dynamically change. It is shown that—depending on the drying rate—dynamic effects have to be taken into account when modeling the survival during drying. Nevertheless, the model based on stationary inactivation data is capable to predict the characteristics of inactivation during a drying process. Therefore, it can serve as basis to optimize the drying process with regard to maximum survival of cells. However, a further refinement of the model with regard to the drying rate is necessary. 相似文献
9.
In this research, rheological properties of blends of pine honey (3%, 6%, and 9%) with sesame pastes (tahin) produced from
hulled roasted sesame seeds, called simply tahin, and from unhulled roasted sesame seeds, so-called Bozkir tahin, were determined
at temperatures ranging from 10°C to 60°C and at speeds ranging from 0.5 to 100 rpm. Tahin and Bozkir tahin blends with pine
honey were found to exhibit non-Newtonian, pseudoplastic behavior at all temperatures. Apparent viscosities versus speed data
were successfully fitted to the power law model. The flow behavior index, n, varied in the range of 0.4226–0.6228 for the tahin–pine honey blends, and in the range of 0.4661 to −0.7266 for the Bozkir
tahin–pine honey blends. The consistency index, K, was in the range of 9.34–36.42 Pa·sn for tahin–honey blends, and in the range of 9.92–37.53 Pa·sn for Bozkir tahin–honey blends. The consistency index (K) increased with increasing honey levels in both tahin types. According
to statistical analysis, the exponential model was a better model to describe the effect of the soluble solids on the viscosity
of tahin samples represented by the pine honey percentage. The emulsion stability of both tahin types improved with the addition
of pine honey. It was also correlated with activation energy (E
a), Arrhenius constant, some sensory properties such as spreadibility, firmness and overall acceptance, and color parameters
such as the C and h. Temperature sensitivity of the consistency index was assessed by applying an Arrhenius type equation, and E
a value appeared in the range of 7.61–10.05 kJ/mol for tahin–honey blends and in the range of 9.02–10.50 kJ/mol for Bozkir
tahin–honey blends. 相似文献
10.
Ferrylmyoglobin [MbFe(IV)=O], formed by activation of metmyoglobin by hydrogen peroxide, inactivates the cysteine proteinases
papain (EC 3.4.22.2) and ficin (EC 3.4.22.3) more efficiently than hydrogen peroxide, but less efficiently than hydroxyl radicals
as generated by peroxynitrite or the Fenton reaction. Metmyoglobin and oxymyoglobin could not inactivate papain and ficin.
Oxidation of papain and ficin by ferrylmyoglobin occurs in enzyme/haem-protein complexes with binding constants of approximately
105 l · mol–1; inactivation of proteolysis by papain plateaus at neutral pH to about 1/3 whereas the inactivation under acidic conditions was larger.
Received: 11 July 1997 / Revised version: 16 September 1997 相似文献
11.
Anni Mikkelsen L. H. Skibsted 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1998,206(3):199-202
Ferrylmyoglobin [MbFe(IV)=O], formed by activation of metmyoglobin by hydrogen peroxide, inactivates the cysteine proteinases
papain (EC 3.4.22.2) and ficin (EC 3.4.22.3) more efficiently than hydrogen peroxide, but less efficiently than hydroxyl radicals
as generated by peroxynitrite or the Fenton reaction. Metmyoglobin and oxymyoglobin could not inactivate papain and ficin.
Oxidation of papain and ficin by ferrylmyoglobin occurs in enzyme/haem-protein complexes with binding constants of approximately
105 l · mol–1; inactivation of proteolysis by papain plateaus at neutral pH to about 1/3 whereas the inactivation under acidic conditions was larger.
Received: 11 July 1997 / Revised version: 16 September 1997 相似文献
12.
Gabriela G. Gastélum Raúl Avila-Sosa Aurelio López-Malo Enrique Palou 《Food and Bioprocess Technology》2012,5(2):665-671
Hurdle technology combining an emerging preservation technique such as low-frequency ultrasound is an alternative for processing
juices that are susceptible to suffer a loss of quality due to traditional heat treatments. Predictive microbiology allows
evaluation of the effectiveness of preservation techniques and its combinations in order to enhance both food quality and
safety. Listeria innocua inactivation by thermo-sonication along with vanillin was investigated. Fermi model (R
2
adj= 0.970 ± 0.02) and surface response methodology (p < 0.05) were utilized in order to evaluate the survival of L. innocua to a multi-target treatment and to predict the interactions of studied techniques, high-intensity/low-frequency ultrasound
(20 kHz/400 W) at selected wave amplitudes (60, 75, or 90 μm), temperature (40, 50, or 60 °C), and vanillin (200, 350, or
500 mg/kg). A combination of ultrasound, vanillin, and temperature enhanced L. innocua inactivation as described by Fermi parameters a and t
c, which decreased as the studied effects increased. A multi-target inactivation effect was observed for a temperature range
of 45–55 °C. 相似文献
13.
Lone Bruun-Jensen Laurette Sosniecki L. H. Skibsted 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1998,206(6):374-377
Acid-catalyzed autoreduction of ferrylmyoglobin [MbFe(IV)=O] decreased with increasing hydrostatic pressure corresponding
to a volume of activation of ΔV
# = +7.2±0.8 ml mol–1, as determined for pressures of up to 250 MPa at 15°C in acidic 0.16 M NaCl solution. For the non-catalyzed autoreduction,
a significant increase in compressibility for the non-protonated heme pigment, corresponding to a compressibility coefficient
of activation of Δκ# = +(4.0±1.1)×10–8 ml mol–1 Pa–1, moderates the effects of pressure, although the volume of activation determined at 30°C was comparable, i. e. ΔV
# = +7.5±2.0 mol mol–1. At pH relevant for meat, the effect of pressure on the transformation of ferrylmyoglobin to metmyoglobin [MbFe(III)] was
approximately half that of the same pressure on the transformation of oxymyoglobin to metmyoglobin, when compared on a logarithmic
basis. This result finds a surprising parallel in the temperature-dependence of the same acid-catalyzed processes to yield
metmyoglobin.
Received: 1 December 1997 相似文献
14.
H. MICHAEL HENDERSON GREGORY BLANK HELENA SUSTACKOVA 《Journal of Food Biochemistry》1991,15(2):107-115
Lipoxygenase (LOX) was determined in pea flour (9.6% moisture) samples which had been exposed to 90–130°C for 5–45 min, and in crude aqueous extracts (5%; pH 6.7) of previously unheated pea flour which had been exposed to 40–80°C for 5–30 min. The rate of thermal inactivation of pea LOX was shown to follow first-order reaction kinetics. The rate constants, k(min?1), ranged from 0.005 to 0.252 for the flour, and from 0.068 to 0.267 (60–80°C) for the crude extract. The respective thermodynamic values were: for the energy of activation (Ea), 126.2 and 64.6 kJmole?1; for the enthalpy of activation (ΔH?), 123.1 and 61.8 kJmole?1; for the free energy of activation (Δ?), 118.0 and 101.4 kJmole?1. The greater thermostability of LOX in the pea flour under dry-heat conditions, and the observed differences in the Ea, ΔH? and ΔS? values, may be accounted for by its possible complexation with other macromolecules and by the structure of the water surrounding the native enzyme. 相似文献
15.
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
16.
Sulphited dried apricots were exposed to hot air flows at 40, 50 and 60 °C and the removal of SO2 was investigated as their moisture content fell from an initial value of 193.2 g kg?1 to a final value of 80–90 g kg?1. A first‐order kinetic model was found for the removal of SO2 between 40 and 60 °C. Temperature quotients (Q10) for the removal of SO2 were 2.84 between 40 and 50 °C and 4.93 between 50 and 60 °C; the activation energy (Ea) was 114.40 kJ mol?1 between 40 and 60 °C. Analysis of the kinetic data also suggested a first‐order reaction for non‐enzymatic browning, with Q10 values of 2.34 between 40 and 50 °C and 5.36 between 50 and 60 °C and an Ea value of 109.36 kJ mol?1 between 40 and 60 °C. Exposure of dried apricots to a 60 °C air flow resulted in a rate constant for brown pigment formation that was 12 and 5 times higher than those at 40 and 50 °C respectively. © 2002 Society of Chemical Industry 相似文献
17.
Thermal characteristics of cell-wall-bound pectin methylesterase (PME) from cucumbers were determined. Heat inactivation of PME followed first-order reaction kinetics. Biphasic inactivation curves indicated the presence of heat-labile and heat-stable fractions. Inactivation of PME accelerated above 65??°C. The z values between 70??°C and 80??°C were 7.6??°C and 9.0??°C for heat-stable fractions of ionically (IPME) and tightly cell wall bound PME (TPME), respectively. Temperature optima for the initial activities of IPME and TPME were 65??°C and 60??°C, respectively. However, for longer periods of activity determination, both IPME and TPME showed a temperature optimum at 50??°C. The E a values for initial activities were 5?kcal mol–1 (20–65??°C) and 7.2?kcal mol–1 (20–60??°C) for IPME and TPME, respectively. 相似文献
18.
Mustafa Ümit Ünal Aysun ener & Kemal en 《International Journal of Food Science & Technology》2007,42(9):1123-1127
Polyphenol oxidase (PPO) was extracted from Sultaniye grapes grown in Turkey, and its characteristics in terms of pH and temperature optima, thermal inactivation, kinetic parameters and potency of some PPO inhibitors were studied. Optimum pH and temperature for grape PPO were found to be 3.4 and 30 °C, using catechol as substrate. Km and Vmax values were found to be 44.5 ± 5.47 mm and 0.695 ± 0.0353 OD410 min?1, respectively. Four inhibitors were tested in this study and the most potent inhibitor was sodium metabisulphite, followed by ascorbic acid. From the thermal inactivation studies in the range of 65–80 °C, the half‐life values of the enzyme ranged between 2.6 and 49.5 min. Activation energy (Ea) and Z values were calculated to be 208.5 kJ mol?1 (r2 = 0.9544) and 10.95 °C (r2 = 0.9517), respectively. 相似文献
19.
Polyphenol oxidase (PPO) was extracted from Emir grapes grown in Turkey and its characteristics in terms of pH and temperature optima, thermal inactivation, kinetic parameters and potency of some PPO inhibitors were studied. The optimum pH and temperature for grape PPO were found to be 4.2 and 25 °C respectively using catechol as substrate. Km and Vmax values were found to be 25.1 ± 2.72 mmol L−1 and 0.925 ± 0.04 OD410 min−1 respectively. Of the inhibitors tested, the most potent was sodium metabisulfite, followed by ascorbic acid. The thermal inactivation curve was biphasic. Activation energy (Ea) and Z values were calculated as 251.4 kJ mol−1 (r2 = 0.996) and 8.92 °C (r2 = 0.993) respectively. Copyright © 2006 Society of Chemical Industry 相似文献
20.
Degradation of sorbic acid in aqueous glycerol solutions at pH 4·0 over the aw range 0·71–1·00 and the temperature range 40°–60°C was found to follow first-order reaction kinetics and to conform to the Arrhenius equation. Activation energy values obtained were 5·8 kcal mol?1 and 7·8 kcal mol?1 for systems at 0·80 aw with and without added Co++, respectively. The rate of sorbic acid degradation was observed to increase with decreasing aw (i.e. increasing glycerol concentration). The presence of added Co++ decreased the rate of sorbic acid breakdown at any particular aw or temperature. Browning of sorbate solutions during storage was markedly inhibited by Co++. 相似文献