Effect of storage temperature on the microbial and color stability of banana purée with addition of vanillin or potassium sorbate / Efecto de la temperatura de almacenamiento en la estabilidad microbiológica y en el color del puré de plátano con la adición de vainillina o sorbato de potasio

1999 ◽  
Vol 5 (1) ◽  
pp. 51-58 ◽  
Author(s):  
X. Castañón ◽  
A. Argaiz ◽  
A. López-Malo
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Microbial Growth ◽  
Storage Temperature ◽  
Color Stability ◽  
The Other ◽  
Potassium Sorbate ◽  
Native Flora ◽  
Color Changes ◽  
Different Temperatures

The microbial and color changes during storage at different temperatures (15, 25 and 35 °C) of ba nana purée preserved by the combination of a blanching, reduced pH (3.4) and water activity ( aw, 0.97) and the addition of 1000 or 3000 ppm of vanillin (VA) or 1000 ppm potassium sorbate (PS) were evaluated and compared. The use of 3000 ppm VA or 1000 ppm PS inhibited for at least 60 days of storage the native flora of the banana purée at any of the temperatures studied. The addition of 1000 ppm VA was not enough to stop the microbial growth. However, at 15 °C the growth was delayed 16 days. In the presence of 3000 ppm VA or 1000 ppm PS the banana purée stored at 15, 25 and 35 °C presented several color changes that contributed to browning. The rate of browning was greater in samples with VA than in those formulated with PS, but the activation energy was 10% lower in the former systems. An analysis of the transition state parameters revealed that Gibbs free energy was similar, indicating that the mechanism of browning did not change in the presence of one antimicro bial or the other.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

scholarly journals Enzymatic Kinetic Issues and Controversies Surrounding Gibbs Free Energy of Activation and Arrhenius Activation Energy

2020 ◽  
pp. 1-13
Author(s):  
Ikechukwu I. Udema ◽  
Abraham Olalere Onigbinde
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Theoretical Research ◽  
Energy Of Activation ◽  
Arrhenius Activation Energy ◽  
Free Energy Of Activation ◽  
Different Temperatures ◽  
The Difference

Background: The equation of the difference between reverse and forward Gibbs free energy of activation (ΔΔGES#) reflects Michaelis-Menten constant (KM) in both directions; this may not be applicable to all enzymes even if the reverse reaction is speculatively Michaelian. Arrhenius activation energy, Ea and (Ea - ΔGES#)/RT) are considered = ΔGES# and KM respectively. The equations are considered unlikely. Objectives: The objectives of this research are: 1) To derive what is considered as an appropriate equation for the determination of the difference in ΔGES# between the reverse and forward directions, 2) calculate the difference between the reverse and total forward ΔGES#, and 3) show reasons why Ea ≠ ΔGES#  in all cases. Methods: A major theoretical research and experimentation using Bernfeld method. Results and Discussion: A dimensionless equilibrium constant KES is given. Expectedly, the rate constants were higher at higher temperatures and the free energy of activation with salt was < the Arrhenius activation energy, Ea; ΔΔGES#ranges between 67 - 68 kJ/mol. Conclusion: The equations for the calculation of the difference in free energy of activation (ΔΔGES#) between the forward and reverse directions and a dimensionless equilibrium constant for the formation of enzyme-substrate (ES) were derivable. The large positive value of the ΔΔGES# shows that the forward reaction is not substantially spontaneous; this is due perhaps, to the nature of substrate. The equality of Arrhenius activation energy (Ea) and ΔGES# may not be ruled out completely but it must not always be the case; the presence of additive like salt can increase the magnitude of Ea well above the values of the ΔGES#. A dimensionless equilibrium constant for the net yield of ES seems to be a better alternative than KM. The Ea unlike ΔGES#  requires at least two different temperatures for its calculation.

scholarly journals Some Thermodynamic Properties of White Yam (Dioscorea rotundata) Slices Dehydrated in a Refractance WindowTM Dryer

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Akinjide A Akinola ◽  
Stanley N Ezeorah
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Moisture Content ◽  
Gibbs Free Energy ◽  
Moisture Diffusivity ◽  
Process Conditions ◽  
Dioscorea Rotundata ◽  
History Data ◽  
White Yam ◽  
Different Temperatures

The objective of this study is to estimate the changes in Enthalpy, Entropy and Gibbs Free Energy of yam slices dehydrated at different temperatures using a Refractance WindowTM dryer. Dehydration of 1.5, 3.0 and 4.5 mm thick yam slices, was performed with water temperatures of 65, 75, 85 and 95oC in the flume of a Refractance WindowTM dryer. During the dehydration operations, the moisture-content history data were recorded. For the process conditions considered, the moisture content history data was used to calculate the moisture diffusivity and the activation energy of dehydration of the samples. Subsequently, changes in Enthalpy, , Entropy, , and Gibbs Free Energy, ), were calculated. For the process conditions studied, the changes in, , , and, varied from 20,381.33 to 25,217.05 J.mol-1., -140.69 to -122.29 J.mol-1.K-1.and 67,934.80 to 70,220.15 J.mol-1, respectively. This study is essential as knowledge of these thermodynamic parameters are useful for the optimal design and sizing of preservation dryers for argo-products. Keywords— Enthalpy; Entropy; Gibbs Free Energy; Refractance WindowTM Dryer; Yam 

scholarly journals The Effects of Natural Weathering on Color Stability of Impregnated and Varnished Wood Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Turkay Turkoglu ◽  
Ergun Baysal ◽  
Hilmi Toker
Keyword(s):  
Scots Pine ◽  
Color Change ◽  
Color Stability ◽  
The Other ◽  
Natural Weathering ◽  
Color Changes ◽  
Oriental Beech ◽  
Total Color Change ◽  
Dark Color ◽  
Copper Arsenate

The aim of this study was to investigate effects of natural weathering on color stability of Scots pine (Pinus sylvestrisL.) and Oriental beech (Fagus orientalisL.) impregnated with some chemicals [tanalith-E (TN-E), adolit-KD5 (AD-KD5), and chromated copper arsenate (CCA)] and then varnished [synthetic varnish (SV) and polyurethane varnish (PV)]. While applying varnish increased lightness, impregnation decreased lightness of the wood specimens before natural weathering. Natural weathering caused greenish, bluish, and dark color tones of the wood surface. Total color change was increased with increasing exposure times in natural weathering. Untreated (control) wood specimens exhibited higher color changes than the other wood specimens in all the stages of natural weathering. The total color changes of untreated Oriental beech specimens were less than untreated Scots pine specimens. The color stability of impregnated and varnished wood specimens gave better results than untreated and solely varnished wood specimens after natural weathering. The best color stability was obtained from both Oriental beech and Scots pine wood impregnated with TN-E before PV coating.

scholarly journals Studying the Effect of Paracetamol Drug on the Conductivity of 0.5M Hydrochloric Acid Solution at Different Temperatures

2013 ◽  
Vol 11 (7) ◽  
pp. 2725-2745
Author(s):  
Hadi.Z. Al-Sawaad
Keyword(s):  
Activation Energy ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Molar Conductance ◽  
Chloride Ions ◽  
The Other ◽  
Constant Concentration ◽  
Enthalpy Of Activation ◽  
Other Hand ◽  
Different Temperatures

In this study paracetamol drug is used to reduce the conductivity of 0.5M hydrochloric acid at different concentrations for each one of them at different temperatures ranged (30-60)°C. Generally , increasing of the concentration of  the inhibitor leads to reducing in conductivity of the acid at constant temperature. On the other hand, at constant concentration of  inhibitor, the conductivity is reduced as temperature increased i.e., paracetamol can adsorbed chemically on the metal or alloy. Furthermore the kinetic study of the molar conductance process reveal that in presence of paracetamol the activation energy and enthalpy of activation are negative compared with their values in absence of paracetamol where they are negative because the reducing the conductivity in presence of paracetamol where the non spontaneous property for the conductance of acid is increased as the paracetamol concentration increased in addition to increasing the negative value of entropy in presence of paracetamol that indicate to restrict for the mobility of hydrogen and chloride ions which correspond to 90.47% as efficiency of reducing the conductance of acid by paracetamol. On the other hand thermodynamic study is achieved which explained the adsorption of paracetamol obey to Freundlisch model. 

Growth of Aerobic Psychrotrophs and Color Changes of Precooked Beef Slices as Affected by Packaging Procedure1

1987 ◽  
Vol 50 (9) ◽  
pp. 733-736 ◽  
Author(s):  
T. P. CARR ◽  
J. A. MARCHELLO
Keyword(s):  
Shelf Life ◽  
Microbial Growth ◽  
The Other ◽  
Lag Phase ◽  
Oxygen Level ◽  
Internal Temperature ◽  
Color Intensity ◽  
Color Changes ◽  
Beef Color

Precooked beef slices from top round roasts were used in replicate trials to determine the effects of packaging treatment upon shelf-life characteristics (microbial growth and color attributes) during retail storage. Roasts were dry-roasted to an internal temperature of 60°C, cooled for 1 h, then sliced (3–4 mm). Slices were packaged in: (a) vacuum; (b) 15% CO2, 40% O2, 45% N2; (c) 15% CO2, 20% O2, 65% N2; or (d) 15% CO2, 10% O2, 75% N2 and held at 4°C for up to 18 d. Enumeration of microorganisms and determination of color attributes were done at 0, 3, 6, 9, 12, 15, and 18 d of storage. Psychrotrophic counts were higher (P&lt;.05) on slices stored 9–18 d in atmospheres containing ambient (20%) oxygen level as compared to the other packaging treatments. Vacuum packaging exhibited a greater lag phase for psychrotrophs. Vacuum packaged slices maintained a superior cooked beef color for 18 d and had greater (P&lt;.05) chroma readings, indicating a greater color intensity.

scholarly journals Utilization ofm-Phenylenediamine-Furfural Resin for Removal of Cu(II) from Aqueous Solution-A Thermodynamic Study

2010 ◽  
Vol 7 (3) ◽  
pp. 757-762
Author(s):  
Tariq S. Najim ◽  
Israa G. Zainal ◽  
Dina A. Ali
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Free Energy ◽  
Room Temperature ◽  
Adsorption Process ◽  
Sorption Process ◽  
The Other ◽  
Weak Values ◽  
Solid Liquid Interface ◽  
Solid Liquid

m-Phenylenediamine was condensed with furfural in absence of catalyst at room temperature. The producedm-phenylenediamine-furfural resin was used for the removal of Cu(II) from aqueous solution. The pH for the optimum removal of Cu(II) was 6. The negative values of Gibbs free energy at low concentration of Cu(II) (20, 30 ppm) indicative of the spontaneous adsorption process, while, at higher Cu(II) concentration (40,50 ppm) the positive and weak values of ∆G° indicate that the process is feasible but non spontaneous. The values of ∆H° were positive indicating that the sorption process is endothermic. On the other hand, the values of activation energy (Ea) were inconsistent with the values of ∆H° both are positive and lie in the range of physisorption. The entropy ∆S° of the process was positive indicative of the randomness of the Cu(II) ions at the solid / liquid interface. The values of sticking probability S* were less than one which indicate a preferable adsorption process and the mechanism is physisorption.

Effect of Potassium Sorbate on the Microbiological Quality of Butter

1979 ◽  
Vol 42 (8) ◽  
pp. 656-657 ◽  
Author(s):  
AJAY KAUL ◽  
JASJIT SINGH ◽  
R. K. KUILA
Keyword(s):  
Sodium Chloride ◽  
Storage Temperature ◽  
Microbiological Quality ◽  
Inhibitory Effect ◽  
Potassium Sorbate ◽  
Mold Growth ◽  
Coliform Count ◽  
Different Temperatures

Butter samples treated with potassium sorbate and sodium chloride were analyzed weekly for bacteriological qualities after storage at different temperatures. Addition of 0.1% potassium sorbate and incorporation of 2% sodium chloride plus 0.1 percent potassium sorbate resulted in inhibition of mold growth in all the samples at the end of 4 weeks at 18 C and 5 C. However the effect of potassium sorbate alone was less pronounced, irrespective of storage temperature. As regards coliform count in control butter, it increased rapidly at 22 C, but decreased when butter was stored at 5 C or – 18 C. Addition of potassium sorbate to butter samples stored at 18 C reduced the coliform count to zero after 4 weeks. while butter with added potassium sorbate and sodium chloride showed a zero count after 1 week, indicating a cumulative inhibitory effect.

Note: Shelf Life Determination of Korean Seasoned Side Dishes

2003 ◽  
Vol 9 (4) ◽  
pp. 257-263 ◽  
Author(s):  
Gi-Tae Kim ◽  
Yong-Duck Ko ◽  
Dong Sun Lee
Keyword(s):  
Shelf Life ◽  
Sensory Quality ◽  
Microbial Growth ◽  
Storage Temperature ◽  
Microbial Quality ◽  
Soybean Sprouts ◽  
Different Temperatures ◽  
Side Dishes ◽  
Physical And Chemical

Three Korean side dishes of seasoned beef soup, soybean sprouts and fried tofu were stored at 0, 3 and 10 C. Changes in sensory, physical and chemical indexes were compared with microbial quality deterioration for shelf life determination. For beef soup, shelf life, based on a microbial quality limit of 106 cfu/g, was comparable to that obtained from sensory quality. The primary quality factor criterion for seasoned soybean sprouts determining shelf life varied with storage temperature. For seasoned tofu, shelf life estimates based on a microbial criterion of 106 cfu/g represented a more conservative estimate than those based on sensory quality at 3 and 10 C. Microbial quality was generally to be a common and sensitive criterion for shelf life determination, thus a microbial growth model was used to estimate shelf life at different temperatures.

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

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