scholarly journals Modified-atmosphere Packaging of Blueberry Fruit: Modeling Respiration and Package Oxygen Partial Pressures as a Function of Temperature

1994 ◽  
Vol 119 (3) ◽  
pp. 534-539 ◽  
Author(s):  
Arthur C. Cameron ◽  
Randolph M. Beaudry ◽  
Nigel H. Banks ◽  
Mark V. Yelanich
Keyword(s):  
Activation Energy ◽  
Mathematical Model ◽  
Steady State ◽  
Modified Atmosphere Packaging ◽  
Vaccinium Corymbosum ◽  
Published Data ◽  
Modified Atmosphere ◽  
Highbush Blueberry ◽  
Partial Pressures ◽  
Low Levels

A mathematical model was developed to characterize the interaction of fruit O2 uptake, steady-state O2 partial pressures in modified-atmosphere (MA) packages ([O2]pkg), and film permeability to O2 (Po2) from previously published data for highbush blueberry (Vaccinium corymbosum L. `Bluecrop') fruit held between 0 and 25C. O2 uptake in nonlimiting O2 (Ro2max,T) and the [O2]pkg at which O2 uptake was half-maximal (K½T) were both exponentially related to temperature. The activation energy of 02 uptake was less at lower [O2]pkg and temperature. The predicted activation energy for permeation of O2 through the film (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{E}_{\mathrm{a}}^{\mathrm{P_{\mathrm{o}_{2}}}}\) \end{document} kJ·mol-1) required to maintain close-to-optimum [O2]pkg across the range of temperatures between 0 and 25C was ≈ 60 kJ·mol-1. Packages in which diffusion was mediated through polypropylene or polyethylene would have values \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{E}_{\mathrm{a}}^{\mathrm{P_{\mathrm{o}_{2}}}}\) \end{document} of ≈ 50 and 40 kJ·mol-1, respectively, and would have correspondingly greater tendencies for [O2]pkg to decrease to excessively low levels with an increase in temperature. Packages that depend on pores for permeation would have an \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{E}_{\mathrm{a}}^{\mathrm{P_{\mathrm{o}_{2}}}}\) \end{document} of <5 kJ·mol-1. Our procedure predicted that, if allowed to attain steady-state conditions, packages with pores and optimized to 2 kPa O2 at 0C would become anaerobic with as little as a 5C increase in temperature. The results are discussed in relation to the risk of temperature abuse during handling and marketing of MA packaged fruit and strategies to avoid induction of anaerobiosis.

scholarly journals Modified-atmosphere Packaging of Blueberry Fruit: Effect of Temperature on Package O2 and CO2

1992 ◽  
Vol 117 (3) ◽  
pp. 436-441 ◽  
Author(s):  
Randolph M. Beaudry ◽  
Arthur C. Cameron ◽  
Ahmad Shirazi ◽  
Diana L. Dostal-Lange
Keyword(s):  
Steady State ◽  
Partial Pressure ◽  
Modified Atmosphere Packaging ◽  
Vaccinium Corymbosum ◽  
Effect Of Temperature ◽  
Modified Atmosphere ◽  
Highbush Blueberry ◽  
Partial Pressures ◽  
Effects Of Temperature ◽  
Increasing Temperature

Highbush blueberry (Vaccinium corymbosum L. `Bluecrop') fruit sealed in low-density polyethylene packages were incubated at 0, 5, 10, 15, 20, or 25C until O2 and CO2 levels in the package reached a steady state. A range of steady-state O2 partial pressures (1 to 18 kPa) was created by placing a range of fruit weights within packages having a constant surface area and film thickness. The steady-state O2 partial pressure in packages containing the same weight of fruit decreased as temperature increased, indicating the respiratory rate rose more rapidly (i.e., had a greater sensitivity to temperature) than O2 transmission through the film. Steady-state O2 and CO2 partial pressures were used to calculate rates of O2 uptake. CO2 Production. and the respiratory quotient (RO). The effects of temperature and 02 partial pressure on O2 uptake and CO2 production and the RQ were characte∼zed. The steady-state O, partial pressure at which the fruit began to exhibit anaerobic CO2 production (the RQ breakpoint) increased with increasing temperature, which implies that blueberry fruit can be stored at lower O2 partial pressures when stored at lower temperatures.

scholarly journals Modified-atmosphere Packaging of `Heritage' Red Raspberry Fruit: Respiratory Response to Reduced Oxygen, Enhanced Carbon Dioxide, and Temperature

1994 ◽  
Vol 119 (3) ◽  
pp. 540-545 ◽  
Author(s):  
Dennis W. Joles ◽  
Arthur C. Cameron ◽  
Ahmad Shirazi ◽  
Peter D. Petracek ◽  
Randolph M. Beaudry
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Partial Pressure ◽  
Surface Area ◽  
Modified Atmosphere Packaging ◽  
Fruit Weight ◽  
Rubus Idaeus ◽  
Modified Atmosphere ◽  
Modified Atmospheres ◽  
Partial Pressures

`Heritage' raspberries (Rubus idaeus L.) were sealed in low-density polyethylene packages and stored at 0, 10, and 20C during Fall 1990 and 1991 to study respiratory responses under modified atmospheres. A range of steady-state O2 and CO2 partial pressures were achieved by varying fruit weight in packages of a specific surface area and film thickness. Film permeability to O2 and CO2 was measured and combined with surface area and film thickness to estimate total package permeability. Rates of O2 uptake and CO2 production and respiratory quotient (RQ) were calculated using steady-state O2 and CO2 partial pressures, total package permeability, and fruit weight. The O2 uptake rate decreased with decreasing O2 partial pressure over the range of partial pressure studied. The Michaelis-Menten equation was used to model O2 uptake as a function of O2 partial pressure and temperature. The apparent Km(K½) remained constant (5.6 kPa O2 with temperature, while Q10 was estimated to be 1.9. RQ was modeled as a function of O2 partial pressure and temperature. Headspace ethanol increased at RQs >1.3 to 1.5. Based on RQ, ethanol production, and flavor, we recommend that raspberries be stored at O2 levels above 4 kPa at 0C, 6 kPa at 10C, and 8 kPa at 20C. Steady-state CO2 partial pressures of 3 to 17 kPa had little or no effect on O2 uptake or headspace ethanol partial pressures at 20C.

Compressive creep of dense Bi2Sr1.7CaCu2Ox

1992 ◽  
Vol 7 (9) ◽  
pp. 2360-2364 ◽  
Author(s):  
J.L. Routbort ◽  
K.C. Goretta ◽  
D.J. Miller ◽  
D.B. Kazelas ◽  
C. Clauss ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Steady State ◽  
Steady State Creep ◽  
Steady State Creep Rate ◽  
Lower Stress ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Partial Pressures

Dense polycrystalline Bi2Sr1.7CaCu2Ox (2212) was deformed from 780–835 °C in oxygen partial pressures, Po2, of 103 to 2 × 104 Pa. Results could be divided into two stress regimes: one at lower stress in which the steady-state creep rate, ∊, was proportional to stress, γ, having an activation energy of 990 ± 190 kJ/mole and being independent of PO2, and another at higher stress in which ∊ was proportional to σn, with n ≍ 5–6. Transmission electron microscopy supported the interpretation that in the lower-stress viscous regime, creep was controlled by diffusion, whereas dislocation glide and microcracking were responsible for strain accommodation at higher stresses.

scholarly journals Influence of Oxygen and Temperature on the Respiration Rate of Fresh-cut Cantaloupe and Implications for Modified Atmosphere Packaging

HortScience ◽  
2012 ◽  
Vol 47 (8) ◽  
pp. 1113-1116 ◽  
Author(s):  
M. Helena Gomes ◽  
Randolph M. Beaudry ◽  
Domingos P.F. Almeida
Keyword(s):  
Steady State ◽  
Shelf Life ◽  
Respiration Rate ◽  
Modified Atmosphere Packaging ◽  
Life Extension ◽  
Modified Atmosphere ◽  
Low Oxygen ◽  
Fundamental Information ◽  
Respiratory Behavior ◽  
Fresh Cut

The respiratory behavior of fresh-cut melon under modified atmosphere packaging at various temperatures was characterized to assess the potential for shelf life extension through low-oxygen and to generate information for the development of appropriate packaging conditions. Cantaloupe melon (Cucumis melo var. cantalupensis ‘Olympic Gold’) cubes were packaged and stored at 0, 5, 10, and 15 °C. Packages attained gas equilibrium after 5 days at 10 °C, 6 days at 5 °C, and 10 days at 0 °C. In cubes stored at 15 °C, decay started before steady-state gas levels were reached. Respiration rates were measured and respiratory quotient calculated once steady-state O2 and CO2 partial pressures were achieved inside the packages. O2 uptake increased with temperature and O2 partial pressure (pO2 pkg), according to a Michaelis-Menten kinetics described by = [( × pO2 pkg)/( + pO2 pkg)]. Respiratory parameters were modeled as an exponential function of temperature: = {[1.34 × 10−17 × e(0.131 × T) × pO2 pkg]/[1.15 × 10−24 × e(0.193 × T) + pO2 pkg]} (R2 = 0.95), Q10 = 3.7, and Ea = 84 kJ·mol−1. A good fit to the experimental data was also obtained considering as constant: RO2 = {[4.36 × 10−14 × e(0.102 × T) × pO2 pkg]/[0.358 + pO2 pkg]} (R2 = 0.93), Q10 = 2.8, and Ea = 66 kJ·mol−1. These results provide fundamental information to predict package permeability and steady-state pO2 pkg required to prevent anaerobic conditions and maximize shelf life of fresh-cut cantaloupe. The kinetics of respiration as a function of pO2 suggests that no significant reductions in respiration rate of fresh-cut cantaloupe can be achieved by lowering O2 levels.

scholarly journals MODIFIED ATMOSPHERE PACKAGING: TEMPERATURE DEPENDENCE OF THE RQ “BREAKPOINT”

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1139c-1139
Author(s):  
Randolph Beaudry ◽  
Arthur Cameron
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Temperature Dependence ◽  
Oxygen Concentration ◽  
Modified Atmosphere Packaging ◽  
Oxygen Demand ◽  
Carbon Dioxide Production ◽  
Modified Atmosphere ◽  
Lower Oxygen ◽  
The Difference

The steady-state oxygen concentration at which blueberry fruit began to exhibit anaerobic carbon dioxide production. (i.e., the RQ breakpoint) was determined for fruit held at 0, 5, 10, 15, 20 and 25 C using a modified atmosphere packaging (MAP) system. As fruit temperature decreased, the RQ breakpoint occurred at lower oxygen concentrations. The decrease in the RQ breakpoint oxygen is thought to be due to a decreasing oxygen demand of the cooler fruit.The decrease in oxygen demand and concomitant decrease in oxygen flux would have resulted in a decrease in the difference in the oxygen concentrate on between the inside and outside of the fruit and thus decreased the minimum amount of oxygen tolerated. The implications on MAP strategies will be discussed.

scholarly journals Pollination Requirements of Three Highbush Blueberry (Vaccinium corymbosum L.) Cultivars

1997 ◽  
Vol 122 (6) ◽  
pp. 891-896 ◽  
Author(s):  
Kenna E. MacKenzie
Keyword(s):  
Seed Coat ◽  
Fruit Set ◽  
Vaccinium Corymbosum ◽  
Harvest Date ◽  
Highbush Blueberry ◽  
Seed Number ◽  
Berry Size ◽  
Low Levels ◽  
Viable Seeds ◽  
Total Seed

The effects of pollination treatments on fruit set and five berry characteristics [mass, diameter, number of apparently viable seeds (well-developed, plump with dark seed coat), total seed number (includes apparently viable and partially developed seeds), and harvest date] were examined on three highbush blueberry cultivars. Pollination treatments included unpollinated, open pollinated, emasculated, and three hand pollinations that used pollen from the same flower, from the same cultivar, or from a different cultivar. Berries matured earliest and were smallest with the most apparently viable seeds in `Northland', `Patriot' had the greatest fruit set and smallest seed number, and `Bluecrop' matured the latest. Fruit set was greater, berry size larger, seed number smaller, and maturation later in 1990 than 1991. For all three cultivars, berries were generally smallest, latest maturing, and had the fewest seeds when pollination was prevented and were largest with the most seeds and earliest maturing in open visitation. Emasculation resulted in berries similar to those from unpollinated flowers. For berry characteristics, cross-pollination was of benefit for `Patriot' and possibly `Northland' but not `Bluecrop'. Thus, commercial highbush blueberry planting designs must be based on the pollination requirements of the particular cultivar. `Northland' berries almost always had seeds, while `Patriot' showed high levels and `Bluecrop' low levels of parthenocarpy.

A MATHEMATICAL MODEL FOR TRAINING IMPULSE AND LACTATE INFLUX AND OUTFLUX DURING EXERCISE

2009 ◽  
Vol 20 (01) ◽  
pp. 147-177 ◽  
Author(s):  
JOHN F. MOXNES ◽  
KJELL HAUSKEN
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Lactate Concentration ◽  
Lactate Production ◽  
Published Data ◽  
Interval Exercise ◽  
Common Concept ◽  
Training Impulse ◽  
The Mathematical Model ◽  
Upper Boundary

This paper provides a mathematical description based on the theory of differential equations, for the dynamics of lactate production and removal. Analytical and numerical results for training/exercise of endurance of athletes are presented based on the common concept of training impulse (Trimp). The relationships between activity, production rate, and removal strategies of lactate are studied. Parameters are estimated from published data. A model for optimum removal of lactate after exercise is developed. The model provides realistic predictions when compared with experimental results. We show some specific examples for the usefulness of the mathematical model by studying some recent problems discussed in the literature. (a) Is interval exercise more beneficial than steady-state exercise? (b) What is the optimum aerobic power during recovery? We discuss whether steady-state exercise gives higher Trimp than interval exercise, when imposing an upper boundary for the lactate concentration as a constraint. The model allows for testing all imaginable kinds of steady-state and interval exercises in search of the optimal exercise regime for individuals with various kinds of characteristics. In general, the dynamic model constitute a powerful tool describing the processes by which the concentration of lactate can be studied and controlled to decrease fatigue and increase endurance.

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