Packaging MOxygen Product and Recycling in Artificial Ecosystematerial Analysis for Food Preservation

  • Troullinos Yannis

Packaging Report

In this practical class, different films for food packagin

Discovering Terrestrial and Aquatic life

The Ecosystem Simulation

Purpose/ Hypothesis

The purpose of this experiment was to create an artificial ecosystem in order to observe the natural changes in life. The column was put together including a terrestrial and an aquatic section to see how the two interact as one. Plants, insects, and fish were added to the column in order to observe how oxygen is produced, used and recycled. The eco-column experiment was done in order to familiarize us with testing water for pH, temperature, and dissolved oxygen levels. Along with familiarizing the participants with the process and meaning of certain environmental tests the eco-column simulation helped to show how life and nature works. It gave insight to how one element affects another in nature. The eco-column simplified the mast works of nature.


Two liter bottles were brought in and the bottoms were cut out of all but one and the tops out of all. After cut, the bottles were assembled together and taped. The eco-column was composed of three different sections; aquatic, decomposition and terrestrial. There was a filter inserted between the decomposition and the terrestrial chambers in order to catch the soil that would try to make its way down to the aquatic chamber. The eco-column was first assembled September 24th. For the aquatic chamber water was brought in, nearly a gallon, from local lakes, ponds, and creeks. For the decomposition and terrestrial the soil was taken from local forest. After assembling the column and inserting water and soil there were instructions to insert rocks, sticks, and insects. After assembly was complete test were done. The aquatic chamber went through various test including turbidity, dissolved oxygen, pH and temperature, along with subjective test such as odor and color. Observations were completed, as well as soil test. At first the columns were tested every week, but after 3 weeks the teacher instructed the class to complete test and observations every two weeks versus every week. The teacher gave out aquatic plants in order to help with dissolved oxygen levels. Once the dissolved oxygen levels and temperature became constant and safe fish were placed into each of the aquatic chambers of the eco-columns. The eco-column experiment lasted around three months; from September to December. The tests were completed five times. Dissolved oxygen and temperature were both tested using a probe in which was placed in the water. The pH levels were tested using a a special paper stick pH tester. In order to test turbidity water samples were taken from the aquatic chamber and put in a machine which read the level. The soil test were completed by taking out a cup of soil from the eco-column the week before. They were then tested for various elements such as; pH, nitrogen, potassium, and phosphorus by putting them in the directed containers in which powder was added to test for the specific element. The eco-column was taken down on December 3rd. The water and soil was dumped outside of the school and the bottles were given to our teacher in order to be used again.


The table below shows how the dissolved oxygen, temperature, and pH levels changed throughout the experiment. It is visible that the pH levels and temperature remained fairly constant over time. The temperature remained around 21 degrees Celsius and the pH levels neutral, 7. The dissolved oxygen levels however were constantly changing. The first day of our experiment, September 24th, the dissolved oxygen level was 1.0. At that level the water was unsafe for marine life, such as fish. There was barely any oxygen circulating throughout the chamber. A week later the level was up to 7.6. Our teacher stated that the range of 7 is a safe number. She ensured her class that they would receive plants and fish when the levels were suitable. About the second week in she added a plant into the aquatic chamber which really helped with the dissolved oxygen levels. Once suitable (about the third week) the fish were added and one can see from the table that the tested fields remained fairly constant.

Water Quality (figure 1)

The table below shows the observations of the aquatic, decomposition, and terrestrial chambers over time. When the eco-column was first assembled, the water was not in very good condition. It reeked of sewage, was yellow and from the chart above the dissolved oxygen levels were as low as they could be. Not only was the aquatic chamber bad, but the decomposition and terrestrial habitats smelled fowl, were full of mold, and life did not survive. From the chart one can easily see that over time the conditions greatly improved and by the end was an ecosystem sustainable for life. By October 22nd the eco-column had greatly improved. There were signs of growth, clear water and the mold was nearly gone. By the last day of the experiment there was no smell, no algae and no signs of mold. From observations and data it is clear that the presence of plants and animals helped to improve water and soil quality. They helped to minimize bacteria and fungus while improving the state of the air and oxygen levels.

Observations of Biomes

(Table 1)

Date Odor Color Aquatic Habitat Decomposition Habitat Terrestrial Habitat
9-24 Sewage Yellow Clear no Algae Moldy Some mold, not much life
10-1 algae Green Turning green Moldy Some life, little mold
10-8 Algae Green Algae growth, clear water Mold, decomposed No plant, some animal
10-22 Some Algae Clear A lot of growth clear water Almost gone No life
11-5 No smell Green Clear Clear No life


  1. Identify two Food Chains or Food Webs in each of your habitats (chambers). Use arrows to illustrate these food chains and food webs; complete sentences are not required. Use extra paper if needed.
  • Aquatic Chamber
  • Decomposition Chamber (top soil chamber)
  • Terrestrial Chamber

On separate sheet

  1. Identify and briefly discuss the biogeochemical cycles which are taking place/which are present in your EcoColumns. Do not merely state that “they are all present”; instead, provide more specific information

The sunlight brings in warmth , energy, and oxygen. While the animals ( fish and insects) breathe in oxygen CO2 is produced. The CO2 is then taken in by the plants and oxygen is released. The cycle then repeats.

  1. Is your ecosystem column a closed or open system? — or is it something in between a closed or open system? Explain how this (closed, open or other) influences the ecosystem column overall.

The eco-column is in between an open and a closed system. It is closed in the sense that it is isolated from the rest of nature. It is open because it has all the regular cycles and interactions of an ecosystem but just in a smaller, and confined. Although it is technically a closed system it is open because it has natural cycles.

  1. What kind of niches are available/present for the various organisms in the column? Be specific, descriptive, and use terminology that is pertinent to the topic.

The fish niche is to clean up the algae present in the aquatic habitat. While the aquatic plants niche is to take in the CO2 produced from the fish and produce oxygen in order to keep the fish alive and dissolved oxygen levels high.

  1. Discuss evidence of ecological succession taking place in your column (or in the column of another lab group if you have not observed any signs of succession in your column).

Our eco-column started out lifeless. The water was dark, the smell was unbearable, the chemical levels were high, and the dissolved oxygen levels were low. Over time the water began to clear, the smell went away the chemicals leveled out and the dissolved oxygen levels rose. The presence of plants cleared up the water and made it livable. After the first plant other plants were able to grow and the ecosystem was able to support life (fish).

  1. Discuss the stability and sustainability of the ecosystem columns in the lab, including your own.

After the first week my groups eco-column became stable, the levels remained constant from that point forward, ours was also capable of sustaining life. However, everyone’s eco-columns weren’t as stable. Several groups struggled with clearing up their water and raising their dissolved oxygen levels. Because of this they were unable to have fish. One groups water turned black due to a fungus and eutrophication occurred.

  1. Discuss three trends or patterns which stand out as you think back on the data which you have been recording for 6 weeks. These trends or patterns should apply to the water quality tests or other observations which you have made over this multi-week time period. Briefly discuss these three trends or patterns, providing possible explanations based on environmental science principles.

My group’s pH, dissolved oxygen, and temperature all follow the same pattern. They started out very low, rose quickly, dropped, and then leveled back out.

Many of our terrestrial insects died so this could have possibly affected the levels, as well as lack of sunlight.

  1. Explain what eutrophication refers to and how this occurs. Apply this explanation to your ecosystem column. How might eutrophication take place in your column? Explain fully.

Eutrophication refers to the increase in nutrients in water such as nitrates and phosphates; it depletes the oxygen and turns the water different colors. Eutrophication happened in one group’s column but not ours. Eutrophication could happen by nutrients from the soil in the terrestrial chamber dropping down to the aquatic chamber and polluting the water. Once the water is polluted the oxygen depletes and the water changes colors and becomes unsafe.

  1. Pick another group in your class. How do your data compare to theirs? Brainstorm some causes/reasons for any differences.

Since we worked at lab stations other groups were always around. I observed that most people had similar results to us. Good temperatures, steady levels of pH and dissolved oxygen with rather clear water. Some groups however were not similar. Some had bad levels, could never get oxygen levels to healthy state and had vast amounts of mold and algae. Some eco-columns were lifeless because insects and plants were unable to survive.

  1. Finally, address any sources of error in this lab. This should be narrated in a “cause and effect” manner and talk about specific problems. A good example would be “water did not drain from the terrestrial chamber so …” while a bad example would be “we messed up the measuring one day.”

The only error my group could find in the lab was the soil test. We could never get enough soil to do the test, so our data is very scarce and not one week could we actually complete the task. The only time we had enough soil was the last time and the results did not seem to be very accurate. I believe something could be done to improve the soil test and raise the accuracy.


Before this experiment I was clueless on the various water and soil test; as well as how to conduct them. I now feel confident that I could complete each test on my own and I am aware of the temperature, pH level, and dissolved oxygen number needed to sustain life. This experiment was very helpful in demonstrating how an ecosystem works and how everything needs and plays off one another. The eco-column gave us the opportunity to experience biogeochemical and life cycles. We learned what is necessary to sustain life and I feel as if that was the most important thing learned from the eco-column experiment.


Botkin, D. B., & E. A Keller (2011). Environmental Science (8th ed.). Hoboken, NJ: John Wiley & Sons.

The EcoColumn. (2013). Retrieved December 12, 2013, from Annenburg Learner website:

EcoColumn Lab. (2013, February 7). Retrieved December 14, 2013, from Teaching Real Science website:


g were examined as far as their physical properties and their ability to preserve grapes, cheese, meat and potatoes. Appropriate measurements and tests we done on specific time intervals.


Table 1. Results for the rapid tests for the identification of packaging materials

Test Material Biting test Breath test Water drop test Water tap test Stretch test Melt test Shrink test Burn test Material Identified*
Burn rate smoke odour Bead formation

* Materials were identified using the “packaging materials identification chart for films” in the practical booklet.

Table 2. Results of the mechanical and physical properties of the packaging material

Parameter Units Material 1:

cellulose 340 DMS

Material 2:

Polypropylene (PP)

Material 3:

Polyethylene (PE)

Width mm 25 25 25
Gauge mm 0.085 0.1 0.03
Area mm2 2.125 2.5 0.75
Force 2580









Extensibility % 6








Mean Value 6.5 32 54


Calculations and Questions:

1. Calculate the tensile strength of the three packaging materials tested.

Table 3. Physical properties of different packaging materials

Material Strength Values (g/m) Strength Mean Values (g/m) Force Mean Values (N) Area (m2) Tensile Strength (MPa)
cellulose 340 DMS 2580


1860 (rejected)*

2560 25.6 2.125×10-6 12.0
Polypropylene (PP) 10360



10873 108.7 2.5×10-6 43.5
Polyethylene (PE) 1200


1860 (rejected)*

1250 12.5 0.75×10-6 16.7

* More than 25% difference from the mean

By using N = ±100 g, Force mean values for each of the materials can be found. Also, Area = Width (m) x Gauge (m) = X m2. Tensile strength = Force (N) / Area (m2) so for the above materials we have:

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Cellulose 340 DMS Tensile strength = 25.6 / 2.125 x 10-6 = 12.0 x 106 N/m2 = 12.0 x 106 Pa = 12.0 MPa, as 1 N/m2 = 1 Pa, while 1 MPa = 1,000,000 Pa

Polypropylene Tensile strength = 108.7 / 2.5 x 10-6 = 43.5 MPa

Polyethylene Tensile strength = 12.5 / 0.75 x 10-6 = 16.7 MPa

2.Define tensile strength and discuss what factors will affect the tensile strength of the packaging material

Tensile strength is the maximum load that a material can support without fracture when being stretched, divided by the original cross-sectional area of the material. Generally, as tensile strength increases, the tougher the material is considered (Hui, 2008). Factors affecting the tensile strength are (Yam, 2010; Fellows, 2009):

  • Plasticiser levels (increased values give less tensile strength and more elasticity
  • Degree of crystallinity (crystal structure)
  • Density of the material (increasing density gives more tensile strength)
  • Manufacturing process (orientation, treatment, coatings)
  • Temperature
  • Physical properties of the material (branching, side groups, chain length, molecular weight)
  • Duration of the time that the force is applied

3.Compare your tensile strength results to those found in literature.

According to Goodfellow Cambridge Ltd. tensile strength for regenerated cellulose is 50 MPa, which, as mentioned, is affected by a lot of different factors. In our experiment, tensile strength of the cellulose used is a lot lower (12MPa).

Paine (1990) gives values of 30 MPa for polypropylene, while in this experiment a value of 43.5 MPa was calculated.

Finally, polyethylene gave an experimental value of 16.7 MPa, while Goodfellow Cambridge Ltd. reports 5-25 MPa for low density polyethylene (LDPE) and 15-40 MPa for high density polyethylene (HDPE). In this experiment it is unknown which exactly was the type of PE used, as there are many different types in market.

As explained, duration of the force applied affects the tensile strength, so different testing machines give different results. There are numerous more factors as noted in question 2, which greatly affect the measurements and results. Thus, comparing values to literature cannot give objective judgement of the experiment.

4.Calculate the moisture vapour transmission rate (g m-2 day-1) for each of the films tested

Table 4. Results of the water vapour permeability test

Test Material Weight (g) Total moisture gained


Moisture gained per day

(g day-1)

Water vapour permeability per 24h (g/m2 24h) Mean value of water vapour permeability per 24h (g/m2 24h)
Day 1 Day 2 Day 3 Day 4 Day 5
cellulose 340 DMS 83.9 84.1 84.4 84.6 84.8 0.9 0.225 45 35
87.1 87.2 87.4 87.5 87.6 0.5 0.125 25
Polypropylene 85.9 86.0 86.0 86.0 86.0 0.1 0.025 5 2.5
87.1 87.1 87.1 87.1 87.1 0 0 0
Polyethylene 84.5 84.5 84.5 84.5 84.6 0.1 0.025 5 5
90.0 90.0 90.1 90.1 90.1 0.1 0.025 5

Circle area = π r2 = 0.005 m2 (r = 40mm = 0.04m)

Number of Days = 4, as Day 1 is the day we started the storage

Cellulose 340 DMS

1st measurements:

Total moisture gained = Weight of Day 5 – Weight of Day 1 = 84.8 – 83.9 = 0.9 g

Moisture gained per day = Total moisture gained (g) / Nr Days = 0.9/4 = 0.225 g day-1

Water vapour permeability per 24h = Moisture gained per day / Circle Area = 0.225 / 0.005 = 45 g/m2 24h (1)

2nd measurements:

Total moisture gained = 87.6 – 87.1 = 0.5 g

Moisture gained per day = 0.5 / 4 = 0.125 g day-1

Water vapour permeability per 24h = 0.125 / 0.005 = 25 g/m2 24h (2)

Mean value of water vapour permeability per 24h = [(1) + (2)] / 2 = 35 g/m2 24h


1st measurements:

Total moisture gained = 86.0 – 85.9 = 0.1 g

Moisture gained per day = 0.1/4 = 0.025 g day-1

Water vapour permeability per 24h = 0.025 / 0.005 = 5 g/m2 24h

2nd measurements:

Total moisture gained = 87.1 – 87.1 = 0.0 g

Moisture gained per day = 0.0 / 4 = 0 g day-1

Water vapour permeability per 24h = 0 g/m2 24h

Mean value of water vapour permeability per 24h = 2.5 g/m2 24h


1st measurements:

Total moisture gained = 84.6 – 84.5 = 0.1 g

Moisture gained per day = 0.1/4 = 0.025 g day-1

Water vapour permeability per 24h = 0.025 / 0.005 = 5 g/m2 24h

2nd measurements:

Total moisture gained = 84.6 – 84.5 = 0.1 g

Moisture gained per day = 0.1/4 = 0.025 g day-1

Water vapour permeability per 24h = 0.025 / 0.005 = 5 g/m2 24h

Mean value of water vapour permeability per 24h = 5 g/m2 24h

5.Discuss the results of the water vapour permeability test.

Water vapour permeability is a measure for breathability or for a textile’s ability to transfer moisture. The results show that PP and PE have relatively low water permeability, while cellulose has a lot more. These values agree with literature (Brennan and Grandison, 2012), which states that PP has lower permeability than PE. Cellulose is also stated as a low barrier of water vapour permeability. These results show that using cellulose to pack food sensitive to humidity such as powders is not considered wise.

6.Discuss the results of the packaging and storage of fresh fruit experiment. Explain what is causing the observed changes in the fruit and how the different packaging/storage conditions influence the shelf life of the fruit.

Table 5. Fresh fruit (grapes) 3 days interval observations

Film Day Weight (g) Drying out Sweating Mould Internal and external appearance of package Storage temperature Type of spoilage General appearance Storage humidity Other changes/notes


Heat seal

1 31.2 NO CHANGE 25 °C GOOD 75%
2 31.2 Ñ´ NO CHANGE 25 °C GOOD 75%
3 31.2 Ñ´ NO CHANGE 25 °C partial oxidisation 75%

And heat seal with 2 holes

1 27.3 NO CHANGE 25 °C GOOD 75%
2 26.8 Ñ´ slight NO CHANGE 25 °C GOOD 75%
3 25.5 Ñ´ Ñ´ slight Ñ´ NO CHANGE 25 °C partial shrinkage and oxidisation 75%
PE and heat seal 1 31.7 NO CHANGE 25 °C GOOD 75%
2 31.6 Ñ´ NO CHANGE 25 °C GOOD 75%
3 31.3 Ñ´ NO CHANGE 25 °C oxidisation and browning 75%
Open tray 1 42.7 NO CHANGE 25 °C GOOD 75%
2 39.2 NO CHANGE 25 °C GOOD 75%
3 36.2 Ñ´ Ñ´ NO CHANGE 25 °C soft, oxidised and dried 75%

Firstly, the tissues of fruits are alive after harvest and they only die through natural senescence, rotting or when they are consumed, cooked or similarly processed. All these tissues “breath”, a phenomenon called respiration with obvious relations to maintenance of the quality and prolonging the shelf life of the product. Specifically, grapes do not respire very intensively and this is the reason they get harvested when they are ripe. Reducing respiration can extend the shelf life but stalling it will make tissues senesce and die. Cooling temperatures can also lower undesirable effects on fruits (Jongen, 2002).

As far as grapes concerned, mould is primarly because of the fungus Botrytis cinerea.

Browning spotted is a chemical process caused by specific enzymes changing the tissues colour to brown, while shrinkage is caused by increased respiration (tissues eventually lose water as shown in the weight measurements causing them to lose volume). Sweating is caused once again because of the respiration in packages where gas permeability is low or very low.

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In the above experiments, it is shown that when using MS and heat seal, grapes got sweaty in day 2 and 3, while in the same packaging with 2 holes, sweating was only slight. This makes sense as the 2 holes allowed the air transfer between package and the environment, lowering the humidity because of the respiration in the package.

In PE and heat seal, sweating was even more obvious as PE has lower gas permeability than MS.

Finally, in the open tray, sweating was absent but mould started to show at day 3, as it partially did in the package with 2 holes. This was caused by a microorganism, probably fungus since grapes have low pH. Another change which was spotted in the open tray was the soft, dried and oxidised appearance of the grapes because of the large amounts of respiration. Room temperatures and total contact with the environment allowed this level of respiration, lowering shelf life dramatically.

7.What changes would you make to the packaging/storage conditions to extend the shelf life of the grapes?

The most important change to the storage conditions would be to lower the storage temperature, as it would significantly reduce respiration. The package should not have holes, as they allow environmental air to get in allowing microorganisms to grow faster.

8.Discuss the results of the packaging and storage of cheese experiment. Explain what is causing the observed changes in the cheese and how the different packaging/storage conditions influence the shelf life of the cheese.

Table 6. Cheese 3 days interval observations

Film Day Weight (g) Drying out Sweating Mould Internal and external appearance of package Storage temperature Storage humidity Oiling Type of spoilage Other changes/notes


Heat seal

1 9.1 NO CHANGE 25°C 75%
2 9.1 NO CHANGE 25°C 75%
3 9.0 Ñ´ NO CHANGE 25°C 75% Ñ´
Cryovac and heat seal 1 19.9 NO CHANGE 25°C 75%
2 19.9 NO CHANGE 25°C 75%
3 19.8 Ñ´ NO CHANGE 25°C 75% Ñ´
Aluminium foil 1 8.2 NO CHANGE 25°C 75%
2 8.1 Ñ´ NO CHANGE 25°C 75% Ñ´
3 7.7 Ñ´ Ñ´ NO CHANGE 25°C 75% Ñ´
Open tray 1 16.9 NO CHANGE 25°C 75%
2 15.5 Ñ´ NO CHANGE 25°C 75%
3 14.9 Ñ´ Ñ´ NO CHANGE 25°C 75% Ñ´

Browning of cheese is significant in high storage temperatures (37°C), less in medium (20°C) and absent in low temperatures of 5°C. Light causes the formation of lipid peroxides in medium temperatures, while compounds such as riboflavin are affected by light unrelated to storage temperature (Kristensen et al., 2001).

Cheese tend to produce free oil when they melt and sweats during storage in relatively high temperatures because of the high humidity of it. When in open air sweating is more and drying out occurs (Wang and Sun, 2004).

From the above, it becomes more obvious in ours experiments why cheese dried out during storage in open tray and why this drying out is more than in aluminium foil (which was not folded enough to keep air from contacting cheese). Another way to see the above is the greater loss of weight in open tray rather in aluminium foil. On the other hand, in both MS and cryovac packages no drying out was noted, as can be seen from the differences in initial and final weight (≤0.1g).

Relatively high storage temperatures (about 25°C) caused the oiling and sweating of the cheese.

9.What changes would you make to the packaging/storage conditions to extend the shelf life of the cheese?

The storage temperature should be as low as about 5°C (refrigerator) in dark and should be kept either in MS or cryovac packaging. Ideally, a modified atmosphere packaging should be used (Khoshgozaran et al., 2012), extending shelf life even more than the usual packages.

10.Discuss the results of the packaging and storage of fresh meat experiment. Explain what is causing the observed changes in the meat and how the different packaging/storage conditions influence the shelf life of the meat.

Table 7. Fresh meat 4 days intervals observations

Film Day Weight (g) Changes

In colour



Moistening Internal and external appearance of package Storage


Type of


General appearance

of product



Other change and/or notes


Heat seal

1 21.0 4°C 75%
2 21.0 slight green Ñ´ slight 4°C colour changes 75%
3 21.0 slight green Ñ´ slight 4°C colour changes 75%
4 21.0 slight green and browning  

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