The Effect of Refrigeration has on the Decomposition ofRaspberries

By Tony Park and Kyle Wolff

Abstract: Our focus question is, “What effect does refrigeration have on raspberries’ rate ofdecomposition?” To test our focus question we got an equal number of strawberries and hadtwo groups with one being the control and the other being the experimental. The experimentalgroup was the group in the refrigeration and the control group was the raspberries in a roomtemperature enclosed box with a cup of water to simulate the darkness and the humidity of arefrigerator. We put the strawberries in two exact same types of cups and checked the mold,smell, and look of the raspberries for 6 days. The raspberries in the refrigeration had onlystarted to mold after day 5 while the raspberries in the box started to mold after the 1st day.Therefore, we found that the experiment supported our hypothesis because the raspberriesthat were not refrigerated had decomposed at a faster rate than the raspberries in therefrigerator.Background information: Our experiment is on the effects of refrigeration on thedecomposition of raspberries. Raspberries are a type of soft fruit that is in the rose family ofplants. Other types of fruits within this family are apples, apricots, blackberries, cherries,peaches, and much more. The type of raspberry that we have picked for our project is theRubus Idaeus. These are more commonly known as red raspberries. We have bought a boxof these to use in our experiment.

Fruits decompose mainly because of bacteria and fungi. The definition ofdecomposition is to cause something to be slowly destroyed and broken down by naturalprocess, chemical, etc according to the merriam­webster dictionary. When fruits ripen, thestarch inside of the fruit turns into sugar. This process can occur when the fruit is either on thetree or outside of the tree. The sugar that is made from the tasteless starch is cane sugar butis mostly made up of glucose. Since there is so much of the starch being made into sugar,However the glucose does not help make the fruit any sweeter. The cane sugar part of the fruitis what causes the fruit to be sweet and delicious. As the fruit gets riper and riper, the sweeterthe fruit becomes..Once these sugars start to turn old, the fruit begins to rot and mold starts toappear. New chemical compounds form and the usual brown color and nasty taste occurs forthe fruit. This mold appears because of the fungal diseases that infect it. The most commonfungal diseases that attack raspberry fruits are gray mold (Botrytis cinerea), soft rot, and alsoleak (Rhisopus and Mucor spp). Another reason why fruits rot is because of the odorless andcolorless gas known as ethylene. When one of the fruits releases this gas, it triggers the otherfruits to release this gas as well. This speeds up their ripening process but also speeds up

their rotting process as well. This is why it is good to remove the rotten fruit away from thehealthy ones for it will rot the others faster. Lastly, temperature can speed up or slow down thetime of fruit. Heating it will speed decomposition and cooling it will slow it down. Coldtemperatures will slow down the fruit because the bacteria that is the main cause of thedecomposition becomes very slow and sluggish. If the fruit is completely frozen, the fruitcannot be decomposed at all because the bacteria is unable to function when frozencompletely.

We are testing the effects of refrigeration on the raspberries we have bought.Refrigeration is the process or effect from a refrigerator to cool foods or other things topreserve them longer for use. We are testing the effects of this to see how fast and whetherthe raspberries outside of the refrigerator will decompose faster. Refrigerators preservesfood longer when inside because of the cold temperatures. Refrigerators are basically largecold storage for food. The cold helps all of the food by slowing down the bacteria that harmsthis food. Therefore, we believe that by having two groups of raspberries, one inside therefrigerator and one outside, the group that is outside will decompose much slower than theother

Focus Question: What effect does refrigeration have on raspberries’ rate ofdecomposition?Hypothesis:The hypothesis is that the raspberries without the refrigeration will decomposeat a faster rate than the raspberries in the refrigerator. We think this because the refrigeratorwill keep the raspberries fresh and hydrated longer compared to the raspberries withoutrefrigeration.Materials: Box of raspberries (1 5for each group), (2) Exactly equal cups, refrigerator, smallenclosed box, cup of water (humidifier)Procedure:1. We put 15 healthy looking raspberries from a new box in two equal sized cups2. Then we labeled each cup A and B3. We placed cup A in a refrigerator and Place cup B in an enclosed box (Makes raspberriesdark like in real refrigerator) with a cup of water (Makes box humid like refrigerator)

4. We recorded the data of the smell, mold, and the sight of the raspberries at 7:30 for thenext 6 days and took pictures putting it on the table. The independent variable was the powerof refrigeration while the outcome as the smell, mold, and sight of the raspberries were thedependent variable.

Results:Chart and pictures of the data we acquired from our experiment

Conclusion:1. These results supported our current hypothesis of raspberries decomposing faster withoutthe refrigeration compared to the raspberries in the refrigerator. We had thought this becausethe refrigerator will keep the raspberries fresh and hydrated longer compared to theraspberries without refrigeration. These results showed the raspberries that were notrefrigerated were almost over ridden with fungus and mold, there was almost no raspberryleft; while the raspberries that were refrigerated you could barely see the fungus and moldstarting to grow. In addition to sight, we also measured the stench of the raspberries. The nonrefrigerated raspberries had a very strong odor and you could smell it from a distance away,while the refrigerated raspberries had a slight odor and in order to smell it you had to put itright under your nose. This proves to us that the raspberries have decomposed enough tostart smelling, but to an extent. It proves to us that the non refrigerated raspberriesdecomposed a lot faster than the refrigerated raspberries because one, you could easily seethe decomposition taking effect on the raspberry that was not refrigerated and could barelysee it on the refrigerated raspberry; and two, the refrigerated raspberries only had a slightodor while the non refrigerated raspberries had a strong stench that could be smelled from adistance.

2. This was a controlled experiment. This was controlled because we had two groups, thecontrol and the experimental group. The control group was the raspberries that were notrefrigerated and the experimental group was the raspberries that were refrigerated. Therewas only one variable in the whole experiment and this was the refrigeration. This variablewas our independent variable, the variable that was tested in the experiment.

3. One possible error in our experiment was measuring the amount of water being needed tohumidify the raspberries. We were getting rid of the variable of humidity because refrigeratorshave humidity to keep foods hydrated longer. To mimic this, we poured water in a cup andplaced it inside the dark enclosed box being used as a “refrigerator” for the control group ofraspberries. This could have affected our experiment because it the water could be muchmore humid than the refrigerator, or could be much less humid than the refrigerator whichcould have a profound effect on our experiments results.

4. A follow up question to our controlled experiment could be what effect does refrigerationhave on animals? We tested the effect refrigeration has on plants but what does it have on thedecomposition of animals? Our follow up experiment to investigate this question would be totake some type of organism, (animal) that was already dead and put one organism in arefrigerator and put another organism in a box in order to have the same environment therefrigerator has. (Dark) We would essentially redo this experiment but with a different subjectand see if refrigeration has such an effect on animals as it does with raspberries. This could

then move us on to investigate other questions such as why does refrigeration have such aneffect on decomposition, and maybe even what other ways could we slow downdecomposition (better or slower than refrigeration) and is there a way to stop decompositionall together?

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"Raspberries." Www.whfoods.org. The George Mateljan Foundation, n.d. Web. 4 Oct. 2013.

Brain, Marshall. "How Food Preservation Works" 01 April 2000. HowStuffWorks.com.<http://science.howstuffworks.com/innovation/edible­innovations/food­preservation.htm> 28October 2013.

Bartzat, Alegra M. "Spoiled Rotten Why Fruits and Veges Go Bad." ­ Biology. BellaOnline's Biology,n.d. Web. 28 Oct. 2013.