Tstl Marie Lumiere D S Pta

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Concernant la présentation orale.

La durée est parfaite (5:28 mins)

Tu parles un peu trop vite ! Certains mots sont mal prononcés.

"no-organic" =} Non-organic potatoes

Attention à la prononciation du morphème –ed de certains mots comme "used", "observed " et à la prononciation de certains mots comme par exemple "France", "chemicals",…. "(surtout "transparents") comme "verify", "agricultural","different", "microorganisms", "temperature"

C'est bien présenté et ton texte est bien écrit.


_I-Cold sweetening of organic and non-organic potatoes__

We have chosen the organic potato theme as well as the non-organic potato theme because today we often consume this tuber. We were also interested in the conservation of organic and non-organic potatoes. We noticed that the French are consuming more and more organic products. In France, 9 out of 10 French people consume organic products. Organic farming is a production method that finds its originality in the use of farming and breeding practices that respect natural balances. Thus, it excludes the use of synthetic chemicals and GMOs. We have also noted that the consumption of potatoes in France per year and per person is 27.5 kg. Organic is better for our health than food from traditional agriculture, and if this is true how do we preserve them to verify this, we wanted to answer a question: do organic and non-organic potatoes keep the same depending on their storage temperature?

II-Environmentally correct cold sugaring :

In general, the population is exposed to a multitude of pesticides through the food products they consume on a daily basis. In agricultural areas, where pesticides are used, these substances become airborne, pollute soils and watercourses and can be systematically absorbed by certain non-target plant species. Cold sugaring is a good technique to preserve potatoes for a long time without the use of pesticides. We therefore wanted to work on the cold sweetening of organic and non-organic potatoes, which consists of storing potatoes at a low temperature (below 5°C). It makes it possible to limit weight loss, to control silver scabies and dartrosis and to reduce or eliminate the germination inhibitor But it also promotes the formation of soluble sugars, in minimal quantities when the tuber is mature. A compromise must therefore be found between a rather high value (9-10°C), making it possible to limit sugar content when cold, and a lower value (6°C), limiting senescence sugar content (limits the ageing of the potato) by keeping them at different temperatures (7-8°C/20°C/37°C).

_1-unfolding of the project __
For the cold sweetening of organic and non-organic potatoes we first placed the potatoes at different temperatures (7-8°C;20°C;37°C) for several weeks in order to be able to observe the effects of these temperatures on the different potatoes.

III- choice of experiments :
To determine the right temperature we performed several experiments, a TLC that allows us to determine which carbohydrates are present in organic and non-organic potatoes placed at different storage temperatures. Then the use of contact agar which allows us to observe whether or not there are microorganisms on the potato slices stored at different temperatures. Counts on different culture media that will allow us to calculate the concentration of microorganisms on an organic and non-organic potato stored at the same temperature . A GOD-POD test that allows us to determine the glucose concentration in the different potatoes that we have previously placed at different temperatures.The purpose of this experiment is to observe the effect of temperature on the amount of glucose present in the potatoes and to determine whether glucose degradation has occurred at low temperatures.

1- experience hypothesis
- For the TLC, we believe that organic potatoes contain more carbohydrates than non-organic potatoes.
- For contact agars, more mould will be present on contact agars of organic potatoes than on those of non-organic potatoes.
- For enumeration on PCA media, more microorganisms will be present on organic potatoes than on non-organic potatoes.
On the Slanetz enumeration medium, we expect to see more microorganisms on organic potatoes because they have not been in contact with pesticides that could kill the microorganisms.
- For the GOD-POD test the carbohydrate concentration will be higher for non-organic potatoes than for organic ones.

IV-Result of the experiments :
Enumeration on pca : Potatoes non-organic

we could not calculate the content for the non-organic potato because on the petri dish there were less than 10 colonies.


We can conclude that the PCA medium was used to count the total flora of the potato. We observed that organic potatoes contain more microorganisms than non-organisms. With regard to the storage temperatures of the potatoes, we can say that those stored at 5°C and 20°C have approximately the same content of microorganisms, but those stored at 37°C have a much higher content of microorganisms than the other temperatures.

Slanetz agar:
Slanetz allows the search for faecal Streptococci. We can notice that the colonies are more numerous on the organic potato boxes than on the non-organic potato boxes. At 37°C, no colonies have developed. At 20°C and 5°C, the concentration of CFU.mL-1 is higher on the organic potato boxes.


Contact agar:
We found that all organic potatoes had mould on them at any storage temperature. While on the non-organic potatoes we did not see any mould at any storage temperature.


We have found that at every storage temperature potatoes, whether organic or not, contain the same carbohydrates. We have seen that potatoes stored at 5°C contain glucose and fructose. Potatoes stored at 20°C also contain fructose and glucose. Finally, potatoes stored at 37°C contain fructose but do not contain glucose but maltose.


We can notice that the glucose concentration in potatoes is higher in organic than non-organic potatoes. We can also see that the lower the storage temperature, the higher the glucose concentration in the potatoes.


V-organic and non-organic potatoes that it is the right temperature?
We have observed that organic potatoes contain more microorganisms than non-organisms. With regard to the storage temperatures of potatoes, we can say that those stored at 5°C and 20°C have approximately the same content of micro-organisms, but those stored at 37°C have a much higher content of micro-organisms than the other temperatures. A high temperature (37°C) can affect the higher concentration of micro-organisms in potatoes, but this temperature prevents the growth of faecal streptococci. Organic and non-organic potatoes contain the same carbohydrates, but the concentration varies between organic and non-organic potatoes and depending on storage temperature. If the potato is organic, it contains less glucose and the lower the storage temperature of the potato, the higher the glucose concentration.
In conclusion, organic potatoes do not keep in the same way as non-organic potatoes and the storage temperature also modifies certain elements of the composition of the potato, the right temperature for cold sweetening and 5°C because the photogen is strongly reduced but still, this choice must be compatible with the culinary use of the tuber and the potato chosen organic or non-organic .

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