Tstl Elise B S Pta

Pour écouter ma présentation orale =} Appuyez ici

Pour regarder mon diaporama =} Appuyez ici

Appréciation

Concernant la présentation orale.

La durée est parfaite (5:25 mins),

Quelques erreurs à éviter : il faut utiliser le futur pour introduire le sujet, par exemple "we will show/speak out…."

Attention à la prononciation de certains mots "transparents" comme "pratiques" =} practices, "diet", "compromise", "microbial", "question", "microorganisms",…..

Sinon, c'est très bien écrit et bien présenté !

potatoes

pomme%20de%20terre
images%20pomme%20de%20terre.jpg

Introduction :
We chose the theme of organic potatoes as well as non-organic because nowadays, we often eat this tuber. We are also interested in the conservation of organic and non-organic potatoes. We have noticed that the French are consuming more and more organic products.
In fact, 9 out of 10 French people consume organic products. Organic farming is a mode of production that finds its originality in the use of farming and livestock practices concerned with respecting natural balances. Thus, it excludes the use of synthetic chemicals, GMOs. We also found that the consumption of potatoes in France per year per person is 27.5 kg.
Eating organic means fighting pollution and chemicals, it is also helping farmers to make a better living from their profession. Eating organic means eating a balanced, varied diet, without pesticides, without GMOs.

Context, problematic :
We therefore wanted to work on the cold sweetening of organic and non-organic potatoes which consists of storing the potatoes at low temperature (below 5 ° C), helps to limit weight loss, to control silver scab. and dartrose and reduce or suppress germination. But it also promotes the formation of soluble sugars, in minimum quantity at maturity of the tuber. It is therefore necessary to find a compromise between a fairly high value (9-10 ° C), making it possible to avoid cold sweetening and a lower value (6 ° C), limiting the sweetening of senescence (limits aging of the apple of earth) by keeping them at different temperatures (7-8 ° C / 20 ° C / 37 ° C).
We also decided to study the potato because it is a tuber on which we can carry out many experiments such as the dosage of carbohydrates as well as the study of the microbial flora of the potato. We will wonder if organic and non-organic potatoes can be stored in the same way according to their storage temperature.
To answer this question we will, firstly present our reflections as well as the process of developing our problematic, secondly, we will make the presentation of our handling protocols and then thirdly we will make the presentation of our results.
We first thought of studying the difference between organic and non-organic carrots in order to determine which ones are better for health.
Subsequently, we found that studying cold sugaring on potatoes would be a better idea because potatoes are easier to grind than carrots.

We then chose to answer the following question: Do organic and non-organic potatoes keep the same way according to their storage temperature? 

For cold sweetening in organic and non-organic potatoes, we first thought that they had to be placed at different temperatures (7-8 ° C; 20 ° C; 37 ° C) several weeks before the experiments to be able to observe the effects of these temperatures on the different potatoes.
enumeration of cells on slanetz agar :
On the enumeration of cells on slanetz agar , we expect to see more microorganisms on organic potatoes because they have not been in contact with pesticides that could kill the microorganisms.
The counts on different culture media allow us to calculate the concentration of microorganisms on an organic potato and a non-organic potato kept at the same temperature.
The enumeration of cells on slanetz agar is used to select Streptococci because the sodium azide in the medium makes it possible to inhibit gram - and to select Streptococci.
handling :
- We first weighed 10g of potato and then we mixed the 10g of potato with 90 mL of sterile EPT.
- We then transferred 1 mL of the mother solution and then we added 9 mL of sterile EPT then we made the dilutions up to 10-4.
- We finally seeded the dilutions from 10-2 to 10-4, we placed 1 mL of each solution in 2 sterile petri dishes for 2 tests then we poured the medium into the dishes then we homogenized.
- Incubate 72 hours at 37 ° C and then read.

slanetz%202

Result for the enumeration of cells on slanetz agar:

Potato kept at 37 ° C:
/ Number of UFC / box 10-2 10-3 10-4
Organic potato First box 0 0 0
Organic potato Second box 0 0 0
Non-organic potato First box 0 0 0
Non-organic potato Second box 0 0 0

We can notice that there are 0 faecal streptococci on Slanetz agars at 37 ° C. We can conclude that the colonies do not develop at 37 ° C.

Potato kept at 20 ° C:
/ Number of UFC / box 10-2 10-3 10-4
Organic potato First box illegible illegible illegible
Organic potato Second box illegible illegible illegible
Non-organic potato First box 7 3 2
Non-organic potato Second box 4 2 0

We can notice that the colonies are more numerous on the Petri dish of the organic potato. We can therefore conclude that faecal Streptococci are more numerous on organic potatoes than on non-organic potatoes.

Potato kept at 5 ° C:
/ Number of UFC / box 10-2 10-3 10-4
Organic potato First box 14 3 2
Organic potato Second box 9 4 0
Non-organic potato First box 1 0 0
Non-organic potato Second box 0 1 0

We can observe that the colons are more numerous on the Petri dish of the organic potato. Faecal streptococci are more present on organic potatoes than on non-organic potatoes.
C (UFC; Organic potato)=(14/((1+0.1*0)*10-2))*1/1*10  =1,4.105UFC.mL-1 

Conclusion
Slanetz agar allows the detection of fecal Streptococci. We can notice that the colonies are more numerous on the Petri dish of the organic potato than on the Petri dish of the non-organic potato. At 37 ° C, no colonies developed. At 20 ° C and 5 ° C, the concentration of UFC.mL-1 is higher on the Petri dish of the organic potato. We can conclude that because organic potatoes are treat by manure and in manure there are many faecal streptococcus.

results obtained for other manipulations :

culture medium PCA :
We can conclude that the PCA medium was used to count the total flora of the potato. We have observed that organic potatoes contain more microorganisms than non-organic ones. Regarding the storage temperatures of potatoes, we can say that those that were stored at 5 ° C and 20 ° C have roughly the same content of microorganisms, but those stored at 37 ° C a much higher microorganism content than other temperatures. We notice that there are more microorganisms in organic potatoes because they are not treated with chemicals.
culture medium Sabouraud :
On all Petri dish no colony was visible, so there was no growth of fungus on Sabouraud plates. The incubation time is 24 h at 37 ° C.
Contact agar plate :
We have seen that on all organic potatoes we observe mold at any storage temperature. Whereas on non-organic potatoes we saw no mold at any storage temperature.
Thin layer chromathography :
We have seen that at each storage temperature the 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 have glucose but maltose.
GOD-POD :
We can notice that the glucose concentration in potatoes is higher in organic than non-organic potatoes. We also see that the lower the storage temperature, the higher the glucose concentration in the potatoes.
General conclusion :

Through our experiments we have been able to observe that organic potatoes contain more microorganisms than non-organic potatoes. A high temperature (37 ° C) can affect the concentration of microorganisms on the potatoes which is higher, however this temperature prevents the growth of fecal streptococci. Organic and non-organic potatoes contain the same carbohydrates but the concentration varies depending on whether the potato is organic or non-organic and also depending on its storage temperature. Indeed, if the potato is organic it will contain less glucose and the lower the storage temperature, the higher the concentration of glucose.

In conclusion, organic potatoes are not stored in the same way and the storage temperature also changes certain elements of the composition of the potato.

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License