“Learn From Your Mistakes!”

               Standing in a lab class for three hours can be a tedious job for a student. For me, it turns out even more frustrating some days because my batch falls in the afternoon session. But it’s a known fact that lab classes are more interesting than theory classes. At least this session of Bio-organic Chemistry lab turned out one. “Extraction of Starch from potato tuber” was the experiment for the day. Theoretical details were explained briefly by our ma’am. I tried to understand all, but was able to grab only a few points. Later, I quickly hurried to grab a beaker, funnel and test tube for myself to get started with the experiment. Initially, we had to crush chopped potatoes till it forms a liquid meshy substance. It was then filtered with muslin cloth and the liquid part was allowed to settle down for starch precipitation. Now, that is a slow process. But I couldn’t stop discussing with my friend about the properties of starch, with the little knowledge I had! Surprisingly there was enough starch separated from just 10g of potato which made us, girls, go woooo… especially the ones who are potato lovers and diet followers!. I fall into the first category.

                

               One of the reason being the discussion with a friend, distracted, I immediately rushed with the beaker containing precipitated starch and added Iodine solution. The colour turned blue black!. Yay! Positive result. The happiness dint last long as I was corrected by my ma’am saying that, Starch precipitate should be filtered and then dried to obtain its dry weight and then diluted for Iodine test. *face palm* I dint know how to proceed. But c’mon, ofcourse I dint stop the experiment with that. The purple precipitate was filtered and dried. Of course the hot-air oven would have rejected my plea to dry the purple coloured precipitate if it could think by itself. But no. I was lucky. The dry weight was obtained. Everyone diluted their powdered starch, resulting in a white solution. When I did mine, it was a purplish, dark blue solution. But once the iodine solution was added by the others it resulted in the same colour change as mine. In the end, the result obtained by all was same. But my dry weight?! Was HIGHER!!. That’s something I need to ponder on, but later.

                

                This swapping of procedures in the experiment raised a question in my mind as to whether the starch entering the body through the potato we consume will turn violet or not?!. I learnt from the answers what ma’am gave and the other, obviously Google.

(1)    When it comes to human body, starch loses some of its characteristics along with it’s name and is called “glycogen”.

(2)    Starch is broken down or hydrolysed immediately into smaller carbohydrate units and hence preventing the formation of blue-black colouration. There is absence of long polymerized chain which is actually responsible for holding the iodine molecules intact.

(3)    Moreover Iodine is in the form of Triiodo thyronine and Tetraiodo thyronine in our body. The iodine bond in these compounds is very strong and breaking of these to react with starch is not possible.

RESULT:  Our body doesn’t have a blue-black precipitate J

        I took an extra information along with me when I walked out of the laboratory. The experiment I did was completely wrong. But I had a feeling of satisfaction that I learnt something today. Very basic, though. Afterall studies can be interesting and the first best teacher in the world is, “Your mistakes”.

Nine-pointer :p ,

Swetha Ananthan.