S4E134 CUBE chatShaala: CURD vs. CURDLING

Uncovering the Science hidden in the Great Indian Kitchen, We had a very interesting discussion around the chemical process of curdling and biological process of making curd. we had discovered the difference in between curdling and curd, in curd we are adding specific population of bacteria (spoonful of curd as an inoculum) in Luke warm milk to make curd. In the session CUBists have also design an experiment to understand protein precipitation.

Webinar Link
https://webinar.hbcse.tifr.res.in/b/kir-vgc-6jf

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Timing:5.30 pm to 9.30 pm
Today’s session will be followed by a workshop on mosquito by 8pm onwards

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Summary quoted by @manmasih
The Curricular 502nd day of ChatShaala 03/08/2021

The discussion started with moina, which is a model for many CUBists. While discussing the feed, we came across the term “milk”. The term led us to questions like wheather Moinas directly eat/drink milk or they feed upon the milk bacteria growing in the milk. It also led us to a question: What happens to the unused milk . Do they turn into curd, and if yes then how ?

In further discussions, we found that casein (widely discussed protein in our syllabus) is an important part of the milk.

There are two ways to turn milk into curd
A: Biological
B: Chemical

In the chemical process, the pH of the milk is decreased chemically by adding lemon juice or vinegar. The decrease in the pH makes the casein clump together, ultimately solidifying the milk.

In the biological process, small amount of curd is used as an inoculum to change milk into curd.

The discussion should be seen as an important one as it was based on our curricular syllabus which most students study.

Traditional practice of adding a spoon of curd in the lukewarm milk after boiling, could be seen as the sterilization of milk and then addition of microbes of our choice.

Proposed experimental design to find out: What changes milk into curd?/ Observation of milk during the curdling process

  1. Take 100ml of milk.
  2. Boil it and cool it for 10 minutes.
  3. Distribute them into four containers (25 ml each) and label them as A, B, C, D
  4. 1 teaspoon of following contents are added in containers:
    A- lemon juice,
    B- vinegar,
    C- curd.
  5. Do not add anything in container D, keeping it as CONTROL.
  6. Cover each of the containers with lid.
  7. Observe them by removing the lid and tilting the container a little to check the state of milk, at an interval of 2hrs.(2nd hour, 4th hour, 6th hour, … after step 6)

Man Masih’s Hypothesis: curd will be formed in Container A,B,C and milk will be spoiled in container D.

@Rechel Turkey and @Seethalakshmy CUBE’s Hypothesis: desirable Curd will be formed in A,B,C and undesirable Curd will be formed in Container D.

The above is written as per my understanding of the discussion. Please, make corrections wherever necessary @KIRAN CUBE @Seethalakshmy @Aswathy Suresh CUBE @Saida @Yash and others…

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