🥄 Curd Culture: Can Milk Alone Begin Fermentation?

CUBE chat
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:petri_dish: CUBE ChatShaala Summary – 28.07.2025

Today’s CUBE ChatShaala centered around comparative observations and citizen science experiments in curd formation carried out by participants from different regions—Tarannum from Dehradun, Uttarakhand and Swapnil from Narayangaon, Maharashtra.

:microscope: Highlights from the ChatShaala Discussion

  • Tarannum’s Method (Dehradun, Uttarakhand )

:black_small_square:Milk boiled and cooled to 5°C above room temperature.

:black_small_square:½ tsp of curd added to 1L milk, stirred well.

:black_small_square:Curd formed in 6–8 hours.

Inference : Controlled warm temperature + starter + agitation facilitates curdling.

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  • Swapnil’s Method (Narayangaon, Maharashtra )

Same initial steps : boil → cool → add 1 tsp starter.

:black_small_square:Transferred to a mud pot and left undisturbed for 48 hours.

Inference : Clay pots retain heat longer, allowing slow fermentation.

:test_tube: Tarannum’s Experimental Setup (2-Bowl Design)

Using 1L of lukewarm milk in all three containers:

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Container A

  • Added 1 tbsp curd and stirred.

Result : Curd formation in 6–8 hrs, and became sour by 20–22 hrs.

Container B

  • No curd added, no stirring.

Result : No curd in 6–8 hrs; curd formed after 20–22 hrs.

Sakshi’s idea- Container C

  • No curd added, but stirred well.

Result : Similar to B – no early curd, late formation.

:dna: Conclusion

Starter (curd) accelerates fermentation.
But even without starter, native Lactobacillus in raw milk eventually leads to curd formation, especially under warm conditions
Stirring without starter doesn’t accelerate the process noticeably.

:thinking: Provocative Questions for the Community

  1. Can we identify the specific strain of Lactobacillus active in Tarannum’s kitchen curd?

  2. What is the source of native bacteria in untreated milk—cow, vessel, air, or hands?

  3. How does the material of the container (mud pot vs steel) affect bacterial activity and curd taste?

  4. Is the sourness due only to Lactobacillus or other microbial agents after 20+ hrs?

  5. Can spontaneous fermentation be replicated using UHT or pasteurized milk?

:bulb: What I Personally Learned Today

I realized how deeply contextual and location-dependent fermentation is. A simple kitchen experiment reveals a lot about the microbial ecosystem we live in. Even without adding curd, Lactobacillus present in milk or environment eventually initiates fermentation—a powerful example of spontaneous microbial action in everyday life. It reinforced the beauty of observation-based learning in science.

:camera_flash: Group photographs during Chatshaala

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:books: Reference

@Arunan @KiranKalakotiR @sakshiconsultant2002 @akanksha @akhil @2020ugchsncnseethala @magpie and others

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My colleagues father was food scientist at Central Food Technology Research Institute (CFTRI) at Mysuru and he had introduced a culture from Japan that created non-sour curd. But after a month of curd to curd spooned cultures, the native sour bacillus took over and the curd soured. Then a new curd line had to be made with Japanese bacillus from lab.

Non-sour curds, made from cultures similar to the Japanese, are now available in the market . I have not experimented to find out when the curd becomes sour again.

There are scientific reports that say curdling overcomes lactose intolerance, but soured fermented lactose is not absorbed well into the bloodstream in the small intestine and is excreted. But the lactose treated by non souring bacillus is absorbed well.

The nutritional benefit of non-sour curd should be told to the society.

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