The science behind Dhokla

Have you ever wondered why is there this particular texture of the dhokla? 
Or have you wondered what makes the dhokla rise? Of course the soda or eno fruit salt that you add to it, but how does it function?  

Have you ever wondered why are there holes in between the dhokla strands that you see?  

Here I’m going answer these questions, which would help you find the science behind each and every recipe that you cook and will help you to master them. 

Dhoklas are made of besan(roasted Bengal gram flour), sour curd/buttermilk, and eno fruit salt / baking soda. Each ingredient contributes itself to play a role in making the final dhokla that we see as an end result. 

1. Besan : besan is the protein source in the dhokla. Proteins when heated along with water (in this case buttermilk contains the required water content) starts to swell and therefore increases the mobility of dry protein content. This is why we get the texture and the mouthfeel that we get in the dhokla. Besan also has a binding property because of which it binds to the flavours and gives a characteristic flavour and aroma of dhokla. 

2. Sour Buttermilk : The catch here is the word sour, which indicates that the curd from which the buttermilk is made has already undergone enough fermention to release carbon dioxide by the lactobacillus bulgaricus and streptococcus thermophilus bacteria. This leads to aeration or leavening resulting in a fluffy, well risen dhokla. Secondly, buttermilk has some portions of the lipids / fats which act like an emulsifying agent and emulsifies the besan molecules to make a homogeneous mixture, thereby giving a smooth mouthfeel. 

3. Eno fruit salt or Baking soda : either of these ingredients may be used but both if these contain sodium carbonate, which when combined with the acidic components present in curd or buttermilk and reacts with some acids such as (cream of tartar) tartaric acids.On heating, these two components react together to produce carbon dioxide molecules which is trapped between the besan molecules and causes the dhokla to rise and give a volume to it. 

I’m giving an example of the reaction between sodium bicarbonate and cream of tartar but a similar reaction occurs with other acids present in the curd/buttermilk used to prepare dhokla. 

Tartaric acid + sodium bicarbonate → sodium tartrate + carbon dioxide + water 

C4H6O6 + 2 NaHCO3 → Na2C4H4O6 + 2 CO2 + 2 H2O

The more gas produced, the greater is the volume of the dhokla and the lighter is the product. But however you cannot use too much of it, or else the dhokla will taste bitter. The holes that you See in between the dhokla structure is because of this carbon dioxide that was trapped during the cooking. 

So here is the entire science behind the making of dhokla and the most importantly the science behind rising of the dhokla. 

I have not attached a recipe here since that will be available on a variety of websites and I would only be adding to the already existing information.. 

But now You know what is to be blamed in case something goes wrong in your recipe, or what is to be done to improve it. 

All the best! Visit this page for more science behind cooking various recipes.