The Science Behind Khandvi

Today, we consider the western foods to be great and yummy, and most preferred, but when it comes to the knowledge and science that goes behind the making of the traditional Indian foods, one might just fall for it all over again. Our grand parents and great grandparents might not have been as educated as we are, but they had way more knowledge and understanding of the foods they cooked everyday than we know of eating everyday. 

Today we shall discuss about khandvi, which is a native dish of Gujarat, India, where people love to eat the roasted gram flour rolls, spiced and flavoured. In Maharashtra, this dish is commonly known as suralichi vadi air patuli. 

Again, I would like to mention that I will not be providing any recipe as that is available on the web on numerous websites. Here we will talk about the uncommon. 

Khandvi is made up of a mixture of besan or roasted Bengal gram flour and buttermilk. Everyone knows that the cooking of this mixture is the most tricky and difficult part of the entire recipe. So here’s why. 

The roasted gram flour is rich in its protein content. This is enhanced by the use of buttermilk, which is also high in proteins. When dissolved in water, these protein molecules absorb moisture  and swell. The volume increases and the viscosity or the resistance to flow decreases. That’s when we say that the batter is thickening. While making khandvi, the thickness of the batter is very important. Because if it becomes too thin, it will be difficult to roll, and if it becomes too thin, it will b too difficult to evenly spread on to the flat surface. It will then form undesirable lumps. 

But what happens to the proteins? 

The proteins in the solution form, or a sol form gets converted to a progel state by denaturation and polymerisation. 

1. Denaturation: it is the phenomenon in which the original structure of the proteins is hampered or changed to a new structure in the presence of various factors like change of temperature, pH, moisture, etc. 

2. Polymerisation: It is the process in which the bond between the two amino acids break due to the reaction with water. 

So as a result, the gram flour mixture thickens in the presence of moisture and difference of temperature. 
Now, when the gram flour mixture is in the progel state, the functional groups (hydrogen bonding and hydrophobic groups) become exposed so that it facilitates formation of the protein network in the second stage. 
Second stage? 

Yes, there is a second stage as well. When this mixture is cooled to room temperature or refrigeration temperature, there is a decrease in the thermal kinetic energy which promotes formation of stable non covalent bonds among the above exposed groups which results in the formation of a gel. So what you see on the flat surface, after you have spread the batter and cooled it, is a gel. Only when a proper gel is formed, you will be able to make rolls out of it. 

The sol state to progel state is a non reversible reaction which progel to gel state is a reversible reaction. On re-heating the gelled batter, it will melt back to the progel state as it must have been experienced when you re-heat some curries made of gram flour. This is because hydrogen bonds are the major contributors to the network formation. 

Next time you can try this by keeping aside some part of the heated mixture and then re-heating it when cooled. Experience for yourself!!

Also, we have used curd in the form of buttermilk. Why curd and nothing else

Curds are an excellent source of leavening agent. Leavening agents are basically substances which lead to rising of the batters and doughs and making it soft and voluminous. This leads to soft gels of the proteins and which is why you have that smooth texture and soft “melt in the mouth” feel of the khandvi. The moisture in the form of buttermilk will keep the khandvi moist and prevent drying and hardening of the khandvi.  Too much or too little of this important ingredient will result in the failure of the recipe. So beware!! 

Here’s all about science behind khandvi. Try the recipes by keeping these points on mind and I’m sure you will never go wrong. You would know how to improve next. 

Keep reading for more recipe sciences. Enjoy scientific cooking. After all, cooking is  an art as well  as a science!!