Science of Making Yummy Curd or Yogurt
Milk gets converted to tasty and yummy Curd. The credit goes to Protein Casein and Bacteria (mostly). Let’s explore the curd making process in depth. At the end of this, I am sure you will find your learning’s helping you in making better curd.
In a glass of milk, complexes of casein proteins in the form of micelles floats around. These complexes have negative charge, so they repel each other. When we add to it curd inoculum you are introducing loads of Lactobacillus strain of Bacteria which will make milk acidic. This causes the casein complexes to change shape and also alter their charge. As a result, instead of repelling each other, the casein complexes coagulate, or come together. As they coagulate, they capture fat and lactose along the way and get combined into a larger and larger solid, which we see as curd.
Why I am not able to make thick creamy curd ?
Some scientific pointers that can help you in making perfect curd.
The type of milk we use – Goat Milk, Full fat milk, Pasteurized Milk, Homogenized Milk, Raw Milk, 2% Milk, 1% Milk, Fat free- will decide how yogurt will turn out to be. The lower the fat, thinner the yogurt.
Curd made from milk warmed at around 70degreeC is thinner and tastes fresh, while curd made from milk held at 90-100degreeC for 10 minutes gives thicker and creamy curd
The more protein in milk, thicker the curd. Heating milk before adding the culture, denatures one of the main whey proteins, lactoglobulin, which allows it to join in the mesh and effectively increases the amount of protein in the milk that will be available to make the curd thick
The stability of protein mesh is also important. This stability is determined by the temperature at which the protein mesh forms, i.e., the temperature at which the curd sets. The curd will be smoother and more stable (less likely to leak whey) when it sets at a temperature around 40-45 degreeC.
To maintain steady temp:
- You could wrap the container in a blanket
- You could keep the container in a pre-heated oven (180 degree 2-3 mins)
Make curd using Yogurt maker or Curd making machine:
Yogurt Maker has inbuilt containers with different capacities. Once inoculum or starter is added to the milk, it can be poured into these containers . Switch it on and leave it for 10-11 hours to get curd of desired thickness. It is an amazing product and have capacity for making curd in large quantity in the hygienic conditions along with retaining its quality. Since they provide multiple bottles, one could add different fruit content and essence to make flavorful curd. Yogourmet, EuroCuisine, Dash, Nutrichef are well known yogurt maker brands.
Making curd with plant starters:
If you have no left over curd to add to make new batch of curd, don’t worry. We share with you some alternatives with science behind it.
- Making curd with Chilly The stem or calyx of chilly are often rich in various lactobacilli. These natural bacteria can serve as starter for lacto-fermentation of the milk. Also capsaicin found in chilly can increase the metabolic rate of the lactobacilli. Add to two cups of milk, 7-8 chilly stems. Once curd sets remove the stems.
- Making curd with chickpeas To make curd without using old or stale curd is to add boiled chickpeas into slightly warm milk. You need to add 3 chickpeas per half a liter of milk.
Some artificial solidifiers:
- Add Gelatin: Add to milk before heating and adding the inoculum. For every 3-4 cups milk, sprinkle 1 teaspoon of gelatin into 1 cup of cold milk. Gelatin must be made into liquid form before adding to milk. Gelatin is a solidifying agent and that magic makes the curd thick.
- Guar Gum: Guar gum is primarily the ground endosperm of guar beans. You can add this to milk before or after adding inoculum or culture. For every 3-4 cups of milk, add 1 teaspoon guar gum.
- Tapioca starch: Add to milk before heating and adding the inoculum. For 3-4 cups of milk, dissolve 2 tablespoons tapioca starch into the milk and heat to 90degreeC. Once milk cool down to 40degreeC, add the inoculum.