what is curdled milk?
The curdled milk will have lumps of milk protein, in greenish water which was once smooth, creamy milk. But curdled milk is not always a bad thing though it is an indication of spoilage. Curdling milk proteins is used as a method in producing more delicious food items like cheese, Yogurt and desserts.
Milk curdles very often in summer due to temperature variations. With the milk price soaring every day we regret to waste the curdled milk which is curdled while boiling. At the same time we are afraid to use it, as it may cause severe illness.
The chemical reaction behind curdling of milk:
Milk is made up of many compounds like fat globules , protein,minerals and sugar. The protein in milk is normally suspended in the colloidal solution which means that the small protein molecules, moves freely and independently. These floating molecules refract light which give milk its whitish color. In the good milk, the protein molecules are in a free state without grouping. But when the PH of the milk goes down they suddenly become attracted to each other resulting in lumps of protein molecules and greenish watery solution. This is exactly what happens when milk curdles. As the PH drops and becomes more acidic the protein casein molecules attract one another and become ‘curdles’ floating in a solution of translucent ‘whey’. The clumping reaction happens more swiftly at warmer temperature than it does at cold temperature.
There are six types of bacteria used for cultures accordingly how they change property of milk.
Lactic acid bacteria, Proteolytic bacteria, Lipolytic bacteria, gas producing microorganisms, Ropy bacteria and sweet curling bacteria. The various flavours have been accounted with specific milk contamination.
How curdled milk differs from spoiled milk?
Milk will curdle as it expires because of cultivating bacteria. As milk ages the bacteria converts its natural sugar lactose, to lactic acid , making it sour and curdle. Milk is pasteurized to eliminate the harmful bacteria, which is natively present in it. Leaving milk at room temperature and leave it to sit without refrigeration allow, suitable conditions for growth of microorganisms resulting in souring and curdling.
Lactobacillus is the major part of the lactic acid bacteria group, named as such because most of the members convert lactose and other sugars to lactic acid.
In both pasteurized and raw milk various microorganisms succeed each other as the chemical environment of the milk changes. The microbes themselves bring about the change. The stages of microbial actions are, Streptococcus, Lactobacillus, yeast, and molds, and finally bacillus.
When resulted lactic acid in the milk, is more, the acidity of the milk rise, resulting in clumping of casein molecules of milk. The high amount of lactic acid, in the milk is the sole reason for characteristic sour smell and spoiling of the milk.
Is eating curdled milk good or bad?
- Milk that curdles from cooking particularly because it was boiled, is not harmful at all in fact curdling in itself is not dangerous it is what causes it.
- If the milk is spoiled naturally may be due to the action of microorganisms, such as, bacteria and fungus, and toxins produced by them gives a sour or foul smell and bitter taste. Then this milk is not good for health and hence the consumption should be avoided.
- Whereas as the artificial curdling is done with rennet, acid, heat, and cultures of bacteria and the products made from this process are not only used for delicious recipes but are also known for its health benefits.
Sandesh is a famous Bengali dish prepared from chhena or paneer. It is easy to prepare and tastes good. Here is my method of preparing dessert Sandesh.
|Prep time||Cook time||Ready in||Yields|
2 hours 2 min
2 hours 42 min
- 1000ml Milk
- 3 tablespoons lemon juice
- 100gms sugar
- pinch cardamom powder
- pinch saffron
- few pistachio's or almond
- Take a thick bottomed vessel. Pour the milk and bring it to boil. stir the milk once or twice with wooden spatula to avoid getting burnt.
- Now simmer the stove and add three spoons of lemon juice and stir gently to start the curdling all over the milk.
- Once you see the clumps forming on the top ,switch off the stove and allow it cool for sometime.
- Take a filter, cover it with a thin cloth which allows only liquid to escape.Pour the curled milk over it and separate curdles from whey.
- Tie the cloth hang it for 10 to 20 minutes to remove remaining water.
- Remove the paneer from the cloth and knead it with your palm for 10 to 15 minutes.This is very important step in this sweet making to get a smooth texture.
- Now add cardamom powder,sugar, saffron and again knead for few minutes till it becomes smooth and soft.
- Now take a non stick pan and gently fry the mixture for 8 to 10 minutes, till it starts roll from sides and there is a change in color.
- Remove from pan make desired shapes in hand or with molds.Allow it cool for 1 or 2 hours and serve it with gratings of pistachios and almonds.
Lemon Juice and Milk
When the lemon juice or vinegar is added to milk it will curdle immediately but adding it to cold milk will not produce a reaction for quite some time. This is the same very reason used to prepare, fresh cheese, like ricotta, and Paneer. Milk is heated at specific temperature and then acid is added, once the milk curdles the solid protein are then strained from the liquid whey and shaped into a round cheese .In this preparation curdling is just harmless and in fact very useful.
Uses of curdled milk.
1.The milk is curdled with citric acid to get Paneer or Cottage Cheese. The coagulated part is poured in a thin cloth and the liquid is squeezed out. This clumps of protein without liquid is called Paneer or Cheese.
- Rasgulla is a syrupy sweet of Bengal and Orissa. Rasgulla along with Chhenapoda,Chhenna Gaja forms a classic Oriya trinity of Chhena(paneer) dessert.
- In the coastal city of Puri the rasgulla are offered to Goddess Laxmi on the rath yatra day. It is believed by historians “the invention of Rasgulla is more than 600 yrs old .it is as old as Rath yatra of Puri”.
- It has been suggested that Bengali visitors to pui temple might have carried the recipe for Rasgula back to Bengal in the nineteenth century.
- The Pahal town located between Bhubaneswar and Cuttack are worldwide known for its Rasgulla and chhena sweets.
- The pahal or original Rasgulla are off-white to cream or even yellowish brown in color .They were crumbly in texture and tend to spoil quickly.
- In the middle of nineteenth century it was introduced to Bengal by a sweet seller named Haradhan Moira.
- In the year 1868 Nobin Chandra Das ,a local confectioner of Kolkata modified the recipe of the rasgulla as he wanted to extend the shelf life of the sweet which was originally highly perishable.
- His son K.C. Das started canning the product leading to wider market.
The popular dessert Rasmalai
2.The whey is used as a nutritional supplement by the body builders, in countries like Switzerland it is also used in soft drinks. It is used for production of Ricotta, Brown Cheese etc.
Video on Making Ricotta
3.The curdled milk is used to make yogurt. The milk is curdled with help of bacteria under anaerobic condition, which results in the fermentation. Yogurt is used daily in many parts of the world.
To know about Yogurt and making of yogurt
- Curd or Yogurt - One of the Elixir of Life
Curd or yoghurt is a very nourishing food .It is a valuable source of protein, calcium, and minerals. Curd has zero carbohydrates, sugars, transfat and high source of Calcium.
4.Milk is curdled with the help of rennet which is a natural enzyme. This milk is used to prepare hard cheese like cheddar, or Swiss.
How make cheddar cheese at home
5.When ingested, commercially prepared milk acts as an intestinal antiseptic by producing beginning lactic acid in the intestine there by preventing the growth of harmful bacteria.
6.Curdled milk is best to treat Typhoid fever, Colitis, Appendix, Inflammation due to intestinal colon infections.
How can you protect milk from spoiling in summer?
“Prevention is better than cure.”The first thing to remember when you buy the milk is to bring it to boil. If it is done all the harmful microorganisms are killed and the milk remains unaffected for a long time.
Pasteurized milk has long shelf life and available in most of the stores, so buying them in summer is a better option.
Store the milk in low temperature or in Fridge which will restrict the growth of micro -organisms .
In summer, boil the milk twice a day to avoid spoiling.
© 2014 cheeluarv
Anna Javier on October 03, 2020:
Oh, I was looking for this! Thanks!
cheeluarv (author) from INDIA on March 27, 2014:
Thanks sujaya , yes, hereafter no more wastage milk ,cheers with cheese.
cheeluarv (author) from INDIA on March 27, 2014:
Thank you billybuc for reading my hub and found it useful. These Bengali sweets are unique in their taste especially Rasogolla,Rasmalai(spongy,juicy) must try kind of dessert. I have not tried cheese so far, have to do.
sujaya venkatesh on March 27, 2014:
no wastage che
Bill Holland from Olympia, WA on March 27, 2014:
Cheese of course; I haven't tried any of the other suggestions. Thanks for this information.