The liquid left after cheese or paneer
Whey protein is made from the liquid left when milk is set for cheese or paneer. The solid curd keeps most of the casein. The liquid still contains protein, along with lactose, a little fat, and minerals. When most of the water is dried out, what is left is a powder.
The pack prints the protein next to the serving. That protein comes from the liquid after it has been filtered and dried. The curd has already kept the casein.
How drying turns that liquid into powder
The powder is ready when the liquid is dry enough to scoop, or to pour from a sachet. Before the drying, the liquid is mostly water, so a large jug becomes a much smaller weight of powder. Filtering changes how much of the original liquid remains. It runs from the milk, to the liquid left after the curd, to the powder in the packet.
After that liquid is filtered and dried, the powder gets one of three names. Concentrate still has more of the original liquid in it, and a label there often shows about 70 to 80% protein. Filter the same liquid again and the name becomes isolate, with the protein share often around 90%. If enzymes then cut that protein into smaller pieces, the name is hydrolysate.
Protein in the dried powder
Once the water is gone, a small scoop of powder can list a lot of protein. The grams look high because the water is no longer there. If the label gives protein for one serving, use that number. If it gives protein per 100 g, multiply by the weight of what you use and divide by 100. A powder at 80 g of protein per 100 g, stirred as a 30 g serving, is 24 g of protein in the glass. A Horlicks Protein sachet is that dried powder, ready to mix. It weighs 36 g and lists 24 g of protein, and the pack says to stir it into 200 ml of cold water or milk. Unflavoured lists fermented yeast protein and whey protein concentrate. Chocolate and Coffee list fermented yeast protein. Use the 24 g the sachet prints.
If the pack says one sachet is a serving, count one sachet. A second sachet is a second serving. The curd comes out before the drying. The thin liquid left after paneer at home is the same kind of leftover, and it is still mostly water. The pouch is that liquid after filtering and drying.
After the powder is mixed, it joins the protein for the day. ICMR-NIN's Dietary Guidelines for Indians, 2024, set that at 0.83 g per kilogram, about 54 g if you weigh 65 kg.1 In the UK the reference for that weight is about 49 g, from 0.75 g per kilogram.2 A serving of 24 g leaves about 30 g of the 54 g for other meals. Half a serving gives you half the protein, because the label is for a full serving.
The Horlicks Protein milkshake is already a drink, not a powder you dry. One 240 ml bottle has 20 g of ultra-filtered milk protein, and that is what you count.
Once the liquid is dried, the weight on the scale is the powder, not the jug it came from. A label that says 80 g of protein per 100 g is describing that dried powder. One sachet weighs 36 g. If the label says 80 g of protein per 100 g, that sachet is about 29 g of protein. If the sachet already says 24 g of protein in 36 g, use 24 g.
In summary, you start with milk set for cheese or paneer. The curd keeps the casein. The liquid that drains off still has protein in it, with lactose, a little fat and minerals. Filter that liquid and dry it, and you have a powder you can scoop or pour from a sachet. If the pack already prints the protein for one serving, use that number. On a Horlicks Protein sachet, the serving is 24 g of protein in 36 g.
Sources
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ICMR-National Institute of Nutrition. Dietary Guidelines for Indians, 2024.
View ICMR-National Institute of Nutrition. -
British Nutrition Foundation. Nutrition requirements, Reference Nutrient Intake for protein, from the 1991 UK Dietary Reference Values.
View British Nutrition Foundation.