What is Whey Powder (Partially Demineralized)?
Whey powder is simply fluid (sweet) whey that has had most of the water removed. It is added to infant formula to provide protein, lactose, fat, and minerals.
Cow and goat milk contain more minerals – calcium, phosphorus, and magnesium – than human milk. Whey powder that is partially demineralized has had a portion of these minerals removed. No other changes are made to the whey powder. As a result, demineralized whey powder has more lactose per gram than whey that has not been demineralized. Manufacturers adjust their recipes to account for the difference in minerals and lactose that comes with using this product.
Why is Whey Powder Added to Infant Formulas?
While there is a wide range of proteins in mammalian milks, two classes predominate: caseins and whey. In human milk, the proportion of casein to whey changes as the infant grows. Early milk is 70-80% whey and decreases to 50-60% within a few weeks. Mature cow milk that is used to make dairy ingredients is about 18-20% whey. Thus, manufacturers add whey to balance out the ratio of casein to whey in order to mimic that of human milk. Given that the percentages change as the infant grows, age-specific formulas (e.g. newborn, Stage 1) have higher percentages of whey.
While the proportional differences of whey to casein have been long known, newer analysis methods are starting to question this view, suggesting that casein levels may be lower than believed. In-depth analysis of specific proteins in each class contribute to this renewed focus on casein and whey. One study, for example, found that 37 out of 166 common proteins in human milk differed between women of different ethnicities over the course of lactation.
Dietary Considerations
Whey powder partially demineralized is not appropriate for vegans since it is derived from fluid milk. It is acceptable for vegetarians who drink milk (lactovegetarians). The OU (Orthodox Union) Kosher considers many infant formulas as OU-D, but not Kosher for Passover. Since whey powder partially demineralized is derived from fluid milk, it is not Cholov Yisroel unless specifically certified as such. For reference, see the Orthodox Union Kosher Dairy Primer.
Interested in learning more about whey? Next, explore What Is Whey Protein Hydrolysate?