Whey Protein Isolate (WPI)

Whey protein isolate is the top of the whey ladder. The ADPI Whey Protein Isolate Standard v4.0 defines it as whey from which enough non-protein constituents have been removed that the finished dry powder holds at least 90% protein on a dry matter basis, produced by membrane filtration and/or ion exchange. The practical consequence of pushing protein that high is that almost everything else leaves with the permeate: ADPI's typical composition is 90.0–92.0% protein on dry basis (89.5% minimum), 0.5–1.0% lactose, 0.5–1.0% fat with a 1.5% ceiling, 2.0–3.0% ash and 4.0–5.0% moisture. That is a fraction of the lactose and fat carried by even a WPC 80, which is what buyers are paying the premium for. The two production routes give measurably different material. Cross-flow microfiltration separates mechanically at low temperature and near-neutral pH, leaving the protein largely undenatured and retaining glycomacropeptide and alpha-lactalbumin. Ion exchange separates on charge using acid and base, typically reaching a higher protein figure but stripping glycomacropeptide out entirely, and shifting the mineral balance — more sodium, less calcium. Neither is better in the abstract; they are different specifications, and a buyer formulating a clear beverage, an undenatured claim or a defined mineral profile should name the route in the enquiry rather than accept whichever is cheaper that month. Colour is cream, flavour bland and clean, scorched particles 15.0 mg/25 g maximum. ADPI permits pH adjustment with a food-grade mineral or organic acid or base. Microbiological limits match the WPC standard: standard plate count 30,000 CFU/g maximum, yeast and mould 100 CFU/g maximum, coliforms and Enterobacteriaceae 10 CFU/g maximum, Salmonella, Listeria and coagulase-positive Staphylococcus not detected. Labelling should declare the protein percentage in 2% increments or as the actual assayed figure with the supporting analysis. Typical uses run from clear and opaque protein beverages and sports powders to gelation in yoghurts and puddings, whipping in toppings and fillings, water binding in meat and sausage, and emulsification in ice cream, margarine and mayonnaise. Low lactose is not no lactose — this remains a milk allergen and must be labelled as one.