Milk protein concentrates are dairy ingredients processed to increase the ratio of protein to other milk solids — typically through ultrafiltration of skim milk — resulting in products with protein content ranging from roughly 40% to over 85% on a dry basis. They are distinct from whey protein concentrates (classified under 040410) because they retain the full casein-to-whey protein ratio of milk rather than the whey-dominant profile of cheese byproduct streams.

A binding ruling is advisable whenever a dairy ingredient has been processed beyond standard concentration or drying — for example, through enzymatic modification, fractionation into individual caseins, or blending with non-dairy components — because such processing can shift classification out of Chapter 4 entirely into Chapter 35 (casein, albumins) or Chapter 21 (food preparations). A ruling provides certainty before commercial volumes are committed and avoids post-entry reclassification penalties.