The phrase "a proprietary blend" is correct and usable in written English.
It is typically used in contexts related to food, beverages, supplements, or cosmetics to describe a unique mixture of ingredients that is owned by a company and not disclosed to the public.
Example: "This protein powder contains a proprietary blend of amino acids designed to enhance muscle recovery."
Alternatives: "exclusive mixture" or "unique formulation".
"A bunch of stuff —— " Ms. Rohe broke in: "A proprietary blend of material".
(The scent has been described as "a proprietary blend of essential oils that create a sense of abundance and joy").
Lobster may generally be for tourists, but the grilled lobster tails, with corn, wax beans, and cherry tomatoes, are transfigured by a sweet, cinnamony seasoning — what Silverman calls, half-seriously, "a proprietary blend of spices".
Mr. Endsley and Mr. Wood are best known for their work in Kneebody, a groove-minded band that draws from myriad sources, ending up with a proprietary blend of electro-acoustic chamber jazz.
In the upcoming season of "Orange Is the New Black" — another series with a proprietary blend of crudity and humanism — one episode revolves around the women's desperate need for sanitary napkins, which the privatized prison has deemed "nonessentials".
Because the formula for Hydroxycut has changed over time and because the product contains different amounts of a proprietary blend of ingredients, the agency said it had not yet determined which of the product's ingredients might constitute a health hazard.
Whatever the reason, KFC has reintroduced its Kentucky Grilled Chicken menu offerings (slow-grilled and marinated in a secret proprietary blend of herbs and spices) previously introduced in 2009 and soon withdrawn after disappointing sales.
Bill Stanley, a vice-president of the construction company that owns the quarry, told me, "We make a customized, proprietary blend of horse-footing sand, and we're sending it all over New York State and out to the Rocky Mountains.
Its crust was faintly lambent, aglow with some ineffable crispy glaze, which harbored visibly intact crystals of sea salt and an evidently proprietary blend of coarsely chopped herbs that certainly included rosemary and dill, among less immediately identifiable vegetative bits.
The increase in REE might have been due to a 340-mg proprietary blend of caffeine anhydrous, guarana, yerba mate and green tea extract.
When the vineyard goes into full production, the Schneiders' planned centerpiece will be 2,000 cases a year of a cabernet franc-based proprietary blend.
