Formulating Protein Beverages: Whey Concentrate, Isolate, and Plant Protein in RTD Applications

The RTD Challenge

A protein powder that performs well in a dry shake or capsule may behave entirely differently dissolved in water at 4% solids, processed to 72°C for 15 seconds, and held in a refrigerated supply chain for four weeks. Protein stability in liquid is influenced by pH, temperature history, mineral content, and the presence of fats and carbohydrates — and each protein type brings its own profile of sensitivities.

WPC 80% in RTD Beverages

Whey Protein Concentrate at 80% protein is the most cost-effective option for standard, opaque, pasteurized RTD shakes. Its retained fat and lactose content contribute to a creamier mouthfeel relative to isolate, which can be an advantage in mainstream dairy-positioned products. The challenges:

• Heat stability: WPC has moderate heat stability. Standard pasteurization (HTST: 72°C/15s) is generally tolerable; UHT processing (135–145°C for a few seconds) is more demanding and can cause protein aggregation and sediment if pH and ionic strength aren't tightly controlled.
• Clarity: WPC is not suitable for clear or translucent beverage formats. Its fat and lactose content will produce a cloudy or opaque product.
• Fat oxidation: The retained fat fraction makes WPC-based RTDs somewhat more susceptible to off-flavor development over shelf life; antioxidants and appropriate packaging are relevant considerations.

WPI in RTD Beverages

Whey Protein Isolate is the preferred choice when the formulation requires higher protein density, a cleaner label (lower fat/lactose), better heat stability for UHT processing, or a less opaque appearance. Its reduced fat content significantly improves oxidative stability relative to WPC.

Research by Arla Foods Ingredients and others in the dairy protein industry has demonstrated that WPI at typical RTD protein concentrations (5–10%) can be processed under UHT conditions with appropriate pH control (generally targeting pH 6.5–7.0 for optimal heat stability) and the right choice of mineral/salt content.

The primary trade-off is cost and, in some formulations, a slightly thinner mouthfeel that may need to be compensated by texture modifiers (starches, gums, or pectins) depending on target consumer experience.

Pea Protein Isolate in RTD Beverages

Plant-based RTD formulation is the fastest-growing segment of the category, and pea protein isolate has become the dominant plant protein for it. The challenges are different in character from whey:

• Flavor: Pea protein can carry beany, earthy, or grassy off-notes depending on the grade and processing. These are most perceptible at higher protein concentrations in neutral-flavored or lightly flavored products. Flavor masking agents, higher-impact flavors (chocolate, vanilla), and enzyme treatment of the protein are strategies formulators use to manage this.
• Sediment and mouthfeel: Pea protein suspensions can settle faster than whey-based products and may have a slightly grainy or chalky mouthfeel at higher concentrations. Hydrocolloid stabilizers (xanthan gum, pectins, or carrageenan) are commonly used to manage this.
• Heat stability: Pea protein is generally heat-stable and can tolerate UHT processing conditions, which is one of its formulation advantages over some other plant proteins.
• pH: Pea protein's solubility can be affected by pH — at near-neutral pH it generally performs best; acidic beverages can cause precipitation.

Application Decision Matrix