The 5 Steps to Achieving Shelf-Stable, Clear Protein Beverages

By Silke Rinsma

Food Technologist

In the evolving world of beverages, clear, protein-rich drinks are becoming increasingly popular among health-conscious consumers. These beverages offer a refreshing and nutritious option post-workout or throughout the day. However, achieving a clear, shelf-stable protein drink involves navigating several complex formulation challenges. From selecting the right protein source to optimizing processing methods; each step is crucial for ensuring both clarity and a refreshing mouthfeel. This guide outlines the five essential steps to successfully develop a clear, high-protein beverage that meets both consumer expectations and industry standards.  

1. Select the right protein source

For a protein beverage to appear clear, it is essential that the proteins dissolve well. The presence of tiny particles or aggregates (> 0.1 µm) will make a drink appear turbid because the particles refract and scatter light. Plant proteins have the tendency to form aggregated structures which are not soluble and refract light, making them unsuitable for clear beverages. One way of making plant proteins soluble is through hydrolysis, which essentially degrades them into smaller peptides, also resulting a clear beverage. However, hydrolysed protein can impart a bitter flavor to the product. In the case of hydrolysed plant proteins (2), clarity largely depends on the degree of hydrolysis, the size of the peptides and the tendency of these peptides to interact.

Most clear beverages are made with whey protein in some of its purest forms, as other residuals like milk fat in a whey protein concentrate would cause turbidity. Beta-lactoglobulin (BLG) is the most abundant protein in the whey complex. In its pure form, BLG is completely clear in liquid and can be obtained from milk or sustainably sourced through precision fermentation.  

In general, consumers are looking for more food and beverage options that align with their values & diets without compromising on taste, nutrition or price. Plant proteins do not always meet the taste or technical requirements, such as clarity or a low viscosity, to give consumers the experience they are looking for. BLG from fermentation is the main whey protein in its purest form, which has all the advantages of whey protein and is and is sourced through precision fermentation, which is much kinder to animals and the planet

2. The perfect concentration  

Increasing the protein concentration in beverages can be challenging, as upon destabilizing conditions such as higher temperatures, proteins will more easily interact with each other and form aggregates. Not only do high concentrations affect clarity, but they can also affect viscosity and mouthfeel (1). Aggregated proteins can cause graininess(1), whereas smaller, functional proteins can start to gel after exceeding a critical concentration, and consequently give an unpleasant mouthfeel.  

Choosing the right protein can help achieving high concentrations, which typically relates to a high solubility, low reactivity (e.g., as a result of electrostatic repulsion) and  a good mouthfeel. In a clear, refreshing protein beverage, while the limits of stability are much higher, a protein concentration of about 4% is commonly seen, and ideal from a viscosity and mouthfeel perspective.  

3. The right level of acidity  

Most clear protein beverages on the market have very low pH (i.e., around pH 3), which is needed to achieve clarity, and pairs well with the commonly used fruity flavors . The downside is that the acidic pH required causes the beverage to become sour and sometimes astringent. At neutral pH, there is less astringency (3) and the mouthfeel is lighter. At a slightly acidic pH (e.g., pH 5) the protein is close to its isoelectric point, which means that the net charge is close to zero, and the protein will have a tendency to interact and aggregate.  

For native whey proteins or BLG specifically, the tendency to interact at the isoelectric point is lower, and reversible.  This is also reflected in a high solubility of native BLG (4) across the full pH range, with high clarity at both acidic and neutral pH, offering more formulation flexibility to accommodate various flavors.  

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Figure 1: Turbidity (NTU) of 5% whey protein isolate (green) and Vivitein^TM BLG (blue) solutions estimated from absorption at 750nm.

4. Other important ingredients  

Protein waters typically have short ingredient lists. In addition to the protein, other ingredients typically include flavor, color, sweeteners and sometimes electrolytes. When selecting these ingredients, one needs to make sure they do not cause the ingredients to interact, specifically through electrostatic effects.

Other ingredients in the drink may be poorly soluble and cause turbidity themselves. Examples are certain colors, flavors, or functional ingredients for e.g., foam reduction. Minerals can be added to a protein beverage for nutritional reasons, specifically when aiming for rehydration. When selecting salts (5), consider their solubility. Certain salts, like sodium chloride or calcium chloride dissolve easily in water, while others, like calcium carbonate have much lower solubility and may sediment over time, noticeable as visible sedimentation at the bottom of the bottle.  

5. The adequate heat treatment

Heat treatment is a critical step in beverage production to ensure microbial safety over shelf life, often at ambient temperatures. Heating a protein above its denaturation point causes unfolding and sometimes aggregation, affecting the clarity of the drink. High-temperature short-time (HTST) pasteurization may be preferred as it effectively kills pathogens while minimizing aggregation. Ultra-high temperature (UHT) processing can also be used, but it requires careful consideration of heat load, electrostatic conditions and ingredient interactions to prevent heat-induced protein aggregation.  

By choosing the right heat treatment method (6), manufacturers can produce clear, stable beverages that meet safety standards and consumer expectations.

Conclusion

By following these five steps, you can develop a clear and stable protein beverage. It starts with selecting a high-quality protein, nutritious, functional and sustainably sourced protein such as Vivitein™ BLG. Other important considerations are concentration, pH, other ingredients and adequate heat treatment. By following these steps, beverage manufacturers deliver breakthrough innovation, bringing the New Standard of Crystal-Clear refreshment to consumers who live Protein-Powered Lifestyles.

If you have any questions, feel free to download the clear beverage formulation sheets at our Beverages Page or reach out to the Vivici team for support on your clear beverage development.

Some sources:  

1. Imai, E., Hatae, K., & Shimada, A. (1995). Oral perception of grittiness: effect of particle size and concentration of the dispersed particles and the dispersion medium. Journal of Texture Studies, 26(5), 561-576.  

2. Wouters, A. G., Rombouts, I., Fierens, E., Brijs, K., & Delcour, J. A. (2016). Relevance of the functional properties of enzymatic plant protein hydrolysates in food systems. Comprehensive Reviews in Food Science and Food Safety, 15(4), 786-800.  

3. Beecher, J. W., Drake, M. A., Luck, P. J., & Foegeding, E. A. (2008). Factors regulating astringency of whey protein beverages. Journal of dairy science, 91(7), 2553-2560.  

4. Gbassi, G. K., Yolou, F. S., Sarr, S. O., Atheba, P. G., Amin, C. N., & Ake, M. (2012). Whey proteins analysis in aqueous medium and in artificial gastric and intestinal fluids. International Journal of Biological and Chemical Sciences, 6(4), 1828-1837.  

5. Gerstner, G. (2003). How to fortify beverages with calcium. Food Marketing and Technology, 10, 16-19.

6. Tadini, C. C., & Gut, J. A. (2022). The importance of heating unit operations in the food industry to obtain safe and high-quality products. Frontiers in Nutrition, 9, 853638.  

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