January 23, 2017—Creating successful protein beverages was the topic of the presentation, “Formulating Protein Beverages: Real World Challenges & Tactical Solutions,” given by Justin Cline, Senior Beverage Scientist at Imbibe. Cline first reviewed protein chemistry and functionality basics.
Protein molecules are either hydrophobic, hydrophilic or electrically charged. When a protein molecule carries a charge, the molecules repel each other in solution. But, by adding acids or bases and bringing the proteins to a net 0 charge (isoelectric point), the molecules are attracted to each other; clump together into a solid mass; precipitate; and fall out of solution.
In beverages, the pH of the isoelectric point should be avoided, as precipitation is not desirable. “Protein properties can be harnessed to build viscosity or create emulsions, or these properties can be detrimental when causing clouding or grittiness in a beverage,” Cline explained.
He advised to determine early the desired protein level and source. The trend is toward packing as much protein into a beverage as possible, but too much can cause issues. “When suspending protein, gums are helpful; for a charge issue, adjusting pH can work. As carbohydrates increase, so does viscosity, and reducing sugars may cause browning. Homogenization can mechanically alter protein structure. These are all issues for consideration,” advised Cline.
Vitamins, minerals, salts, whole grains and other solids all have potential to negatively interact with proteins, especially at higher levels. During processing, order of addition and pH monitoring are key. Emulsions and physical stress on the protein can alter its functionality, and hydration of the protein is very important. Protein is very sensitive to heat, which causes denaturation; and upon cooling, gelling and thickening.
Cline offered several case studies for consideration. “In an average nutritional shake with 3-4% protein, neutral pH (6.6-7) and that uses casein, the protein’s isoelectric point is avoided,” Cline shared.
He recommended grouping ingredients according to their properties during processing. Protein and hydrocolloids should be left on their own to hydrate properly. Vitamins and minerals should be separated from other solids to avoid interactions. In addition, fractionating the water during production is important. Most of the water should be kept for hydration of the protein, for at least 20 minutes. The rest of the water is best retained for hydrating other ingredients, like hydrocolloids.
Each ingredient needs to hydrate separately and completely, so they do not compete for water. This ensures good ingredient functionality, proper stabilization and no grittiness. Cline recommended keeping 5-10% of the water to adjust total solids at the end of processing.
In higher solids beverages, the same rules apply, but interactions with protein are more likely. Commonly used whey proteins are prone to denaturation and thicken at higher temperatures/longer times. “Adjust pH lastly, after everything is added and total solids are adjusted,” Cline instructed. “The whole batch should then be allowed to come to equilibrium and then the pH checked again. It is important to allow an acid or base to completely mingle with the protein.”
“In high-acid clear beverages with whey protein isolate,” advised Cline, “make sure the protein is completely hydrated, the pH is below 3.5 and few other ingredients, just sweeteners and flavors, are used.”
Beverage stability over time is heavily dependent on protein denaturation. The product may look great when first made, but over time, the denatured protein can build a very unpleasant web or haze that looks like mold.
To summarize a few points, Cline stressed understanding a processing plant’s capabilities. Know that heat processing and protein denaturation release cooked and sulfur notes that mellow over time, as protein reaches equilibrium in a few weeks. Therefore, he recommends refraining from formula changes until the product has properly aged. Also, ask suppliers for information on ingredients, and share as many product and processing details with them as possible—since that aids their understanding in how to help. Cline also urges that shelflife studies be completed before commercialization, as proteins change over time.
“Formulating Protein Beverages: Real World Challenges & Tactical Solutions,” Justin Cline, Senior Beverage Scientist, Imbibe,
The summary above is an excerpt from the “2016 Protein Trends & Technology Magazine: Formulating with Proteins.”