Masking Off-Notes in High Protein Drinks: The Efficacy of Icon Foods’ MonkSweet™ LS4 Monk Fruit Extract and Steviol Glycosides in Concert
by Thom King, Icon Foods, Chief Innovations Officer/Food Scientist
High-protein ready-to-drink (RTD) beverages represent one of the fastest-growing segments in the functional food and performance nutrition landscape. Consumers ranging from athletes to health-conscious individuals are increasingly seeking convenient, portable, and nutrient-dense formats to meet their daily protein requirements. Let the race to 50 grams of protein per serving begin. In the realm of the 12-ounce RTD delivery system, that is tantamount to packing 10 lbs of potatoes into a 5 lb bag. Protein is the new black and has gained popularity among fitness enthusiasts, individuals seeking convenient nutritional options, but even more, consumers on anti-obesity medications (AOMs) like GLP-1 analogs.
Formulating a palatable high-protein beverage is notoriously difficult. Protein isolates, hydrolysates, branched-chain amino acids (BCAAs), creatine, and adaptogenic botanicals can all contribute to chalky, bitter, metallic, barnyard, or astringent off-notes that undermine the sensory experience.
Artificial sweeteners have historically been used to mask these issues, but they often introduce their own problems—chemical aftertastes, poor solubility, instability during thermal processing, and consumer resistance due to health perceptions. In response, formulators are shifting toward natural, clean-label alternatives that not only replicate sweetness but also act as flavor modulators to mask bitterness, off-notes, and enhance the overall flavor profile.
Monk fruit extract, specifically mogroside V, and some steviol glycosides like the ones found in MonkSweet™ LS4 can mask these off-flavors, enhancing the palatability of high protein beverages, delivering a clean sweetness and preserving desirable flavors.
The Challenge of Off-Notes in Protein Systems
Off-notes in protein beverages stem from the inherent chemical structure of protein-derived compounds. Whey protein isolates and micellar casein can have a milky or sulfuric aftertaste. Plant proteins—particularly pea, rice, and hemp—tend to exhibit grassy, earthy, or beany flavors. Hydrolyzed proteins, while beneficial for rapid absorption and digestive ease, release bitter peptides as a byproduct of enzymatic cleavage.
In addition, many functional beverages are fortified with vitamins, minerals, electrolytes, or nootropics, which further complicate the flavor landscape. Ingredients like magnesium, potassium, green tea extract, or L-carnitine are beneficial nutritionally but contribute metallic, sour, or bitter notes.
To address these multi-source off-notes, formulators must employ sweeteners that do more than provide high-intensity sweetness. They must interact synergistically with taste receptors to modulate bitterness perception, enhance mouthfeel, and stabilize sweetness delivery across a wide pH range and temperature.
MonkSweet™ LS4: A Synergistic Solution
Icon Foods’ MonkSweet™ LS4 was developed specifically to meet these formulation challenges. This proprietary blend combines high-purity monk fruit extract (mogroside V) with advanced steviol glycosides (primarily rebaudioside M). The result is a synergistic sweetener system that acts as both a sugar replacer and a comprehensive taste modulator.
Key Functional Benefits:
- Bitterness Masking: The combination of Reb M and mogroside V offers rapid sweetness onset and effectively blunts early-stage bitterness from hydrolyzed proteins and amino acids.
- Clean Finish: Unlike Reb A or lower-grade monk fruit, LS4 delivers a smooth dissipation of sweetness with minimal residual taste.
- Sweetness Synergy: When paired with sucrose, erythritol, allulose, or soluble fibers, MonkSweet™ LS4 completes the sweetness curve, closely mimicking sucrose without introducing glycemic load.
- Low Usage Rate: Due to its high potency, MonkSweet™ LS4 is used at very low inclusion rates, leaving room for other functional ingredients and simplifying labeling for regulatory compliance.
below is a chart detailing how much MonkSweet™ LS4 (as a percentage of total formula weight) is needed to achieve sugar reductions from 10% to 90%.
| Target Sugar Reduction (%) | MonkSweet™ LS4 Required (% of Total Formula) |
| 10% | 0.03% |
| 20% | 0.07% |
| 30% | 0.10% |
| 40% | 0.13% |
| 50% | 0.17% |
| 60% | 0.20% |
| 70% | 0.23% |
| 80% | 0.27% |
| 90% | 0.30% |
Mechanism of Action
Steviol glycosides like Reb M selectively bind to human sweetness receptors T1R2 and T1R3, triggering a strong and clean sweetness response. Unlike older glycosides like Reb A or stevioside, which can also stimulate bitter taste receptors (TAS2R family), Reb M shows minimal off-target activity, resulting in a purer sensory signal.
Mogroside V, the active sweetening compound in monk fruit extract, complements this mechanism by modulating the onset and longevity of the sweetness perception. When combined in the precise ratio found in MonkSweet™ LS4, the result is a sweetening system that not only delivers high-intensity sweetness but also disrupts the neurological perception of bitterness.
By preemptively activating sweet receptors and dampening the response to bitter stimuli, MonkSweet™ LS4 functions at the neural integration level, masking undesirable flavors before they are registered by the brain. This mechanism is particularly effective in beverages with complex matrices such as high-protein drinks, where multiple bitterness vectors are present.
Application in High-Protein Beverages
In sensory trials and real-world applications, MonkSweet™ LS4 has been shown to significantly enhance flavor profiles in RTD beverages containing:
- 30g whey protein isolate
- Pea/rice protein blends (20–25g)
- Hydrolyzed collagen peptides (15–20g)
- Creatine monohydrate (3g)
- BCAAs or EAAs (5–8g)
- Functional additives (e.g., magnesium, ashwagandha, green tea extract)
Results across various formulations demonstrated a 40–60% reduction in perceived bitterness, improved overall sweetness quality, and greater consumer acceptability. Many brands were able to eliminate additional bitter blockers or acidity regulators from their ingredient panels as a result.
MonkSweet™ LS4 also demonstrated excellent pH stability (2.5–7.5), high solubility in both hot and cold fill applications, and no adverse interactions with protein denaturation or emulsification agents.
MonkSweet™ LS4 represents a new generation of natural sweeteners—one that does more than reduce sugar. It actively transforms the sensory experience of high-protein beverages by masking bitterness, smoothing sweetness delivery, and enhancing overall flavor harmony.
For formulators striving to deliver clean-label, great-tasting, and functionally rich RTDs, MonkSweet™ LS4 is a strategic asset. Its advanced blend of monk fruit and steviol glycosides provides a scientifically validated pathway for overcoming one of the most persistent challenges in nutritional beverage development.
As the demand for high-protein, low-sugar products continues to accelerate, and consumers become increasingly discerning about taste and label transparency, MonkSweet™ LS4 is well-positioned to be the go-to ingredient for next-gen product innovation.
As the high-protein market continues to evolve, it presents significant opportunities for Icon Foods and our treasured customers to pave the way for more sustainable and health-focused food ingredients. MonkSweet™ LS4, the perfect combination of V50 monk fruit extract and organic RM95 stevia leaf extract, makes sweetening high protein products a cinch.
Reach out to your Icon Foods representative for MonkSweet™ LS4, samples, documentation formulation and usage guidance.
Since 1999 Icon Foods has been your reliable supply chain partner for sweeteners, fibers, sweetening systems, inclusions and sweetness modulators.
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