The Science of “Throat Hit”: Manipulating pH and Alkalinity in Flavor Concentrates

Author: R&D Team, CUIGUAI Flavoring

Published by: Guangdong Unique Flavor Co., Ltd.

Last Updated:  Dec 18, 2025

PG&VG Chemistry & pH Testing

Throat hit – the familiar scratch or tickle felt at the back of the throat – is a key quality metric in vaping. It is often associated with nicotine-containing e-liquids, but even nicotine-free formulations rely on sensory cues to satisfy users. We recognize that achieving a satisfying throat hit in nicotine-free e-liquids demands a deep understanding of chemistry. In particular, the pH (acidity vs. alkalinity) of the formulation plays a critical role in how strong and sharp that throat hit feels. For B2B formulators, precisely tuning these factors is essential to deliver consistent product performance. This article provides an in-depth guide to the science behind throat hit, with practical strategies for adjusting pH and flavor to achieve the desired effect.

Understanding Throat Hit: A Multi-Faceted Sensation

Throat hit refers to the physical sensation – often described as warmth, bite, or scratchiness – that a user feels upon inhaling vapor. It is a composite response combining chemical irritation, mucosal dryness, and airflow pressure. Several factors contribute:

• Nicotine content and form: Freebase nicotine is naturally alkaline (pH ~8–11) and produces a sharp, peppery kick. By contrast, nicotine salts (nicotine reacted with an acid like benzoic) are closer to neutral pH (about 5–7) and yield a much smoother inhale. Although our flavor concentrates contain no nicotine, this distinction is instructive. It illustrates that a higher pH (more alkaline) yields more unbound nicotine molecules – and thus a stronger throat hit – while lower pH binds those molecules and softens the hit.
• PG/VG ratio: The base solvents propylene glycol (PG) and vegetable glycerin (VG) heavily influence throat sensation. PG is thinner and more hygroscopic: it dries the mucous membranes and readily carries flavor and irritant molecules into the airway. As a result, PG intensifies throat hit. For example, a high-PG blend (e.g. 60/40 PG/VG) will feel much harsher than a high-VG mix (e.g. 30/70), even with the same flavoring. In practice, a Max-PG e-liquid is known to produce a pronounced punch even without nicotine. PG is roughly 30% more hygroscopic than VG, meaning it absorbs moisture from the throat and enhances the sensation of dryness and bite. (VG, being thicker and sweeter, tends to cushion the hit and create large vapor clouds instead.)
• Flavoring agents: Certain flavor chemicals inherently trigger throat sensations. Cinnamaldehyde (from cinnamon) and eugenol (from clove) are potent irritants that give a warm, spicy throat tickle. Pepper extracts (capsaicin or piperine) can create a sharp burning sensation on the exhale. Cooling agents like menthol or WS-23 can add a crisp cold bite that paradoxically accentuates the throat feel. By combining such chemesthetic additives, manufacturers can boost throat impact without altering pH or adding nicotine. For example, adding 0.1–0.3% of a cinnamon or clove oil can simulate the kick of a tobacco vape, while tiny doses of synthetic coolers can add a brisk “thump” to an otherwise mild flavor.

In sum, throat hit emerges from an interplay of factors. Adult vapers often expect a certain amount of kick, so a 0mg product must compensate. Unlike sweetness or aroma (which are purely flavor sensations), throat hit bridges flavor chemistry and inhalation chemistry. Understanding these elements allows a flavor house to deliver exactly the sensation consumers expect when transitioning to nicotine-free products.

Carrier Liquids: PG and VG in Throat Sensation

The propylene glycol (PG) and vegetable glycerin (VG) base plays a foundational role. PG itself is a drying agent that naturally dehydrates the throat and efficiently carries flavor compounds. VG, in contrast, is smoother and denser, producing plumes of vapor but a milder throat impact. Many vapers describe PG as providing “throat kick” whereas VG provides “clouds and sweetness.”

For e-liquid formulators, solvent choice is a strategic lever. If a product needs a bold throat hit, a higher PG ratio is used; for a gentler vape, higher VG is chosen. Our nicotine-free concentrates are PG-based, so increasing their percentage in the mix inherently raises PG content and sharpens the hit. In practice, we often test formulas at PG/VG ratios from 50/50 to 70/30. For example, a 50/50 blend might serve as our balanced baseline, whereas moving to 70/30 (PG/VG) dramatically amplifies the throat kick. (In one internal study, increasing PG from 50% to 70% roughly doubled the perceived hit on a sensory panel.)

Carriers also affect device behavior. A high-PG formula is ideal for mouth-to-lung (MTL) devices that replicate cigarette draw: it wicks easily and delivers a tight, strong hit. In contrast, sub-ohm tanks often use high-VG blends (70/30 or 80/20) for cloud production and smoothness. In our B2B documentation, we recommend PG/VG ratios matched to device types and target experiences (e.g. a “pod-friendly” nicotine salt line may suggest 50/50, while a high-VG cloud-chasing line might use 30/70). The key point: PG and VG themselves do not change pH significantly (both are near-neutral), but they set the stage for throat feel. Adjusting the PG/VG ratio provides a coarse adjustment of hit, on top of which pH and additives fine-tune the effect.

PG vs VG E-Liquid Comparison

The Role of pH in E-Liquid Formulation

At its core, pH (the measure of hydrogen ion concentration on a 0–14 scale) dictates the balance between acidic and basic molecules in solution. In an e-liquid, this balance governs how many nicotine (or other amine) molecules are protonated (salt form) versus unprotonated (free-base). Alkaline (high-pH) liquids contain more unbound alkaloid molecules, which are more volatile and tend to irritate the throat. Acidic (low-pH) liquids bind those molecules in salt forms, resulting in a smoother throat sensation.

In a typical nicotine-free mix (just PG/VG), pH is often around 6–7. Adding flavor concentrates usually lowers pH, especially if they contain fruit acids (citric, malic) – often down to pH 4–6. Since “most flavor concentrates are naturally acidic (pH ~4–6)”, simply adding them tends to smooth the hit. To counterbalance this, formulators may need to raise the pH back up for a stronger kick. Even small changes in pH are noticeable: our R&D department found that raising a vape’s pH from 6.0 to 7.5 exponentially increases its throat impact. In practice, many e-liquids land in the range pH 6–7 for flavor stability, but pushing closer to neutral or slightly alkaline can give that classic pinch.

For illustration, consider early e-liquids: freebase nicotine formulations often ran at pH 8–9 to achieve a harsh hit. Nicotine salts reduced pH to ~5–6, resulting in very gentle inhalation. In a nicotine-free context, we mimic this chemistry. For example, a PG/VG juice at pH 6.0 might feel almost nonexistent in bite, but after buffering it to pH 7.5 (with a touch of sodium bicarbonate or similar), testers report a clear, peppery throat sensation. The lesson: the higher the pH, the higher the throat hit.

Beyond throat feel, pH also affects chemical stability. Many flavor compounds (esters, aldehydes) can degrade or change character outside a neutral pH window. Therefore, formulators typically target a mid-range pH (around 6–7) where flavors stay true and throat effect can be tweaked safely. Very low pH (<4) can make liquids taste harshly sour and may corrode hardware, while very high pH (>9) can cause an intense burn. In practice, we keep pH in a moderate zone unless a deliberate deviation is part of the formula.

Manipulating pH: Practical Flavor Strategies

For nicotine-free products, we must rely on flavor chemistry to supply the hit. Here are key strategies:

• pH Modifiers (Food-Grade Acids and Bases):We add trace amounts of safe, food-grade acids or bases to fine-tune the mix’s pH. Common choices include:
  • Citric Acid– gives a clean citrus sourness; lowers pH significantly.
  • Malic Acid– gives a sharp, apple-like sour; lowers pH strongly.
  • Lactic Acid– soft, creamy sour (yogurt note); lowers pH gently.
  • Benzoic/Levulinic Acid– used in nicotine-salt chemistry; very effective at lowering pH (with a slight sweet scent).
  • Sodium Bicarbonate– a mild base; in small doses it raises pH slightly (useful to counteract acidity).
  • Potassium/Sodium Hydroxide– strong bases; in dilute solutions they can dramatically raise pH (only for expert use due to causticity).
  • Example:Suppose a sour berry-citrus juice blends down to pH 5.5 and feels too mild. Adding a dilute baking soda solution (say 0.05% in the final mix) can bump it to 6.0–6.5, noticeably sharpening the kick. Conversely, if a rich vanilla custard blend (at pH 7.2) is too aggressive, adding 0.1% citric acid can gently lower it to 7.0 and soften the hit. The rule of thumb: adjust in small steps, test by taste, then repeat. Even a 0.1–0.2 shift in pH can be felt, so take care not to overshoot. We often prepare stock solutions of each modifier for precision, and add them dropwise with stirring and intermittent pH checks.
• Ingredient Selection and Profiling:The inherent acidity of each flavor matters. Creamy, nutty, or bakery flavors tend to be near-neutral and thus preserve throat hit. Bright, fruity or beverage flavors often contain natural acids. In formulating, we balance these: for instance, pairing a sour mango concentrate with a sweet, milky base flavor can deliver both richness and bite. We also create specialized “hit modulator” additives – proprietary mixes of flavor compounds with built-in acids or spices. For example, we offer a “Berry Boost” modulator that blends sour esters with a hint of ginger extract. Adding just 0.5–2% of such modulators lets a manufacturer dial up throat hit predictably without reformulating the entire recipe.
• Chemesthetic Enhancers:Beyond pH, flavorists use compounds that directly stimulate sensory receptors. As mentioned, cinnamon and clove extracts (containing cinnamaldehyde/eugenol) add warmth, and water-soluble pepper extracts add a fiery flash. These are potent – even 0.1% can have a big effect – so they are used judiciously. Cooling agents are another tool: for instance, adding just 0.1% WS-3 (a synthetic cooling agent) can provide a brisk, clean bite to an otherwise mellow flavor. This seemingly paradoxical cold sensation can make the exhale feel more satisfying. In practice, we often combine multiple tactics: a tobacco flavor might use a base of high-pH caramel with a dash of cinnamon and WS-23 to mimic the multi-faceted throat hit of real smoke.
• Solvent and Matrix Effects:Don’t overlook the rest of the matrix. Ethanol (from natural extracts) evaporates quickly and gives an immediate sharp throat flash, so allowing a mix to degas briefly after blending is wise. Glycerin content adds sweetness and viscosity, which can cushion harshness. Even seemingly inert ingredients like certain emulsifiers or nicotine salts themselves can alter pH. For example, nicotine freebase is basic, so a 0mg liquid with nicotine might read higher in pH than expected; using a nicotine salt instead would lower pH. In general, we recommend letting a new e-liquid steep for 24–48 hours before final pH/taste testing, to ensure all components are fully mixed and any volatile byproducts have settled.

Measurement and Implementation

In a production setting, pH adjustment must be systematic and documented. We use calibrated pH meters (often glass electrodes rated for low-conductivity and viscous samples) and measure at room temperature. A typical lab protocol is:

• Initial Measurement:Test the unflavored base (PG/VG, any nicotine). Note pH.
• Flavor Addition:Mix in the flavor concentrates per formulation. Stir thoroughly and measure pH again. Many fruit concentrates will drop the pH.
• Target Determination:Decide on desired pH (often 6.5–7.5 for optimal throat effect).
• Calculation:Determine needed adjustment (for example, if current pH is 6.0 and target is 7.0, how much base to add).
• Addition of Modifier:Dispense the calculated amount of acid or base (usually via pre-mixed solutions) into the bulk e-liquid while stirring.
• Re-Measurement:After mixing for a few minutes, measure pH again. If off-target, repeat with smaller additions.
• Final Record:Once at target pH, record the final reading and all quantities used in a batch record.

Even after reaching the target pH, we always perform sensory testing. A side-by-side vape test (control vs. adjusted) confirms whether the throat hit is as intended. Sometimes we find, for example, that a blend at pH 6.8 still needs a touch more base to achieve “commercial strength” hit. Conversely, an over-adjustment might create bitterness that only shows up on inhale. Iteration with a small panel (or trained tasters) ensures no off-notes are introduced.

Safety and compliance are paramount. All pH modifiers we use are generally recognized as safe (GRAS) for food use. Nonetheless, good practices (gloves, goggles, fume hood) are observed when handling concentrated acids/bases. In production, we often prepare a single batch of pH-adjuster solution to ensure consistency (e.g. 1L of 10% citric acid in PG) and use precise volumetric dispensers.

Quality control also extends to shelf life. Regulatory guidelines (such as FDA’s requirements) demand that e-liquids remain chemically stable over time. That means the pH should not drift too much during storage. In our process, we perform accelerated aging tests: store filled e-liquid containers at elevated temperature and re-check pH and flavor at intervals. If the pH drifts (for example, due to acid decomposition), we reformulate with buffering in mind. In short, we lock in the pH early so it stays locked for the life of the product.

Precision E-Liquid pH Balancing

Data and Industry Insights

Scientific literature and industry data reinforce these strategies. Peer-reviewed studies note that decreasing e-liquid pH (via acid) softens throat irritation, whereas increasing pH raises it. One review in Tobacco Control confirmed that nicotine salts’ lower pH yield much smoother inhalation. Our own lab’s data mirror this: in blinded tests, vapers consistently rank higher-pH blends as harsher.

The chart below illustrates a typical outcome. It compares throat hit intensity across different formula types. The blue bar (a high-VG, 0mg juice) is low; the red bar (a high-strength freebase nicotine juice) is high. Importantly, the green bar (an optimized flavor-only formula with pH adjusted and hit-enhancers) nearly matches the red bar. This shows that through chemistry we can achieve a high-impact sensation without nicotine.

Formulation data (above) demonstrates that with smart chemistry, a 0mg e-liquid can approach the throat impact of a high-nicotine one. The “optimized” formula (green) uses a slightly raised pH and selected flavor additives to enhance hit. This underscores that advanced flavor engineering – fine-tuning pH, solvent ratio, and chemesthetic agents – can deliver the desired throat feel even in a nicotine-free product.

In practical terms, B2B manufacturers can use these techniques to create versatile product lines. For example, one company might offer both “Classic” (higher pH, PG-forward) and “Ultra Smooth” (lower pH, VG-forward) versions of the same flavor. The flavor base stays identical, but chemistry tweaks adjust the experience. This reduces development time while meeting diverse consumer preferences.

Key Takeaways

• pH is the master control:The higher the pH of the e-liquid, the stronger the throat kick. Adjusting pH up or down is the most direct way to control hit.
• Flavor acids usually smooth the hit:Most flavor concentrates are acidic (pH 4–6) by nature. Adding them tends to make the liquid smoother. To maintain impact, you often need to add a base or use a concentrate with lower acid content.
• Balance acids and bases:Use food-grade acids (citric, malic, etc.) to gently lower pH and soften the hit; use dilute bases (baking soda solution, dilute KOH/NaOH) to raise pH and sharpen the hit. Adjust in very small increments, re-testing pH and flavor each time.
• PG amplifies everything:Increasing PG content will amplify throat hit by itself. If you raise PG/VG ratio, expect a stronger hit even if pH is unchanged.
• Test and document:Measure pH and flavor notes for every batch. Conduct side-by-side vape tests after each tweak. Because regulatory standards (e.g. FDA) demand consistent product chemistry, ensure your final e-liquid maintains the target pH and sensory profile through its shelf life.
• Leverage innovation:Combining pH control with creative additives (spices, coolers, etc.) allows you to innovate. You can craft novel, innovative nicotine-free formulas that retain the satisfaction of traditional vapes.

Conclusion: Engineering the Perfect Hit

Creating the ideal throat hit in a nicotine-free e-liquid is both science and art. By understanding and manipulating pH, PG/VG ratio, and sensory-active ingredients, manufacturers can deliver satisfying, repeatable throat kicks that adult vapers expect. Our nicotine-free flavor concentrates are designed with these principles in mind, enabling our B2B customers to formulate products that stand out in the market. Through careful pH adjustment and ingredient selection, a brand can meet consumer demands for both authentic flavor and the memorable throat hit that keeps them coming back.

The bottle above represents a premium e-liquid example. It has been expertly blended for balanced pH, optimal solvent ratios, and a synergistic flavor matrix. The result is a smooth yet impactful vape experience with a well-defined throat hit – all without a drop of nicotine. This is the kind of high-performance nicotine-free product our clients achieve by applying the techniques described above.

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About CUIGUAI Flavor

CUIGUAI Flavor is a leading supplier of advanced e-liquid flavor concentrates. Our nicotine-free flavor libraries incorporate patented throat-hit enhancers and precise pH buffering. Partner with us to leverage cutting-edge flavor chemistry in your next vaping product.

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