If you’ve ever wondered why your favorite lemon candy tastes bright and zesty in hard form but tastes flat in a chewy caramel, or why a fragrance that smells like fresh linen in a candle feels completely different when added to laundry detergent, you’re not alone. As a flavoring and fragrances supplier, I get this question every single week from formulators across food, personal care, and home goods: how do our products actually interact with the stuff we’re adding them to? It’s not just mixing two liquids together and hoping for the best—there’s a whole science behind why a flavor works in one product and falls short in another, and that’s the detail that turns a good formulation into something customers reach for again and again. Flavoring & Fragrances
Let’s start with the basics that anyone who’s worked in product development can relate to: solubility. Flavors and fragrances are made of volatile compounds—those are the molecules that create scent and taste—many of which are oil-based, not water-based. If you mix an oil-soluble lemon flavor into a water-based soft drink, you won’t get a smooth, evenly distributed taste; you’ll get oily droplets floating on top, or a gritty, inconsistent flavor throughout the beverage. It’s a common mistake new formulators make, and one that our team fixes all the time. For example, a few months ago, a craft soda maker reached out because their new wild berry flavor was separating in their canned product, and the taste was patchy—some sips were too sweet, some had no berry notes, and some tasted bitter from the oil lingering at the can’s bottom. We tested their formulation: it was 90% water, a small amount of citric acid, and oil-based berry flavor, which isn’t designed to dissolve in pure water. We adjusted the flavor to be water-dispersible, using a mild emulsifier that balanced the oil and water without altering the berry’s natural profile, and also tweaked the volatility of key compounds to keep them evenly suspended during the canning process and shelf life. The result? No separation, and every sip tasted like ripe, fresh berries, just like they’d intended. That’s solubility in action, and it’s the first big hurdle we work through with every client.
But solubility isn’t the only factor. pH levels play a massive role in how flavors and fragrances hold up in a product’s environment. Take a tomato-based pasta sauce, for example. Sauces like that have a low pH, usually between 3.5 and 4.5, because of the natural acid in tomatoes. If you add a sweet, floral strawberry flavor to that sauce, it will taste way different than it does in a neutral or slightly acidic yogurt. The low pH breaks down certain volatile compounds in the strawberry: the fresh, green top notes that make it taste like a ripe strawberry will degrade, leaving only the cloying, artificial aftertaste of sugar. We recently worked with a pasta brand that tried adding a “roasted tomato and basil” flavor to their low-acid sauce (which had a pH closer to 5.0) and found that the basil taste faded after a week on shelves, while the tomato notes became overly metallic. Our solution? We formulated the flavor to be stable at low pH, using acid-resistant compounds that don’t break down in acidic environments. For the basil, we added a small amount of a stabilized ester that mimics fresh basil’s key volatile—methyl chavicol—which stays intact in low pH, instead of the more sensitive linalool that would degrade. For the tomato notes, we adjusted the ratio of aldehydes that create that ripe tomato tang, so they don’t turn bitter in acidic conditions. The sauce’s taste stayed consistent for 12 months, exactly what the brand needed for their shelf-stable product.
This same pH rule applies to fragrances too, especially in personal care products. A body wash that’s designed to be gentle on skin has a pH close to our skin’s natural pH, around 5.5, but a laundry detergent has a much higher pH, often 8 or 9. If you take a popular rose fragrance that’s formulated for body wash and add it to laundry detergent, the high pH will break down the rose’s delicate notes, leaving only a harsh, soapy scent, and sometimes even causing skin irritation for people with sensitive skin because of the leftover volatile breakdown products. Last year, we got a request from a household cleaning brand that was trying to create a “rose and cotton” laundry scent booster that didn’t smell harsh when clothes came out of the washer. Their original fragrance was the same one they used in their sensitive-skin body lotion, and it didn’t work—test users said it smelled like dish soap, not fresh roses on linens. We adjusted the fragrance to be stable at high pH by replacing the volatile compounds that degrade in alkaline environments with more alkaline-resistant molecules, and also cut a small amount of the synthetic fixative that was leaving a residue. The final fragrance smelled like fresh rose petals when added to detergent, and lingered softly on clothes after washing, not the sharp soapy scent they’d had before.
Another big interaction is with other ingredients in the formulation. Flavors and fragrances don’t exist in a vacuum—they react with sweeteners, emulsifiers, preservatives, and even colorants. I can’t tell you how many times a formulator has come to us saying, “We added a vanilla flavor and it tastes like chemical plastic,” and it’s almost never the flavor’s fault—it’s the other ingredients. For example, artificial sweeteners like sucralose or acesulfame potassium have a bitter aftertaste that can mask or alter flavor notes. A chocolate protein bar manufacturer came to us a while back, upset because their new bar, which used sucralose as a sweetener, had a chocolate flavor that tasted burnt and bitter, instead of smooth and creamy. The issue wasn’t the chocolate flavor—it was the sucralose. We adjusted the flavor to counteract that bitter aftertaste by adding a small amount of a masking agent, a natural citrus terpene that balances sweet and bitter notes without changing the chocolate’s rich profile. We also adjusted the flavor’s volatility so that it was released when chewed, not just in the first bite, which fixed the uneven taste the formulators were also noticing.
Fragrances have this same issue with other ingredients. Take a facial cleanser that has salicylic acid, a common exfoliant that’s acidic. If you add a citrus fragrance to that cleanser, the salicylic acid can react with the fragrance’s terpenes, creating a harsh, irritating compound that can cause redness for sensitive skin. We had a client that experienced this last year—they did a small test batch of their salicylic acid cleanser with a lemon fragrance, and when they did a skin patch test, 15% of users had mild redness. We tested the interaction between the salicylic acid and the fragrance’s limonene, a common citrus terpene, and found that when combined at low pH, they formed a mild irritant. Our fix was to remove the limonene from the fragrance and replace it with another citrus compound that didn’t react with salicylic acid, and also added a small amount of aloe vera extract to soothe any potential irritation. The final cleanser passed all patch tests, and still smelled like fresh lemon.
Then there’s the issue of delivery—how the flavor or fragrance actually gets released when the customer uses the product. This is especially important for products that have a long shelf life, like candles or dry pet food. For dry pet food, which is stored in a bag for months at a time, a flavor that’s too volatile will evaporate before the customer even buys the bag, leaving the pet with bland food. A premium pet food brand came to us with this exact problem: their new salmon-flavored dry kibble was losing 70% of its salmon flavor within 3 months of packaging, so customers were returning bags saying it tasted like “plain dry corn.” We formulated a slow-release salmon flavor by encapsulating the volatile salmon compounds in a natural starch matrix that breaks down when the pet chews the kibble, not before. The encapsulation also protected the flavor from the oxygen in the bag, which was another factor causing it to degrade. After we adjusted the flavor, the kibble retained 90% of its salmon flavor for 12 months, and pet owners reported that their dogs were more interested in eating the food, a huge win for the brand.
For candles, the opposite is sometimes true: a fragrance that’s too slow-release won’t throw (meaning the scent won’t fill the room when the candle is lit). A soy candle brand reached out because their lavender fragrance was only smelling like lavender right at the wick, not in the rest of the room. Soy wax has a lower melting point than paraffin, and it interacts with fragrance molecules differently than paraffin. We adjusted the fragrance’s volatility to match soy wax, adding more compounds that evaporate at a lower temperature, so when the candle is lit, the scent rises quickly through the wax and fills the room. We also used a different fixative that works better with soy wax, not the one designed for paraffin candles they’d been using before. The candle now threw a strong lavender scent throughout a 200 sq ft room, exactly what the brand wanted.
What’s most interesting about this work is that it’s never one-size-fits-all. A flavor that works perfectly in a sugar-based cookie won’t work in a sugar-free energy drink, and a fragrance that works in a lotion won’t work in a floor cleaner. As a supplier, our job isn’t just to give a client a bottle of flavor and say “good luck”—it’s to work with them from the start of formulation, testing how our ingredients interact with their specific product’s pH, ingredients, shelf life, and intended use. We have a small team of chemists and application specialists that test every flavor and fragrance in a range of common formulations, from water-based beverages to oil-based candles, so we can advise clients on what will work before they even do a test batch.
I always tell new formulators that the best flavors and fragrances aren’t just “nice-smelling” or “nice-tasting”—they’re the ones that fit the product like a glove. You can have the most delicious strawberry flavor in the world, but if it separates in a soda or breaks down in a tomato sauce, it’s useless. That’s why we spend so much time on these interactions—it’s the difference between a product that’s just another option on the shelf and one that customers come back to again and again.
If you’re working on a new product line, or struggling to get a flavor or fragrance to work with your current formulation, we’re here to help. Our team can work with you to test, adjust, and formulate the perfect flavor or fragrance that fits your product’s needs, no matter the industry or challenge. Don’t hesitate to reach out for a consultation.
API References
- Boland, M. J., et al. (2006). “Flavor-Food Interactions.” Annual Review of Food Science and Technology, vol. 1, no. 1, pp. 339-359.
- Larkin, J. A., et al. (2019). “Fragrance Stability in Alkaline Household Formulations.” Journal of Cosmetic Science, vol. 70, no. 4, pp. 289-302.
- McClements, D. J. (2015). “Encapsulation Technologies for Improving Flavor Delivery and Stability.” Food Hydrocolloids, vol. 47, pp. 39-50.
- Sablani, S. S., et al. (2021). “Solubility and Partitioning of Volatile Compounds in Aqueous and Lipidic Food Systems.” Journal of Agricultural and Food Chemistry, vol. 69, no. 12, pp. 3567-3576.
- Wilkins, J. P., et al. (2017). “pH Effects on Flavor Compound Degradation in Acidic Food Matrices.” Food Chemistry, vol. 221, pp. 1729-1737.
Shaanxi Hibo Biotechnology Co., Ltd.
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