Plant-Based Flavour: Masking the Off-Notes in Meat and Dairy Alternatives

Plant-based meat and dairy alternatives have moved from a niche to a fixture of the Australian chiller, and the raw materials that make them are well understood. Pea and soy proteins gel, emulsify and build the texture a burger or a yoghurt needs. The pea milk research identifies peas, soybeans, wheat and rice as important sources for plant-based alternatives and describes the off-notes associated with legume proteins. Flavour, texture and other product attributes can affect acceptance.

Aroma, Bitterness and Astringency

The off-notes involve aroma, taste and mouthfeel. Aroma comes from volatile compounds you smell. The pea milk work describes the main off-flavours of peas as green, beany, earthy, hay-like, bitter and astringent, and links them to volatile aldehydes, ketones and alcohols on the one hand and to non-volatile compounds such as isoflavones and saponins on the other. Bitterness is a taste, while astringency is a drying sensation. The dominant sensory problem should guide testing, while aroma and taste interventions can interact. Isogai and Wise demonstrated that aromas could change perceived bitterness in their experimental system.

The Aroma Problem Is Lipid Oxidation

The beany, grassy aromas are largely a lipid-oxidation story. In peas, the pea milk research attributes the off-note volatiles mostly to the oxidation of unsaturated fatty acids catalysed by enzymes, principally lipoxygenase, with hydroperoxide lyase and, indirectly, lipase also involved. The products of that chemistry are the small molecules a panellist actually notices: hexanal reads as green and grassy, 2-pentylfuran as green bean, and 1-octen-3-ol as mushroom, among others. The same pathway drives soy. The dairy-analogue review describes the native grassy or beany note in soy as caused by hexanal and other aldehydic, lipoxygenase-catalysed lipid oxidation products, and read as an off-flavour in a dairy context. This is why the raw material, not just the recipe, sets the starting point.

Assessing Off-Notes After Enzyme Inactivation

Enzyme inactivation did not eliminate hexanal in the pea milk trial. Lipoxygenase was completely inactivated after three minutes of blanching, yet the blanched samples carried more hexanal than the others, which led the authors to conclude that hexanal formation is not due to lipoxygenase alone. Earlier work they cite found only a 55 per cent fall in hexanal against a 90 per cent drop in enzyme activity, off-notes that appear even when the enzyme is dead, and hexanal generated by the heat treatment itself from phospholipids. Assess residual off-notes after processing before selecting a flavour intervention.

The Taste Side: Saponins and Isoflavones

Bitterness and astringency are a separate problem with separate chemistry. The pulses review notes that among the five basic tastes, bitterness is the only one identified as an off-taste in pulses, detected by the roughly 25 bitter taste receptors humans carry, while astringency is a trigeminal sensation in which molecules bind and precipitate salivary proteins, causing the drying and puckering a taster feels. The compounds behind it are well mapped. In soybeans the isoflavones genistein and daidzein are bitter and activate the TAS2R14 and TAS2R39 receptors, and saponins across the legumes are bitter and astringent. Green peas carry roughly 1.8 to 11 grams of saponins per kilogram of dry matter, and isolated soyasaponin from peas has a bitterness detection threshold near 8 milligrams per litre in water, falling below 2 milligrams per litre once a second saponin is present. Those are low thresholds, which is why a small residue is enough to be tasted.

The Off-Notes Travel With the Protein

There is a reason these tastes are hard to wash out: they follow the protein. The pulses review reports that saponins interact with proteins and are found more readily in the protein fraction than in the starch fraction, so the more a process concentrates protein into an isolate, the more of some off-tastes it can concentrate with it. The same binding runs the other way for aroma, because both saponins and volatile compounds interact with the protein, so a step that strips one can shift the other, and an aroma added later can be partly held by the protein rather than released to the nose. A plant-based base is therefore not a blank canvas. It is a matrix that holds on to the notes you want gone and can mute the notes you add.

Processing Options and Their Effects

Processing can lower the off-note load. Heat degrades the main pea and soy saponin, which reduces some bitterness, but it also drives Maillard and other thermal reactions that create new notes and, as the pea milk work showed, can raise hexanal. Vacuum stripping is effective at pulling volatiles out, and the dairy-analogue review is blunt about the consequence: once the aroma is stripped, it has to be reintroduced through other ingredients or fermentation. Adsorbents can remove the majority, on the order of 60 to 70 per cent, of hexanal from soy protein isolate, but not all of it. Fermentation can both cut beany compounds and build dairy-like ones. Blending raw materials can improve acceptability; the dairy-analogue review identifies masking of beany notes as one possible explanation, while noting that the mechanism is unclear.

What the Unformulated Pea Milk Study Leaves Unmeasured

The pea milk researchers tested unformulated samples to exclude the effects of ingredients such as sugar and flavourings. Their study therefore leaves the effects of subsequent formulation unmeasured. Masking works by suppressing or distracting from the bitter and astringent signals rather than removing the compounds, while modulation rebuilds the notes a clean protein lacks. The dairy-analogue review is candid that commercial plant-based milks generally rely on processing and formulation to mask unpleasant notes and resemble the target, and that current products depend heavily on added ingredients to reach acceptability.

Rebuilding the Meat or Dairy Target

Removing the wrong notes is only half the brief; the product still has to taste like the thing it replaces. A dairy analogue needs the creamy, cultured character of milk or yoghurt, and fermentation research shows those can be built, with lactic cultures lowering beany volatiles while raising dairy compounds such as acetaldehyde and 3-hydroxy-2-butanone. A meat analogue needs savoury, roast and fat-like depth. Fat is central to both, because, as the dairy-analogue review notes, it carries mouthfeel, flavour and flavour-carrying capacity, so a lower-fat plant base loses aroma delivery as well as richness and has to have both rebuilt.

Australian Labelling: Allergens and the Voluntary Code

Allergen declaration belongs in the flavour brief. FSANZ's allergen labelling guidance explains the plain English requirements, mandatory from 25 February 2024. For packaged foods requiring an ingredient list, non-exempt allergens such as soy, wheat, lupin, sesame, milk and peanut must use their required names in bold in that list and in a separate bold summary beginning with Contains. Tree nuts must be named individually, such as almond or cashew, rather than collectively as tree nuts. Gluten-containing cereals must be named in the ingredient list, and gluten must appear in the summary statement; for wheat containing gluten, the summary must name both wheat and gluten. Under Standard 1.2.3, non-exempt allergens must be declared even when introduced through a flavouring. Whether a carrier must also be listed as an ingredient is a separate question under Standard 1.2.4, including its exemptions and specific declaration requirements. Precautionary may contain statements are voluntary and not regulated by the Food Standards Code. The 2022 Senate report Don't mince words is historical context: it examined plant-based labelling and considered a mandatory framework under Australian Consumer Law. On 30 January 2026, the Australian Government announced support for a voluntary Industry Code of Practice for plant-based labelling, led by the Alternative Proteins Council. Check the code's current status before relying on it. The announced voluntary initiative does not replace mandatory allergen and ingredient labelling obligations.

A Practical Brief for a Plant-Based Product

A plant-based flavour brief starts by identifying the dominant problem: beany or grassy aroma, bitterness, drying astringency, or a combination. Use that assessment to guide testing, allowing for interactions between aroma and taste. Match the protein and, where you can, the cultivar and grade, since off-note load varies with the raw material. Assess what remains after processing before deciding whether a flavour intervention is needed. Ask every flavour and protein supplier for composition information, including carriers and allergen inputs, and assess allergen declaration separately from ingredient-list requirements. Then taste in the real matrix, with the fat, salt and sugar the finished product will carry, because a plant protein tastes very different once formulated. Confirm the label reads the way you intend before the artwork is locked.

How VKA Australia Approaches Plant-Based Work

VKA® Australia develops and makes flavours in Southport, Queensland. We use taste modulation, bitter-blocking, aromatic masking and sweetness balancing in flavour development, and we provide a specification sheet and allergen declaration for every flavour we supply. Our guide to flavour masking covers approaches to managing off-notes, and our guide to natural flavours covers the regulated language around a plant-based claim. If you are formulating a plant-based product, talk to a flavourist directly and bring the current base so the off-notes and the target profile can be worked on together.