Any time you have a flavor that has a vanilla, custardy, or buttery note to it, it will have one or all of the "custard note" family: acetyl propionyl, butanoic acid, and acetoin. Most, but not all, flavor houses have eliminated diacetyl from all formulations. No flavor sold by The Flavor Apprentice is made with diacetyl. Each custard note has a particular flavor, and as flavor is subjective, you will find that you prefer some more than others. The unique flavors of diacetyl, butanoic acid, acetyl propionyl, and acetoin are rather obvious, and once a person learns how to recognize them, they are easy to spot. Just like once you know the flavor of cinnamon, you can usually tell if a cocoa recipe has cinnamon in it just by taste! By definition, a vanilla custard flavor, no matter who makes it, will have some combination of acetoin, butanoic acid, and acetylpropionyl (or diacetyl) in it. Just like it would be hard to bake a cinnamon roll with no cinnamon, it would be nearly impossible to create a vanilla custard, ice cream, caramel, or bakery flavor without custard/butter flavor components. Some fruits (and therefore fruit flavors) even include custard/butter notes!

Acetoin (3-Hydroxybutanone) – Sweet, buttery, creamy, dairy, milky, fatty Not to be confused with the solvent acetone, acetoin occurs naturally in apples, butter, yogurt, asparagus, blackcurrants, blackberries, wheat, broccoli, brussels sprouts, cantaloupes and maple syrup. Acetoin is often used with diacetyl to make artificial butter flavoring as they both occur naturally in butter and lend it the characteristic flavor. Acetoin can, in production, dehydrogenate to form diacetyl in trace amounts. It is highly unlikely for this reaction to happen after flavor blending. For customers wishing to avoid even trace amounts of diacetyl, this means that any flavor that contains acetoin can potentially also contain trace diacetyl, even though diacetyl was not an intentionally added component of the formula. If you would like to avoid acetoin, you may wish to shop our diketone-free (DX) line of flavors.

Acetylpropionyl (2,3-Pentanedione) - Toasted, nutty, buttery, creamy, cheesy, and caramellic with marshmallow and molasses nuances Acetylpropionyl is a buttery diketone with similar organoleptic properties to acetoin and diacetyl, which can also occur in dairy, fruit, and honey products. Though it may look very similar to diacetyl, the extra carbon makes it quite distinct as it is a very difficult bond to break. As such, it does not carry the same risk as acetoin of becoming diacetyl. The National Institute of Occupational Safety and Health have found significant respiratory damage and genetic changes in brain tissue in animal studies.

Butanoic Acid (butyric acid) - Sharp, acidic/sour, dairy-like, cheesy, creamy, buttery with a fruity nuance Butanoic acid is a fatty acid which makes up 3-4% of butter in its triglyceride form. As such, it can be found in milk, especially buffalo, sheep, and goat milk, lending the characteristic tang of each. It is also in kombucha, butter, and cheeses (especially parmesan). Butanoic acid is not a diketone, and as such is often used as a replacement butter/custard note in flavors which have had diketones removed from their formula. While it is used at low levels to accentuate a butter note, it is not commonly used at concentrations as high as acetoin or acetylpropionyl. If overdone it can lend a rather unpleasant aftertaste to a flavor, as butanoic acid is also one of the main scent components of vomit. Butanoic acid can also cause sore throat, coughing, and irritation when inhaled, though has not been brought to light as particularly hazardous, unlike diketones.

Diacetyl (butanedione, 2,3-diketobutane) - Sweet, creamy, buttery, milky, with a caramellic toffee nuance Diacetyl is a natural byproduct of fermentation, and occurs in alcoholic beverages as well as cultured dairy products (such as cultured cream, cultured/European-style butter, yogurt, or sour milk). It can also be found in some fruits, especially stone fruits such as peach, nectarine, and plum, and thus is in some natural fruit extracts. Diacetyl is often used with acetoin to make artificial butter flavoring as they both occur naturally in butter and lend it the characteristic flavor, and are entirely safe to consume in food. It has gained some press in the past decade as workers in several factories that manufacture butter flavoring have been diagnosed with bronchiolitis obliterans, a rare and serious lung disease. The United States National Institute for Occupational Safety and Health has suggested diacetyl, when used in artificial butter flavoring (as used in many consumer foods), may be hazardous when heated and inhaled over a long period, and may induce bronchiolitis obliterans as well as beta-amyloid aggregation (which is linked to Alzheimer’s disease). In light of these concerns, diacetyl has been removed from many products that use artificial flavoring, and is not added to any flavors sold by The Flavor Apprentice.

For our full range of eliquids visit http://www.rainbowvapes.co.uk

Trustpilot Strawberry (Ripe) Flavoured Flavour...
Trustpilot Strawberry (Ripe) Flavoured Flavour Apprentice Liquid concentrate Water soluble.This strawberry flavor is a bit different from our original strawberry, a bit more ripe tasting.Ingredients: Natural and Artificial Flavors, Propylene...
£1.35
£1.35
Trustpilot Water soluble.   A...
Trustpilot Water soluble.   A warm, creamy, vanilla flavor. Try blending with coffee, fruit, or nut flavors! *** Note: This flavor contains 'custard' ingredients: Acetoin.    Ingredients:Natural & Artificial Flavor,...
£1.35
£1.35
Trustpilot Cheesecake (Graham Crust) Flavoured...
Trustpilot Cheesecake (Graham Crust) Flavoured Flavour Apprentice Liquid concentrate Water soluble.This cheesecake is quite different from our original. It has more of a pronounced graham cracker note. (at least to...
£1.35
£1.35
Trustpilot Sweetener Flavoured Flavour Apprentice...
Trustpilot Sweetener Flavoured Flavour Apprentice Liquid concentrate Water soluble.Use this one to sweeten other flavors.   *** Note:  sometimes crystals can form, they will dissolved if warmed. - also, can...
£1.35
£1.35
Trustpilot Vanilla Bean Ice Cream...
Trustpilot Vanilla Bean Ice Cream Flavoured Flavour Apprentice Liquid concentrate Water soluble.An elegant and rich vanilla flavor with hints of vanilla bean.*** Note: This flavor contains 'custard' ingredients: Acetyl Propionyl....
£1.35
£1.35
Trustpilot Vanilla Custard Flavoured Flavour...
Trustpilot Vanilla Custard Flavoured Flavour Apprentice Liquid concentrate Water soluble.A rich, buttery custard flavor. stronger than our Bavarian Cream flavor.   *** Note: This flavor contains 'custard' ingredients: Acetoin &...
£1.35
£1.35
Trustpilot Vanilla Swirl Flavoured Flavour...
Trustpilot Vanilla Swirl Flavoured Flavour Apprentice Liquid concentrate Water Soluble.This is our vanilla custard flavor that has had the "Custard Notes" removed. It is a very useful vanilla, good on...
£1.35
£1.35
Trustpilot Sweet Cream Flavoured Flavour...
Trustpilot Sweet Cream Flavoured Flavour Apprentice Liquid concentrate Water soluble.A  light cream, very useful for blending with other ingredients. this is called sweet cream, but it is not really that sweet,...
£1.35
£1.35
Trustpilot   Graham Cracker Clear...
Trustpilot   Graham Cracker Clear Flavoured Flavour Apprentice Liquid concentrate Water soluble. This version of graham cracker does not contain caramel color.It is translucent, but does have a slight amber...
£1.35
£1.35
Trustpilot Marshmallow Flavoured Flavour Apprentice...
Trustpilot Marshmallow Flavoured Flavour Apprentice Liquid concentrate Water soluble.A light, sweet marshmallow - good for blending with other flavors.*** Note: This flavor contains 'custard' ingredients: Acetoin & Acetylpropionyl   Ingredients:Natural...
£1.35
£1.35
Trustpilot Dragonfruit Flavoured Flavour Apprentice...
Trustpilot Dragonfruit Flavoured Flavour Apprentice Liquid concentrate Water soluble.It is a mellow fruity flavor with tropical accents.Ingredients: Natural and Artificial Flavors, Propylene Glycol, Triethyl Citrate   
£1.35
£1.35
Trustpilot Strawberry Flavoured Flavour Apprentice...
Trustpilot Strawberry Flavoured Flavour Apprentice Liquid concentrate Water soluble.This is a fresh, natural strawberry flavor.*Note: Occasionally, this flavor can show a bit of clouding, but this is normal.Ingredients: Natural and...
£1.35
£1.35
Trustpilot RY4 Double Caramel Flavoured...
Trustpilot RY4 Double Caramel Flavoured Flavour Apprentice Liquid concentrate. Water soluble.This flavor is a stronger and more caramel type flavor than our original RY4.Some customers detect a very slight fruity/floral...
£1.35
£1.35
Trustpilot Raspberry (Sweet) Flavoured Flavour...
Trustpilot Raspberry (Sweet) Flavoured Flavour Apprentice Liquid concentrate Water soluble.A variation on our original raspberry flavor. Ingredients: Artificial Flavor, Propylene Glycol, Water    
£1.35
£1.35
Trustpilot Koolada 10 PG Flavoured...
Trustpilot Koolada 10 PG Flavoured Flavour Apprentice Liquid concentrate Koolada is used specifically to give that "cold" feeling at the back of the mouth.It does not really have a 'taste',...
£1.35
£1.35
Trustpilot Cotton Candy Flavoured Flavour...
Trustpilot Cotton Candy Flavoured Flavour Apprentice Liquid concentrate Water soluble.This is made from ethyl maltol, diluted to 10% in PG.It is not a strong flavor, since ethyl maltol won't dissolve...
£1.35
£1.35
Trustpilot Taste description:This is Acetyl...
Trustpilot Taste description:This is Acetyl Pyrazine at 5% in Propylene Glycol at 10.00 ppm.  Roasted, nutty, bready and yeasty, with popcorn and corn chip nuances good for graham cracker flavors (enhancer)Mosciano, Gerard P&F 17,...
£1.99
£1.99
Trustpilot Caramel (Original) Flavoured Flavour...
Trustpilot Caramel (Original) Flavoured Flavour Apprentice Liquid concentrate Water soluble. This is our original caramel, back by popular request. More rich than candylike, with a toasty, maple, brown sugar flavor.*** Note:...
£1.35
£1.35
Trustpilot Dairy/Milk Flavoured Flavour Apprentice...
Trustpilot Dairy/Milk Flavoured Flavour Apprentice Liquid concentrate This is a dairy/milk note, very gentle.It is not a flavor on its own, but rather a blender to be used in conjunction...
£1.35
£1.35
Trustpilot Water soluble. A smooth...
Trustpilot Water soluble. A smooth flavor with a fresh, natural banana taste. *** Note: This flavor contains 'custard' ingredients: Acetoin. *We now offer DX Banana Cream, substituting Butyric acid for...
£1.35
£1.35
Trustpilot Peanut Butter Flavoured Flavour...
Trustpilot Peanut Butter Flavoured Flavour Apprentice Liquid concentrate Water soluble.This is a rich and creamy, realistic peanut butter*** Note: This flavor contains 'custard' ingredients: Acetoin & Acetylpropionyl.   Ingredients:Natural &...
£1.35
£1.35
Trustpilot Water soluble.Sweet and fruity....
Trustpilot Water soluble.Sweet and fruity. Ingredients:Natural & Artificial Flavor, Propylene Glycol, Water  
£1.35
£1.35
Trustpilot Key Lime Flavoured Flavour...
Trustpilot Key Lime Flavoured Flavour Apprentice Liquid concentrate A fresh lime flavor, good either on its own, or combined with other flavors.*This flavor contains natural ingredients that can sometimes (not...
£1.35
£1.35
Trustpilot Mango Flavoured Flavour Apprentice...
Trustpilot Mango Flavoured Flavour Apprentice Liquid concentrate Water soluble.Fresh, natural tasting mango.Ingredients:Natural  & Artificial Flavor, Propylene Glycol.  
£1.35
£1.35
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