Flavor Investigator: Lemon

Lemon (Citrus limon (L.)) is a species of fruit from the flowering plant family Rutacae (citrus family) that originated from Asia.  However, today they are now grown commercially worldwide in tropical, semi-tropical and warm temperature countries. This fruit shares the same family as many other well-known fruits including oranges, grapefruit and limes

Lemon flavour is used across the board for applications ranging from savoury to sweet. This versatile fruit can be taken to the extreme levels of tartness in order to produce sour lemon candies or used in desserts such as tarts, meringues or cheesecakes. In the savoury world, lemon is typically paired with chicken, asparagus or dill.

What is beneficial

Important Flavour Components in Lemon

The flavour of lemon can be described as being aromatic of rose, lavender and pine with a slight note of herbaceous.  The compound which is important for producing lemon flavour is citral. Citral produces the characteristic “citrus” flavour and can be found in the form of two isomers, neral and geranial.  Neral’s lemon odour is less intense but sweeter than geranial. Citral is not or poorly soluble in water but readily soluble in alcohol or oils.

Limonene is also an important component used in lemon flavourings. Naturally found in the rind, it is a major constituent in several citrus oils and has an odour which will change based on it chirality. The R enantiomer smells more like orange with the S-enantiomer smells like lemon. It is often used to mask the bitter taste of alkaloids.

Alpha-Terpineol is another major constituent in lemon as it is basically found in every citrus oil or fruit.  This component has been described to have a pine, terpenic, lilac, citrus, woody and floral notes. It is uses are excellent for citrus, tropical fruits, apple, tomato and coffee flavour.

 

Forms of Lemon Flavour  

Lemon juice as you might be aware is the juice obtained from the pulp of a lemon.  Unlike the rind, it is quite sour due to the dominance of citric acid. Lemon peel oil is also a commonly used as an outlet for lemon flavours. It is produced from rind which allows it to have more of a “lemon” flavour when compared to juice. Additionally, oils contain higher citral and limonene content than the juice itself. If you are looking to have more “lemon” flavour in your cooking try using the zest and make sure not to use the pith (inner white layer) as this can add bitterness.

Regular Lemons vs Meyer Lemons

People typically are referring to Eureka or Lisbon lemons when they are referring to “regular” lemons. When compared to Meyer lemons, regular lemons are noticeably larger in size and have a thicker, bright skin.  In regards to taste, regular lemons are highly acidic but have a moderate sweetness.

Meyer lemons on the other hand are much smaller and round than regular lemons. Unlike lemons they have a distinct yellow to orange skin which is also thin. With flavour, they are less acidic than regular lemon so much that they can be raw. In addition, their rinds have aromatics which produce a spicy bergamot fragrance which is a variety or sour orange.

The Problem with Lemon Flavour

One of the major challenges with flavours with lemon is the stability of lemon. As mentioned above, the most important flavour components of lemon are citral and limonene.  These compounds can undergo chemical degradation which lead to a major loss of flavour and undesirable off-flavour.

One way to help preserve this flavour is the encapsulation of citral and limonene in the form of an emulsion or micelles as this can isolate the citral and limonene from reactive molecules in aqueous phase such as proton, metal and free radicals.

During aging however citrus oils and fruits initially have lots of D-limonene but not as much alpha-terpineol but over time the D-limonene decreases and alpha-terpineol increases.

Potential Flavour Combinations for Lemon

• Lemon and Basil: Lemon pairs well with basil because basil contains liquorice notes which pair well with citrus. This combination is so popular there is a variety of basil known as “lemon basil.” It contains clear citrus note which are mild enough that they do not overwhelm subtler flavours.
• Lemon and Lime: Although these two flavours fall in the same family and each have their own characteristic flavour. However, it is hard to differentiate the two unless you use the rind. Lime peels have flavour notes of spicy pine and lilac character while the lemon peel has more apparent rosy and herbal characteristics.
• Lemon and Thyme: Slowly becoming popular in even sweet foods, thyme itself has a piney and peppery taste with bitter, slightly lemony and minty notes. Due to these subtle notes it pairs well with lemon with its fresh, acid notes.