Hard Cider Aroma Sources

The Source of Aroma Compounds In Hard Cider
The Source of Aroma Compounds In Hard Cider

The aroma of hard cider is vital to its flavor and ultimately, it’s quality. If a cider has unpleasant or off-flavors, it can turn off potential drinkers or for home cider makers, the loss of bragging rights at your next get-together or family reunion. That aroma is generated from three key factors.

  1. Apple Varietal Impact: Every apple and even the same apple grown in different locations (terrior), or in different years (vintage) will have unique characteristics that will impact the aroma and flavor.
  2. Fermentation Impact: The yeast you use, the temperature at which you ferment, the nutrients in your juice, enzymes you might employ, and even the clarity of your juice will impact the aroma and flavor of your hard cider.
  3. Maturation Impact: Whether or not you age your hard cider, how long you age your cider, whether you age your cider on oak, or if you decide to age your cider on its lees, impacts the aromas and flavors your hard cider will have.

These factors are generally understood or at least make sense when we start thinking about the cider making process. However, what I found interesting was some research done on the island of Madeira in Portugal(1). Researchers wanted to assess whether they could use the volatile compounds (aroma) of hard cider made on the island as a fingerprint to know where on the island it was made. This was interesting as it showed how apple variety, terroir, vintage, yeast, and other processes impacted aromas. However, it also broke down the major volatile compounds found in each cider. Basically, the aroma of the hard cider made on the island is dominated by the following(1).

  1. Esters – The main contributor to volatile compounds were esters. This was in ciders produced in all locations. Averaging the amounts shows that esters represent around 44% of the volatile compounds. These were ethyl esters derived from ethanol and acetates derived from acetic acids.
  2. Higher Alcohols – Often called fusel alcohols, these are usually highly volatile and were the second largest contributor to volatile compounds in hard cider. When I averaged this data, it indicated that around 34% of the compounds are from high alcohols. Fusel alcohols are generally created through biosynthesis of sugars or through the degradation of amino acids (Ehrlich pathway).
  3. Acids – Acids are approximately 10% of the volatile compounds in the cider. Volatile acids are formed when lipids are metabolized by yeast. If these are too strong, they tend to create negative aromas like sweat, fat, rancid meat, or cheese(1).
  4. Phenols – Like acids, phenols were on average about 10% of the volatile compounds in hard cider. These are created through a decarboxylation process of certain acids. These are often noted as leather, horse, barnyard, smoke or medicinal.

I am certain that not every hard cider will have this exact volatile compound profile and like most things in cider, I am sure you can make one that is completely opposite the above results. However, as you look to make better and more craft ciders, understanding how you can impact the creation of aroma and flavors through volatile compounds is critical.

(1) A. Sousa and associates, Geographical differentiation of apple ciders based on volatile fingerprint, Food Research International 137  109550 2020

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For more information on aroma, check out these articles about esters, fusel alcohols, tannins, and acids.

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