In 1912, French chemist Louis Camille Maillard identified a chemical reaction between amino acids and reducing sugars. Amino acids are the building blocks of proteins and reducing sugars are those like glucose, fructose, and sucrose. This is a common reaction in bread and baked foods but also occurs in wine, beer, and hard cider. In cider and wine, browning or the amber color often desired in cider can be created by enzymatic and non-enzymatic reactions. The Maillard reactions are non-enzymatic meaning they are driven by chemical reactions between compounds versus needing an enzyme, like oxidase, to enable the reaction. Besides creating color, they also create aromas. Many of the positive aromas are noted as caramel, roasted, or buttery, while bitter, burnt, and even rancid can described the the other end of the spectrum. Madeira wines use Maillard reactions to obtain their unique characteristics but, beer may provide some of the best examples. Think of dark bitter beers tasting of coffee or chocolate and you are seeing an extreme example of Maillard reactions.
In wine, sulfite (SO2) is added to suppress both oxidative reactions as well as Maillard reactions. The yellowing or browning or most white wines is undesirable and why sulfites are often aded immediately after fermentation completes. I find this to be an interesting dilemma for cider makers. We often appreciate the tawny and deep amber color of a cider so encouraging these types of reactions would be positive. The good thing to remember is that Maillard reactions don’t require oxygen to occur so you can get the coloring without oxidation. These are chemical in nature and can be part of the active aging process of cider. This would be the argument against adding sulfites post fermentation, or at least until the reactions occur to the desired level.
Maillard reactions are just another example of the complex but interesting processes involved in making cider. Checkout some of the articles below or checkout the Mālus Trivium page for other interesting articles and facts about making hard cider.
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