Piqûre Acroléique… If you are like me, you may still be wondering how that is pronounced. Then, you might be wondering what it is and what it has to do with apples or hard cider. Piqûre Acroléique is the creation of 3-hydroxypropionaldehyde (3-HPA) from glycerol, which is created by a lactic acid bacteria (LAB) called Lactobacillus collinoides (1). The 3-HPA is a precursor to acrolein. Acrolein is responsible for undesirable bitter and peppery flavors. This is especially a concern for calvados or applejack, which are spirits distilled from hard cider. Basically, Piqûre Acroléique is a cider and calvados fault. You’ve probably never heard of it, because like most things about hard cider, there hasn’t been a lot of research done on it.
Glycerol is a by-product of the alcohol fermentation of glucose. Lactobacillus collinoides, which is commonly found in hard cider converts the glycerol into 3-hydroxypropionaldehyde (3-HPA) setting up the additional steps in the process to make acrolein. The good news is that acrolein appears to be a very volatile and reactive molecule. Meaning, it tends to evaporate and combine with other compounds over time, which significantly reduces its influence. Even with the concentration influence of distillation, the acrolein tends to dissipate with time.
(1) N. Sauvageot and associates, Glycerol metabolism in Lactobacillus collinoides: production of 3-hydroxypropionaldehyde, a precursor of acrolein, International Journal of Food Microbiology, 55 (2000) 167 –170
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