Enzymes are naturally-occurring in almost all foods we eat, plant and animal. In plants they are mainly a defense mechanism. The main enzyme group is the polyphenol oxidases (PPOs). These enzymes are stored outside the plant’s vacuoles (flavour and water stores). Plant vacuoles support their parent structure because they are held at a higher internal pressure than the surroundings, giving them strength. The crunchiness of a piece of fruit or vegetable arises because, as we bite, the vacuoles are ruptured and the sudden release of pressure makes a sound and a perception of crisp/crunch etc.
However, when a plant is damaged, the ruptured vacuoles allow the enzymes in and they react with oxygen to produce new compounds. These compounds are insecticidal and/or antimicrobial, and protect the plant from further attack by insects, molds and bacteria.
Anti-oxidants, such as lemon or lime juice, will retard enzyme activity. Lemons or limes are common ingredients in many cocktails. High-proof (40%) alcohol will also destroy enzymes.
Muddled cocktails use pressure to extract flavour from herbs and other plants, usually in the presence of one of these acids. While this is successful, enzymes can be activated internally and out of sight, degrading flavour, because the acid can only act on exposed surfaces. This results in something that still looks fairly green (if it was mint for example), but whose flavour is partly degraded. Part of the modernist approach is to pay attention to these subtleties.
A typical modernist approach is to freeze the herbs in liquid nitrogen, making them very brittle. They can then be pulverised (almost to a dust) while the temperature is too low for enzymes to act. If alcohol is then added while the herb is still frozen, the alcohol will destroy the enzymes as thawing proceeds. This is the gold-standard approach, but not very helpful for a home kitchen.
The alternative is to blend the herbs in the alcohol/acid mix. If done hard and fast enough, the flavour can be released and enzyme activity blocked (by the alcohol/acid) before the extra oxygen introduced by blending can take effect.
The mix is strained (fine tea-strainer), and remaining ingredients added (they are not added at the blending stage to maintain alcohol percentage as high as possible so as to retard the enzymes).
The mix is then shaken over ice in the normal way (or any other way you like – it makes no difference), and the cocktail strained and served.
One spectacular cocktail is the Thai-basil daiquiri. The YouTube video explains the evolution (if you can keep up).
Blend 15 Thai-basil leaves (use older Thai basil with the large dark leaves – the new and fresh doesn’t have the same depth of flavour), 120ml white rum and 45ml fresh lime juice. Strain. Add 40ml simple syrup (simple syrup is equal weights of sugar and water brought to a boil, cooled, stored – best made in bulk). Add a small pinch of salt (recommended for many cocktails – it should not taste salty). Shake over ice (15 seconds). Strain. Serve.
Highly recommended – seriously fresh and interesting flavour. According to Dave, it should be greener than Kermit.
Cheers and Happy New Year!