Review – The Science of Garlic

The plants of the genus Allium are some of the most prevalent and recognisable in cooking. Have you chopped an onion lately? Pressed some garlic? Sliced a leek? Then you have been availing yourself of one of Mother Nature’s most generous gifts; long stemmed bulbs of pungent, fragrant delight that have been used for well over five thousand years to impart savoury magic to a multitude of regional dishes prepared by chefs across the globe.

Allium sativum, or what we know as garlic, originated in the area of Western China set alongside the modern borders of Kazakhstan and Kyrgyzstan. Ancient peoples bestowed the plant with a litany of curative properties that no doubt sped its propagation across Asia and into Europe so that everyone from the Egyptians to the Romans quickly found ways to incorporate it into the national pharmacopeia. You could say the great pyramids of Egypt were built of garlic; the plant was used to feed and sustain the unfortunate slaves who were forced to drag stone after stone across scorched desert to satisfy the grandiosity of ancient pharaohs. Yes, without the architectural despotism of Cheops the world might never have been introduced to marinara sauce. Although various papers have claimed that garlic cures everything from cancer to the common cold, it has transformed throughout the ages from highly sought medicine to unrivalled flavouring. Garlic is simply an inextricable part of global cuisine.

The science of garlic

What is the taste of a garlic bulb before you eat it? Like the tree falling in the forest, this Zen-like riddle is a thought puzzle that penetrates deeply into the nature of the plant itself. The raw, stinging aroma that distinguishes the freshly cut clove bears little resemblance to the passive inoffensiveness of an untouched bulb. When the garlic is prepared and its fragile cell walls are torn open, the enzyme alliinase is set loose and quickly begins to convert components stockpiled inside the clove into a cache of chemical weapons. Alliin is one of the major constituents of pristine garlic, but the powerful aroma that really identifies the plant is allicin. This small chemical, along with allylmethyl sulfide and ajoene, are downstream products of garlic degradation. Though degradation often seems a deleterious, unwanted process, in the case of the Allium clan, these events serve to protect the plant from predators. Unfortunately for garlic, far from balking at the odorous armament, humans took a curious liking to the spicy odour of its trademark weapon. So much so that today it is as prevalent in Punjab as it is popular in Paris.

Practically, what this means for the cook is that the more you chop garlic (or onions, shallots, and leeks, for that matter), the more you are damaging the tissue and promoting synthesis of those strong-smelling compounds. At low temperatures, a chilled garlic clove for example, the enzyme activity is weakened and chopping will give a more tamed product. Consequently, at higher temperatures the enzyme is outright destroyed. Roasted garlic contains very little of the flavours we associate with minced garlic since the cells remain largely intact during the critical stages of roasting and very little allicin or its progeny are formed.

As much as we laud garlic for its intense flavour, it is often equally reviled for its persistence, with the term “garlic breath” termed as much out of anguish as fondness. Is there a real cure out there, or do you need to delete your Tinder profile and start afresh? Recent research has identified a number of foods containing polyphenols (click over to enzymatic browning for a refresher) that were instrumental in deodorising garlic breath. Tea, apples, parsley, and mint were a few of the compounds noted, but there are certainly many more out there that could prevent a first date from being a final date.

For an excellent graphic on the chemistry of garlic click on over to Compound Interest

The science behind our friend garlic

2 Comments

  1. I just found your blog through your neighbour, Elias. I love these pictures of the garlic scapes. They’re my favourite part of garlic!

    • Immortal Pestle
      November 26
      Reply

      Thanks so much, Kristen! Garlic does get a pretty intense workout in house 🙂

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