Allicin steam distillation

Garlic supplements - powder tablets or capsules, steam-distilled oil, vegetable oil macerate extract, or extract aged in dilute alcohol - are widely available and are taken by millions. Since the active principle, allicin, is not present in garlic bulb, the supplements rely on the presence of precursor alliin and enzyme alliinase. In tests on 24 commercial brands of enteric-coated tablets, all except one gave low dissolution allicin release 83% of the brands released less than 15% of their potential allicin.78,79 Relevant factors were impaired enzyme activity caused by excipients and slow tablet disintegration. Caveat emptor ... 

The essential oil, which is present in the fresh bulb in a concentration of 0.1 to 0.3%, contains diallyl sulphide, diallyl trisulphide and allyl methyl disulphide (derivatives of allicin) as main components. Apart from further allyl polysulphides, the steam distilled oil contains limonene as non-sulphurous component [111]. The high pungency of garlic oil makes it necessary to dilute it, commonly in vegetable oil. One gram of oil is equivalent to 900 g of fresh garlic or 200 g of dehydrated garlic powder [112]. 

Material derived from garlic by steam distillation or extraction in an oily medium contains various allicin transformation products. 

The transformation products of allicin and odier thiosulfinates present in crushed garlic is greatly accelerated and expanded upon heating such as during steam distillation or cooking. As many as 20 different sulfides have been identified in the steam distillate and include diallyl mono to hexasulfides, allyl methyl mono to hexasulfides dimethyl mono to hexasulfides, and allyl 1-propenyl di and trisulfides [38]. 

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