The distinguishing flavor of fresh garlic is associated with
thiosulfinates and various other volatile substances produced by alliinase
(EC4.4.1.4) like S-alkyl-substituted cysteine sulfoxide derivatives, alkyl
alkane thiosulfinates, pyruvic acid, and ammonia[20]. The enzyme action
starts as soon as garlic tissues are disrupted. The major substrate in garlic
is non protein amino acid alliin (S-allyl-L-cysteine sulfoxide). Allicin
(diallylthiosulfinate) formed by enzymatic activity constitutes about
60 to 80% of total garlic thiosulfinates. Gene coding for the enzyme
alliinase has disclosed that it is constituted of 448 amino acids having
a molecular mass of 51.45 kDa and carbohydrate amount of 5.5–6.0%
with 55000 kDa. Alliinase enzyme contain 10 cysteine residues, all exist
in S-S bridges which make the enzyme inactive by their reduction, or
by removing pyridoxal coenzyme factor. Indeed, none other compound
outside the thiosulfinates has been discovered to contribute for a fairly
large portion of the pharmacological preparations of mashed garlic at
similar levels. Allicin amount in fresh garlic varies to a large extent.
According to British pharmacopoeia 1998, the minimum allicin content
ensuring pharmaceutical and economic viability of garlic powder
products is 4.5 mg/g. It is well observed that garlic allicin content varies
with various geographical regions. Difference in allicin content among
various ecotypes is directly related to genetic variations[19].