Hydrolysis of sinalbin or sinigrin by enzymatic action releases which compound?

• A. Benzaldehyde
• B. Allyl isothiocyanate
• C. Glucose
• D. Sulfuric acid

Answer: (B)

Glucosinolates in plants are cut by the enzyme myrosinase when tissue is damaged, which removes the glucose part and leaves an unstable aglycone that rearranges into an isothiocyanate. The specific isothiocyanate formed depends on the side chain of the glucosinolate. For sinigrin, the side chain is an allyl group, so the rearranged product is allyl isothiocyanate—the volatile compound responsible for mustard oil’s pungent aroma. Sinalbin would produce a different isothiocyanate corresponding to its p-hydroxybenzyl side chain, but the common teaching point centers on the isothiocyanate class produced by glucosinolate hydrolysis. The other options do not represent this characteristic enzymatic hydrolysis product.