In the mustard paste, sinalbin is hydrolyzed by myrosinase to p-hydroxybenzyl isothiocyanate (I), sinapine acid sulfate and glucose. It was found that the three decomposition products were formed from sinalbin, and two of them were isolated from the mustard paste and identified as p-hydroxybenzyl alcohol (II) and di-(p-hydroxybenzyl)-disulfide (IV), respectively. II was a major product and IV was a minor product.