Soy sauce is a condiment that originated in ancient China and is
extensively used in modern China and Southeast Asia. Benzoic acid
and sorbic acid are prevalently used as preservatives in soy sauce.
However, adverse effects have been associated with benzoic acid at
low doses. In sensitive individuals, conditions such as asthma, urticaria,
metabolic acidosis and convulsions have been observed
(Tfouni & Toledo, 2002; WHO, 2000). Some clastogenic activity
has also been observed with in vitro assays, therefore, the use of
benzoic acid must be controlled. Sorbic acid and its leopoldite
are safe and effective preservatives recommended by the Food
and Agriculture Organization (FAO) and World Health
Organization (WHO). However, strict standards have been set by
the China Health Ministry to monitor its usage, which have been
implemented since 2004. The maximum allowed combined content
of benzoic acid and sorbic acid in soy sauce is 1.0 g/kg (GB/T
5009.29, 2003). Therefore, it is necessary to ensure that low levels
of these preservatives are used in soy sauce to meet regulatory
standards.
Many methods for the determination of benzoic and sorbic
acids in soy sauce are available in the literature. HPLC is the most