Effects of Sulfur Dioxide on Food Quality - Food Shelf Life Stability: Chemical, Biochemical, and Microbiological Changes - page 280

or in vivo are metabolized quickly and harmlessly. 84 Thus, from the available evi-
dence, we see that despite the somewhat indiscriminate reactivity of S(IV) in foods,
this is not associated with any known toxicological hazard to humans.
A critical appraisal of the evidence presented by Til and Feron, 83 on whose
research the acceptable daily intake (ADI) of S(IV) has been set by the European
Community, indicates that there are a number of minor toxicological effects that
have not yet been explained. Of particular interest is the observation that toxic effects
are sometimes associated with the oxidized lipid fraction of sulfited diets, and it is
speculated here that sulfite-specific oxidation products may be involved. However,
the compelling reasons why much effort has turned to seeking alternatives to sulfur
dioxide is the fact that some individuals are abnormally sensitive to low concentra-
tions of SO 2 88 in the head space above sulfited foods, or as a result of eructation
after a sulfited food has been eaten and come into contact with the acid environment
of the stomach.
Estimates 89 of the per capita consumption of sulfur dioxide (taking account of
all the possible forms in which it may be added to food) in the U.S. by reference
to 782 food products reveal a daily intake that is 44% of the ADI (210 mg per person
per day based on an individual weighing 60 kg). On the other hand, a total diet
survey suggests that the typical intake is probably somewhat lower at 18 mg per
person per day, with extreme users reaching some 64 mg per person per day.
Alcoholic beverages, soft drinks, sausages, and hamburgers are the most significant
contributors to the dietary intake of sulfur dioxide. Dehydrated fruits can also be a
significant source of dietary sulfur dioxide for those who eat them. These levels of
consumption of sulfur dioxide are among the highest intakes of food additives in
relation to their ADI values. This evidence, taken together with the abnormal sen-
sitivity of certain individuals to gaseous SO 2 , has been the principal reason why
there has been particular interest in reducing the levels of the additive and finding
suitable replacements.
T HE A LTERNATIVES
There have been a number of comprehensive reviews outlining the main issues that
need to be considered for replacing sulfur dioxide in foods. 90,91 The role of S(IV)
in controlling the diverse spoilage reactions in food as an antimicrobial agent, an
inhibitor of browning, and an antioxidant are recognized and our ability to offer
suggestions for replacements is based on a good understanding of the mechanisms
of its preservative action. It is often said that the complete role of S(IV) in food
extends beyond the obvious chemical reactions associated with its preservative
action, and includes as yet unknown contributions to subtle changes in quality. For
this reason there is a need to understand the full range of contributions of S(IV) to
the quality of preserved foods.
Whereas S(IV) is unique in its ability to control simultaneously several forms
of food spoilage, there are possible replacement food additives to control individual
spoilage processes. Thus, alternative antimicrobial agents could include benzoates
and sorbates, and antioxidants include citrate, tocopherol, and BHT, among the wide
range of food additives currently available for these purposes.