Fundamental Food Microbiology, Third Edition - Fuad Fathir

498 FUNDAMENTAL FOOD MICROBIOLOGY
I. INTRODUCTION
Many chemical compounds, either present naturally, formed during processing, or
legally added as ingredients, can kill microorganisms or control their growth in
foods. They are, as a group, designated as antimicrobial inhibitors or preservatives. 1,2
Some of the naturally occurring preservatives can be present in sufficient amounts
in foods to produce antimicrobial action, such as lysozyme in egg white and organic
acids in citrus fruits. Similarly, some of the antimicrobials can be formed in enough
quantities during food processing to control undesirable microbial growth, such as
lactic acid in yogurt fermentation. However, others can be naturally present or formed
in small quantities and essentially do not produce antimicrobial action in foods, e.g.,
lysozyme in milk (13 mg/100 ml) and diacetyl in some fermented dairy products.
Among the many food additives, some are specifically used to preserve foods against
microorganisms (such as NO 2 in cured meat to control spore germination, especially
of Clo. botulinum) whereas others are added principally to improve the functional
properties of a food (such as butylhydroxyanisol, BHA, used as an antioxidant,
although it has antimicrobial properties). Use of some of the preservatives started
as far back as 6000 B.C. Examples include salting (which had nitrate as a contaminant)
of fish and meat; burning sulfur to generate SO 2 to sanitize the environment and
equipment used for baking and brewing; smoking fish and meats; and adding spices,
herbs, acids, and alcohol to foods (from fermentation).
Following the discovery of the microbial role in food spoilage and in foodborne
diseases, many chemicals have been introduced since the late 1900s to control
microorganisms in foods. The safety of the chemicals on humans was not tested
before adding to foods, and some of the chemicals used were later found to be
harmful to humans. To protect U.S. consumers, in 1958, the Food Additive Amendment
was passed (see Appendix C). According to this amendment, a food processor
wanting to use a food preservative and other additives must prove their safety, by
the procedures recommended, before their incorporation. This law, however, granted
an exemption to substances used for a long time, found to be safe, and considered
as generally regarded as safe (GRAS) substances.
In recent years, the possible effect of different preservatives and other additives
on human health from long-term use through different foods has been questioned.
Many of them are of nonfood origin or added at a level not normally present in
foods, and some are synthetic. The effect of interactions of the different preservatives
in the body consumed through different foods, especially in children and debilitated
and elderly people, the possible cumulative effect from the consumption for many
years, and their interactions with each other and with other chemicals (e.g., medications)
have not been determined. Many health-conscious consumers are interested
in foods that do not contain any preservatives, especially those not normally found
in foods or present in much a lower concentration than that added to foods. This
has resulted in the search for preservatives that are either naturally present in the
food of plant and animal origin or produced by safe food-grade microorganisms
used to produce fermented foods. They are also designated as biopreservatives. 1
Some of these have been used, not always as preservatives, for a long time in foods
and have been found to be safe (such as lactic, acetic, and propionic acids), whereas