Hospitality
Institute of Technology and Management; St. Paul, Minnesota
Introduction
Spices and herbs have been used for thousands of centuries by many cultures to
enhance the flavor and aroma of foods. Early cultures also recognized the value
of using spices and herbs in preserving foods and for their medicinal value.
Scientific experiments since the late 19th century have documented the
antimicrobial properties of some spices, herbs, and their components (17, 20).
Antimicrobial
Effectiveness of Spices and Herbs
Table 1 describes the relative antimicrobial effectiveness of some spices and
herbs.
Table
1. Antimicrobial Effectiveness of Spices and Herbs*
Spices
and Herbs |
Inhibitory
Effect |
Cinnamon,
cloves, mustard |
Strong |
Allspice,
bay leaf, caraway, coriander, cumin, oregano, rosemary, sage, thyme |
Medium |
Black
pepper, red pepper, ginger |
Weak |
*
Adapted from Zaika (20).
Studies in the past
decade confirm that the growth of both gram-positive and gram-negative foodborne
bacteria, yeast. and mold can be inhibited by garlic, onion, cinnamon, cloves,
thyme, sage, and other spices. Effects of the presence of these spices / herbs
can be seen in food products such as pickles, bread, rice, and meat products.
The fat, protein, water, and salt contents of food influence microbial
resistance. Thus, it is observed that higher levels of spices are necessary to
inhibit growth in food than in culture media (17). Table 2 is a list of
various spices and herbs and their inhibitory effect on various microorganisms.
Table
2. Inhibitory Effects of Spices and Herbs*
Spice
/ Herb |
Microorganisms |
Reference |
Garlic |
Salmonella
typhymurium, Escherichia coli, Staphylococcus aureus, Bacillus cereus,
Bacillus subtilis, mycotoxigenic
Aspergillus, Candida albicans |
(1,
5, 9, 15) |
Onion |
Aspergillus
flavis, Aspergillus parasiticus |
(16) |
Cinnamon |
Mycotoxigenic
Aspergillus, Aspergillus parasiticus |
(1,
3, 4) |
Cloves |
Mycotoxigenic
Aspergillus |
(1,
7) |
Mustard |
Mycotoxigenic
Aspergillus |
(1) |
Allspice |
Mycotoxigenic
Aspergillus |
(1,
7) |
Oregano |
Mycotoxigenic
Aspergillus, Salmonella spp., Vibrio parahaemolyticus |
(1,
2, 10, 12) |
Rosemary |
Bacillus
cereus, Staphylococcus aureus, Vibrio parahaemolyticus |
(19) |
Bay
leaf |
Clostridium
botulinum |
(8) |
Sage |
Bacillus
cereus, Staphylococcus aureus, Vibrio parahaemolyticus |
(18,
19) |
Thyme |
Vibrio
parahaemolyticus |
(2,
12) |
*
Adapted from Shelef (17).
Microbial
Contamination of Spices
Spices and herbs may be contaminated because of conditions in which they were
grown and harvested. Spores of both Clostridium perfringens and Bacillus
cereus have been found to be present in spices and herbs (11, 13).
Contaminated spices have been reported to have been causes of foodborne illness
and spoilage. Fewer microorganisms are present in spices with higher
antimicrobial activity such as sage, cloves, and oregano. However, all spices
and herbs should be cleaned and decontaminated with ethylene oxide, irradiation,
or other acceptable methods (6).
Antimicrobial
Compounds in Spices and Herbs
Essential oils extracted from spices and herbs are generally recognized as
containing the active antimicrobial compounds. Table 3 is a list of the
proximate essential oil content of some spices and herbs and their antimicrobial
components.
Table
3. Antimicrobial Components of Spices and Herbs*
Spice
/ Herb |
Proximate
Essential Oil Content (%) |
Antimicrobial
Component(s) |
Garlic |
0.3
- 0.5 |
Allicin |
Mustard |
0.5
- 1.0 |
Allyl
isothiocyanate |
Cinnamon |
0.5
- 2.0 |
Cinnamaldehyde,
Eugenol |
Cloves |
16
- 18 |
Eugenol |
Sage |
0.7
- 2.0 |
Thymol,
Eugenol |
Oregano |
0.8
- 0.9 |
Thymol,
Carvacrol |
*
Adapted from Shelef (17).
Allicin and allyl
isothocyanate are sulfur-containing compounds. Allicin, isolated from garlic
oil, inhibits the growth of both gram-negative and gram-positive bacteria.
Sulfur-containing compounds are also present in onions, leeks, and chives.
Eugenol, carvacrol, and
thymol are phenol compounds and, as Table 3 indicates, are found in cinnamon,
cloves, sage, and oregano. The essential oil fraction is particularly high in
cloves, and eugenol comprises 95% of the fraction. The presence of these
compounds in cinnamon and cloves, when added to bakery items, function as mold
inhibitors in addition to adding flavor and aroma to baked products. Paster et
al. (14) have shown that essential oils of oregano and thyme (which
contain carvacrol and thymol) are effective as fumigants against fungi on stored
grain. These investigators have proposed using them as an alternative to
chemicals for preseving stored grains.
Antioxidant
Action
Spice extractives, such as oleoresin of rosemary, can provide inhibition of
oxidative rancidity and retard the development of "warmed-over" flavor
in some products. Thus, some spices not only provide flavor and aroma to food
and retard microbial growth, but are also beneficial in prevention of some
off-flavor development. These attributes are useful in the development of snack
foods and meat products (6).
Summary
Although the antimicrobial activity of some spices and herbs is documented, the
normal amounts added to foods for flavor is not sufficient to completely inhibit
microbial growth. The antimicrobial activity varies widely, depending on the
type of spice or herb, test medium, and microorganism. For these reasons, spice
antimicrobials should not be considered as a primary preservative method (6).
However, the addition of herbs and spices can be expected to aid in
preserving foods held at refrigeration temperatures, at which the multiplication
of microorganisms is slow.
Zaika (20) has
given an excellent summary of the antimicrobial effectiveness of spices and
herbs. A partial listing of this summary is as follows.
Thus,
food product safety and shelf life depend in some part on the type, quantity,
and character of spices and herbs added to the products.
References