Copyright 1997 by O. Peter Snyder
Hospitality Institute of Technology and Management; St. Paul, Minnesota

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 
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) 
0.3 - 0.5 
0.5 - 1.0 
Allyl isothiocyanate 
0.5 - 2.0 
Cinnamaldehyde, Eugenol 
16 - 18
0.7 - 2.0 
Thymol, Eugenol 
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).

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.

  1. Microorganisms differ in their resistance to a given spice or herb.
  2. A given microorganism differs in its resistance to various spices and herbs.
  3. Bacteria are more resistant than fungi.
  4. The effect on spores may be different than that on vegetative cells.
  5. Gram-negative bacteria are more resistant than gram-positive bacteria.
  6. The effect of a spice or herb may be inhibitory or germicidal.
  7. Spices and herbs harbor microbial contaminants.
  8. Spices and herbs may serve as substrates for microbial growth and toxin production.
  9. Amounts of spices and herbs added to foods are generally too low to prevent spoilage by microorganisms.
  10. Active components of spices / herbs at low concentrations may interact synergistically with other factors (NaCl, acids, preservatives) to increase preservative effect.
  11. Nutrients present in spices / herbs may stimulate growth and/or biochemical activities of microorganisms.
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.
  1. Azzouz, M. A. and Bullerman, L. R. 1982. Comparative antimycotic effects of selected herbs and spices, plant components and commercial antifungal agents. J. Food Protect. 45:1248-1301.
  2. Beuchat, L. R. Sensitivity of Vibrio Parahaemolyticus to spices and organic acids. J. Food Sci. 41:899-902.
  3. Bullerman, L. B. 1974. Inhibition of aflatoxin production by cinnamon. J. Food Sci. 39:1163-1165.
  4. Bullerman, L. B., Lieu, F. Y., and Seier, S. A. 1977. Inhibition of growth and aflatoxin production by cinnamon and clove oils, cinnamic aldehyde and eugenol. J. Food Science. 42:1107-1109, 1116.
  5. Dankert, J., Tromp, Th. F. J., Devries, H. and Klasen, H. J. 1979. Antimicrobial activity of crude juices of Allium ascalonicum, Allium cepa and Allium sativum. Zb. Bkr. Hyg., I. Abt. Orig. A245:229-239.
  6. Giese, J. 1994. Spices and seasoning blends: A taste for all seasons. Food Technol. 48(4):87-98.
  7. Hitokoko, H., Morozumi, S., Wauke, T., Sakai, S., and Kurata, H. 1980. Inhibitory effects of spices on growth and toxin production of toxigenic fungi. Appl. Env. Microbiol. 39:818-822.
  8. Huhtanen, C. N. 1980. Inhibition of Clostridium botulinum by spice extracts and aliphatic alcohols. J. Food Protect . 43:195-196, 200.
  9. Johnson, M. G., and Vaught, R. H. 1969. Death of Salmonella typhimurium and Escherichia coli in the presence of freshly reconstituted dehydrated garlic and onion. Appl. Microbiol. 17:903-905.
  10. Julseth. R. M. and Deibel, R. H. 1974. Microbial profile of selected spices and herbs at import. J. Milk Food Technol. 37:414-419.
  11. Kneifel, W. and Berger, E. 1994. Microbial criteria of random samples of spices and herbs retailed on the Austrian market. J. Food Protect. 57:893-901
  12. LLewellyn, G.C., Burkitt, M. L., and Eadie, T. 1981. Potential mold growth, aflatoxin production and antimycotic activity of selected natural spices and herbs. J. Assoc. Off. Anal. Chem. 64(4):955-960/
  13. Pafumi, J. 1986. Assessment of microbiological quality of spices and herbs. J. Food Protect. 49:958-963
  14. Paster, N., Menasherov, M., Ravid, U., and Juven, B. 1995. Antifungal activity of oregano and thyme essential oils applied as fumigants against fungi attacking stored grain. J. Food Protect. 58:81-85.
  15. Powers, E. M., Layer, R., and Masuoka, Y. 1975. Microbiology of processed spices. J. Milk Food Technol. 38:683-687.
  16. Sharma, A., Tewari, G. M., Shrikhande, A. J., Padwal-Desai, S. R., and Bandyopadhyay, C. 1979. Inhibition aflatoxin producing fungi by onion extracts. J. Food Sci. 44:1545-1547.
  17. Shelef, L. A. 1983. Antimicrobial effects of spices. J. Food Safety. 6 29-44.
  18. Shelef, L. A., Jyothi, E. K., and Bulgarelli, M. 1984. Effect of sage on growth of enteropathogenic and spoilage bacteria in sage containing broths and foods. J. Food Sci. 737-740, 809.
  19. Shelef, L. A., Naglik, O. A., and Bogen, D. W. 1980. Sensitivity of some common food-borne bacteria to the spices sage, rosemary, and allspice. J. Food Sci. 45(4):1045-1044.
  20. Zaika, L. L. 1988. Spices and herbs: Their antimicrobial activity and its determination. J. Food Safety. 9:97-118.


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