Spices are dried plants or parts of plants which are used primarily for flavouring, seasoning, and imparting aroma or colour to foods and beverages. For the purposes of this discussion herbs, the aromatic leaves and flowers of certain plants, are included as spices. Condiments are spices and blends of spices which may be formulated with flavour accentuators and potentiators to enhance the flavour of foods. ‘Spices and condiments’ is the official nomenclature adopted by the International Organization for Standardization (ISO, 1972).
Gums include a wide range of plant and microbial polysaccharides, or their derivatives, which hydrate in either cold or hot water to form viscous solutions or dispersions. In addition to tree exudates, actual gums include seaweed extracts (e.g., agar, alginates, and carrageenan), gums from seed (e.g., locust bean, guar), and microbial gum (e.g., xanthan). As hydrocolloids, gums usually exhibit suspending, dispersing, and stabilizing properties, or they may function as emulsifiers, impart gelling properties, or be mucilaginous. Some gums serve as binders, flocculating agents, film formers, foam stabilizers, mould release agents, or lubricants (Peppier and Guarino, 1984).
A. INTERNATIONAL COMMERCE
Spice-bearing plants are chiefly indigenous to the Asian tropics but are grown commercially in many tropical and some temperate climates (e.g., in Hungary). Herbs are grown in more temperate climates of the Mediterranean, Middle East, North Africa, and North America and widely throughout Europe. India, one of the major spice producers and exporters, accounts for more than 50% of the international trade now estimated at 400 million dollars annually. The United States spice
Reprinted from: Microorganisms in Foods 2. Sampling for microbiological analysis: Principles and specific applications. 1986. 2nd Ed. International Commission on Microbiological Specifications for Foods.
consumption, alone, is around 500 million pounds per year. The spice map of the world continues to change as some sources decline, others are revitalized, and new areas of spice production are developed (Peppier and Guarino, 1984).
The major sources of gums include India, Sudan, North Africa, Iran, Asia Minor, Pakistan, and Mediterranean countries (Peppier and Guarino, 1984).
B. COLLECTION OF SPICES AND GUMS
Spices are produced from botanically diverse plants grown in a wide variety of soils and climates. Depending on the spice, various parts of the plant are used, such as the seed (mustard and nutmeg), the berry (pepper), the fruit (celery seed and nutmeg), the leaves (oregano and bay), the root (horseradish), or the bark (cinnamon) (ICMSF, 1980, pp.
731-751).
As with grains, the primary consideration after harvesting is to dry the plant portion to a water activity level sufficiently low to prevent spoilage. Subsequently, further processing may involve, depending on the spice, such treatments as grinding, pulverizing, cleaning, and sort-ing. Some of these operations may be carried out at or near the point of harvest; others may be done at a remote site after shipment in international commerce. The microflora of spices reflects the diversity of raw materials from which they are derived, together with the varied and climatic conditions under which the plants are grown. These factors are further influenced by conditions of drying and storage, both of which may be extremely primitive (ICMSF, 1980, pp. 731-751).
Processing methods for many gums are proprietary, but patents and other literature provide some insight. Most tree gums are collected by hand and sorted, graded, packed, and shipped from the growing area.
The processor further grades, cleans, mills, and blends the gum. As with spices, the water activity of the crude material is reduced to a level to preclude microbial growth. For example, gum ghatti is sundried and pulverized. Carrageenan is extracted from red algae with hot water, filtered and concentrated to about 3% gum content, precipitated with ethanol, dried, and milled (Peppier and Guarino, 1984).
C. MICROBIOLOGY OF SPICES, GUMS, AND HERBS
These products commonly carry large numbers of bacteria and moulds, in the case of herbs mainly of soil origin. Conditions of handling after
Reprinted from: Microorganisms in Foods 2. Sampling for microbiological analysis: Principles and specific applications. 1986. 2nd Ed. International Commission on Microbiological Specifications for Foods.
Spices, condiments, and gums 215
harvest often permit extensive contamination and microbial growth although drying with heat somewhat reduces microbial numbers. The predominating flora is generally composed of aerobic spore-forming bacteria. Non-spore-forming bacteria, indicator organisms, and pathogens may be found.
The numbers of microbial contaminants can be reduced by treatment with ethylene oxide and to a lesser extent with propylene oxide.
Irradiation is also effective in reducing microbial populations (ICMSF,
1980, p. 746).
Bacterial spoilage subsequent to harvesting and drying constitutes no problem, but spoilage by fungi may occur during storage and shipping.
Of major concern is the role of contaminating microorganisms as spoilage agents in foods where spices and gums are used as ingredients. Spices contaminated with excessive numbers of spore-forming bacteria may be responsible for the spoilage of canned foods and processed meats (ICMSF,
1980, pp. 747-748). Though spore-forming organisms capable of causing gastroenteritis are found in small numbers in spices, they present no public health concern unless the foods into which the spices are incorporated as ingredients are mishandled to the extent that the small number of Bacillus cereus and Clostridium perfringens, for example, are permitted to multiply extensively. Salmonella is found infrequently, but in a wide variety of spices, and on rare occasions has been responsible for outbreaks of human salmonellosis (Laidley et al., 1974; Lystad et al., 1982; Gustavsen and Breen, 1984).
D. SAMPLING PLANS
In the first edition of this book (p.115) sampling plans and micro-biological limits were suggested for spices and gums. In retrospect, it is felt that these recommendations were inappropriate. A considerable portion of these commodities in international commerce would not meet the suggested limits; furthermore, failure to meet the limits might or might not have borne a relationship to food quality or safety.
It is now our recommendation that spices and gums be treated as raw agriculture commodities. Accordingly, the ultimate use of such products will be the determinant. A spice or gum which is unsatisfactory for one purpose may be quite adequate for another. For example, black pepper containing large numbers of aerobic spore-forming bacteria may cause spoilage when used as an ingredient in canned foods or cooked sausage, but it could be used as a condiment on the table
Reprinted from: Microorganisms in Foods 2. Sampling for microbiological analysis: Principles and specific applications. 1986. 2nd Ed. International Commission on Microbiological Specifications for Foods.
for seasoning cooked foods. A manufacturer using spices and gums must determine whether the microbiological quality of these products is satisfactory for the use intended (NCA, 1968). If it is not, his alter-natives are to seek another source or to render the available product satisfactory. Treatment with ethylene oxide has been practised exten-sively for many years but there is some concern over its continued use.
Gamma-irradiation may be an effective alternative provided flavours are not impaired.
In commercial practice the microbial and colour problems, and to some extent variability, are overcome by using extracts of the spices.
For convenience in use these are often diluted on a carrier such as salt or a finely ground cereal (usually rusk, i.e., ground non-sweetened biscuit). Another approach is to use microencapsulated extracts using gelatin or starch as the encapsulant. Use of these forms is increasing at the expense of ‘raw spices’.
REFERENCES
Gustavsen, S. and Breen, O. 1984. Investigation of an outbreak of Salmonella oranienburg infection in Norway, caused by contaminated black pepper. American Journal of Epidemiology, 119, 806-812
ICMSF. 1980. Microbial Ecology of Foods. Vol. 2. Food Commodities. Academic Press, New York
ISO (International Organization for Standardization). 1972. Spices and Condiments.
Nomenclature finalized draft proposal. TC-34/SC-7, ISO, Budapest
Laidley, R., Handzel, S., Severs, D., and Butler, R. 1974. Salmonella weltevreden outbreak associated with contaminated pepper. Epidemiology Bulletin (Department of National Health and Welfare, Ottawa), 18 (4), 62
Lystad, A., Aasen, S., and Lassen, J. 1982. Food-borne disease surveillance. Outbreak of Salmonella oranienburg infection (Norway). Weekly Epidemiological Record, 57, 329-330
NCA (National Canners Association). 1968. Laboratory Manual for Food Canners and Processors, vol. 1, 3rd ed. AVI Publishing Co. Westport, Conn.
Peppler, H.J., and Guarino, P.A. 1984. Spices and condiments. In Compendium of Methods for the Microbiological Examination of Foods, 2nd ed., ed. M.L. Speck. American Public Health Association, Washington, DC
Reprinted from: Microorganisms in Foods 2. Sampling for microbiological analysis: Principles and specific applications. 1986. 2nd Ed. International Commission on Microbiological Specifications for Foods.