These two are essentials not only for culinary but for medicinal uses.
A spice is a dried seed, fruit, root, bark, or vegetative substance used in nutritionally insignificant quantities as a food additive for flavor, color, or as a preservative that kills harmful bacteria or prevents their growth. It may be used to flavour a dish or to hide other flavours. In the kitchen, spices are distinguished from herbs, which are leafy, green plant parts used for flavoring.
Many spices are used for other purposes, such as medicine, religious rituals, cosmetics, perfumery, or for eating as vegetables. For example, turmeric is also used as a preservative; liquorice as a medicine; garlic as a vegetable.
A spice may be available in several forms: fresh, whole dried, or pre-ground dried. Generally, spices are dried. A whole dried spice has the longest shelf life, so it can be purchased and stored in larger amounts, making it cheaper on a per-serving basis. Some spices are rarely available either fresh or whole, for example turmeric, and must be purchased in ground form. Small seeds, such as fennel and mustard seeds, are used both whole and in powder form.
The flavor of a spice is derived in part from compounds that oxidize or evaporate when exposed to air. Grinding a spice greatly increases its surface area and so increases the rates of oxidation and evaporation. Thus, flavor is maximized by storing a spice whole and grinding when needed. The shelf life of a whole spice is roughly two years; of a ground spice roughly six months. The “flavor life” of a ground spice can much shorter. Ground spices are better stored away from light.
An herb is a plant that is valued for flavor, scent, medicinal or other qualities. Herbs are used in cooking, as medicines, and for spiritual purposes.
Herbs have a variety of uses including culinary, medicinal, or in some cases even spiritual usage. General usage differs between culinary herbs and medicinal herbs. In medicinal or spiritual use any of the parts of the plant might be considered “herbs”, including leaves, roots, flowers, seeds, resin, root bark, inner bark (cambium), berries and sometimes the pericarp or other portions of the plant.
Culinary use of the term “herb” typically distinguishes between herbs, from the leafy green parts of a plant (either fresh or dried), and spices, from other parts of the plant (usually dried), including seeds, berries, bark, root and fruit. Culinary herbs are distinguished from vegetables in that, like spices, they are used in small amounts and provide flavor rather than substance to food.
Many culinary herbs are perennials such as thyme or lavender, while others are biennials such as parsley or annuals like basil. Some perennial herbs are shrubs (such as rosemary, Rosmarinus officinalis), or trees (such as bay laurel, Laurus nobilis) – this contrasts with botanical herbs, which by definition cannot be woody plants. Some plants are used as both an herb and a spice, such as dill weed and dill seed or coriander leaves and seeds. Also, there are some herbs such as those in the mint family that are used for both culinary and medicinal purposes.
Plants contain phytochemicals that have effects on the body.
There may be some effects when consumed in the small levels that typify culinary “spicing”, and some herbs are toxic in larger quantities. For instance, some types of herbal extract, such as the extract of St. John’s-wort (Hypericum perforatum) or of kava (Piper methysticum) can be used for medical purposes to relieve depression and stress. However, large amounts of these herbs may lead to toxic overload that may involve complications, some of a serious nature, and should be used with caution. One herb-like substance, called Shilajit, may actually help lower blood glucose levels which is especially important for those suffering from diabetes. Herbs have long been used as the basis of traditional Chinese herbal medicine, with usage dating as far back as the first century and far before.
Medicinal use of herbs in Western cultures has its roots in the Hippocratic (Greek) elemental healing system, based on a 4-fold elements healing metaphor. Famous herbalist of the Western tradition include Avicenna (Arabian), Galen (Roman), Paracelsus (German Swiss), Culpepper (English) and the botanically inclined Eclectic physicians of 19th century/early 20th century America (John Milton Scudder, Harvey Wickes Felter, John Uri Lloyd). Modern pharmaceuticals had their origins in crude herbal medicines, and to this day, many drugs are still extracted as fractionate/isolate compounds from raw herbs and then purified to meet pharmaceutical standards.
Some herbs are used not only for culinary and medicinal purposes, but also for psychoactive and/or recreational purposes; one such herb is cannabis.
Herbs are used in many religions. For example, myrrh (Commiphora myrrha) and frankincense (Boswellia spp) in Christianity, the Nine Herbs Charm in Anglo-Saxon paganism, the neem tree (Azadirachta indica) by the Tamils, holy basil or tulsi (Ocimum tenuiflorum) in Hinduism, and many Rastafarians consider cannabis (Cannabis sp) to be a holy plant. Siberian Shamans also used herbs for spiritual purposes. Plants may be used to induce spiritual experiences for rites of passage, such as vision quests in some Native American cultures. The Cherokee Native Americans use white sage and cedar for spiritual cleansing and smudging.