Processing is what farmers do to a crop after harvest. Nurturing the living plants is part of the agrarian cycle. But after harvesting, the agrarian cycle is complete, and further handling is properly called processing. Some crops require little processing. Indeed, many fruits and vegetables can go from field to table with a simple washing. For example, after picking and packing, the apple growers' work is done. Not so with tobacco growers.
Forms of Processing
Raw tobacco contains moisture that must be removed before manufacturing can begin. As the leaves are the only plant part that is sold, tobacco processing focuses on drying or curing the leaves. As much as 90 percent of the weight of raw tobacco is lost in curing. Proper curing is important. An average field crop can be greatly improved by careful curing. Conversely, a fine field crop can be ruined in the curing barn. Thus, tobacco growers must be as skilled in curing as they are in cultivating. There are three curing methods in common use in the United States: aircuring, fire-curing, and flue-curing.
AIR-CURING. Air-curing is the oldest form of tobacco processing. Burley, Maryland, and Connecticut Valley tobaccos are air-cured. Maturity of the living plant is judged by color, and plants are ripe when the leaves change from dark green to light green to yellow. In air-curing cultures, growers harvest the entire plant. Stalks are cut at the bottom, laid on the ground, and allowed to wilt. The stalks are then spiked—or pierced near the bottom with a metal tool—and sticks are inserted through the stalks. Typically, five or six plants are hung on a stick. Some Burley growers hang the tobacco sticks on outdoor racks to hasten curing, but most Burley is barn-cured. After spiking, growers carry the plants to the curing barn and hang them in tiers, leaving air spaces in between.
Historically, air-curing barns have been designed to provide protection from rain and wind but afford ample air exchange and circulation. The plants cure naturally without artificial heat, but fans are sometimes used to improve air movement. Curing times vary with environmental factors like humidity and temperature, but plants usually remain in the curing barn for four to six weeks. As they cure, the leaves continue to change from light green to light brown, mahogany, or gold.
When the leaves have thoroughly dried and coloring is complete, leaves are stripped from the stalks. Growers then bulk the leaves, forming them in piles and covering them with fabric for protection. Many growers scatter the stripped stalks in the fields and thus return their substance to the earth. When preparing the leaves for market, growers sort or grade the cured leaves by color and tie them in small bundles. More recently, some tobaccos are pressed into bales. The tobacco is stored carefully to remain in order—that is, moist enough to be pliable yet dry enough not to mold or mildew. At marketing time, growers carry their tobacco to a warehouse for auction or, more recently, directly to a purchaser by prearrangement.
Air-curing produces flavorful tobaccos highly valued by the trade. Most Burley is consumed in cigarettes, but some Burley is blended into pipe tobaccos and other smoking products. Connecticut Valley leaf, the most valuable tobacco in the world, is used in premium cigars. Approximately 40 percent of the total U.S. tobacco crop is air-cured.
FIRE-CURING. Fire-curing is practiced along the Tennessee–Kentucky border and in some parts of Virginia. Fire-curing is a variation of aircuring in which small fires are built on the floors of the curing barns to aid drying. Great care is taken to maintain the correct temperature and humidity and thus affect a proper cure. Sometimes, very little firing is needed, and dry weather can delay firing for several days. In damp weather, however, growers light a series of low fires. Hickory and oak are the fuels of choice, and fires are sometimes fed with sawdust so they smolder rather than flame. Several firings may be needed to completely cure and smoke the leaves. Purchasers value the rich, smoky flavor of dark-fired tobacco, and a high smoke volume is maintained during the final curing stage. When the tobacco is finished, roof ventilators purge the heat and smoke.
As in air-curing cultures, fire-cured tobacco is stripped and bulked. When ready, the leaves are graded and tied. Leaves are assorted by color or stalk position, four or five grades being typical. The rustic flavor of fire-cured leaf is popular in chewing tobacco, snuff, pipe tobacco, and in certain European cigars. Less than 10 percent of the American crop is fire-cured.
FLUE-CURING. Also called Bright leaf, flue-cured varieties account for about half of American tobacco production. Areas of Virginia, North Carolina, South Carolina, Georgia, and Florida flue cure tobacco. Most flue-cured tobacco is consumed in cigarettes. A major cultural difference from other types is how Bright leaf is harvested. Tobacco leaves do not all ripen at once. The bottom leaves ripen first, then those next to the bottom and so on to the uppermost leaves. Waiting for the upper leaves to ripen ensures that the bottom leaves are overripe and nearly worthless. Therefore, Bright leaf growers harvest the leaves as they ripen, breaking off a few leaves every week until all leaves have been harvested. Unlike Burley and dark-fired tobacco, the stalk is not harvested. This method assures all leaves are harvested at the proper time.
Historically, flue-curing evolved from fire-curing. Fire-cured leaves are strongly flavored and coated by smoke and soot. By the 1880s, however, demand for milder, more aromatic cigarette tobaccos drove the development of flue-curing. Artificial heat flows from an outside furnace through a network of stovepipes, or flues, running parallel to and a few inches above the floor of the curing barn. An exhaust pipe vents smoke and soot outside. Thus, the leaves are cured rapidly by artificial heat free of ashes, soot, and smoke. Moreover, even temperatures are easier to maintain with flues, resulting in a more uniform cure. Temperatures as high as 71 degrees Celsius (or 160 degrees Fahrenheit) are applied, and the tobacco is fully cured in a few days rather than several weeks. After curing, leaves are bulked—there are no stalks to strip—and stored until marketing time.
▌ ELDRED E. PRINCE JR.
Gately, Iain. Tobacco: The Story of How Tobacco Seduced the World. New York: Grove Press, 2001.
Goodman, Jordan. Tobacco in History: The Cultures of Dependence. London: Routledge, 1993.
Hirschfelder, Arlene B. The Encyclopedia of Smoking and Tobacco. Phoenix, Ariz.: Oryx Press, 1999.
Kluger, Richard. Ashes to Ashes: America's Hundred-Year Cigarette War, the Public Health, and the Unabashed Triumph of Philip Morris. New York: Vintage Books, 1997.
air-curing the process of drying leaf tobacco without artificial heat. Harvested plants are hung in well-ventilated barns allowing the free circulation of air throughout the leaves. Air-curing can take several weeks. Burley tobacco is air-cured.
air-cured tobacco leaf tobacco that has been dried naturally without artificial heat.
snuff a form of powdered tobacco, usually flavored, either sniffed into the nose or "dipped," packed between cheek and gum. Snuff was popular in the eighteenth century but had faded to obscurity by the twentieth century.
flue-cured tobacco also called Bright Leaf, a variety of leaf tobacco dried (or cured) in air-tight barns using artificial heat. Heat is distributed through a network of pipes, or flues, near the barn floor.
It is of critical importance to properly identify, collect, preserve, and transport forensic scientific evidence for processing. During the investigation of a crime, the initial objectives regarding evidence are to thoroughly document and photograph the scene and to annotate the description and location of evidence to be gathered. A systematic process is then used to collect and package evidence for transport to the laboratory. Photographing may continue throughout the sample collection process, particularly if there are multiple layers of evidence that can only be seen as those above them are removed.
Paper packets, envelopes, and bags are most commonly used for specimen collection, because they do not gather evidence-destroying moisture or condensation. Nonporous, leakproof, and unbreakable containers are used for collecting and moving liquids, and clean, airtight metal canisters are used to transport arson evidence. Plastic bags are sometimes used to collect dry or powdered evidence. Blood and other moist evidence can be moved from the crime scene to the lab in plastic containers only if the transport time is less than two hours, in order to avoid the introduction and proliferation of contamination-causing bacteria. Upon receipt at the processing area, all items of evidence must be cataloged, then removed and allowed to completely air dry. After drying, evidence can be repackaged in paper or other suitable containers as necessary.
When packaging evidence, it is imperative to avoid cross-contamination by separately and securely packaging and sealing different items. At the start of the custody chain, the evidence container must be clearly marked with the initials of the collector, the date and time of acquisition, a detailed description of both the evidence specimen and the location from which it was collected, and the investigating agency's name and case file number.
The chain of custody typically refers to the paper trail, evidence log, or other forms of documentation pertaining to the collection (whether by sampling or legal seizure), custody, control, transfer, analysis, presentation, and final disposition of material and/or electronic evidence.
In order for evidence to be admissible and credible in court, it is essential that the chain of custody remain intact. Every contact with, or movement of, a piece of evidence must be documented in detail in order to verify that it was never unaccounted for or potentially tampered with. A specific, and appropriately credentialed, individual must be assigned physical custody of individual items of evidence. In law enforcement proceedings, this generally means that a detective will have overall responsibility for the integrity of the evidence; he or she will document its receipt and sign it over to an evidence clerk who is responsible for storing the evidence in a locked and secured area. Every single transaction involving any piece of evidence must be chronologically documented in minute detail from the moment of collection through presentation in court, in order to establish authenticity, and to defend against allegations of tampering. The documentation must include a detailed description of the location and conditions under which the evidence was collected, the identity (and possibly the credentials) of every handler of the evidence, the duration of each movement of the evidence, the level of security for each movement, as well as the overall storage of the item, and a specific description of the manner and conditions under which each transfer of the evidence occurred. If the chain of custody is broken at any time, the evidence is likely to be inadmissible or of minimal, if any, legal value.
see also Bloodstain evidence; Cameras; Crime scene investigation; Disturbed evidence; Physical evidence; Quality control of forensic evidence.