 Contaminated seed is the likely source for most reported sprout-associated outbreaks. Knowing as much as possible about where and how the seed was produced and handled can increase the chances of starting with clean seed. In this module, we will help you be aware of the questions that need to be asked of seed growers, conditioners and or suppliers. It may also help in understanding some of the constraints growers face in producing seed for sprouting. A multitude of field and vegetable crop seeds are sprouted for human consumption, such as alfalfa, clover, onion, radish, broccoli, lentils and mung beans. Seed for sprouting is produced throughout the world, but the major suppliers are in the U.S., Canada and Australia. Crop production practices vary with the type of crop in the area where it's grown. In this review, we will use alfalfa seed as an example, but many of the factors discussed, such as potential sources of contamination and good agricultural and manufacturing practices to minimize contamination will apply to any type of seed. Approximately 80 million pounds of alfalfa seed are produced each year in the United States. The primary market for that seed is planting stock to produce forages to support livestock. Only a small fraction of the seed produced is used for sprouting. If the seed growers are unaware that the seed is to be used for human consumption, they may unknowingly use agricultural practices that create a potential health risk. Potential sources of contamination are present in the field and in the harvest equipment, as well as at the conditioning, seed supplying and or sprouting facility. Although the precise method of contamination of seeds is not known, some possible sources of contamination include agricultural water, animal waste or manure, poor sanitation of equipment, or poor personal hygiene. Contamination of seed may be sporadic and at low levels, but once pathogens are present, they are likely to survive for extended periods of time under normal seed storage conditions. Therefore, it's important to reduce the risk of contamination as much as possible at each step in the production, conditioning and distribution process. FDA's Guide to Minimize Microbial Hazards for Fresh Fruits and Vegetables addresses common sources of contamination in an agricultural environment and ways to minimize them. A summary of that guide is included with this video. Seed distributors and sprouters buying seed directly from growers should ask questions to ensure GAPs were followed before purchasing seed for sprouting. Buyers may utilize contracts with growers or conditioners that specify good agricultural and manufacturing practices to reduce the possibility of contamination. For alfalfa seed and other perennial crops, the season begins when the forage that has grown during the winter or early spring is removed in an operation called clipback. If there's enough forage or plant material present and previous chemical use doesn't restrict it, this clipping can actually be a hay harvest. In some areas, sheep are brought into the seed fields to remove this winter growth. However, manure from sheep and other animals can be a source of human pathogens. If the seed from the field is destined for the sprout market, sheep should not be allowed to graze. If sheep have grazed the field, the seed should not be used for sprouting. Growers may use commercial fertilizers and or manure to maintain the fertility of the soil for maximum crop production. The application of manure should be avoided during the production of a seed crop for sprouting. If manure is used, growers should follow good agricultural practices such as composting and maximizing the time between application and harvest to minimize microbial hazards. The use of untreated manure or raw manure should be avoided. Drift or runoff from adjacent fields where manure is used from nearby manure storage or treatment sites or animal production areas may also be a source of contamination. All crops require water. In some areas, water supplied through rainfall is supplemented by irrigation. Growers use a diverse variety of water sources including canal water and well water to irrigate their crop. It's applied to the surface of the soil by flood, furrow, or sprinkler irrigation systems. If the seed is to be used for sprouting, growers should evaluate the quality of their water source and follow appropriate good agricultural practices such as runoff control and animal exclusion to ensure and maintain water quality. In the field, the seed is protected from contamination by the seed pod. But once harvest begins, the seed is exposed to a substantial amount of dirt and debris. Mechanical damage is also an important issue. Any damage to the seed code caused by harvest equipment could aggravate contamination by making removal of pathogens during subsequent steps more difficult. In many areas where the seed is grown for commercial planting stock, it's desiccated using chemicals that dry the standing crop in preparation for harvest. However, if seed is to be used for sprouting, chemical drying agents should not be used. Rather, the crop should be cut at the base of the plant and laid in long rows to air dry. A standard combine is used to pick up the crop in the windrow and thresh the seed from the pod. The equipment should be carefully adjusted to separate the very small seed from a large amount of plant material without damaging it. The equipment should also be adjusted to minimize soil uptake during harvest. Seed goes from the combine into bins or a truck for transport to the conditioning facility. If the seed is destined for the sprout market, it should be transported in a manner that will minimize contamination from soil, manure, animal and rodent urine. Seeds should be protected with a tarp during storage and shipping. Conditioning is the process of cleaning the seed to remove weed seeds, debris and dirt. Equipment such as an air screen cleaner, specific gravity separator, velvet rolls, disc and cylinder separators, and or a spiral separator may be used. As with the harvest process, conditioning has the potential to damage seed and to spread localized contamination throughout the seed lot. It's important to limit sources of contamination and minimize the risk of cross-contamination in the conditioning facility. Seed, cleaning equipment, storage bins and supplies such as shipping bags should be protected from contamination by rodents, birds, insects and reptiles. If seed is damaged and pathogens are present, they can lodge in cracks in the seed coat and may make subsequent seed disinfection more difficult. Thus seed conditioners should make every effort to separate out damaged seed and to minimize damage to seed destined for sprouting. Seed damage may be inadvertent such as improper settings or overloading of equipment or it may be purposeful as in scarification. Scarification is the scratching of the seed coat to improve the percentage and uniformity of germination of a seed lot with a high hard seed percentage. A number of different techniques, chemical and physical, may be used. Once the seed is cleaned, it's stored in the warehouse in both bins or bags prior to distribution. During storage, seed should be protected from contamination by animals, insects or agricultural or industrial wastes and chemicals. Good manufacturing practices, GMPs, for seed storage include storing seed in closed impermeable containers in a clean area dedicated to seed storage. Containers should be positioned in such a way that contact with contaminants is minimized and regular inspection is possible. Visual inspection of the seed and the area between and around storage containers allows monitoring of pest problems and timely control if necessary. Most seed is distributed to suppliers and sprouters in 50 pound bags. The bag provides one of the first lines of defense against post harvest contamination. Clean bag should always be used if the seed is destined for sprouting and stored in a clean environment. Seed suppliers and sprouters should purchase seed in bags or other containers which clearly and prominently display the following information. Supplier information, lot number, seed type, germination and purity, date of harvest, seed company and or country of origin. The lot number is important in maintaining the identity of the seed and if recorded facilitates tracking the seed from the growers field to the conditioner, supplier, sprouter and back again. The lot number may be found on a tag attached to the bag or it may be printed directly on the bag. The conditioner may test individual seed lots for purity and germination. Screening for the presence of pathogens is not typical although some seed distributors are beginning to adopt seed testing programs. Often seed goes through one or more distributors before reaching the sprouter. At each step of the distribution chain, seed should be visually inspected for evidence of contamination including insects, water stains and presence of rodent or bird droppings. Additionally, a black light can be used to detect product that has been contaminated with rodent urine. Bags of seed that have been contaminated with rodent urine will glow. If evidence of contamination is found, seed should not be used for sprouting. After inspection, seed should be stored in a clean and sanitary area. Stored seed in surrounding areas should be inspected frequently to ensure that pests including rodents are not present. The definition of a lot is important. Currently, a lot may be defined as all of the seed from a specific field or a truckload. It may also be defined as all the seed of a given variety from a growers farm. In addition, some suppliers may mix various quantities of seed and assign a lot number to that container. Assigning a lot number to the smallest discrete unit helps limit the amount of seed that might need to be recalled in the event of a problem. Some suppliers mix seed lots to adjust quality factors such as percent germination or to increase the size of the lot. However, mixing lots is not recommended because it may spread contamination and hampers trace back. Some seed from other countries may be mixed prior to arrival at the distributor. Suppliers should make every effort to ensure that they know the precise origin of the seed they sell for sprouting and that the information is also passed to the buyer. Because of recent food safety concerns associated with sprouts, it's strongly recommended that suppliers establish a sampling plan and criteria for seed sold to sprouters. Suppliers should first examine samples from desired seed lots prior to committing to purchase. If the seed sample passes the initial examination and the lot is purchased, it should be re-examined thoroughly upon arrival. Sampling procedures should be established to ensure examination is as representative as possible of the entire lot. Visual seed examination uses magnification to look for evidence of rodent droppings, excretia, fungus, molds, or a large number of cracked and broken seeds. Seed samples should also be evaluated under black light for signs of urine. This is in addition to examining seed bags upon arrival and periodically during storage. Some distributors are beginning to test seed for pathogens such as E. coli 0157H7 and Salmonella. Contamination of seed is probably at low levels and sporadic. Sprouting seed first and then testing either the water or the sprouts may increase the likelihood of finding pathogens if they are present. Microbial testing procedures are described in more detail later in this video. While a negative result does not guarantee the absence of pathogens, a positive result would allow a supplier to ensure the seed is not sold for sprouting. If microbial tests are done, seed should be held in quarantine until the results of testing show no contamination. Results of seed testing should be maintained by lot number. Sprouter should ask suppliers if seed has been tested for pathogens and which tests were done. The more testing that is conducted, the better the chances of detecting a problem if it exists. Using good quality seed is an important step towards producing the safest possible product. Everyone needs to establish safeguards that prevent contaminated seed from entering the food chain. Individual sprouters need to develop a relationship with their seed supplier and insist upon receipt of clean seed from a reliable source. Seeds for sprout production should be grown, conditioned, stored and transported under conditions that minimize exposure to pathogens. Good agricultural practices should be systematically implemented to reduce the potential for contamination of seeds for sprout production. Increasing awareness of the potential for contamination from the field through the sprouting facility and implementing GAPs and GMPs to improve handling of seeds and sprouts will reduce the risk of foodborne disease. Additional recommendations for producing sprouts are contained in the following modules.