Food Source Information Sunflower Seeds and Oil

Sunflower (Helianthus annuus L.) is one of the few crop species that originated in North America (most originated in the fertile-crescent, Asia or South or Central America). It was most likely domesticated by Native Americans around 1000 BC, who carried it eastward and southward of North America. (Putnam, et al, 1990)

Sunflowers were probably first introduced to Europe through Spain. The crop, spread through Europe as a curiosity until it reached Russia, where it was readily adapted. In Russia, selection for seeds that were high in oil began in 1860. This selection for high producer varieties was largely responsible for increasing oil content from 28% to almost 50%. The high-oil lines from Russia were reintroduced into the U.S. after World War II, which rekindled interest in the crop. However, it was the discovery of the male-sterile and restorer gene system that made hybrids feasible and increased commercial interest in the crop. Production of sunflowers subsequently rose dramatically in the Great Plains states because of new niches for the seeds, including oil, snack food, and birdseed. Production in these regions in the 1980s declined mostly because of low profit margins as well as pests. Sunflower acreage is now moving westward into dryer regions; however, 85% of the North American sunflower seed is still produced in North and South Dakota and Minnesota. (Putnam, et al., 1990)

In 2016, there were 6 recalls involving sunflower seeds contaminated with Listeria monocytogenes. (Food Safety News, June, 2016) Taylors Candy, Inc. (Alsip, IL) recalled 5.5 oz. Stuckeys bags of kernels and Rucker’s Makin’Batch Candies Inc., recalled the Dollywood Cajun mix that was distributed in the Dollywood Theme Park in Tennessee.  On June 7, Giant Eagle announced four additional recalls we of bulk sunflower kernels sold in Market District and/or Giant Eagle stores in Pittsburgh, PA, Cleveland, OH, Indianapolis, IN, and Columbus, OH. All second recall expansions followed an initial recall and then a first expansion of the initial recall.

The most recent sunflower-seed related outbreak was due to possible Listeria monocytogenes contamination in 2018. This recall has ended. The brand Inspired Organics LLC, voluntarily recalled all sunflower butter for potential contamination; no illnesses were reported.

Plant

Sunflower (Helianthus annuus) is an annual broadleaf plant that can be successfully grown in most regions of North America. It is the only oilseed native to the northern Great Plains of North America and has been grown commercially in Canada since the early 1940s. Sunflower began as an important agronomic crop in the U.S. in the 1950’s, starting in North Dakota and Minnesota. Contemporary sunflowers trace their ancestry to plants found at archeological sites dating from 3,000 BC.

Sunflowers grow best in locations with full sun. They are remarkably tough and will grow in any kind of soil as long as it is not waterlogged. They survive in soils that are slightly acidic to somewhat alkaline (pH 6.0 to 7.5). Sunflowers can tolerate drought, which befits plants whose ancestors grew happily in dry prairie regions. They are so easy to grow that they often plant themselves, springing up unbidden beneath a bird feeder.

Sunflower seed, leaves, and stems emit substances that inhibit the growth of certain other plants. They should be separated from potatoes and pole beans. Where sunflower seeds are regularly used as bird feed, toxins from the accumulated seed hulls eventually kill the grass below. Harmless to animals or people, the toxins eventually biodegrade in the soil.

Sunflower roots spread widely and can withstand some drought. However, it is best to water them regularly during their most important growth period, which is approximately 20 days before and after flowering. Deep, regular watering encourages root growth, which is especially important with taller sunflower varieties bearing top-heavy blooms.

Sunflowers do not require fertilizing. However, because they grow vigorously (they can easily grow 6 feet in just 3 months). Slow-acting granular fertilizer should be used, especially if the soil is of poor quality. The better the enrichment, the larger the flowers. Too much nitrogen, however, can delay flowering. Spreading a 2- or 3-inch mulch layer of some kind of organic material on the soil will reduce moisture loss through evaporation and discourage weeds.

While a few sunflower varieties do not need any staking, plants that grow over 3 feet tall or are multi-branched should be supported. Their branches are fairly brittle, especially at the points where they join the stems. They are vulnerable to summer winds and rain. Loosely-tied plants that are staked with lengths of cloth or other soft material as needed will help support large seed heads.

The High Plains region of Colorado and Kansas are unique because it is one of the few places that produces a larger size kernel (up to one inch). Europeans like to eat them one at a time so this variety is frequently exported to Europe.  (Gordon, 2011)

The National Sunflower Association (NSA) refers to sunflower seeds/kernel as:

• “In-shell means the seed is left intact with the “meat” of the seed still in the shell. It is normally roasted and seasoned. It is eaten as a snack by cracking the shell with one’s teeth, discarding the hull and eating the delicious morsel within. ‘Chew and spit’ is a great American pastime, especially at baseball games and other outdoor events.”
• “Kernel means the processor has mechanically removed the hull. The resulting kernel is now in a convenient form to be sold raw or roasted for snacking or as an ingredient.”

Diseases, Insects, Animals, and Sunflowers

Sunflowers are usually robust but are sometimes infected with fungal diseases such as mildews and rusts. Downy mildew causes mottling and pale areas on upper leaf surfaces and a fuzzy mold growth on their undersides. Eventually the leaves wither and die. The oldest leaves are usually infected first. Downy mildew is most likely to occur on cool, damp nights and warm, humid days and spreads by means of tiny spores carried to plants and soil via wind and rain or contaminated by garden tools. It will not kill a mature plant; it mars its appearance.

Rust appears on upper leaf surfaces first as yellow or white spots that turn brown or black. Puffy blisters then appear on the undersides. The disease may spread to stems and flowers causing distorted growth. Rust sometimes spreads to the cultivated sunflowers from weeds such as wild mustard, shepherd’s-purse, pigweed, and lamb’s-quarters. (Friskop, 2011)

If fungal diseases are identified early, spraying with a general garden fungicide as directed on the product label can protect healthy foliage. Remove and destroy seriously infected plants. Keep the area weeded and clean up plant debris from the garden in the fall. Disinfect tools by dipping them in a solution of 1 part household bleach to 4 parts water. Plants should be handled with clean hands and not touched when wet.

A small, gray sunflower moth sometimes lays its eggs in developing sunflower blossoms. Its larvae are greenish-yellow with 5 brown stripes down their backs. They feed in the flower and destroy seeds, creating a mass of webbing and debris. The worms can be removed by hand from the plants and disposed of properly. If lots of plants are infested, spray or dust the flowers with a product containing Bacillus thuringiensis (Bt) as soon as you see the larvae. The larvae will eat the bacterium and soon die. Because sunlight and rain rapidly inactivate Bt, respraying is necessary. In developed countries, neonicotinoids are used predominantly used as seed dressings for a broad variety of crops including oilseed rape and sunflowers (primarily imidacloprid, clothianidin, and thiamethoxam). (Goulson, 2013) Their advantages of low toxicity to vertebrates, high toxicity to insects, flexible use and systemic activity led to neonicotinoids swiftly becoming among the most widely used pesticides globally; they are now used more than any other class of insecticides and comprise approximately one quarter of all insecticides used. They are licensed for use in more than 120 countries. (Jeschke, et al., 2011)

Birds and squirrels can be a problem when seeds ripen and harvest time approaches. If you do not plan to use the seeds, it is fun to watch wildlife enjoy the bounty. You may want to cut the flower heads off and lay them out in the sun to dry and provide easier access to wildlife. Conversely, to deter birds and squirrels, barrier devices are most effective. As seed heads mature and flowers droop, cover each one with white polyspun garden fleece. It will let light and air in and keep pests out. Also, try cutting away the few leaves that are closest to the heads to make it harder for birds to perch and feed.

Deer will readily eliminate a sunflower patch. As they favor the new, tender leaves at the top of the plants, a 36-inch chicken wire barrier supported by 6-foot bamboo stakes should keep them at bay. Simply raise the wire as the plants grow. L. monocytogenes has been identified in healthy white tail deer (Odocoileus virginianus) as well as fallow deer (Dama dama), (McCrum, et al., 1967; Eriksen, et al., 1988). The outbreak in fallow deer occurred during the winter and early spring and isolates were found in both the deer and surrounding soil samples.

Food Processing Steps

“Raw, natural ingredients may require additional food processing steps to be safe for human consumption. For customers who require additional food processing steps, Red River Commodities can custom roast sunflower products and other grains, beans, and seeds through the SunGold Foods division.” (Red River Commodities)

Sunflower production is concentrated in the northern Midwest where they are able to thrive in the dry and windy areas due to their deep root structure. In 2009, 44 percent of production was in North Dakota, 28 percent in South Dakota, and the rest, scattered throughout California, Colorado, Kansas, Minnesota, Nebraska, Oklahoma, and Texas. Optimal planting time in the northern regions is from early May extending into June. In southern states such as Texas, sunflowers can be planted several months later. Most production is contracted prior to planting. Typically, buyers provide specific types of hybrid seed and agree to purchase the crop at a set price. Quality standards also affect the future payment, especially for confection seed. Sunflowers are harvested between late September and early November.

Producers apply nitrogen, potassium, and potash (potassium carbonate) in the spring. Pesticides and herbicides are commonly applied because pests, weeds, and disease can be significant problems. Recent improvements in sunflower varieties that are resistant to Sclerotiniawilt (stalk and head rot) have reduced pesticide use. (USDA, 2016)

Usually, the seeds are processed via the procedures of drying, cleaning, grading, roasting, and potentially flavoring(s) can be added.

•  Drying: After harvesting, sunflower seeds are rapidly dried to under 10% moisture content by a drying machine, or by sun-drying. There are 2 levels: the low level and the high level, and the seeds with initial moisture content 5.1% are separated from foreign matters on the sieves. The sunflower seeds are dried in a chamber drier to get 1.2% seeds moisture content. Temperature of the seeds is kept below 80℃ during drying process. To get 9.2% moisture content, the seeds are placed in the wet medium (wet cotton tissue) for 30 minutes.
• Screening and cleaning: The dried seeds are delivered onto wire screens and shaken to remove dirt and unwanted debris to ensure they can meet the determined specifications. They are next transferred to a large bin for further cleaning.
• Grading by sizing: The cleaned seeds are passed on to sizing screens that have holes that allow smaller-sized seeds to fall through. The largest seeds will be further processed as snack foods. The medium-sized seeds are for ingredient-use in topping for cookies, salad, or ice cream, etc. The smallest seeds are for bird or pet feed.
• Roasting and de-hulling of food-grade seeds: The largest seeds are transferred to large ovens where they are dry roasted, reducing the moisture level in the seed further or after de-hulling the largest seeds, they are transferred to the ovens for roasting. The medium-sized seeds are directly sent to specialized de-hulling machines to remove their shells, and then roasted in oil.
• Flavoring of food-grade seeds: The food-grade seeds can be flavored as required. Flavoring can be accomplished in many ways. After the warm seeds are roasted, they are put into a large, rotating container that make the seed move around, combining with the flavoring. Sometimes the oil is used to make better flavoring result by making seeds and flavorings stick better.
• Packing: In the last step, the seeds are delivered to packaging machines, in which the sunflower seeds are weighed and packaged.

Multiple small confectionery processing plants are located throughout sunflower-producing states to take advantage of local distribution. Some of the seed is roasted, much like peanuts, while some is de-hulled and the kernels are sold as confectionery “nuts.” Food processors purchase sunflower kernels to sell directly to consumers as packaged snacks or as an ingredient in other food products. Most hulls are used as turkey bedding, though some are ground into pellets to provide fiber in animal feed. (USDA, 2016]

As exports of crude sunflower oil have declined, exports of refined oil have risen; by 2009/2009, 81,000 metric tons of refined oil were exported – mainly to Canada. (USDA, 2016)

Sunflower seed oil is cold-pressed and entails minimal processing to produce a light, flavorful oil suitable for some cooking needs. Sunflower seed oil manufacture involves seed cleaning, seed de-hulling, seed grinding, seed pressing, extracting crude oil and crude oil refining.

• Cleaning: The prepared sunflower oil seeds are passed over magnets to remove the trace metal before de-hulled and passed through the special cleaning machine to remove other foreign matters.
•  De-hulling: Sunflower seeds from the oil-type contain about 20%-30% hulls that are sometimes removed before oil extraction to ensure the quality of both oil and sunflower meal. De-hulling is done when the seed has a moisture content of 5% after cleaning. The usual process consists of cracking the seeds by the mechanical action of a centrifugal or pneumatic sheller, which can also be completed by abrasion. Then the resulting mixture is winnowed to separate the hulls from the kernels. Some oil sunflower seeds have thin hulls that are difficult to remove, so they can be free from de-hulling to avoid oil loss.
•  Grinding: The prepared sunflower oil seeds are passed over magnets to remove the trace metal before being de-hulled. For more surface area to be pressed, the de-hulled seeds are ground into coarse meal of proper consistency by mechanized grooved rollers or hammer mills. Then the meal is heated to facilitate the oil extraction. While during oil pressing, some impurities are also released with the oil, and they should be removed before the oil can be edible.
• Pressing: The heated meal is continuously-fed into a screw press. Pressure generally increases from 68,950 to 206,850 kilopascals as the oil is squeezed out through the slots in the barrel, and is recovered.
• Extracting additional oil with solvents: The remaining oil cake in the press can be processed by solvent extraction to get maximum yield. A volatile hydrocarbon (the most commonly used one is hexane) dissolves the oil out of the oil cake, and then the oil is recovered by distilling the solvent out, and then the solvent passes through the matter to be collected at the bottom.
• Removing solvent traces: 90% of the solvent remaining in the extracted oil simply evaporates and it is collected for reuse. The remaining solvent is regained by the use of the stripping column. The oil is boiled by steam. The lighter solvent floats upward as it condenses and is collected at the same time.
•  Refining the oil: Refining the oil is to remove color, odor, and bitterness. Refining involves heating the oil to 40°C -85°C (107-188°F) and mixing an alkaline substance such as sodium hydroxide or sodium carbonate with the oil. Then soap forms form the undesired fatty acids and the alkaline additive, and usually it is removed by a centrifugal process. The oil will be further cleaned to remove soap traces and then dried.
  The oil is also de-gummed at this time by treating it with water-heated steam of 85°C -95°C (188-206 degree Fahrenheit), or water with acid. Most of the gum is the phosphatides to be precipitated out, and the dregs are removed by a centrifugal process. Oil that will be used in cooking is then bleached by filtering it through fuller’s earth, activated carbon, or activated clay that can absorb some pigmented materials from the oil. By contrast, oil that will be refrigerated (for use in salad) is rapidly chilled and filtered to remove waxes. This procedure is to ensure the oil will not partially solidify in the refrigerator. The final process is the deodorization of the oil, in which the steam is passed over hot oil in a vacuum at 225°C -250°C (440-2485°F) to distill the volatile and odor components from the oil. Typically, to avoid the trace metals that might promote oxidation within the oil and hence shorten the oil’s shelf-life, 1% critic acid will also be added into the oil after deodorization.
• Packing the oil: Pure oil is measured/ packed in clean containers, and some are bottled for domestic sale, bottled for exports or domestic sales in specialty stores, or cans for exports.

In 2016, SunOpta (a sunflower kernel supplier) supplied kernels to First Source of Tonawanda, NY which packages and distributes candy and specialty food nationwide. First Source received two consumer reports of Illness (unconfirmed) and contacted SunOpta. SunOpta subsequently notified First Source of positive Listeria monocytogenes results. Confectionary products containing the kernels were supplied by SunOpta to more than three dozen companies, including retailers such as HyVee and snack giants Hershey’s and General Mills that recalled specific consumer products. (Bleach, 2016)

Approximately 25% of all sunflower seed production is used to produce birdseed.

Ten-twenty percent of U.S. sunflower production is used in shelled kernels, whole seeds, and nut and fruit mixes containing sunflower seed. Kernels are also used in processed foods, such as granola bars and breads. Confectionary sunflower seed competes with nut crops such as peanuts, almonds, walnuts, cashews, and specialty grains such as millet and flax used in the production of multi-grain breads.

Sunflower oil is considered a high-quality oil and is more expensive than other oils such as soybean oil. Food processors use the oil for frying foods (including potato chips), in salad and cooking oil, margarine, and dairy substitutes. The majority of the sunflower oil supply is mid-oleic, which does not require hydrogenation. Mid-oleic oil has no trans fats, low monounsaturated fat, and a neutral taste. It is also more durable than most other vegetable oils when used in industrial frying. These qualities make food processors willing to pay a premium for sunflower seed oil over soybean oil. (USDA, 2016)

Culinary Attributes

Larger sunflower seeds (in shell) are roasted, salted, and packaged for human consumption and are classified as either large or jumbo. Medium-sized seeds (kernel) are de-hulled and packaged for human consumption as well. These are primarily used for the bakery industry, but are also traded domestically and exported. Smaller seeds, known as “striped bird food”, are sold in North American birdseed markets.

The black-shelled oil seed variety is richer in oil and therefore better suited to the production of sunflower oil. Compared with other vegetable oils and animal fats, the oil in sunflower seed is very high in polyunsaturated fatty acids, making it easily digestible and provides a good option when choosing cooking oil, particularly if high cholesterol is a concern.

Sunflower seed butter, sold as SunButter, may be a suitable alternative in people who have peanut allergies. Sunflower seed allergy is quite rare unlike peanut or tree-nuts (cashew, walnuts, hazelnut, etc.) allergies.

Cultural Attributes

In the United States, kernels are added to salads and casseroles for a crunchy texture or to ready to eat confectionary treats.

Sunflower seeds are commonly eaten as a snack or rather than as part of a meal. Europeans enjoy eating sunflower seeds one at a time so the larger (~1 inch) seeds are exported from Kansas and Colorado to this region. (Gordon, 2011)

In the food culture of India, pitta is increased by spicy foods and can be inhibited by sunflower seeds. Pitta is an oily, sharp, hot, spreading liquid. (Sen, 2004)

In Israel, they are known as pitzhuhim, from the root word to crack and were often consumed at the end of a meal. At soccer games, they were often consumed by the fistful, and shells were spit on the floor. (Melamed, 2011)

In Germany and other Central European regions, the flour made from the seeds is used in making dark bread, sonnenblumenbrot (sunflower bread).

Raw sunflower seeds contain protein and substantial amounts of key minerals, including magnesium, potassium, iron, and calcium. Sunflower seeds contain 521 calories per 100 grams and are high in protein (25.5 g per 100g) and no cholesterol. They are also rich in magnesium and potassium. Sunflower seeds are additionally rich in polyunsaturated fatty acids compared to other oilseeds

Sunflower seeds have been associated with antioxidant, antimicrobial, anti-inflammatory, and wound healing properties due to its composition of micronutrients and phytochemicals. The edible seeds are a source of flavonoids and phenolic acids that exert pharmacological effects and biological benefits on the host. The vitamin E and other tocopherols found in sunflower seeds provide antioxidant activities that have been associated with reduced risk of cardiovascular disease and some cancers. Sunflowers have been shown to increase antioxidant capacity by increasing antioxidant enzyme activity and reducing reactive oxygen species. In addition, bioactive peptides found in sunflower seeds have been associated with antihypertensive benefits by increasing ACE inhibition.

Apart from these functional benefits, sunflower seed butter (or sunflower butter) has been popularized as an alternative to peanut butter. The rising prevalence of peanut allergies in the United States has led to many schools implementing nut-free policies to protect students with anaphylactic allergies; consequently, sunflower butter is often used in substitute, providing a greater amount of vitamin E, iron, magnesium, phosphorous, and zinc when compared to peanut butter.

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