The classification of sunflower seeds changes according to the pattern of its shell or hull. If the shell is solid black, it is an oilseed sunflower. With these, you produce sunflower oil. If the shell is striped, it is a non-oil sunflower seed or confectionery sunflower seed. These usually become snack food products. Whether to make them as snacks or oil, processing sunflower seeds include steps like drying, screening and cleaning, grading, roasting and de-hulling, flavoring, grinding, pressing, refining, and packing.
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From bird feed to human snacks: uses of sunflower seeds
Sunflower seeds are one of many types of seeds used in food and feed production. In a typical production setup, you divide non-oil sunflower seeds into three categories according to size. Large seeds (in-shell) are roasted, salted, and packed for human consumption as snacks. Medium-sized seeds are de-hulled and packed for human consumption as well, mainly for the baking industry as an ingredient or garnish. The small seeds become feed for birds. A seed sizing machine will be of great help to size them according.
The first commercial use of sunflower seeds in North America was animal feed for poultries. Demand for sunflower oil is increasing due to its health benefits, and the seed also has nutrients and medicinal uses.
How to start processing sunflower seeds
The sunflower seeds process begins with drying the seeds using a dryer or sun-drying. After reaching a moisture content of under 10%, you move the seeds to wire screens to remove dirt. Then you transfer them to a large bin for further cleaning. Once this is over, grade the seeds according to their sizes: large seeds go to a large oven that will roast them; medium-size ones go to de-hulling machines to remove the shells before roasting in oil. You can apply flavoring and send them for weighing and packing.
Solid and liquid: sunflower seeds for oil production
Sunflower oil is the largest market segment for sunflower seeds. To extract it, you can use two different methods: cold press and hot press or refined sunflower oil. To start with, the seeds usually undergo cleaning, de-hulling, and grinding processes. For the cold press method, you press the seeds mechanically to extract the oil. Then it undergoes filtration to remove impurities. This method produces sunflower oil that is used for low heat cooking, and skin and hair care products.
In the hot press method, you slightly heat the seeds before mechanically pressing them. This method extracts more oil than the cold press one, but the taste changes along with its chemical properties due to heat application.
You can add a solvent, like hexane, to extract more oil out of the cake after pressing. Then you remove the solvent by boiling the oil using steam in a stripping column where it vaporizes. As it condenses, it is collected at the same time. Next step is to refine the oil by adding sodium hydroxide and then separating it using a centrifuge. The oil undergoes degumming and removal of wax by winterization process or cooling. Then put the oil in a bleacher pressure vessel and steam injection process to remove odors and give a clear or transparent color. Finally, measure the oil and pack it in containers. Refined sunflower oil is mainly used for high heat cooking as it is more stable in a wide temperature range.
Environmental impact of sunflower seeds
Growing sunflower plants for sunflower seed production is sustainable. The sunflower plants can be a source of food for birds and pollinators like bees, and can also help clean contaminated soil. The cake produced as a by-product in the oil extraction process can be used as livestock feeds, and the hulls can be used as animal beddings. Sunflower plants don’t need much fertilizer to grow and can even withstand drought.