In common oil production, sesame is not necessary to be hulled. However, sesame seed coat contains high fiber and calcium oxalate, which makes color of oil and seed meal deeper and the cake is bitter that can only serve as feeds and fertilizer. Hence, sesame needs hulling when processed into food or seed cake for protein intake.
Traditionally, the sesame seeds are soaked into water to make the husk expand; husk and seed are separated by buoyancy. Salt water can be used to adjust density in flotation separation. In experiment, hot thin alkali solution such as NaON, sodium borate and NaCIO solution can be used to loosen or break the husk.
Besides, we often use huller in sesame seed processing. However, the sesame is easy to get broken in drastic mechanical friction. Meanwhile, the machine has some dead angles that a few sesames cannot be fully hulled. We use vertical cylinder huller to make the sesame move relatively and they are huller by soft friction between sesames.