Remove Non-hydrated Phospholipids in Okra Seed Oil by Silicon Dioxide

Water degumming, mainly removes hydrated phospholipids, is the most common method applying in traditional edible oil production. Silicon dioxide (SiO₂) adsorption has been proved as a green and efficient method for removing phospholipids from rapeseed oil. But both methods exhibited poor effect on okra seed oil. Based on a hypothesis that SiO₂ can adsorb non-hydrated phospholipids, removal effect of non-hydrated phospholipids in okra seed oil was studied. Single factor test and response surface design were used to optimize the SiO₂ adsorbing process in water-degummed oil. Meanwhile, the qualities and flavor changes of okra seed oil before and after degumming were compared and analyzed. The results showed that the optimized degumming procedure was: 1.43% (w/w) of SiO₂ added into the water-degummed oil, and the mixture was stirred at 33.52℃ for 30.47 min. The maximum non-hydrated phospholipids removal rate reached 43.3%. Comparing with crude okra seed oil, the optimal degumming method resulted in the increase of peroxide value and the decrease of induction period (IP) of the oil. However, it had the same safety as the water and the SiO₂ degumming methods. It could retain 62% of total phenols, which was less than the water and the SiO₂ degumming methods (both about 79%). The differences of E-nose sensors among oils were most likely caused by the pyrazines. It is necessary to study the composition and properties of phospholipids and develop new methods to further improve the phospholipids removal rate of okra seed oil.