Research On Theory And Application Of New Aqueous Production Technology Of Oil

Edible lipids are important sources of energy and nutrition for the body,as well as carriers of essential fat-soluble vitamins,and provide essential substances that cannot be synthesized in the body,such as essential fatty acids.Therefore,oil production is important and necessary.Presently,the widely used traditional extraction method of oil has disadvantages of harming the environment or wasting valuable protein resources;therefore it is necessary to develop new oil extraction theories and technologies.In this paper,tea seed,rapeseed,white sesame and black sesame are used as research materials,and a new aqueous oil extraction theory is established,and application is carried out under the guidance of this theory,and a pilot test of tea seeds.The new aqueous oil extraction theory is supposed to be as follows.When an appropriate amount of water or saline solution is mixed with broken oilseeds,water molecules form hydrogen bonds with hydrophilic substances and hydrophilic aggregation occurs.Hydrophobic forces originating from the hydrogen bonds result in the cohesive force of the oil changing from less than its adhesive force to the surface of hydrophilic solid particles to that greater than its adhesive force to the surface of hydrophilic particles aggregated,thereby discharging free oil.The experimental results indicated that the relationship curve between oil recovery and amount of water added was parabolic,and the type of curve was not related to the type of oil,i.e.,within the range of amount of water added below that resulted in the highest oil recovery,it was positively correlated with the hardness and cohesion of the aggregated hydrophilic particles and the number of hydrogen bonding in them.In the range of amount of water added above that resulted in the highest oil recovery rate,it was negatively correlated with the hardness and cohesion of the hydrophilic aggregates and the oil recovery rate while the number of hydrogen bonds was relatively stable;and this may be due to the compounds such as phospholipids,amino acids,phenols which may be dissolved in excessive water and caused emulsification or that water in excess of that for forming the maximum number of hydrogen bonds in the hydrophilic particles aggregated may formed a clatharate-structure with the hydrophilic particles which can hold oil and thereby reduce its recovery rate.Therefore,the amount of water added above or below that gives the maximum oil recovery rate was found to be harmful for obtaining good oil recovery rate;however,different varieties of oilseeds had different amounts of added water resulting in the highest oil recovery.Proper baking was found to be the key factor to deactivate enzymes and to reduce the acid value of oil and stabilize its color.On the other hand,excessive baking reduced oil recovery rate and the solubility of proteins.Other factors including the degree of cell disruption,stirring time and temperature during extraction,and the addition of salt were found to be auxiliary factors of improving oil recovery rate.The theory is mainly based on the fact that the basic reagent used to separate oil in oilseeds is water,so the whole theory is put forward around the nature of water and the physical and chemical properties of oilseed kernels,and has been tested and proved.By appling the new aqueous oil extraction theory and using four types of oilseeds as studying materials,the research on small scale application was carried out.The results obtained were as follows: for extracting tea seed oils,baking temperature 115 ?,baking time 90 min,grinding fineness 74 ?m,the amount of water added 1.2 ml,the amount of salt added(sodium chloride 0.1 g + sodium bicarbonate 0.008 g),the stirring time 40 min,and the stirring temperature 65 ?;for extracting rapeseed oils,baking temperature 115 ?,baking time 2 min,grinding fineness 61 ?m,water volume 1.5ml,stirring time 30 min,stirring temperature 50 ?;for extracting white sesame oil,baking temperature 115 ?,baking time 1 min,grinding fineness 154 ?m,salt water added 1.95 ml(6.00 %(w / w)),stirring time 25 min,stirring temperature 64 ?;for extracting black sesame oil,baking temperature 115 ?,baking time 1 min,grinding fineness 154 ?m,salt water added 1.95 ml(6.35 %(w / w)),stirring time 30 min,stirring temperature 65 ?.Under the best conditions,water exerts its maximum effect,the recovery rates of tea seed,rapeseed,white sesame,and black sesame oils were94.79 %,94.73 %,96.02 %,and 96.54 %,respectively.The obtained oil was clear,transparent,light in color,and good in quality.The acid value and peroxide value of the four oils produced by this method were much better than those produced by high-temperature pressing or solvent extraction.They were also better than China's national standards of refined oils.To further promote factory production,the experiment on selected studying material-tea seeds on a pilot scale was carried out,using the same method as that developed in the small-scale experiment,self-assembling production line and matching equipments,expanding the processing scale to 50.0 kg.The oil recovery rate exceeded94 %,and the residual oil content in the defatted powder was 3.71 %.They were also better than China's national standards of refined oils.The above results show that the new aqueous method is a technnology which has low water addition,high oil recovery rate,needs simple technical equipments,no wastewater discharge and produces products with good quality.Therefore,developing an economical,high-efficiency,environmentally-friendly and safe new aqueous method of producing oil on a commercial scale is very promising in future.