| Camellia oleifera oil is rich in unsaturated fatty acids and traces active ingredients.Initially recorded in the Materia Medica and now listed in the Chinese Pharmacopoeia,it is dual-use vegetable oil with high nutritional value and has great commercial potential in the agricultural,food and pharmaceutical industries.The crude oil obtained by pressing C.oleifera seeds contains impurities such as phospholipids,pigments,free fatty acids and so on,which will affect the flavor of the oil,aggravate the rancidity of the oil,and reduce the oxidation stability of the oil.As a result,crude oil requires refining.The traditional refining process of edible oil has many process steps,uses a large amount of acid,alkali,and water,and high operating temperature,resulting in a significant loss of trace active substances in the oil,a reduction of the antioxidant capacity of the oil,and simultaneously generation of a large amount of process wastewater.Moreover,the phospholipid content and acid value in the crude oil of C.oleifera seeds are lower than traditional edible oil,so it is necessary to streamline the process and moderately refine to improve the edible quality and medicinal value of oil.In this study,C.oleifera oil was refined based on the adsorptive decoloring process and the adsorptive deacidifying process.The degumming effect while decoloring the adsorptive decoloring process was investigated and the effect of removing free fatty acids of the adsorptive deacidifying process was studied.Setting polyphenol content and refining indexes including phospholipid content,the yellow color value,and acid value as response values,response surface was used to fit the regression process parameters.Multiobjective based optimizing of the relevant results resulted in optimal process parameters that improved the polyphenol content of C.oleifera oil and the medicinal value of C.oleifera oil.The C.oleifera oil obtained by the adsorptive refining process was evaluated for antioxidant function and correlation analysis with polyphenol content.The main conclusions are as follows:1)Adding a small amount of activated clay for decolorization can achieve the equivalent effect of degumming to the single-factor optimal process of acid degumming.When the citric acid at 0.5% of the oil weight added at 90 ? for 30 minutes,water at 3%of the oil weight and stirring speed at 60 r/min,the acid degumming process resulted in49.39% degumming of C.oleifera oil.When the activated clay at 2% of the oil weight added at 45 ? for 10 minutes,and the stirring speed was 100 r/min,adsorptive decoloring and degumming process can make the degumming rate of C.oleifera oil reach 51.39%,and the decolorization rate was 95.74%.Studies have shown that the adsorptive decoloring process in the refining process of C.oleifera oil possesses a degumming effect at the same time.Thus the acid degumming procedure in the traditional refining process could be left out.2)Modifying C.oleifera husk powder can effectively remove the free fatty acids in C.oleifera oil which cause an increase in acid value.The cellulose-based modified C.oleifera husk deacidifying adsorbent was made and characterized in the laboratory.In the process of adsorption and deacidification,the acid value of C.oleifera oil decreased from 0.32 mg KOH/g to 0.04 mg KOH/g at the modified C.oleifera husk powder at 3.5% of the oil weight added at 30 ? for 10 minutes and the stirring speed at 140 r/min.Studies have shown that the refining of C.oleifera oil can use an adsorptive deacidifying process to efficiently remove free fatty acids instead of alkali refining.3)The critical process parameters in the two-step adsorption method are optimized by the response surface fitting model and multi-objective-oriented modeling,and the optimized parameters can effectively improve the color,phospholipid content and acid value and reduce the loss of polyphenols of C.oleifera oil.Taking the quality of commercially available C.oleifera oil as the optimization goal,a response surface fitting model based on the polyphenol content,yellow color value,phospholipid content and acid value was obtained.A mathematical model was established with a multi-objective orientation to obtain the optimal adsorptive decoloring and degumming process: The amount of activated clay added is 4.53%,the adsorption temperature is 48 ?,the adsorption time is 10 minutes,and the stirring speed is 101 r/min.The optimal adsorptive deacidifying process: The addition amount of modified C.oleifera husk powder is 2.67%,the adsorption temperature is 30 ?.The adsorption time 10 minutes,the stirring speed is 139 r/min.Under this optimized process,the polyphenol content of C.oleifera oil was 22.11 mg/kg(after adsorptive decoloring and degumming from crude oil)and 36.68 mg/kg(after adsorptive deacidifying from crude oil),yellow color value was 6.0(133.4 mm).Phospholipid content was 53.016mg/kg,the acid value was 0.08 mg KOH/g,which is consistent with the predicted value.The loss of polyphenols in C.oleifera oil prepared by the traditional refining process is nearly 97.5%,which was reduced to 60% by the adsorptive refining process.The refined C.oleifera oil prepared by this process reached the standard of medical injection C.oleifera oil,it is indicating that the two-step adsorption process can prepare medical C.oleifera oil.4)The antioxidant capacity of refined C.oleifera oil obtained by the two-step adsorption method is significantly improved,and it is related to the content of polyphenols in the oil.By evaluating the antioxidant function,compared to the traditional refining process,the DPPH free radical scavenging capacity of C.oleifera oil has increased by nearly ten times,the iron ion reduction capacity has increased by nearly fifteen times,and the ABTS free radical scavenging capacity has increased by nearly six times.The polyphenol content of C.oleifera oil is highly significantly correlated with its antioxidant capacity.The reasonalble degree of polyphenols was 0.9834 with DPPH free radical scavenging ability,0.9840 with iron ion reducing ability,and 0.9636 with ABTS free radical scavenging ability.In conclusion,the study shows that the phospholipid content,color,acid value and peroxide value of C.oleifera oil can be effectively improved through a two-step adsorptive refining process based on response surface optimization;it also can enhance the retention rate of polyphenols and improve the antioxidant function of C.oleifera oil.Furthermore,this process has the prospect of application in the food and medicine industry because of its gentleness and simplicity. |
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