Effect Of Lipid Concomitants On The Stability Of Flaxseed Oil And Oil-in-water Nanoemulsions

Flaxseed oil can be an important source of plant-based omega-3 polyunsaturated fatty acids,with the potential to restore dietary fat intake balance and improve the health of the body.However,flaxseed oil is highly sensitive to oxidation and has a bitter taste and is insoluble in water,which severely limits the application.Flaxseed oil is rich in endogenous lipid concomitants including polar,nonpolar,amphiphilic,which can improve the environmental stability of oil and nanoemulsions based on antioxidant and interfacial effects.In view of this,this topic prepared linseed oil with significant differences in lipid concomitants through five extraction techniques such as low temperature pressing,microwave pretreatment and fluid extraction.On the basis of structural characterization and analysis,the influence of endogenous lipid concomitants on the quality characteristics and stability of oils and nanoemulsions was explored.It attempts to reveal its key material basis,and provides a theoretical basis for optimizing the extraction techniques of linseed oil,constructing a high-stability nanoemulsion system and expanding its application in functional foods.The main research results obtained are as follows:Based on the choice of extraction techniques,linseed oil with significantly different endogenous lipid concomitants was obtained.Five extraction techniques were optimized and established,including cold-press?CP?,microwave pretreatment coupled with cold-pressed?MPCP?,accelerated solvent extraction?ASE?,supercritical CO₂ extraction?SCO₂E?,and subcritical fluid extraction?SFE?.Different oil extraction techniques have specific effects on the endogenous lipid concomitants in linseed oil.Among them,the content of tocopherol,carotenoids,chlorophyll,flavonoids,phospholipids and cyclic peptides in ASE and MPCP oils are relatively high.The total amount of phytosterols in SFE oils and fats is higher?599.33 mg/100g?,which is an increase of 8.50 to 68.48%compared to other techniques?P<0.05?.The total phenol and free fatty acid content of SCO₂ E oils is relatively high,which is an increase of 7.77-68.53%and 25.27-44.05%compared with other techniques.The above results indicate that different extraction techniques have different effects on the enrichment of lipid concomitants in linseed oil,but the overall enrichment effect of ASE and MPCP is better.It provides key materials for the next step to clarify the material basis of the stability of oils and their emulsions.Clarified the effect of lipid concomitants on the quality of flaxseed oil:the oxidative stability,in-vitro antioxidant activity and interfacial tension of linseed oil in different extraction techniques are significantly different?P<0.05?.The endogenous lipid concomitants is the key material basis for the difference.Correlation analysis results show that tocopherol,sitosterol,carotenoids,chlorophyll,flavonoids,phospholipids,cyclic peptides can improve the oxidative stability of linseed oil,while free fatty acids can reduce the oxidative stability of linseed oil.Total phenols and flavonoids were significantly positively correlated with DPPH and FRAP,which can improve the in-vitro antioxidant activity of linseed oil.In addition,tocopherols,chlorophyll and phospholipids have interfacial activity and can be adsorbed at the oil-water interface to reduce the interfacial tension,which will have a significant effect on their digestion characteristics,oil emulsification characteristics and micellization ability.The effect of lipid concomitants on the physical and chemical stability of flaxseed oil nanoemulsion.The nanoemulsion systems stabilized by Tween 80?T80?and sunflower seed phospholipid?S90?are the research objects.The experimental results show that,in the S90 emulsion,the physical and chemical stability of the ASE and MPCP emulsions is better,and the chemical stability of the CP and SFE emulsions is better.The physical and chemical stability of SCO₂E emulsion is poor.In T80 emulsion,the physical stability of each emulsion is better,there is no significant difference?P>0.05?,the chemical stability of ASE and MPCP emulsion is better,SCO₂E emulsion has the worst chemical stability.Correlation analysis results show tocopherol,phospholipid,and chlorophyll have interfacial activity,which can accumulate at the oil-water interface and increase the initial potential of the emulsion.It may also play a role in promoting emulsification and reduce the initial particle size of the emulsion and then improve the physical stability of the emulsion during storage.Phytosterols?except stigmasterol and?-sitosterol?,flavonoids,and cyclic peptides can inhibit the production of lipid hydroperoxides and improve the oxidative stability of the emulsion,while metals Ionized iron can promote the production of lipid hydroperoxides and adversely affect the oxidation stability of the emulsion.