| Fish oil is rich in polyunsaturated fatty acids such as docosahexaenoic acid(DHA)and eicosapentaenoic acid(EPA),which possesses many health benefits for human beings.However,the application of fish oil in functional foods is limited due to its sensitivity to oxidation,poor solubility in water,and the unpleasant flavor.The traditional encapsulation approach for fish oil is microencapsulation,whereas the form of obtained product is simple,and fish oil is easily to be oxidized during the preparation process.In recent years,the development of electrospinning technology,especially the coaxial electrospinning,provides a new approach to improve the stability of bioactive substances.Nevertheless,the application of electrospinning in food science is relatively novel and less explored,especially in the preparation of fish oil-loaded functional foods.To date,there are only a few studies to encapsulate fish oil using single electrospinning,and the oxidative stability of encapsulated fish oil needs further improved.Therefore,in this study,in order to further improve the oxidative stability of encapsulated fish oil,we tried to improve the existing method by adding glycerol as plasticizer and using alcohol as shell layer to modify the electrospinning process.Then,two approaches were proposed to encapsulate fish oil,one was using the coaxial electrosun nanofilm,and the other was to prepare zein/fish oil/ferulic acid(zein/FO/FA)electrospun nanofilm by adding ferulic acid as antioxidant.This study will form the basis for developing novel fish oil functional food,and promote the application of electrospinning in the field of functional foods.The research contents and results of this paper are as follows:1.Preparation of electrospun zein/Fish oil(zein/FO)single nanofilm and its property.The modified electrospinning was adopted to prepare zein/FO single nanofilm.When80% ethanol was adopted as solvent,and the concentration of zein and fish oil were 25%(w/v)and 7.5%(w/v),respectively in the electrospinning solution,the optimal eclectrospinning condition was as follows: adding 3% glycerol into the polymer solution,and the modified electrospinning technique with ethanol as shell solution was adopted.Under the optimal conditions,the obtained zein/FO single nanofilm had good morphology with average diameter being 390 nm.The encapsulation efficiency(EE)and loading capacity(LC)of fish oil inzein/FO single nanofilm was 94.89% and 21.90%,respectively.The results of thermogravimetric analysis(TGA)and fourier transform infrared(FTIR)indicated that fish oil was encapsulated in the nanofilm and the molecular interaction was occurred between the various components of nanofilm.Oxidative stability analysis showed that electrospinning was an effective method to significantly enhance the oxidative stability of encapsulated fish oil,and the total amount of fish oil that released from zein/FO single nanofilm was 91.26%indicated by the in vitro release study.2.Preparation of electrospun fish oil coaxial nanofilm and its property.The coaxial electrospinning was used to encapsulate fish to further improve the oxidative stability of encapsulated fish oil.Firstly,the above fish oil-loaded single nanofilm solution was chosen as core solution,the influence of the shell solution composition and electrospinning parameters was investigated.The optimal electrospinning conditions were:the concentration of shell polyvinyl pyrrolidone(PVP)and ethanol was 31% and 100%,respectively,shell solution flow rate was 0.2 mL/h,core solution flow rate was 0.4 mL/h,voltage was16 kV,and distance was 14 cm.Under the optimal conditions,the obtained fish oil coaxial nanofilm had distinct core-shell structure and good morphology with average diameter being 560 nm.The EE and LC of fish oil in coaxial nanofilm was 96.91% and 14.54%,respectively.Fish oil was encapsulated in coaxial nanofilm and there existed interaction among the components of nanofilm indicated by the FTIR results,which led to the improvement of thermostability of encapsulated fish oil.Oxidative stability analysis showed that,the encapsulated fish oil in coaxial nanofilm exhibited the best oxidation stability compared to unencapsulated fish oil and encapsulated fish oil in the above single nanofilm under both anaerobic and aerobic conditions.Finally,the in vitro release study revealed that83.4% of fish oil was released from coaxial nanofilm,and the release mechanism was controlled by a combination of diffusion and macromolecular chain relaxation.These results demonstrated that although the oxidative stability of encapsulated fish oil in the coaxial nanofilm was obviously enhanced,its release property was decreased.3.Preparation of electrospun zein/FO/FA single nanofilm and its property.In order to solve the poor release property of the encapsulated fish oil in the coaxial nanofilm,zein/FO/FA single nanofilm was prepared using the modified electrospinning byadding ferulic acid into the electrospinning solution.The optimized electrospinning conditions were: ferulic acid concentration 3%(w/v),adding 3% glycerol into the polymer solution,voltage 16 kV,distance 14 cm,ethanol flow rate 0.2 mL/h.Under the optimal conditions,the obtained zein/FO/FA nanofilm had good morphology with average diameter being 450 nm.The EE and LC of fish oil in zein/FO/FA nanofilm was 94.44% and 19.53%,respectively.And for ferulic acid,the EE and LC were 88.18% and 9.11%,respectively.Then,fish oil was successfully encapsulated into the nanofilm and the molecular interaction was occurred between the various components of nanofilm demonstrated by TGA and FTIR results.Oxidative stability analysis also showed that,,encapsulated fish oil of zein/FO/FA nanofilm had the best oxidation stability in comparation with unencapsulated fish oil and encapsulated fish oil of zein/FO nanofilm under both anaerobic and aerobic conditions.The total amount of fish oil and ferulic acid released from zein/FO/FA nanofilm was 93.48% and 98.52%,respectively,and the release analysis showed that the release of encapsulated fish oil from zein/FO/FA nanofilm was controlled by a combination of diffusion and macromolecular chain relaxation.,These results demonstrated that encapsulated fish oil of zein/FO/FA nanofilm possessed high oxidative stability and good release property. |
PDF Full Text Request