| Astaxanthin is a natural biologically active substance extracted from aquatic organisms.It has a variety of functions of nutrition,health care and physiology.The poor solubility of astaxanthin in water,poor stability to light,heat and oxygen,and low bioavailability limit its application in functional foods.Therefore,it is particularly necessary to search some suitable techniques to broaden the application of astaxanthin in functional foods.Based on amphiphilic starch which is non-toxic and harmless and has the function of carrying fat-soluble nutrient molecules,and can protect the biological activity of nutrients in food,improve its water solubility,targeting and slow-release properties,it has become one of the research hotspots in recent years.In this dissertation,astaxanthin was used as the embedding object.Based on the preparation of octenyl succinic anhydride(OSA)modified starch with different degrees of substitution,the influence of OSA modified starch with different degrees of substitution on the law,properties and effects of embedding astaxanthin was studied.Applied research provides the theoretical and technical basis.The main findings are as follows:1.Firstly,three different substitution degrees of(DS=0.0081,DS=0.0116,DS=0.0314)octenyl succinic acid starch(OSAS)were prepared with natural corn starch as the material and their performance was compared.Infrared spectroscopy analysis showed that natural corn starch reacted with OSA and was successfully modified.X-ray diffraction analysis showed that the esterification reaction only changed with the hydroxyl groups on the starch surface.Scanning electron microscopy(SEM)observation shows that after the substitution reaction of natural corn starch,the surface of the particles will be damaged to a certain extent,and with the increase of DS,the damage becomes more and more obvious.When the DS increases to 0.0314,the edges of the starch granules' polygons began to partially disappear,and the holes that appeared became larger.With the increase of the degree of substitution,the critical micelle concentration of the modified starch is getting lower and lower,the emulsification ability is also increased,the swelling power in the gastrointestinal juice is also increased.Its solubility,emulsification ability,and light transmittance are also increasing with the increase of the degree of substitution.The content of fast digestion starch reduced,the content of resistant starch(RS)increased from 8.79% to 15.50%.2.Secondly,by optimizing the preparation conditions,the optimal preparation parameters of the OSA modified starch-astaxanthin composite carrier system were constructed.Determine the optimal range of OSAS concentration,core-wall ratio,p H value and ball milling time on the basis of single factor experiment.Through orthogonal experiment,the conditions for preparing OSA modified starch-astaxanthin are obtained: by constructing OSA modified starch-astaxanthin composite carrier system,the preparation conditions: when the OSAS concentration is 15 mg/m L,the core-to-wall ratio is 10%When the p H is 6.5,homogenize with a homogenizer at 12000 rpm for 5 min to obtain a coarse emulsion,then spray-dry the emulsion at a temperature of 190 ? and a feed rate of20% to obtain composite particles,and then place the microcapsules at 300 rpm/min Ball milling in a ball mill for 0.5 h,the final octenyl succinate starch-astaxanthin composite particles(OSAS-AST)were obtained,and the embedding rate was 67.17±1.631%.3.According to the optimized conditions,the OSA modified starch-astaxanthin composite carrier system with different degrees of substitution was prepared,and a variety of technical methods and indicators were used to study theefffects,properties and properties of embedding astaxanthin in different degrees of substitution OSA modified starch..As the degree of substitution increases,the embedding rate of OSA modified starch-astaxanthin composite particles with different degrees of substitution is getting higher and higher.Among them,when the degree of substitution is 0.0314,the embedding rate is the highest,83.22±0.831%,The color of the composite particles is increasingly orange-red.The solubility results of OSA modified starch-astaxanthin composite particles with different degrees of substitution show that OSA modified starch can promote the solubility of astaxanthin in water,and as the degree of substitution increases,the solubility of astaxanthin in water increases.The higher the DS increases to 0.0314,the solubility of astaxanthin in water is 15 times higher than the solubility of free astaxanthin in water.The results of Fourier Infrared Spectroscopy showed that astaxanthin was successfully loaded with OSA modified starch.The results of X-ray diffraction analysis showed that astaxanthin was loaded in the OSA modified starch in an amorphous form.Scanning electron microscopy results showed that the OSA modified starch powder particles with different degrees of substitution were uniform and the general shape was "curved",while the unmodified natural starch embedded astaxanthin particles shrank.In terms of antioxidant activity,the antioxidant capacity of the OSAS-AST composite particles was concentration-dependent.4.The in vitro release characteristics and anti-tumor effects of astaxanthin in the constructed OSAS-AST composite carrier were studied by in vitro experiments.The gastrointestinal juice release curve results show that OSA modified starch has colontargeting properties,is not easy to release in the gastric juice,and slowly releases in the intestinal juice.In addition,as the degree of substitution increases,OSA modified starch releases astaxanthin more and more slowly.The release curves of OSA modified starchastaxanthin composite particles with different degrees of substitution basically conform to the Higuchi model and the Weibull mathematical model,and can predict the release of astaxanthin in the gastrointestinal juice well.The toxicity evaluation results showed that OSA modified starch with different degree of substitution had no inhibitory effect on HT-29 cells,while OSA modified starch-astaxanthin composite granules(OSAS-AST)had anti-cancer activity in a concentration-dependent manner.5.In summary,this article uses octenyl succinate starch as a carrier to deliver astaxanthin.By optimizing the preparation conditions,a new type of octenyl succinate starch-astaxanthin(OSAS-AST)composite delivery system is constructed.The results show that the OSAS-AST composite system plays a good role in embedding,solubility conversion,delivery and protection of astaxanthin,and the release of astaxanthin is colontargeted,and the release curve conforms to the Higuchi model and the Weibull mathematical model.It is proved that the degree of substitution is not only an important factor affecting the performance of OSA modified starch,but also a key factor affecting the embedding,solubility conversion,delivery,sustained release and protection of astaxanthin by the OSAS-AST composite system.Those results indicate that this new type of OSA modified starch-astaxanthin delivery system has good application prospects. |
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