Solubilization Of Citrus Flavone By Using Octenyl Succinic Anhydride Esterified Waxy Corn Starches In Different Molecular Weights

Citrus flavones,an important plant dietary flavones,are diverse,and the most abundant are flavanones such as naringin and its aglycones.A large number of studies have pointed out that citrus flavonoids have multiple beneficial biological activities that are inseparable from human life and health,such as anti-oxidant and antibacterial,anti-allergic and anti-cancer,hypoglycemic and lipid-lowering.In China,millions of tons of citrus peel residues and other by-products are produced during the annual production and processing process,and the citrus flavonoids contained in them are more than tens of thousands of tons.The industrial extraction technology of citrus flavones has become increasingly mature,but the water solubility is particularly low,and the problem of low bioavailability due to poor water solubility generally exists,which greatly limits its direct application in the fields of food and medicine.Therefore,it is necessary to choose suitable solubilization methods and auxiliary materials to embed and solubilize citrus flavones.Exploring the solubilization technology of poorly soluble flavonoids to improve its bioavailability is one of the hot topics in the field of food and medicine at home and abroad,among which amphiphilic compound embedding is one of the most important methods.The modified product?OSA esterified starch?obtained by the esterification of starch with octenyl succinic anhydride?OSA?is a typical amphiphilic molecular derivative.OSA esterified starch has the characteristics of good stability,encapsulation and rheology,and is a hot spot for research and development as a solubilizing adjuvant for drugs in recent years.On the other hand,OSA esterified starch is still a high-viscosity macromolecular compound.Therefore,in order to better meet the production and application requirements of products with low viscosity requirements in the industry,the original high-viscosity OSA esterified starch needs to be appropriately degraded.Based on the comparison of the solubilizing effect of OSA esterified starch from different sources and degree of substitution on citrus flavones in the early stage of the project team,the law between the water solubility of two citrus flavones and the structural parameters of the molecular weight of OSA esterified starch was fitted,and the interaction between citrus flavone and OSA esterified starch was systematically analyzed in this paper.The specific research contents and results are as follows:?1?Using waxy corn starch as raw material and enzymatic hydrolysis of?-amylase at medium temperature to complete the preparation of octenyl succinic waxy corn starch ester?OSAS?with different molecular weights,completed viscosity,swelling,sedimentation paste transparency,physical properties and FT-IR and SEM structure characterization.The results showed that the physical properties of OSAS with different molecular weights?1.0×10⁴-2.0×10⁵?,such as viscosity,swelling,settling,and paste transparency,decreased with the decrease of molecular weight,especially the viscosity was significantly reduced in the range of 0.0035-0.0010 Pa?s and the transparency of the paste was significantly reduced in the range of 28.6-23.1%.The esterification of OSA groups with waxy corn starch molecules mainly occurred on the surface of starch granules,and the enzymatic hydrolysis mainly broken the granules without introducing other substances.?2?Constructing two citrus flavone naringin?NR?and naringenin?NE?as the object to construct a citrus flavone and OSAS saturated water system,and systematically study the influence of different molecular weight OSAS on the solubility of citrus flavone in water system.The stability evaluation of the solubilizing system was completed from many aspects such as light,temperature and humidity.The results showed that the content of citrus flavones in both NR and NE showed a trend of increasing first and then decreasing with decreasing molecular weight of OSAS.The samples of NR-M-OSAS and NE-M-OSAS with the highest citrus flavonoids had aqueous phase solubility curves that conform to type A_L in the Higuchi and Connors classification,indicating that both NR and NE citrus flavones were compatible with M-OSAS.The encapsulation was completed at a ratio of 1:1.In NR-M-OSAS water system with a molar concentration of 50 mmol·L^-1,the solubility of NR could reach 848.83 times the inherent solubility in water,NE solubility could reach 1023 times the inherent solubility in water.This confirmed that the amphiphilic molecule OSAS could indeed significantly improve the solubility of citrus flavones such as NR and NE.In addition,no matter from the temperature,light or humidity environment,the stability of OSAS,NR and NE water systems was better than free NR and NE.?3?Multispectral methods were used to characterize the changes in the characteristics of citrus flavones before and after compounding with OSAS.The particle size distribution and microscopic morphology of citrus flavones and OSAS aggregate particles were measured and observed by laser particle size analyzer and TEM,and the solubilization state between saturated citrus flavones and OSAS aggregates was comprehensively analyzed.FT-IR results showed that both NR and NE citrus flavones were determined to be contained in the M-OSAS molecular cavity of OSAS aggregates.XRD results showed that NR and NE citrus flavones were existed in M-OSAS in an amorphous state after being wrapped,and there were non-covalent forces such as hydrogen bonds or van der Waals forces.DSC results verify the correctness of FT-IR and XRD experimental conclusions.NR and NE were inclused by non-covalent bond force.¹H-NMR results further confirmed that NR and NE two citrus flavones entered the M-OSAS molecular cavity through wide ports.The particle size and TEM results showed that the particle diameters of the NR-M-OSAS and NE-M-OSAS self-aggregates were 257.07 and 222.53 nm,and they were uniformly distributed in the range of 10-1000 nm.Moreover,both aggregate particles were spherical,and were obviously dispersed in the aqueous solution.