Research On The Preparation Of Fucoxanthin-OA-protein Self-assembled Particles And Intestinal Absorption Characteristics

Fucoxanthin is a kind of lutein derived from Marine brown algae with antioxidant activities,anti-obesity,vision protection and other physiological activities.But poor solubility in water and difficulty in dissolving and absorbing in hydrophilic environment has limited its application in food industry.Protein is an important carrier of active component transport system,it is of great significance to study the interaction between fucoxanthin and protein,to improve its dispersion characteristics and intestinal absorption effect in hydrophilic environment,and to develop health food and nutritionally fortified food with fucoxanthin as the core functional component.In this study,the processing stability of fucoxanthin and its absorption effect in different dietary forms were studied,water-dispersed fucoxanthin-oleic acid(OA)-protein self-assembled particles with strong absorption effect were constructed.The assembly mechanism of fucoxanthin and protein was further analyzed.Furthermore,the antioxidant activity and visual protection function of fucoxanthin-OA-protein particles in vivo were preliminarily discussed.The results are as follows:The characteristic spectrum changes of fucoxanthin were observed under the conditions of food processing.The results showed that fucoxanthin is very sensitive to many processing conditions such as high pressure,high temperature,light exposure,acidic pH,etc.The degradation rate is as high as 50%-76%,but it is stable in alkaline environment.The serum response value of fucoxanthin in mice at 4 h was detected by high-performance liquid chromatography(HPLC).And the intestinal absorption differences of the three dietary forms of fucoxanthin(direct oral administration,routine protein embedded,and oil delivery)were contrasted.The results showed that the absorption efficiency of fucoxanthin by direct oral administration was poor,and the response value of fucoxanthin in serum was only 65.6 pmol/mL.After the assembly with bovine serum albumin(BSA),the serum response value was increased to 94.5 pmol/mL,but compared with 369.2 pmol/mL of oil delivery,the improvement of intestinal absorption by routine protein embedding is still very limited.In addition,the study also found that the proportion of fucoxanthinol,Amarouciaxanthin A and fucoxanthin in the serum of mice was 26.43%,50.35%and 23.21%,respectively,after 4 h of gavaging the sample of fucoxanthin dissolved in soybean oil.The proportions of the three serum components were 26.03%,18.83%and 55.13%after protein embedding.The results showed that the delivery medium could effectively regulate the absorption form of fucoxanthin and thus affect its physiological function.A water-dispersed fucoxanthin-OA-protein self-assembly particles which have strong absorption characteristics was constructed with pH-driven method.The effects of reaction conditions such as OA concentration,protein concentration,protein structure and initial alkaline pH on the particles morphology,the encapsulation efficiency of fucoxanthin and intestinal absorption were systematically studied by taking the response value of serum fucoxanthin in mice as evaluation indexes.Dynamic light scattering test results showed that particles sizes were 211.93 nm,480.70 nm,292.77 nm and 236.97 nm,with carriers of BSA,sodium caseinate(NaCas),zein and sodium caseinate-zein complex(NaCas-zein)and the encapsulation efficiency were 83.70%,79.00%,88.70%and 80.15%,respectively.BSA had the most obvious promoting effect on the absorption of fucoxanthin in vivo compared with the other three protein carriers.When the molar ratio of OA to BSA was 4:1,The initial pH is 11,and the BSA concentration was 1%,the fucoxanthin-OA-protein particles had the best absorption effect,the serum response value at 4 h was 336.9 pmol/mL,reaching 91.2%of the oil delivery effect.Compared with traditional protein embedding and oil delivery,OA-BSA delivery system which constructed in this study can promote fucoxanthin to be absorbed by intestinal tract mainly in its original form(fucoxanthin accounts for 86.99%).The transmittance(700 nm)of the embedded particles in the aqueous solution reached 95%,indicating good water dispersion and stability.The results of fluorescence spectrum showed that the OA did not affect the fluorescence quenching of protein by fucoxanthin.Further analysis by Stern-Volmer equation shows that the binding ratio of fucoxanthin to protein is 2:1,and the binding force between BSA and fucoxanthin was the biggest.The binding ability of BSA to fucoxanthin was increased by 5 times with the intervention of OA.Molecular Docking(MD)results show that OA,fucoxanthin bind to different regions of BSA respectively.The Fourier transform infrared spectroscopy(FT-IR)showed that the presence of OA had no significant effect on the effective embedding of fucoxanthin in 4 proteins.Fucoxanthin-OA-BSA particles were fed to mice for 15 days,the accumulation of fucoxanthinol was detected in the eye tissue of mice by HPLC analysis,indicating that fucoxanthinol,the digestive product of fucoxanthin,plays an important role in the vision protection of fucoxanthin.In addition,the results of the total antioxidant capacity(T-AOC)in vivo showed that T-AOC of serum and eyes in the direct gavage of fucoxanthin group was increased by 21.9%and 21.14%respectively.The group gavaged fucoxanthin-OA-BSA particles T-AOC of serum and eyes was increased by 55.90%and 39.27%,respectively.The results indicated that the water-dispersed fucoxanthin-OA-protein self-assembed particles constructed in this study had a good vision protection function.