| Colostrum a substance of high nutritional value.However,the low bioavailability of immunoactive substances in bovine colostrum affected its immune function.To solve this problem,this study prepared bovine colostrum liposome to slow release bovine colostrum immune active substance and improve its bioavailability and immune function.The main results are as follows:1.Preparation of bovine colostrum liposome.Based on the encapsulation rate of bovine colostrum liposome,the best preparation technology of bovine colostrum liposome was selected from the film dispersion method,organic solvent injection method and reverse evaporation method.The encapsulation rate of bovine colostrum liposome prepared by this method was high,reaching(44.12±2.44)%.The effects of soybean phospholipid content,bovine colostrum content,organic phase(organic solvent dissolved soybean phospholipid)volume and ultrasonic time on the protein encapsulation rate of bovine colostrum liposome were investigated by single factor analysis.The optimal formula for preparing bovine colostrum liposome was selected by response surface design analysis and model fitting.When the content of phospholipid was 74.9 mg,the content of bovine colostrum was 6.152mg/m L,and the volume of organic solvent was 6.25 m L,the protein encapsulation rate of bovine colostrum liposome was the highest,the protein encapsulation rate was(44.12±2.44)%,and the immunoglobulin G(Ig G)encapsulation rate was(24.7±7.5)%.In order to adapt to the production of food enterprises,This paper further optimized the preparation process and method of bovine colostrum liposome.After dissolving phospholipid and β-sitosterol in soybean oil without organic solvent and mixing with bovine colostrum with a probe for 10 min,a stable emulsion was formed.Then,the protein encapsulation rate of bovine colostrum liposome was(57.02±1.22)%.The encapsulation rate of Ig G was(49.03±1.55)%.Finally,the method without organic solvent was selected for follow-up experiment.Laser confocal microscopy(CLSM)showed that the bovine colostrum liposome was round and smooth in appearance.Fourier infrared spectroscopy showed that C=O of bovine colostrum reacted with PO42-in phospholipids,and combined with phosphoric acid through hydrogen bonding,confirming that phospholipids embedded bovine colostrum.2.In vitro digestion of bovine colostrum liposome.In this study,static in vitro digestion was adopted to investigate the digestive characteristics of bovine colostrum and bovine colostrum liposome by measuring the changes of particle size,electric potential,protein bands and Ig G contents during digestion.The results showed that the particle size of bovine colostrum liposome remained basically unchanged in the gastric digestion stage,but in the intestinal digestion stage,the particle size first increased and then gradually decreased due to the presence of pancreatic lipase and bile salt.Because the protein in bovine colostrum was positively charged at low p H,the potential of bovine colostrum liposome was positive in the simulated gastric digestion stage,and the potential decreased significantly after entering the intestinal fluid and producing lysophospholipids.SDS-PAGE showed that bovine colostrum Ig G coated with liposome remained longer in intestinal digestion than uncoated bovine colostrum igg,indicating that liposome protected the functional substance of bovine colostrum and made it release slowly.The results of CLSM showed that the bovine colostrum liposome remained basically intact at the stage of gastric digestion,but after reaching the intestinal fluid,the liposome was broken due to the presence of pancreatic lipase and bile salt,and the bovine colostrum was released.3.Studies on the in vivo digestion and absorption characteristics of bovine colostrum liposome and the Bioavailability of Ig G.The serum Ig G content of bovine colostrum and bovine colostrum liposome was determined at 0h,0.5h,1h,2h,3h,5h,7h,9h and 12 h by inadministration of bovine colostrum and bovine colostrum liposome to study the digestion and absorption characteristics of bovine colostrum liposome Ig G in vivo.The results showed that the serum Ig G content of bovine colostrum group reached its peak at 0.5h,while that of bovine colostrum liposome group reached its maximum at 2h.The Ig G content of bovine colostrum liposome serum was significantly higher than that of bovine colostrum group after 12 h.Within12h,the area under the curve of bovine colostrum group was 144.07625,and the area under the curve of bovine colostrum liposome suite was 164.4855,indicating that Ig G absorption in bovine colostrum liposome group was higher than that in bovine colostrum group,and Ig G slow release effect was achieved.In addition,we analyzed the peptides of 2h digestion of mouse intestinal contents.The results showed that the number of short chain peptides of 2h digestion of bovine colostrum was more than that of bovine colostrum liposomes.In addition,the immunoactive peptides were analyzed by online software Peptide Ranker and Biopep.The results showed that the immune-related peptides included GFLP,TGLF,GFLV,SAPRHGSLGFLPR,HGSLGFLPR and TPGFL,among which the bovine colostrum liposome group contained 5 immunoactive peptides,and the bovine colostrum group contained 4immunoactive peptides.The abundance of immunoactive peptide in bovine colostrum liposome group was significantly higher than that in bovine colostrum group,suggesting that the immunoactivity of bovine colostrum liposome may be higher than that of bovine colostrum.Then,the bioavailability of bovine colostrum Ig G was investigated by mouse metabolism experiment.The results showed that bovine colostrum Ig G had no significant effects on body weight,food intake and organ index of mice,indicating that bovine colostrum igg had no adverse effects on the growth and development of mice,and the bioavailability of bovine colostrum igg was37.15%.The Ig G bioavailability of bovine colostrum liposome was 75.669%,and that of bovine colostrum liposome was 2.04 times that of bovine colostrum.4.The immunosuppressed mouse model was established by intraperitoneal injection of cyclophosphamide(CPX)to study the effect of bovine colostrum liposome on immune function.The results showed that bovine colostrum liposome alleviated weight loss,intestinal injury,spleen enlargement and thymus atrophy in mice,and the effect of bovine colostrum liposome was significantly better than that of bovine colostrum.The results of serum and intestinal cytokines and immunoglobulin showed that bovine colostrum liposome could restore the expression of serum and intestinal cytokines IL-4,IL-10,TNF-α,IFN-γ,Ig G and Ig A of immunosuppressed mice,and improve the imbalance of Th1/Th2,and the effect was better than that of bovine colostrum.The results showed that bovine colostrum liposome had immunomodulatory function. |
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