| As natural polymers,proteins and polysaccharides not only have the advantages of a wide range of sources,green and safe,but also have many special functional activities in addition to their own nutrition,and are widely used in food,medicine and cosmetics industries.Lactoferrin(LF),as an important member of milk protein,has multiple functional activities such as antibacterial,antiviral,antioxidant,anticancer and immune regulation.However,the application of lactoferrin is limited due to its sensitivity to environmental factors and gastrointestinal digestion.Therefore,in this study,lactoferrin and neutral lactose disaccharide(La)were used as raw materials to prepare lactoferrin-lactose complex by heat treatment method,and the effects of different environmental factors(lactoferrin/lactose ratio,pH value and ionic strength)on the lactoferrin-lactose(LF-La)complex were studied.The mechanism of the self-assembly of LF-La complex was also discussed.Furthermore,its stability in the simulated digestion process was evaluated to provide theoretical reference for the development and research of novel functional food and nutrient delivery system?The main research results of this study are as follows:(1)The effects of different glycoprotein ratios,pH values and ionic strength on the formation of LF-La complex were analyzed by turbidity,average particle size,Zeta potential and scanning electron microscopy(SEM).The results showed that the addition of La increased the turbidity,average particle size and Zeta potential of the complex solution.Both pH value and ionic strength can affect the state of LF-La complex in aqueous solution.Nanoparticles with smaller particle size are formed in the environment of weak acid and weak alkalinity,and low concentration of salt ions.(2)The microstructure and physicochemical properties of LF-La complex self-assembled aggregates were investigated by Zeta potential,average particle size,fluorescence spectra,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM)and polyacrylamide gel electrophoresis(SDS-PAGE).The results showed that the Zeta potential of LF-La complex increased and the average particle size changed after heat treatment.The interaction between LF and La can enhance the absorption intensity of amide band,cause the red shift of-OH band,and increase the content of ?-helix in LF.The maximum absorption peak intensity of intrinsic fluorescence was reduced and the red shift of amino acid residues was inhibited.The blue shift of ANS exogenous fluorescence peak was inhibited,and the intensity of exogenous fluorescence was decreased.And the molecular weight of LF-La complex increases with the increase of La proportion.(3)The vitro digestion model was established to study the structural properties changes of lactoferrin and LF-La complex during digestion.The results showed that LF-La complex could inhibit the degradation of pepsin and the digestion of trypsin to a certain extent.In the process of digestion,the addition of La has a certain protective effect on LF.After digestion,the iron content and iron binding ability of LF-La complex were significantly increased.And the 1:1 LF-La complex after intestinal digestion has higher DPPH antioxidant capacity.(4)Lactoferrin tablets were prepared by powder direct compression method.The preparation process of lactoferrin tablets was optimized by single factor and response surface experiment,and the quality characteristics of lactoferrin tablets were studied.The results showed that the optimal preparation process of lactoferrin tablet was as follows: 46.66% of whole milk powder,5% of collagen peptide and 46.40% of mannitol.Quality characteristics analysis showed that the room temperature sealing group was better than the other two groups in whiteness,hardness,chewiness and moisture absorption. |
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