Study On Co-extraction Behavior Of Non-starch Components Of Purple Sweetpotato And Construction Of Stable Anthocyanin Microcapsules

Purple sweet potato belonging to sweet potato of convolvulaceae family,its flesh is purple red,and it has multiple functions such as coloring,antioxidant,etc.in food processing.At present,purple potatoes are mostly eaten fresh,and secondly,potato starch is their main processing by-product.However,in the traditional wet starch production process,a large amount of high protein wastewater is generated,which brings environmental burden and resource waste.This study used a simple alkaline solution and acid precipitation method to recover the crude protein from purple potato.The chemical composition and microstructure were studied,and it was found that the crude protein was a composite colloidal particle of protein/anthocyanin/polysaccharide.This type of non-starch component colloidal particle has pH responsiveness,thermal stability,and good emulsifying properties;Finally,using positively charged chitosan as a flocculant,one-step extraction of non-starch components from purple potatoes was achieved through complex coagulation,and microcapsules rich in purple potato protein/anthocyanins were prepared,providing technical support for the high-value utilization of purple potatoes throughout the entire industrial chain.The specific research is divided into the following three parts:(1)Study on the physicochemical composition of non-starch component colloidal particles in purple sweetpotatoPurple sweetpotatoes undergo wet homogenization and static precipitation to remove starch particles,and the upper clear liquid is acid precipitated to obtain crude protein.The protein content of purple potato crude protein is 68.65 ± 0.13%,which is rich in 18 kinds of amino acids.The content of Essential amino acid accounts for 42.5% of the total amino acid content,and the EAA/NEAA is 0.74.The calculated amino acid score of purple potato crude protein is 79.3.The results of gel electrophoresis showed that there were two bands in the crude protein of purple sweet potato,and the corresponding molecular weights were52.9 k Da and 22.9 k Da,respectively,which was speculated to be Sporamin B.The content of anthocyanins in the crude protein of purple sweet potato is 93.47 mg/100 g.Through structural identification by HPLC-MS,it was found that the crude protein of purple sweet potato mainly contains anthocyanins with paeoniflorin,Cyanidin and petunidin as aglycones.The microscopic morphology analysis found that the particle size of purple potato crude protein was 200 nm at pH 6.0-7.0,showing the properties of composite colloidal particles,and the Isoelectric point of crude protein was at pH 4.0.(2)Study on the colloidal particle structure and functional properties of purple sweetpotato non-starch componentsThe colloidal particles of purple sweetpotato crude protein are thermally stable,and when heated to 100 ℃,they do not cause aggregation,but are sensitive to Ionic strength.When the Ionic strength increases to 0.1-0.3 M,the particle size of purple sweetpotato crude protein particles becomes smaller and dissociates,indicating that the formation of purple sweetpotato crude protein colloidal particles depends on electrostatic interaction.Pickering lotion was prepared with coarse protein colloidal particles as emulsifier and medium chain fatty acid ester as oil phase.The effects of colloidal particle concentration,pH and oil phase volume fraction on the formation of lotion were investigated.The results showed that the minimum particle size of the high internal phase lotion was 25.68 when the pH of the colloidal particle system was 4.0,the concentration was 1.0%,and the volume fraction of the oil phase was 80% μ m.It can be applied to the construction of 3D printed food.(3)Extraction of non-starch components from purple potato by chitosan complex coagulationChitosan was used to obtain purple sweet potato protein/anthocyanin/chitosan complex coalescence microcapsules by complex coalescence of purple sweetpotato protein and anthocyanin with opposite charges,and the microcapsules have high recovery of protein and anthocyanin.The encapsulation efficiency of microcapsules reached the highest value of 90.85% when the molecular weight of chitosan was 10 w,and the loading capacity of microcapsules reached the highest value of 44.59% when the molecular weight of chitosan was 15 w.Microcapsules wrapped with anthocyanin can well protect the anthocyanin to enter into the gastrointestinal tract,reduce the loss of anthocyanin at the non-absorption site and enhance the bioavailability of anthocyanin.Microcapsules have certain scavenging effect on DPPH radicals and ABTS radicals,among which microcapsules formed by 30 w chitosan have the strongest scavenging ability on DPPH radicals with 46.93%,and microcapsules formed by 10 w chitosan have the strongest scavenging ability on ABTS radicals,which can have 63.49% scavenging rate.