Study Of Ready-to-use 3D Printed Sodium Alginate Blended Gels

Food 3D printing technology has the advantages of personalized customization of product shape and accurate customization of food nutrients.At present,3D printing still has a series of problems in food processing,such as strong randomness of raw material selection,short storage life of high moisture content and so on.In order to solve those problems,sodium alginate and rice starch wereutilizedas basic materials,the mathematical relationship among skeleton molecular structure,gel characteristic parameters and 3D printing effect was established by using room temperature extrusion-based 3D printing technology.Purple potato anthocyanin was loaded as a functional factor deliveryinto food gel system.It aimed to provide theoretical support for the development of nutritious and beautiful ready-to-eat3D printed food.The contents and main results of the study were as follows:1.Taking Ca²⁺-induced sodium alginate gelas an example,the structure-activity relationship among molecular structure,rheological properties and printing effect was established.Four kinds of sodium alginate with different molecular weight and M/G ratio were added to calcium solution to prepare hydrogels,and the R-value,molecular weight,rheological properties,hydration distribution properties,printability parameters,as well as Spearman’s correlation coefficient were characterized and analyzed.The results showed that the stability and uniformity of the gel system could be ensured by R=0.23～0.30.The continuous gel filament could be extruded when the G’_LVR of the gel was 450～800 Pa（for0.84 mm nozzle）,and the stable self-supporting ability could be maintained when the thixotropic modulus recovery rate was higher than 90%.The extrusion fluency was negatively correlated with the viscosity parameter K and positively correlated with the molecular weight The self-supporting ability was positively correlated with the modulus series parameters(especially G’_LVR),and the printing deviationσis positively correlated withδand T₂₂,indicating that the binding ability of gel network and moisture was the key factor to adjust the rheological properties and affect the printing performance.2.Sodium alginate/rice starch co-coagulant was prepared to improve the storage quality of ready-to-eat 3D printed food.Takingσ_n and G’_LVR as indexes,the rice starch（RS）concentration,sodium alginate（SA）addition as well as co-heating temperature were optimized by response surface designing,and the optimized values were 24.6%,1.56%and 86.0℃,respectively.The printable RS/SA gel was then prepared as the experimental group,and the RS gel without adding sodium alginate was control group.The texture,spectrum,short-range starch molecular order series coefficients,hydration distribution and microscopic gel network morphology were compared.The results showed that the addition of sodium alginate could significantly（P<0.05）reduce the relative crystallinity and FTIR_1047/1022of newly prepared and retrograded starch,while the increase FWHM₄₈₀.The peak area(A₂₂)of starch gel in the control group decreased significantly（P<0.05）after regeneration,but there was no significant（P>0.05）change in the experimental group.3.Equipped with purple potato anthocyanins,develop colored,low-GI 3D printing function food.According to the printing performance,the addition amount of purple potato anthocyanin（PPA）was optimized,and the effects of different buffer pH（2.0-8.0）on the chromaticity,texture and hydration properties of RS/SA/PPA gel were studied.Results showed that 0.3%addition of PPA could improve the appearance and edible value without destroying the printing performance.This work could guide the rapid screening of printable sodium alginate gel materials in the food industry,and enrich new types of ready-to-eat 3D printed food system.It was helpful for opening up the market in the field of premium functional food.