Coaxial 3D Printed Nanocellulose Based Food Functional Materials And Their Applications

As a disruptive and creative emerging technology,3D printing technology is expected to provide new technologies and new ways for the intelligence and digitization of the food industry.At present,relevant research is still at a primary stage,mainly focusing on the printing performance optimization of ink and the shaping of the material.The structure customization and control capabilities of 3D printing,especially coaxial 3D printing,are rarely utilized for the development of food functional materials,which greatly limits the development of food 3D printing.Cellulose is a biomass which widely existes in food and dietary fiber.Its nanofibers are widely used in 3D printing due to their wide range of sources,safety and non-toxicity,good biocompatibility,degradability,high strength and good thixotropy,high zero shear viscosity and shear-thinning characteristics.Therefore,the development of 3D printing ink that meets the special needs of food safety with nanocellulose as the substrate is of positive significance to the development of the food industry.In this study,nanocellulose was used as the substrate to develop food 3D printing inks with excellent printability,high printing accuracy and shape retention ability,and explore its applications in lactic acid bacteria delivery and intelligent food packaging by coaxial 3D printing technology.The main researches are described as follows:1.3D printed bacterial cellulose-based lactic acid bacteria delivery compositeBacterial cellulose was used as the matrix to combine with sodium alginate and kcarrageenan for the shell.Chitosan and lactic acid bacteria were co-cultured to be the core.Then,the lactic acid bacteria delivery composite was successfully constructed in one step by coaxial3 D printing technology.It presents a core-shell fiber structure with hollow microchannels,and the lactic acid bacteria are successfully embedded on the inner wall of the fiber.This composite has good texture and fermentation performance as well as excellent lactic acid bacteria protection and delivery efficiency.The survival rate of lactic acid bacteria in the 3D printed bacterial cellulose-based lactic acid bacteria delivery composite material before and after fermentation of In vitro digestion were increased by 33.21% and 36.44%,respectively,compared with the commercial lactic acid bacteria powder.The composite before and after fermentation both have a significant effect on enteritis mice,which can extend the length of the colon and effectively reduce the infiltration of inflammatory cells and the secretion of related inflammatory cytokines.2.3D printed nanocellulose-based integrated smart label for fruit freshness keeping and visual monitoringFood packaging systems with single function of freshness keeping or monitoring may not be able to meet all practical needs.In this study,with nanocellulose/sodium alginate/kcarrageenan/blueberry anthocyanin as the shell material and chitosan/1-methylcyclopropene as the core material,the nanocellulose-based integrated smart label for fruit freshness keeping and visual monitoring was successfully constructed by coaxial 3D printing technology.The nanocellulose-based 3D printing ink containing blueberry anthocyanins exhibits high formability and printing fidelity,as well as the visual p H rapid response capability for freshness monitoring.The 1-methylcyclopropene was trapped and loaded on the core layer by the electrostatic interaction between chitosan and nanocellulose,realizing its controlled released.The 3D printed label can extend the shelf life of litchi by 6 days and sensitively indicate the change in its freshness.Headspace-Gas Chromatography-Ion Mobility Spectroscopy(HS-GCIMS)has confirmed the accuracy of the label indication results.3.3D printed carboxymethyl nanocellulose-based cushioning-antibacterial food packaging materialFor constructing an environmentally friendly degradable cushioning-antibacterial food packaging material to minimize the loss of fruit and vegetable during storage and transportation,a 3D printed cushioning food packaging material was prepared using carboxymethyl nanocellulose as a matrix,supplemented with acrylamide derivatives/glycerin.the effects of glycerin content and crosslinking time on the microstructure,cushioning properties and resilience performance of the materials have been discussed.Then,with this material as the shell layer,silver nanoparticles were fixed as the core layer by coaxial 3D printing technology to prepare a cushioning-antibacterial dual-function food packaging material.The minimum cushioning factor of the material is 4.29 and its three-time compression rebound rate is above90%.It also has obvious antibacterial effects on Escherichia coli and Staphylococcus aureus.Moreover,its degradation rate reaches 76.17% after 14 days.