Study On 3D Printing Technology Of Selenium-enriched Silver Carp Surimi Products

At present,selenium-enriched fish is rich in resources and has broad prospects for industrial development.However,there is relatively little study on the deep processing process of selenium-enriched fish,and the selenium-enriched resources have not been fully utilized.Especially,the characteristics of selenium-enriched chub,which has less meat and more spines,greatly reduce consumers’ purchasing desire and restrict the industrial development of selenium-enriched chub.3D printing of selenium-enriched chub can improve the processing utilization of selenium-enriched chub and increase the social benefits of the industry but also provide solutions for precise nutrition and personalized food.In this study,firstly,the optimal gelatin extraction process of selenium-enriched silver carp skin and scales was investigated.Secondly,the effects of printing parameters,the ratio of minced fish to water(fish-water ratio),and gelatin addition on the printing quality of chub fish minced fish were investigated.Finally,the effect of the heating method on 3D-printed surimi products was investigated.This study aims to provide a basis for the development of the deep processing industry of seleniumenriched silver carp.The specific study contents and results are as follows:(1)The best extraction material and process for gelatin of selenium-enriched silver carp were determined.Gelatin was prepared by hydrochloric acid extraction,acetic acid extraction,and hot water extraction on fish skin and scales.It was found that the fish skin gelatins extracted by the three methods were higher than the fish scale gelatins in terms of yield,gel strength,gelling temperature,melting temperature,and protein molecular weight.Among them,the acetic acid-extracted fish skin gelatin had the highest gel strength(615.33 g),the highest elasticity(1.86 ± 0.11),and the highest melting temperature(33.09 ± 0.95 °C),and the highest yield(48.38%)of hot water-extracted fish skin gelatin.The three fish scale gelatins were higher than fish skin gelatins in terms of hardness,chewiness,and selenium content.Among them,the hot water-extracted fish scale gelatin had the highest hardness(963.96±97.45)and chewiness(2017.70±73.74 g).The acetic acid-extracted fish scale gelatin had the highest selenium content up to 2.50 mg/kg.in addition,the isoelectric points of all gelatins were located at p H 9.0 or 10.0,and the protein molecular weights were concentrated in four collagen chains of γ,β,α1,and α2;the scanning electron microscope structure showed that the fish skin gelatin was flaky and the fish scale gelatin was concave or convex;the selenium content of all gelatins was by DB61/T 556-2018 standard for selenium enrichment in non-central African ready-to-eat aquatic products.Comprehensive comparative analysis showed that acetic acid-extracted fish skin gelatin could be the best extraction material and process for selenium-enriched silver carp gelatin due to its superior gel strength,elasticity,gelling temperature,melting temperature,and other advantages.(2)The optimal printing parameters,fish-to-water ratio,and gelatin addition for 3D printing of surimi of selenium-enriched chub were determined.Firstly,the accuracy,print stability,and print formability of 3D printed surimi of selenium-enriched chub were used as indicators,and it was found that the best 3D printed products of selenium-enriched chub were printed under the conditions of 90% filling density,1.5 mm nozzle diameter,1.0 mm nozzle height,400 mm/min printing speed,20 mm filament diameter and 90:10 fish-water ratio.Next,the effects of gelatin addition(0%,1%,2%,3%,4%,5%)on the gel characteristics,rheological properties,and printing effects of selenium-enriched chub minced fish in 3D printing were analyzed.It was found that the rheological properties,gel strength,hardness,cohesion,chewiness,and water retention capacity of the minced fish-gelatin composites increased with the increase of gelatin addition.At 4% gelatin addition,the 3D-printed selenium-enriched minced fish had the best molding effect,which effectively improved the problems of easy soup flow and insufficient deformation of 3D-printed minced fish products.Therefore,the final amount of gelatin addition in 3D printed surimi of selenium-enriched chub was determined to be 4%.(3)The best heating method for 3D printed surimi products of selenium-enriched chub was determined.The effects of two-stage heating in the water bath,vacuum low-temperature steaming,and microwave heating on 3D printed surimi products of selenium-enriched chub were analyzed in terms of steaming loss,selenium content,and printing effect.The results showed that there was no significant difference(p > 0.05)between different heating methods on the steaming loss of 3D printed surimi products of selenium-enriched silver carp.The heated finished products conformed to the selenium enrichment standard of DB61/T 556-2018 for non-central African ready-to-eat aquatic products,and the selenium content of the samples heated in only two stages of the water bath was significantly higher than that of the unheated samples(p < 0.05),reaching 0.77 mg/kg,and their 3D printed selenium-enriched chub fish minced products had the best molding effect.Therefore,the best heating method for 3D printing selenium-enriched chub minced fish products was a two-stage heating method with a water bath at 40°C for 30 min and a water bath at 90°C for 20 min.