Research On Additive Manufacturing Of Purple Potato Mud System Based On Spontaneous Nutritional Components Change

With the development of food industry,people have increased the demand for personalized food appearance and nutrition.Food additive manufacturing technology is a food processing technology that can meet the above needs.However,there are still deficiencies in the research on additive manufacturing.First,the printability of 3D/4D ink is difficult to judge;Second,there are relatively few studies on the nutritional changes of 4D printing at present;Third,the research on food 5D printing has not been reported,and the food 5D printing technology has not been studied.In view of the above problems,starting with the 3D printing properties of purple potato mud,this paper studies the 3D printability of purple potato mud,and puts forward a method to predict the printability of ink based on near Red foreign.On this basis,through the improved formula,a food simulation system rich in ergosterol was configured to study the nutritional changes of 4D printing and the effect of 4D printing structure design on the conversion of ergosterol to vitamin D2.Then,the real food system was configured by adding mushroom waste to the purple potato mud,and the effects of microwave pretreatment,ultrasonic pretreatment and 3D printing technology on the conversion of ergosterol to vitamin D2 in the real food system were studied.Finally,probiotics and tea polyphenols were added to the purple potato mud system for the preliminary study of food 5D printing.The 4D printing color change was used to indicate the 5D printing change formed by the proliferation of probiotics.The specific research contents are as follows:1)The relationship between purple potato puree formulations and printing properties based on 4D/5D printing applications was investigated,and different purple potato puree formulations were classified by studying the rheological properties of different formulations used for 3D printing,and then a prediction model based on near-infrared spectroscopy was developed to predict the rheological properties of purple potato puree.The results showed that all purple potato purees exhibited shear thinning and shear recovery properties;and the apparent viscosity,energy storage modulus（G’）,loss modulus（G’’）and complex modulus（G^*）of purple potato purees increased with the increase of purple potato powder addition.The apparent viscosity and G’’are related to the extrudability of the mashed potatoes,and G’and G^*are related to the shape maintenance ability of the mashed potato print structure;based on the actual 3D printing experiments and the measured rheological parameters and the fitted power-law model using PCA analysis and Fisher’s discriminant analysis of rheological parameters,the purple potato mud was classified into four categories,supportable but not flowable,flowable and supportable,flowable and poorly supportable,and flowable but not supportable.The NIR spectra in the wavelength range of 921～1361 nm showed a strong correlation with the rheological properties.The models based on PLS,PCR and BP-ANN using appropriate NIR spectral parameters for modeling can perform well to predict the rheological properties of purple potato puree,and all models have R² greater than 0.95 and RPD values greater than 3.0.Therefore,the models can indirectly but quickly predict the 3D printing properties of purple potato puree.2)The effect of 4D printing on nutritional changes was investigated.Ergocalciferol was added to purple potato puree as a base material for 3D printing;4D printing was achieved by converting ergocalciferol to vitamin D₂ by UV-C radiation.First,the formulation used in the previous step of the experiment was modified to study the 3D printability of these simulated food systems.Then the maximum amount of ergocalciferol added and the optimal conversion time were determined.It was found that the conversion of ergosterol to vitamin D₂ could be promoted by printing model design.the surface area of the irradiated model could be expanded to promote the conversion of ergosterol to vitamin D₂ when the material weight was the same.the filling ratio inside the model could be reduced when the model was the same,decreasing the model weight and thus improving the conversion.The results showed that the ink at ergosterol concentration lower than 0.65 mg/g can be printed well and the optimal irradiation time is 4 h.At the same model weight,expanding the irradiated area by model design can effectively increase the production of vitamin D₂ from 3.631μg to 4.586μg.Reducing the internal filling ratio by model design is also an effective means to increase the conversion rate,and when this ratio is 70%,more vitamin D₂ production can be achieved with minimal use of raw materials.However,the highest concentration of vitamin D₂ in the purple potato puree model was 1.701±0.035μg/g at a filling ratio of 40%.3)The effect of UV combined with microwave and ultrasound on the conversion of ergocalciferol to vitamin D₂ in real food systems was investigated.The ergocalciferol-rich mushroom scraps（mushroom roots）were added to purple potato puree,which was microwave and ultrasonically treated and 4D printed to investigate the effects of microwave,ultrasound and 3D printed structure design on the conversion of ergocalciferol to vitamin D₂ in real food products.The results showed that the vitamin D₂ content in the products pretreated with microwave and ultrasound was 2.2 to 3.8 times higher than that in the model after UV irradiation alone.Partial least squares（PLS）regression analysis showed that appropriate microwave and ultrasound treatments can have a beneficial effect on the conversion rate.3D printed models were designed to have the greatest effect on irradiated area,followed by microwave pretreatment,and the least effect by ultrasound treatment.This study also explains the reason for this beneficial effect,the main mechanism of which is to change the environmental state in which the ergosterol is placed and thus more easily converted to vitamin D₂ by physical field treatment,and a BP-ANN model was developed to predict the changes in vitamin D₂ and ergosterol content.The R² of the prediction models developed by the artificial neural network were higher than 0.90 and the RPD values were greater than 3,which indicated that the artificial neural network has good applicability and can help to predict the contents of ergosterol and vitamin D₂ in real food systems.4)Preliminary exploration of 5D printing technology.Probiotics and tea polyphenols were added to the sweet milk purple potato puree system,and then a preliminary study of 5D printing research was conducted through probiotic fermentation.Through the probiotic fermentation it can be found that as the fermentation process proceeds,the p H of the purple potato puree decreases,causing the color of the purple potato puree model to change from the initial purple to red.And this color change will be more obvious as the fermentation time increases,and the color change can indicate the proliferation of probiotic bacteria population,forming a 5D change based on 4D printing.The addition of tea polyphenols could help boost the number of probiotics in the model and inhibit the growth of mycobacteria.At 8 h into fermentation,the number of probiotic bacteria in the experimental group containing tea polyphenols was 4.78×10¹⁶ CFU/g,which was higher than the number of probiotic bacteria in the experimental group with the addition of probiotics only.The number of molds also decreased accordingly,being 6137±527 CFU/g in the experimental group without the addition of tea polyphenols and probiotics,while the number of molds was 33±9 CFU/g in the experimental group with the addition of probiotics and tea polyphenols.