4D printing induced by microwave and ultrasound for mushroom mixtures: Efficient conversion of ergosterol into vitamin D2

This study hoped to use microwave and ultrasound combined with 4D printing technology to promote the conversion of ergosterol into vitamin D2 in printing model with mushroom scraps. Under the UV irradiation, the conversion was different in the printed model with different irradiation areas and different physical field pretreatment. Compared with raw materials, vitamin D2 concentrations in the printed models was 4.6 time higher. Vitamin D2 in the product after physical field pretreatment was 2.2-3.8 times higher than that without pretreatment. From partial least square regression (PLS) analysis, irradiation area had the greatest impact while ultrasound treatment had the least. Pretreatment enhanced vitamin D2 content, possibly because pretreatment meant ergosterol was more susceptible to UV radiation, and expansion of the irradiated area increased the beneficial effect. This study established an artificial neural network model to predict ergosterol and vitamin D2 content.