Rheological properties, antimicrobial activity and screen-printing performance of chitosan-pigment (FeO(OH)·xH2O) composite edible ink

This paper prepared 4 inks mainly based on chitosan with different molecular weight and different mass percentage, and pigment (FeO(OH)·xH2O). The inks were characterized using Fourier transform infrared spectroscopy (FT-IR). Rheological properties were discussed by shear rate, time, temperature, oscillatory modulus, yield stress, and screen-printing simulation. Antimicrobial activity was analyzed by the growth inhibition zone. The inks were also applied to screen printing on substrates containing coated paper, nori, chocolate, etc. The print performance of the inks on coated paper was investigated by contact angle, optical density, print fastness and scratch resistance. 4 inks possessed obvious thixotropy and different linear viscoelastic regions. The experimental yield stress was 39   Pa and viscosity recovery rate was up to 76% after 105   s. Growth inhibition zone achieved 12.0   mm in diameter and optical density reached 1.2 with contact angle being 73°. The results indicate that the developed ink is applicable for screen printing.