Formulation and Evaluation of Edible Ink from <i>Clitoria ternatea</i> L. (Butterfly Pea) and <i>Hibiscus rosa-sinensis</i> L. (Hibiscus)

Background: Colour additives, encompassing pigments and dyes, are applied topically to alimentary products, pharmaceuticals and cosmetics. Synthetic food colourants may pose health risks to consumers and may induce toxicological effects upon ingestion. In contrast, natural food colourants are regarded as innocuous, non-toxic and environmentally biodegradable. Edible ink is a viscous liquid or paste containing dyes or pigments, is used to impart chromatic hues and intricate patterns onto the surface of food products. Aim: The objective of this study is to formulate edible ink from Clitoria ternatea L. and H. rosa-sinensis L. Methods: The Pigment extraction was carried out using the solvent extraction method, wherein the factors considered were ethanol concentration, liquid feed ratio, extraction time and temperature. The resultant pigments were used to prepare the edible ink and subsequently subjected to an array of physical, functional and shelf-life analysis. Result: The findings indicate that the optimal extraction conditions were achieved with 80% ethanol concentration, 1:4 liquid feed ratio, 60 min extraction time and 50ºC temperature. The physical properties evaluation revealed that the edible ink exhibited desired attributes, while the antioxidant values were 109.72±1.106 for C. ternatea L. and 110.87±1.050 for H. rosa-sinensis L. edible ink. Furthermore, the cytotoxicity assessment revealed that the formulated inks were non-cytotoxic at lower concentrations, and the microbial study confirmed that both inks remained safe for up to 30 days with excellent colour retention when applied to food substrates. Conclusion: This study successfully developed a non-toxic, antioxidant-rich edible ink from C. ternatea L. and H. rosa-sinensis L. under optimised conditions. The formulated ink has demonstrated effective colour performance, stability and safety, ensuring its potential use in the food industry. Major Findings: The study concludes by highlighting the optimised formulation of edible inks from C. ternatea L. and H. rosa-sinensis L., which exhibits antioxidant activity, non-cytotoxic, microbial stability and promising application in food products.