Ultrasound-assisted anthocyanin enrichment of cold-brewed hibiscus tea prepared in a hard-cap espresso machine for color 3D food printing

ABSTRACT: Ultrasound was used for the anthocyanin enrichment of cold-brewed hibiscus tea prepared in a hard-cap espresso machine. Preliminary tests without (control) and with pretreatment with ultrasound were conducted to determine the best temperature conditions (5, 10, 15, 20, 25 ºC) and extraction time (10, 30, 60, 90 and 120 seconds), and the pretreatment with ultrasound at 10 ºC for 60 seconds was used for the subsequent steps. Ultrasound pretreatment increased anthocyanin content in the tea up to 32% in a fast and low-cost approach. Delphinidin-3-sambubioside and cyanidin-3-sambubioside were identified as major compounds in the tea. In addition, given the ability of anthocyanins to change color in response to pH variations, a thickening and gelling agent was investigated to enable color 3D printing. In this way, people with difficulty chewing or swallowing can be stimulated to consume bioactive compounds from cold-brewed tea in a customized way by using a 3D food printer.