Multi-stage block freeze concentration via gravitational method applied to increase of the nutritional content of Morinda citrifolia L. tea

The processing of Morinda citrifolia fruit normally results in a large number of waste leaves that hold many bioactive compounds with nutritional and pharmacological properties. This work aimed to evaluate the effects of a multi-stage block freeze concentration (BFC) via gravitational method on the physicochemical properties of the leaf extract (noni tea). The results in solid retention showed fractions almost 7 times most concentrated than the initial feed. In addition, when compared to the initial content, the BFC process showed an efficiency higher than 90% in the retention of phenolic compounds. Assays in liquid chromatography allowed the detection and quantification of phenolic compounds, in which the total amount increased by more than 1000% in relation to the initial content after each BFC step. Finally, it was also possible to observe a significant increase in the antioxidant activity of the concentrated product after the simulated in vitro digestion process. It was concluded that using a non-thermal, sustainable, low-cost processing, promoted the obtaining of concentrated fractions with high biological and nutritional values with promising properties for application in the development of functional foods from agroindustrial wastes.