Effect of falling‐film freeze concentration on bioactive compounds in aqueous coffee extract

Abstract

AbstractFalling‐film freeze concentration (FFFC) is a technology used to concentrate liquids by freezing. This study demonstrated the effect of FFFC on bioactive compounds in coffee extract and their antioxidant activity. Coffee extract containing 5% solids was freeze‐concentrated in 2 successive steps. The main bioactive compounds, chlorogenic acids and caffeine were detected by RP‐HPLC. The antioxidant activity and phenolic content were assessed by ABTS, DPPH, and Folin–Ciocalteu assays. The solution was concentrated 2.09 times after 2 FFFC steps. A concentration index of 2.1 was obtained for bioactive compounds for the concentrated fraction. The antioxidant activity was preserved and a correlation between antioxidant activity and the content of bioactive compounds was confirmed. Coffee bioactive compounds were distributed in proportion to the total solids content of the ice and liquid. Overall, the results showed that FFFC is an effective technique to concentrate liquids that preserves the functional properties of the coffee extract.Practical applicationsThe falling film freeze concentration is a new freeze concentration technique which is in development to be used in future industrial applications of food fluids concentration. This study demonstrates the preservation of bioactive compounds and bioactivity of this technique applied to the concentration of coffee extract. The research has applications in the coffee industry in the production of concentrated coffee extract and freeze‐dried soluble coffee.