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

Abstract

Falling‐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 applications The 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.

Influence of Cryoconcentration on Quality Attributes of Apple Juice (Malus Domestica cv. Red Fuji)

“…As mentioned above, this behavior could be associated with the use of low temperatures in CBCC to concentrate bioactive compounds, since the damage to the sensitive components is minimal and, therefore, this process allows a higher anthocyanin concentration than other concentration technologies. A similar trend was observed by Correa et al [39] and Silva et al [40] during the freeze concentration of coffee extract and apple juice, respectively.…”

“…Hence, the cryoconcentrated samples presented an increase up to 3.4 (TPC), 3.0 (TFC), and 2.8 (TFLC) times compared to the initial value. This tendency has been observed with liquid samples such as orange juice [14], strawberry juice [15], blueberry juice [17], pineapple juice [19], yerba mate [38], and coffee extract [39] obtained by the various CC techniques.…”

“…Specifically, the TBC retention was approximately 66%, 77%, and 85% for TPC, 63%, 71%, and 77% for TFC, and 61%, 64%, and 71% for TFLC along the cycles. Orellana-Palma et al [17,19] and Correa et al [39] presented comparable values for fruit juices with CBCC and aqueous coffee extract with FFCC. Specifically, the studies informed TBC retention values from 70% to 95% and 90%, respectively.…”

Effects of Centrifugal Block Freeze Crystallization on Quality Properties in Pineapple Juice

“…The fresh juice group had the highest amount of volatile compounds, and the areas corresponded with twelve esters, three acids, three alcohols, three ketones, three aldehydes, and two unknown compounds. Several authors reported that esters are the major volatile compounds in pineapple and may contribute to the pronounced fruity aroma, although their qualitative and quantitative composition may differ among the analyzed samples .…”

Solute inclusion and freezing rate during progressive freeze concentration of sucrose and maltodextrin solutions

“…[6,[18][19][20] Recent research has investigated these parameters applying freeze concentration to various food products, such as for example apple juice, dairy and coffee extract. [21][22][23][24][25] A common problem is that with increased product concentration, the viscosity of most concentrates will increase. This increase in viscosity will hinder mass transfer of solutes from the boundary layer to the bulk and therefore enhance solute inclusion.…”