Volatile compounds, sensory quality and ice morphology in falling-film and block freeze concentration of coffee extract

Abstract

Please cite this article as: Moreno, F.L., Quintanilla-Carvajal, M.X., Sotelo, L.I., Osorio, C., Raventós, M., Hernández, E., Ruiz, Y., Volatile compounds, sensory quality and ice morphology in falling-film and block freeze concentration of coffee extract, Journal of Food Engineering (2015), doi: http://dx.doi.org/10.1016/j.jfoodeng. 2015.05.018 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ruth.ruiz@unisabana.edu.co AbstractCoffee extract was freeze-concentrated through block and falling-film techniques.Solute retention and concentration efficiency were determined after one stage of these processes. Ice morphology was characterized through image analysis.Preservation of volatile compounds was determined through GC-MS. The effect of coffee extract on flavour was determined after freeze concentration through sensory evaluation. Solute occlusion was higher for falling-film than for block freeze-concentration, with an average distribution coefficient of 0.45 and 0.29, respectively. The ice crystal size was lower for the falling-film technique; this explains the higher solute occlusion. The dewatering capacity was higher for the falling-film technique, as this process is faster than block freeze-concentration. The most abundant volatile compounds of the coffee extracts were preserved after freeze concentration with both techniques. In the same way, no differences were found in most of the sensory attributes of the freeze-concentrated extract obtained using both techniques. Our results confirm the benefits of the block and falling-film freeze concentration techniques in preserving the quality of coffee extracts.

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

“…For progressive FC (PFC), the studies showed higher retention of solutes in the ice fraction when it was compared with BFC. Specifically, Moreno et al compared PFC and BFC and obtained a concentrate coffee extract with final CI values close to 1.33 and 1.55, respectively. The lower CI value in PFC indicated that the ice fraction presented more solutes entrainment in the ice fraction than BFC.…”

“…Hence, FC can be used as a concentration technology to protect and retain various heat‐labile components, resulting in a minimal loss of important components, as mentioned recently by Petzold et al . Thus, studies demonstrated that FC technology allows the retention of different properties in black currant juice , coffee extract and pear juice , coffee extract , and apple juice , among other liquid samples.…”

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

“…The total soluble solids content of the solution was monitored every 30 min using an Atago refractometer (PAL‐BX/RI, Atago, Japan). °Brix measured in the samples were converted to a percentage of total solids using the equation: %Solids = 0.87% × °Brix, as reported by (Moreno, Quintanilla‐Carvajal, et al, ; Moreno, Raventós, et al, ). Each step was completed when the concentration index (CI) reached a range of 1.4–1.5.…”

“…In the food industry, the nutritional and sensory properties of the product may be affected by the processing of raw materials at high temperatures, as is the case for concentration by evaporation. Thus, freeze concentration (FC) has been implemented as an alternative in the food industry (Moreno, Quintanilla‐Carvajal, et al, ; Moreno, Raventós, et al, ; Sánchez, Ruiz, Auleda, Hernandez, & Raventos, ).…”

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

“…It is therefore considered a mild concentration technique. [2,3] During freeze concentration water is frozen as ice crystals, which excludes the solute molecules, when the degree of supercooling is not too high. [4] Supercooling is the process of lowering the temperature below the freezing point while the ice crystals are not yet formed due to absence of nucleation.…”