Application of nanofiltration for coffee extract concentration Original Research Article

Currently it is very important that good-quality products are produced at an adequate price. In the case of instant coffee there are several production technologies. Some of these technologies do not provide good quality, and others — while the quality of the product is good — the cost is too high and needs to be reduced. As it is well known from the literature, the organics rejection of nanofiltration (NF) membranes should be very high. The aim of this work was to find a suitable NF membrane for coffee extract concentration running at optimal operation parameters which conform to given experimental conditions and to check the economical efficiency of the process compared to reverse osmosis (RO). In these experiments the filterability of the coffee extract was investigated on a laboratory-scale crossflow NF apparatus using a flat-sheet NF-45 type membrane. The influence of process parameters (recirculation flow rate, pressure, temperature) on the permeate flux and total solid rejection was investigated. The experimental data were modeled by using Rautenbachʹs osmotic pressure model. The cost estimation of the NF and the RO was also made. With using NF the investment (lower applied pressure, higher flux) and operation costs (lower pressure) of the equipment can be reduced compared to RO.