Recipient Organization
COMPACT MEMBRANE SYSTEMS, INC.
335 WATER STREET
WILMINGTON,DE 19804
Performing Department
(N/A)
Non Technical Summary
Osmotic distillation is an excellent method for highly concentrating thermally sensitive liquids at low temperatures. However, commercial success of this process has been limited due to lack of membrane stability during the processing of economically interesting liquids. We believe that our high flux, non-porous perfluoromembrane is an ideal candidate for OD in that it has high flux rates and will maintain stability by avoiding wet out and membrane fouling. We will use coffee to demonstrate the feasibility of a process that combines cold extraction with osmotic distillation to produce a coffee concentrate that has never seen high temperatures. We expect these cool concentrates to be superior in taste and convenience to conventionally brewed coffee. In so doing, we will introduce to the industry a novel food processing technique that enhances the value of beverage based food products.
Animal Health Component
30%
Research Effort Categories
Basic
(N/A)
Applied
30%
Developmental
70%
Goals / Objectives
Our key objectives in Phase I are first to produce CMS membrane modules that maintain high fluxes and do not wet-out during the concentration via osmotic distillation of cold extracted coffee and second to produce a cool coffee concentrate that is superior in taste and convenience to conventionally brewed coffee. We will use coffee to demonstrate the feasibility of a process that combines cold extraction with osmotic distillation to produce a coffee concentrate that has never seen high temperatures. We expect these cool concentrates to be superior in taste and convenience to conventionally brewed coffee. In so doing, we will introduce to the industry a novel food processing technique that enhances the value of beverage based food products. During Phase I, coffee will be extracted from coffee beans at low temperature. This will result in an aqueous solution of coffee flavor components. After extracting the flavor components, we will expose the relatively dilute coffee
solution to a concentration process called osmotic distillation, which can achieve concentration levels that are much higher than can efficiently be achieved by reverse osmosis or other concentration techniques. Osmotic distillation, or OD, is a process for concentration of solutions by removing the volatile solvent across a non wetted microporous membrane into a stripping solution, where the solvent passes in the gaseous phase. Most commonly, as in the case of coffee, the volatile solvent is water, and the stripping solution is most commonly a concentrated salt brine. The microporous membrane must be hydrophobic to prevent the solution from penetrating the pores. Possibly the most difficult aspect of the OD process is that the hydrophobic microporous membranes lose their hydrophobicity over time due to contamination and wetting out by the process fluids. In the case of most economically interesting fluids such as coffee, the fluid contains surface tension reducing agents, i.e., oils,
that eventually migrate into the membrane pores. This initially reduces the rate of dewatering, since the pores of the membrane are being blocked by concentrated feed solution. Eventually, the brine and feed streams mix as the air filled pores no longer separate the two miscible liquids. Therefore, while there is great opportunity to service the beverage production industry with OD, this has not yet been commercially successful, due to relatively low flux and wetting out of the microporous membrane. We believe that our high flux, non-porous perfluoromembrane is an ideal candidate to establish high initial OD rates, and that the CMS membrane will be able to maintain those rates by avoiding wet out and membrane fouling. The coffee concentrate that will be produced from this cool extraction and concentration process will have never had bitter components extracted from the bean and will have never seen heat. The net result is a better tasting product that is also more convenient than
having to fresh brew coffee. One can envision a machine similar to cold drink machines in fast food restaurants where when one pushes a button the cold coffee concentrate mixes with the hot water as it goes into your cup.
Project Methods
We will use coffee to demonstrate the feasibility of a process that combines cold extraction with osmotic distillation to produce a coffee concentrate that has never seen high temperatures. Coffee will be extracted from coffee beans at low temperature. After extracting the flavor components, we will expose the relatively dilute coffee solution to a concentration process called osmotic distillation, which can achieve concentration levels that are much higher than can efficiently be achieved by reverse osmosis or other techniques. We expect the resulting cool concentrate to be superior in taste and convenience to conventional brewed coffee. In so doing, we will introduce to the industry a novel food processing technique that enhances the value of beverage based food products. The CMS technology will be used to produce membrane modules that maintain high fluxes and do not wet out during the concentration via osmotic distillation of cold extracted coffee. We will prepare
and test modules that have the CMS non-porous membrane coating on a microporous support of polypropylene hollow fiber. These modules will then be tested for performance and stability during osmotic distillation of coffee on a test rig that will be built by CMS personnel. The coffee used during OD will be cold extracted at CMS using Sivetz Coffee Inc. cold extraction equipment. Coffee beans will be purchased freshly roasted and will be ground just before extraction and concentration. To produce the coffee concentrate, osmotic distillation will be run at 25C and 40C until the rate of concentration, or water removal, starts to drop off from viscosity buildup. During the osmotic distillation processing we will measure the water vapor transport rate, monitor the membrane stability, and determine ease of cleaning the membrane system between uses. These key factors will be used to determine the overall economics of the concentration process. The quality of the concentrates will be evaluated
by the Natick Army Labs. Samples will be tested for acidity, pH, specific gravity, and color quality. Flavor quality will be measured using HPLC and sensory testing. Prior to any taste testing, samples will be tested for microbiologically stability to ensure safe sampling. The control sample in these quality tests will be conventionally brewed coffee, brewed from the same freshly roasted and freshly ground coffee beans, and brewed just prior to sampling. The concentrated coffee product that we are proposing should remain stable at room temperature due to its high solids concentration and associated low water activity. We will determine microbiological activity and correlated shelf stability of the OD coffee concentrates at various levels of high concentration, i.e., 60, 65, 70, 75 percent solids and others if warranted. We will use standard plate count procedures to assess the microbial quality of our concentrates.