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Abstract
The production of reduced caffeine coffee beverages (so called ‘half-decaf’) has recently gained increased commercial attention. Ultrafiltration (UF) can offer a viable alternative to the use of solvents in the decaffeination process, also operating at ambient temperatures, and a low operational cost. This paper reports the development and evaluation of the fouling occurring during the selective reduction of caffeine from coffee brews using a commercially available synthetic tight ultrafiltration (TUF) polyethersulphone (PES) membrane (GP95PP – Alfa Laval) with a 2 kDa molecular weight cut off (MWCO). Performance is reported in terms of fluxes, hydraulic resistances, and component rejection ratios. A cross-flow rig was operated at transmembrane pressures of 2–9 bar and cross-flow velocities of 0.04–0.1 m/s at temperatures in the range 25–50 oC. The process is viable: a retentate is produced with a much reduced caffeine concentration whilst still rich in higher molecular weight bioactives. Commercial PES membranes (GP95PP – Alfa Laval) had a permeate flux of 6.5 L m-2 h-1 and a fouling index (FI) of ca 60%. Rejection ratios were ca 30% for caffeine, ≥ 90% for both polyphenols & proteins, & ≥ 80% for melanoidins, over a 29 hr filtration period. Membrane surface modification due to fouling takes place, altering the hydrophobicity. An effective cleaning protocol is reported comprised of 0.5% w/v NaOH at 500 C. The flux decline and recovery are reported for multiple fouling and cleaning cycles.
Original language | English |
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Pages (from-to) | 14-23 |
Number of pages | 10 |
Journal | Food and Bioproducts Processing |
Volume | 136 |
Early online date | 16 Sept 2022 |
DOIs | |
Publication status | Published - 30 Nov 2022 |
Bibliographical note
Funding Information:We thank our industrial collaborators: Andrew Downie of Bettys & Taylors Group for the supply of coffee, and David Carr of Kerry Ingredients, Cam Gloucestershire for the supply of dead-end prefiltration cartridges. DM acknowledges EPSRC for support (grant EP/V047078/1 ).
Keywords
- Cleaning
- Coffee
- Decaffeination
- Fouling
- Ultrafiltration
ASJC Scopus subject areas
- Biotechnology
- Food Science
- Biochemistry
- General Chemical Engineering
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SynHiSel - EPSRC Programme grant
Mattia, D. (PI), Chew, J. (CoI), Lewis, R. (Researcher) & Turner, C. (Researcher)
Engineering and Physical Sciences Research Council
1/02/22 → 31/01/27
Project: Research council