|Humphries, E - NCSU|
|Reina, L - NCSU|
Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2002
Publication Date: January 1, 2003
Citation: Fasina, O.O., Fleming, H.P., Humphries, E.G., Thompson, R.L., Reina, L.D. 2003. Crossflow filtration of brine from cucumber fermentation. Applied Engineering in Agriculture. 19(1):107-113. Interpretive Summary: Conventionally, fermentation and storage of cucumbers is carried at salt levels between 6 and 15%. Since only 1-4% salt level is desired in finished pickle products, the excess slats are disposed of during further processing. This has created environmental problems within the pickle industry because many companies cannot meet the 230 ppm of chloride limit set by the U.S. Environmental Protection Agency for the discharge of wastewater into freshwater bodies. We are presently conducting research in our laboratory on the fermentation of cucumbers in 2% salt brine using bag`n`box concept. One of the objectives of the project is that the brine derived from the fermentation process can be incorporated into finished pickle products. To be able to achieve this, the microbial cells and sediments in the brine must be removed by an appropriate separation technology, hence this study. In particular, crossflow filtration was applied to the brine obtained from cucumber fermentation process. Results from the study show that operating pressure, membrane pore size, brine concentration, and feed flow rate significantly affected the amount of filtered brine obtained from the filtration process. No microorganisms were detected in the filtered brine. In addition, the chemical composition of the brine was not affected by the filtration process. In summary, this study showed that crossflow filtration could be successfully used to remove microbial cells and sediments present in brine from cucumber fermentation. The results from this study will be used by process engineers in the scale-up of the appropriate filtration system that will be used to clarify the brine obtained from a cucumber fermentation process.
Technical Abstract: Due to environmental concerns, pickle companies are considering ways of reclaiming the brine obtained from cucumber fermentation. The removal of microbial cells is crucial in use of the brine in finished pickle products. The effects of transmembrane pressure (41.37 to 165.47 kPa), feed flow rate (7.8 to 15.5 L/min), pore size (500,000 NWCO and 0.2 um), and cell concentration (optical density of 0.171 to 1.170 at 640 nm) on permeate flux during the crossflow filtration of brine obtained from bulk fermentation of cucumber were studied. Results indicate that the microfiltration membranes exhibited a large flux decline during the first 15 min of operation when challenged with the fermentation brine. The net decline in permeate flux increased with transmembrane pressure, flow velocity, pore size, and cell concentration. Filtration through filter pore size of 0.2 um or smaller effectively removed the microbial cells present in the brine. Only the transmembrane pressure significantly affected the resistance of the cake formed at the filter surface. From the results obtained from the study, it is possible to use microfiltration to filter sediments and microbial cells from brine obtained from cucumber fermentation.