Ultrafiltration of coconut milk emulsion 'gata' using cellulose acetate and polyamide membranes
2006
del Rosario, E.J. | Dimapasoc, M.J.L. | Panagsagan, M.C.N. | Cabanducos, D.S., Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of Chemistry
Cellulose acetate (CA) membranes were prepared from 25% CA in N,N-dimethylformamide (DMF) and were used in the ultrafiltration (UF) of coconut milk emulsion (CME) with and without emulsifier,namely sodium caseinate or carrageenan. All UF fractions were analyzed for protein,carbohydrate,oil and phosphate. High values of the membrane rejection coefficient (sigma sub r) for protein and carbohydrate were obtained, especially with added emulsifier,the sigma sub r values for phosphate and oil decreases in the presence of emulsifier. The retentates after ultrafiltration of CME, with and without added sodium caseinate or carregeenan, were tested for stability. After 3 min of immersing the samples in a hot water bath (80 deg C), the retentate without added emulsifier separated into two distinct liquid layers. No change was observed in the retentate with added emulsifier, which shows that ultrafiltration of CME in the presence of added emulsifier, either sodium caseinate or carrragenan, enhanced the stability of CME. Two sets of polyamide membranes were also prepared from 30% polyamide (nylon-6) and were used in the ultrafiltration of CME. Membrane rejection of coconut oil was 100% while sigma sub r values were 94.7% and 88.4% for membranens prepared from dope mixtures containing H2SO4 and HCl, respectively. The results were interpreted in terms of the effectiveness of UF in facilitating the separation of the oil-rich and aqueous phases, i.e. creaming of the CME. Addition of either sodium caseinate or carrageenan to CME during ultrafiltration resulted in dehydration and concentration of the oil and most soluble components of CME in the retentate without significant creaming.
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