Hiroshi Nabetani

Differential permeation of oil constituents in nonporous denser polymeric membranes

Abstract Edible oil processing has become one of the prime targets for membrane applications. In the present study, attempts were made for the first time to examine the applicability of the transport equations for oil systems. Permeability of the constituents of the homogeneous mixtures and rejections of individual constituents were studied. Oleic acid permeated preferentially when compared with triglycerides. The total permeate flux increased from 90.6 to 151xa0g/(m 2 xa0h) when the oleic acid content in the feed was increased from 1.9 to 21.2%, which is mainly due to the increase in the permeation rate of oleic acid. The synergistic effect of preferential sorption and concentration dependent solubility as well as diffusivity could be responsible for the higher relative permeability of oleic acid. In the present case of processing liquid mixtures (oleic acid and triglycerides) by nonporous denser membranes, the contribution of solution-diffusion to transport is more than usually observed in reverse osmosis (RO) membranes. Higher operating temperature and pressure increased the total permeate flux. Relative permeation rate of oleic acid increased with pressure. In case of phosphatidylcholine (PC) and triglycerides (solute–solvent) system, the rejection of PC was above 98% and it did not vary significantly either with feed concentration or with operating conditions. The membrane rejected chlorophyll almost completely.

Recovery of oligosaccharides from steamed soybean waste water in tofu processing by reverse osmosis and nanofiltration membranes

The recovery of soybean oligosaccharides from the steamed soybean waste water in tofu (soybean protein curd) processing was carried out by using reverse osmosis and nanofiltration membranes. The feed solution was prepared by isoelectric and ultrafiltration treatments. Concentrations of the total oligosaccharides of 10% (w/v) and 22% (w/v) were obtained by using the RO and NF membranes in a batch operation. The chemical oxygen demand of the feed solution was simultaneously reduced from 8400-8700 ppm to 27-160 ppm. The permeate flux was mathematically analyzed by the osmotic pressure model with concentration polarization, the simulated results agreeing well with the experimental ones.

A forced-flow membrane reactor for transfructosylation using ceramic membrane

A forced-flow membrane reactor system for transfructosylation was investigated using several ceramic membranes having different pore sizes. beta-Fructofuranosidase from Aspergillus niger ATCC 20611 was immobilized chemically to the inner surface of a ceramic membrane activated by a silane-coupling reagent. Sucrose solution was forced through the ceramic membrane by crossflow filtration while transfructosylation took place. The saccharide composition of the product, which was a mixture of fructooligosaccharides (FOS), was a function of the permeate flux, which was easily controlled by pressure. Using 0.2 micrometer pore size of symmetric ceramic membrane, the volumetric productivity obtained was 3.87 kg m(-3) s(-1), which was 560 times higher than that in a reported batch system, with a short residence time of 11 s. The half-life of the immobilized enzyme in the membrane was estimated to be 35 days by a long-term operation.

Application of dense membrane theory for differential permeation of vegetable oil constituents

Abstract Our earlier study on nonaqueous liquid mixture system (triglycerides and oleic acid) showed that the contribution of solution-diffusion to transport in nonporous (dense) membranes is more than usually observed in reverse osmosis membranes. Triglycerides and oleic acid were independently studied in the present study. The results showed that pressure had significant effect on the permeation rates. The behaviour of pure systems was similar to triglycerides–oleic acid mixture. In the present study on triglycerides–tocopherols model system, tocopherols preferentially permeated through nonporous membranes. Increased concentration of tocopherols increased the feed viscosity, however, the total permeate flux remained practically constant. Whereas in triglycerides–oleic acid mixture system, increased concentration of oleic acid reduced the feed viscosity and increased the total flux. The comparative performance of these two different systems revealed that viscosity does not play significant role in the permeation. Further, the analysis establishes that dense membrane theory could qualitatively explain the differential permeability of oil constituents.

Protease hydrolysis of water soluble fish proteins using a free enzyme membrane reactor

Abstract The hydrolysis of fish proteins in an aqueous extract of Alaskan pollack by a protease was investigated using a free enzyme membrane reactor (FEMR). Batch experiments were also carried out to determine the optimum temperature, pH, and some kinetic parameters. From the modeling and simulation of the continuous FEMR experimental data, a reduction in enzyme activity in the system was suggested, which appears to be due to both reversible and irreversible deactivation. Although a high level of conversion was obtained the productivity of the FEMR system used was not high due to the relatively low permeate flux and a small membrane area.

Solvent-Free Esterification of Oleic Acid and Oleyl Alcohol Using Membrane Reactor and Lipase-Surfactant Complex

Oleyl alcohol and oleic acid were esterified using lipase-surfactant complex (LSC) in a solvent-free reaction system. LSC showed a higher reaction rate than the crude enzyme in the reaction system. Optimum LSC activity was obtained at 180 mg/g-solution water addition. A preliminary study of the membrane reactor system using a microfiltration membrane and a solvent-free reaction was performed, and the feasibility of the reactor system was confirmed.

A forced flow membrane enzyme reactor for sucrose inversion using molasses

We have developed a bioreactor which uses enzyme immobilized within a ceramic membrane support (1 mm thickness). Substrate is forced through the membrane by cross-flow filtration with the reaction taking place during the process of crossing the membrane. The bioreactor is termed forced-flow membrane enzyme reactor, FFMER. Invertase, which uses sucrose to form glucose and fructose, was tested in this system. The immobilized invertase membrane converted 100% of the sucrose in a feed stream made up of a 50% molasses solution. Because molasses contains many substances besides sucrose, this method is applicable to processes using substrates present in “impure” feeds.

Lipase-surfactant complex as catalyst of interesterification and esterification in organic media

A lipase-surfactant complex (LSC) was prepared by mixing an aqueous solution of lipase MF-30 derived from Pseudomonas sp. and an alcoholic solution of sorbitan monostearate. The LSC efficiently catalyzed the interesterification of triglyceride and fatty acid in hexane, as well as that of palm oil and fatty acid. The LSC catalyzed the esterification of fatty acids with mono- and diglyceride, methanol and cetyl alcohol in hexane. Catalytic activities of the LSC were higher than those of a crude lipase in esterification.

Hollow-fibre enzyme reactor integrated with solvent extraction for synthesis of aspartame precursor

Abstract A new process for the simultaneous enzymic synthesis and purification of N-(benzyloxycarbonyl)- L -aspartyl- L -phenylalanine methyl ester (ZAPM), a precursor of aspartame, has been developed. The enzymic reaction between N-(benzyloxycarbonyl)- L -aspartic acid (ZA) and L -phenylalanine methyl ester (PM) was carried out in a biphasic hollow-fibre rector with an aqueous phase an a butyl acetate phase. The reaction took place in the aqueous phase and by maintaining the pH at 5, the product (ZAPM) was extracted into the organic phase. Product purity was greater than 90% and reasonable productivity could be achieved with this system.

Performance of Perstractive Enzyme Reactor for Synthesis of Aspartame Precursor

A perstractive enzyme reactor was used for the synthesis of N-(benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester (ZAPM), the precursor of the artificial sweetener, aspartame. The synthesis of ZAPM in the reactor proceeded by an enzymatic reaction between N-(benzyloxycarbonyl)-L-aspartic acid (ZA) and L-phenylalanine methyl ester (PM) in the aqueous phase. The synthesized ZAPM in the aqueous phase was mainly extracted into the organic phase, therefore, the concentration of ZAPM in the aqueous phase could be kept low. As a result, high conversion of ZAPM was obtained with this system. The partition coefficients of substances in the aqueous/butyl acetate biphasic system, the mass transfer coefficients of substances through the membrane and the enzymatic kinetics of ZAPM synthesis were determined experimentally. The reaction model which was based on the material mass balance equations was discussed to estimate the performance of the perstractive enzyme reactor system. The calculation values using the model and the experimental data showed good agreement with the concentration changes of the substances in the system.