Pervaporation aroma compounds, recovery

Aroma compounds recovery of tropical fruit juice by pervaporation... 

Karls son HOE, Loureiro S, and Tragardh G. Aroma compound recovery with pervaporation-temperature effects during pervaporation of Muscat wine. J. Food Eng. 1995 26 177. 

Karlsson HOE and Tragardh G. Pervaporation dilute organic-water mixtures A literature review on modeling studies and application to aroma compound recovery. J. Memb. Sci. 1993 76 121. 

Pereira CC, Rufino JRM, Habert AC, Noberga R, Cabral LMC, and Borges CP. Aroma compounds recovery of tropical fruit juice by pervaporation Membrane material selection and process evaluation. J. Food Eng. 2005 66(l) 77-87. 

Raisi A, Aroujalian A. 2011. Aroma compound recovery by hydrophobic pervaporation The effect of membrane thickness and coupling phenomena. Sep. Purif. Technol. 82 53-62. 

Karlsson HOE and Tragardh G (1993), Pervaporation of dilute organic-waters mixtures. A literature review on modelling studies and applications to aroma compound recovery , 7 Membr Sci, 76,121-146. 

In comparison with adsorptive/absorptive techniques for aroma recovery from bioconversions, the disadvantage of pervaporation is the fact that both sorption and diffusion determine the overall selectivity. While the sorption selectivity is very high (equal to that of adsorptive/absorption), the diffusion selectivity favours water owing to the simple fact that water is a smaller molecule than aroma compounds and thus sterically less hindered during diffusion (Table 19.1). The overall (perm)selectivity P=SD) is therefore lower than in strictly sorption controlled processes, although it is still favourable compared with that for evaporation. This shortcoming compares, however, with operational advantages of pervaporation as outlined before. 

Most research on aroma recovery by organophilic pervaporation has been conducted using aqueous aroma model solutions [25-28], although in recent years significant interest has been devoted to the recovery of aroma compounds from natural complex streams, such as fruit juices [29-31], food industry effluents [32] and other natural matrixes [33]. The increasing demand for natural aroma compounds for food use, and their market value, opens a world of possibilities for a technique that allows for a benign recovery of these compounds without addition of any chemicals or temperature increase. However, in most situations, dedicated requests by industrialists are formulated in cooperation with marketing departments, which translate into the need for a correct public perception. 

The recovery of flavors and fragrances from diluted aqueous streams may be of industrial interest under different circumstances (1) recovery of complex aroma profiles and/or target aroma compounds from active biocatalytic processes (2) recovery of complex aroma profiles and/or target aroma compounds from natural extracts and industrial processes aqueous streams. Pervaporation offers a unique solution for the recovery of complex aroma profiles. An example for the recovery of complex aroma profiles, faithful to their origin, is the recovery of a muscatel aroma from an ongoing wine-must fermentation [31, 32]. 

Scale-up of pervaporation for the recovery of natural aroma compounds in the food industry. Part 2 Optirrrization and integration... 

Generally, alcohols showed higher separation factors when present in model multicomponent solutions than in binary systems with water. On the other hand, aldehydes showed an opposite trend. The acmal tea aroma mixmre showed a rather different behavior from the model aroma mixmre, probably because of the presence of very large numbers of unknown compounds. Overall, the PDMS membrane with vinyl end groups used by Kanani et al. [20] showed higher separation factors and fluxes for most of the aroma compounds. Pervaporation was found to be an attractive technology. However, as mentioned above the varying selectivities for the different aroma compounds alter the sensory prohle and therefore application of PV for recovery of such mixmres needs careful consideration on a case-by-case basis. 

Recovery/Concentration of Flavor/Aroma Compounds by Pervaporation.201... 

Cristina C, Pereira CLP, Ribeiro JR, Nobrega R, Borges CP. 2006. Pervaporative recovery of volatile aroma compounds from fruit juices. J. Membr. Sci. 274 1-23. 

Isci A, Sahin S, Sumnu G. 2006. Recovery of strawberry aroma compounds by pervaporation. J. Food Eng. 75 36 2. 

Despite the low number of existing works on PVPRs, the investigations tend to cover the two main common applications of organophihc pervaporation i.e. the recovery of aroma compounds from process streams (Karlsson and Tragfirdh, 1993 Pereira et al, 2006 Trifunovic et a/., 2006) and the removal of volatile organic compounds (VOC) from aqueous effluents (Konieczny et al, 2008 Lipnizki and Field, 2002 Peng et al, 2003 Urkiaga et al, 2002). 

A. Baudot, M. Marin, and H. E. Spinnler, The recovery of sulfur aroma compounds of biological origin by pervaporation. Flavour Science. Recent Developments (A. J. Taylor and D. S. Mottram, eds.), Hartnolls Ltd., Bodmin, UK, 1996, p. 301. 

Fig. 23.4 Organophilic pervaporation (PV) for in situ recovery of volatile flavour compounds from bioreactors. The principle of PV can be viewed as a vacuum distillation across a polymeric barrier (membrane) dividing the liquid feed phase from the gaseous permeate phase. A highly aroma enriched permeate is recovered by freezing the target compounds out of the gas stream. As a typical silicone membrane, an asymmetric poly(octylsiloxane) (POMS) membrane is exemplarily depicted. Here, the selective barrier is a thin POMS layer on a polypropylene (PP)/poly(ether imide) (PEI) support material. Several investigations of PV for the recovery of different microbially produced flavours, e.g. 2-phenylethanol [119], benzaldehyde [264], 6-pentyl-a-pyrone [239], acetone/buta-nol/ethanol [265] and citronellol/geraniol/short-chain esters [266], have been published...

VOC thermal stability. Separation of VOCs from water by pervaporation generally requires heating the feed water to only 50-70 °C. This is significantly lower than the temperatures involved in distillation or steam stripping, a considerable advantage if the VOCs are valuable, thermally labile compounds. This feature is important in applications such as flavor and aroma recovery in the food industry. 

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