Owen J. Catchpole

Supercritical antisolvent fractionation of propolis tincture

Abstract Propolis is used by bees for strengthening and waterproofing a hive, and for sterilizing the hive against microbial infections. Propolis contains a high concentration of flavonoids, which are used in a wide range of cosmetic and health food preparations for their antimicrobial properties. Propolis is usually dissolved in ethanol or ethanol/water mixtures to remove insoluble material such as waxes and detritus from the hive. The resultant solution is a propolis tincture. A new supercritical antisolvent/extraction process has been developed for the fractionation of propolis tincture to obtain flavonoids and essential oil fractions by extraction, and remove high molecular mass components by antisolvent precipitation. Flavonoids are practically insoluble in pure CO2, but sufficiently soluble in CO2+ethanol to enable their separation from high molecular mass and/or more polar components. In the first step of the process, supercritical CO2 is used both as an anti-solvent to precipitate high molecular mass components, and as a solvent to extract the ethanol and soluble components of the propolis. This extract is then fractionated in two separation steps to create a concentrated flavonoid fraction as the primary product, and an essential oil/ethanol fraction as a secondary product. The effects of pressure, temperature, flow rate ratio, tincture composition and tincture concentration on product quality and yield were determined at a laboratory and pilot scale. The tincture concentration of propolis has the greatest effect on the yield and concentration of flavonoids in the product fraction when pure ethanol is used as the solvent. The flow rate ratio becomes important when the tincture also contains water. The process has been successfully scaled up to a demonstration scale using optimized pressure, temperature, flow ratio and tincture concentrations obtained from laboratory and pilot scale trials.

Near-critical extraction of sage, celery, and coriander seed

Abstract Near-critical extraction of coriander seed, Dalmatian sage, and celery was performed on a pilot-scale extraction apparatus. Sage and celery were extracted using liquid carbon dioxide to obtain oleoresins. Coriander seed was extracted at 250 bar and 40°C. Coriander extract was fractionated into triglycerides and essential oils by using two separation stages at different pressures. Extractions were carried out using a range of particle diameters, carbon dioxide flow rates, and packed bed flow configurations to establish relationships between extract yield and extraction time/carbon dioxide usage. The particle diameter had the largest influence on both yield and extraction time for all materials. The flow rate and packed bed flow configuration affected only the rate of extraction of triglycerides. The extraction of essential oils/oleoresins was found to be intraparticle diffusion controlled, whilst triglycerides were found to be both film and particle diffusion controlled. A mathematical model was developed which satisfactorily predicts extract yields as a function of extraction time, flow rate, and particle diameter. The model contains only one adjustable parameter, the intraparticle diffusion coefficient, De, which is a constant for each herb.

Fractionation of fish oils using supercritical CO2 and CO2+ethanol mixtures

Abstract This work reports the countercurrent extraction and fractionation of a range of crude fish oils using supercritical carbon dioxide and carbon dioxide+ethanol mixtures. Vitamin A palmitate was extracted from model Cod liver oil/vitamin mixtures using pure CO2. The separation factor was low, due to similar solubilities of the vitamin ester and the oil. Vitamin A was also recovered from Cod liver oil ethyl esters\vitamin A mixtures. The separation factor was substantially improved over the non-esterified oil, due to large differences in the solubilities of the esters and vitamin A in supercritical CO2. Solubilities of fish oils and squalene are reported using CO2+ethanol mixtures at 333 K, ethanol concentrations from 0 to 12% by mass and pressures from 200–300 bar. Solubilities of all oils and squalene increased exponentially with linear increases in the ethanol concentration. The solubility of polar components increased more rapidly than non-polar components. Pilot scale removal of fatty acids from Orange Roughy oil and squalene from deep sea shark liver oil was carried out using CO2+ethanol as the solvent. The extent of fatty acid removal from Orange Roughy oil was superior to pure CO2, whereas the degree of separation of squalene from shark liver oil was inferior. Throughput was substantially increased relative to pure CO2 in both cases. Mass transfer behaviour and product purity results are also presented for the demonstration scale production of squalene and diacyglycerylether fractions from deep sea shark liver oil using pure CO2. Fractionation results are compared with previous experimental results obtained at a laboratory and pilot scale to obtain the height of a transfer unit (HTU) and packed height required as a function of scale. Modelling of flooding at supercritical conditions was carried out to enable optimal design of the packed column. A liquid–liquid flooding model gave reasonable correlation of literature flooding data, obtained at a laboratory and pilot scale.

Supercritical extraction of herbs I: Saw Palmetto, St John's Wort, Kava Root, and Echinacea

Abstract Extract yield and concentration of selected active components are presented for the supercritical extraction of dried Saw Palmetto berries, St Johns Wort flowers and stems, Kava root and stems, and aerial portions of Echinacea purpurea using supercritical CO2; and CO2+ethanol mixtures. Whole Saw Palmetto berries were obtained from America, and ground Kava root and stem from Fiji and Vanuatu. St Johns Wort and Echinacea were grown in New Zealand. Fatty acids and phytosterols were extracted from St Johns Wort at a total yield of 10–12% by mass. Kava lactones were obtained from Kava root at a yield of 3–8% by mass. The yield was highly dependent on the source and part of the plant used. Hyperforin, and plant waxes were recovered from St Johns Wort at a yield of 6–7% by mass. Hypericin was not extracted. Alkamides, plant waxes and other lipophilic solutes were extracted from Echinacea at a total yield of 2–3% by mass. Other desirable actives, such as chichoric acid and associated polyphenolic derivatives were not extracted.

Supercritical fluid assisted, integrated process for the synthesis and separation of different lipid derivatives

The partial synthesis of ethyl esters from corn and fish oil was carried out in a stirred tank at supercritical conditions and the products were separated from the reaction mixture using the supercritical fluid. Corn oil can be almost completely converted to ethyl esters under optimized conditions and the rate of reaction is comparable to atmospheric pressure conditions. Some concentration of polyunsaturates occurs in the partially converted glyceride fraction of fish oil, as the enzyme used, Lipozyme TL-IM, allows preferential esterification of the saturates and mono-unsaturates that are concentrated in positions 1 and 3 of the triglycerides. By judicious selection of the processing conditions, good separation of ethyl esters from the partially reacted glycerides was achieved.