NUTRIZEAL recently expanded its supercritical carbon dioxide extraction plant capability with the addition of an ethanol co-solvent system. The Nelson-based company owns the bigger of the two supercritical carbon dioxide (SCD) extraction plants in the southern hemisphere. The SCD process uses pressurised carbon dioxide to extract some lipids, resins, and carotenoids out of biomass. Managing director Richard Daniell says with the new co-solvent technology it is also now the biggest in its class in the world. “To the best of our knowledge, we have the only large scale nutraceutical grade supercritical fluid extraction plant in the world that also has co-solvent capability,” he says. Nutrizeal manufactures and sells a range of quality nutraceutical ingredient products, including marine extracts. It has three divisions – these are freeze drying, SCD extraction that manufactures bulk ingredients, and secondary processing, which further processes ingredients into retail format products as a service to some customers. Daniell, a science graduate in biochemistry with a personal interest in what he calls micro nutrition, explains how and why the company acquired the SCD technology and how it adds value to Nutrizeal clients’ operations. A former employee of the then Ministry of Agriculture and Fisheries, Daniell established Nutrizeal in 1995 after consultation with his employer. “We’d identified a need to add value to domestic export products in the agricultural and fisheries sector, but it was outside the Ministry’s core business. I started Nutrizeal to fill the niche,” he says. Working with two part-time staff, he started up a freeze drying plant, making bulk nutraceutical ingredients such as mussel powder. About three years later the business opened a hard gel encapsulating plant to complement this service. Daniell’s vision was to utilise the latest technologies to bring the finest natural product extracts from New Zealand and the Pacific to the rest of the world. With this in mind he started to look around for technologies to add another dimension to the company’s capabilities. He explored and settled on SCD extraction. The extraction process Daniell approached New Zealand Hops in Nelson. At the time, the company sent hops to the northern hemisphere for SCD extraction. The two companies subsequently established Extract Solutions Ltd (ESL) as a joint venture between Nutrizeal and the hop industry. ESL built a SCD plant in 2002. The hop industry utilised the plant to conduct its hop extraction on-shore and Nutrizeal’s interest was to process nutraceutical products in it. To allow Nutrizeal to focus on the nutraceutical market, in April 2006 it acquired all the shares in ESL. “The combination of ESL’s supercritical capability and Nutrizeal’s freeze drying, encapsulations, and presence in the nutraceutical industry adds significant strength to the combined business,” Daniell says of the decision. The SCD technique uses carbon dioxide, which under certain pressure and temperature conditions behaves as a solvent and can therefore be used to dissolve and extract some lipids, resins and carotenoids out of biomass. Carbon dioxide, or CO2, is an atmospheric gas composed of one carbon and two oxygen atoms. It is present in Earth’s atmosphere at approximately 379 parts per million or 0.038 percent by volume. It is a non-flammable, colourless, and odourless natural constituent of air. At conditions above its critical temperature and pressure it is an ideal and gentle, natural solvent. This critical point is at pressures above 73 atmospheres and temperatures over 31 degrees Celsius. At this point the gas becomes a hybrid, with the density of a liquid and the flow properties of gas. The pressure forces the gas through the cell walls of the material in the vessel and separates the desired component quickly. By varying temperature and pressure above these limits SCD can be used to extract components from raw materials selectively. “Figuring out a new extraction protocol for a new product can sometimes be a significant challenge – there are so many variables that the options are endless,” Daniell says. “We have our own pilot plant, but nearly always utilise the services of Industrial Research Ltd (IRL) as the first step in establishing new processes. They’re very knowledgeable and capable in the field of supercritical extraction. They have world renowned experts and over 20 years experience in supercritical research.” Invariably, however, there is some on-site trial work as well as, he comments, “…we seem to be experimenting in one way or another all the time.” ESL purchases liquid carbon dioxide. A truck delivers it once or twice a month and pumps it into the on-site storage vessel. The liquid CO2 is pumped into a further storage vessel, then pressurised with a large piston pump up to the desired extraction pressure. A SCADA computer system monitors and controls the extraction cycle. A client transports the biomass in containers to the plant premises. The biomass comes in various forms, ranging from seeds, flakes, or powder, to liquid. In some instances, for example with some seeds, ESL does pre-processing activities. It has a milling plant on site. It is also possible to freeze-dry the product before milling it. The biomass then goes into the SCD plant. Here, a technician places feedstock into an extraction vessel, typically 450 kilograms at a time. The extraction plant usually operates as a continuous operation, but can work in batches. The extraction plant is set to the desired parameters, and the pressurised SCD is pumped through the feedstock in the vessel. The dense SCD dissolves the required extract and takes it into solution. The solution passes through a pressure reduction valve into the first of two separator vessels. The reduced pressure causes the higher molecular weight compounds to drop out of solution, and a further pressure drop into a second separator causes the lower molecular weight compounds to precipitate. Known as fractional separation, this is one of the techniques that can be applied to make more than one extract from a given feedstock. Extraction times vary widely from product to product (from two to 15 hours) and depend on variables such as the amount of material to be extracted, its solubility in SCD, and its value. The technician collects the extract from the separator via a valve at the bottom of each of the separator vessels. They then either pack it in containers for shipment in bulk form, or occasionally pack extracts into cans. The system is washed thoroughly between loads and the company disposes of the mined out biomass in an environmentally approved manner, usually in landfill. Under pressure The entire process is conducted at exceptionally high pressures – the extraction itself can be at pressures of up to 500 bar (7300psi). This, Daniell says, makes for very specialised engineering. “For example, an extraction vessel with a volume of around 1000 litres weighs 14 tonnes. At maximum extraction pressure there’s an upward pressure on the extractor vessel closure, or lid, of about 2000 tonnes. Much of the plant is therefore constructed from unusual materials such as titanium stainless steel.” Daniell says the technique has many benefits. Because the process works at a fairly low temperature, there is no thermal degradation of the extracts, which are often heat sensitive bioactive compounds. It is a non-intrusive technology using an inert, food grade gas, which means complete retention of product integrity and biological activity without solvent residues or impurities in the product. The process allows maximum product recovery and a high extract yield with minimum loss of volatiles. The co-solvent process works the same, but with ethanol added to the carbon dioxide. SCD is a good solvent for non-polar materials. The addition of a small quantity of a co-solvent such as ethanol increases SCD’s ability to dissolve polar compounds. The plant uses a vacuum evaporation process to remove ethanol residues from extracts where ethanol is a co-solvent. A rigorous quality control system governs the extraction process. The plant operates under ISO9001 and a series of licences issued by authorities such as NZFSA. The factory floor houses three 850-litre extraction vessels capable of operating at up to 500 bar and 100 degrees Celsius. Daniell says the core plant design was provided by specialist Austrian SCD design company Natex. It took about five man-years to customise this design to meet the specific needs he identified for the plant. Transfield Worley from New Plymouth, at one stage with 40 people working on the ESL project, did the civil and materials handling design, work, and acted as project managers from design through to commissioning. Although most of the equipment came from Natex, Fitzroy Engineering in New Plymouth built some of the plant components. The addition of co-solvent capability was managed partly in-house, with significant assistance from Connell Wagner in Wellington. Wide expertise Today Nutrizeal employs 30 to 35 staff with a wide range of expertise in technology, electronics, computerisation, customer service, research and development, and international business practices. The company has in-house packing lines for extract freshness and operates a competitive supply route. “We’re able to offer complete product solutions from conception and innovation through to market launch and ongoing customer support. Our manufacturing capabilities allow the development of long term, committed partnerships with our customers,” says Daniell. Nutrizeal operates under an internationally recognised risk management program registered and audited by the New Zealand Food Safety Authority (NZFSA).The company is licensed by NZFSA for the production of fish and shellfish products, meat products, and bee products. It is also listed by the European Union and the US for the export of seafood products. Nutrizeal continues to provide extraction services to the hop industry. New Zealand Hops pellets its dried hops at its own facility near Nelson. Nutrizeal then makes hops extract, a golden, thick, honey-like resin paste with all the natural hop variety specific brewing characteristics. Other Nutrizeal clients include big names such as Interpath and Pharmalink International. SCD extraction techniques can also make flavours and fragrances, and Nutrizeal has frequently been asked to supply these. The company opted not to make flavours and fragrances itself, but recently established a relationship with German industrial giant Evonik Degussa to market Evonik’s food flavours and fragrances in Australasia. “For now, we want to remain focused on the nutraceutical market, whilst being able to respond to other enquiries for SCD products.” Daniell says. Jenny Baker is an Auckland-based freelance writer.•