R&D must be market oriented and the most promising technologies and products, selected after thorough evaluation for market potentials, should be commercialized. In research programs the entire production chain should be studied including primary production, harvesting, storage and processing technologies, product development and evaluation, marketing studies and economics.
Hence, a multidisciplinary approach is needed and both the public and private sector must participate. Introduction of agricultural commodities as industrial raw products is often hampered because the current raw materials used by industry are inexpensive, readily available and of acceptable quality. Thus, the specific advantageous properties of agricultural raw materials must be identified and exploited. Process technologies enabling exploitation of such preferential properties need also to be developed.
This paper presents a brief description of the background of the EC-surplus situation and of proposed measures for surplus reduction, especially by non-food applications of crops. This includes relevant R&D programs within the EC in general and in the Netherlands in particular. Some examples of research on new/industrial crops directed to exploiting preferential properties for technical applications are presented in more detail.
Although plants contain many unique valuable components that cannot, or only at very high costs, be produced by the chemical industry, it will be very difficult to introduce plant materials as replacement for current synthetic products. This is largely due to the relative primitiveness of many agricultural non-food processing technologies. Little investments have been made in this area in the last five decades, while the chemical industry invested billions of dollars in R&D. Thus, for the development of the raw products for industry based on agricultural materials new processing technologies have often to be developed.
In the proposed strategy, cooperation is essential between agriculture as the raw material supplier, the agricultural research field, and industry. As little is known on the specific characteristics of agricultural materials for modern technical applications, it is difficult to compare characteristics of most plant materials with the technical specifications demanded by industries. For this reason, the EC-countries direct much agricultural R&D effort in the coming years to characterize potential raw materials. In cooperation with industry, non-food process technologies and intermediate and consumer products will be developed. As the agricultural sellers market has changed into a buyers market, agriculture can only profit from the interesting opportunities that exist at the expense of very large investments in R&D.
Recently, the non-food uses have been assigned a key-area for EC-research (Rexen 1991). Especially within ECLAIR, CAMAR, and AIR, much emphasis is put to this area. To obtain support from the EC AIR-program, research projects must show a strategic approach and be market oriented. This means that the entire production chain must be represented in the project including pilot plants on a near reality scale for economic evaluation and participation of the industry. Additional conditions are amongst others, that processes and products to be developed must be "environmental and energy friendly" (Rexen 1991).
National research programs. In a number of EC countries, e.g. Germany, France, and The Netherlands, substantial research programs on increasing the non-food applicability of agricultural crops are or have been initiated. In The Netherlands, the research programs are initiated by the Ministry of Agriculture, Nature Management and Fisheries, some of them in cooperation with the Ministry of Economic Affairs. The total budget that has been allocated until now exceeds the equivalent to US$ 30 million. The Dutch programs focus on (increased) industrial application of carbohydrates, oils, fibers, and secondary metabolites from arable crops and proteins from plant and animal origin.
In addition to organizing and/or subsidizing these programs, in 1989, the Agrotechnological Research Institute (ATO-DLO) was founded in Wageningen, by the Ministry of Agriculture, Nature Management and Fisheries of the Netherlands. ATO-DLO consists of seven research divisions and now has 270 employees. The division Industrial Crops, Products and Process Technologies employs over 65 research workers involved in research on new and traditional crops for industrial utilization. The topics concur in general with those of the ministries. Research programs are multidisciplinary between scientists trained in plant physiology, organic chemistry, and biochemistry, biotechnology, processing technology, polymer and materials science, (molecular) physics, and the development of appropriate agrologistic systems.
In several programs, the entire production chain is studied including crop harvesting, storage, extraction, pre-processing, processing, product evaluation, and economics. Cooperation with plant breeders and agronomists is critical for improving the yield potential of the desired raw material. Close contacts/cooperation with chemical or non-food processing industries exist for developing economically feasible applications for agricultural raw materials.
Important topics within each research program are: (1) characterization of the agricultural raw material from an industrial perspective; (2) development of extraction, preprocessing, and processing techniques that can be applied by industries willing to use agricultural raw materials as an alternative to current raw materials; (3) development of required (bio)reactor systems; and (4) development of intermediate and/or other products.
Fiber crops. Fiber hemp (Cannabis sativa L.), fiber flax (Linum usitatissimum L.) and elephant grass (Miscanthus sinensis L.) are being studied for chemical, physical, and morphological characteristics that determine fiber quality. The relationship between fiber quality and harvesting date and processing conditions are under evaluation. Process technologies and products are being developed. Applications include fibers for reinforced composites, building and construction materials, and geotextiles (see hereafter) and pulp and cellulose for the paper industry.
Oilseed crops. The oil content and triglyceride and fatty acid compositions of a large number of oil seed crops and the yield of the desired fatty acids in relation to sowing and harvesting dates are being evaluated. Advanced techniques are being developed for enzymatic hydrolysis of specific fatty acids such as labile fatty acids or technical fatty acids on the 1,3 positions of the triglycerides. Development of bioreactor and enzymatic transesterification technologies for modification of triglycerides of new oil crops is in progress.
Carbohydrate crops. Inulin, a linear ß2-1 polyfructoside from root chicory (Cichorium intybus L.) and Jerusalem artichoke (Helianthus tuberosus L.), showing a degree of polymerization of DP 3 to DP > 70, is used as a sweetener after hydrolysis. Applications which exploit the polymeric nature of inulins are a novel approach and deserve much attention. The 3-D molecular structure of inulin is being studied and selective oxidation and cross-linking techniques are studied for valorization of the inulins.
Protein crops. The proteins of new or underutilized crops such as faba beans (Vicia faba L.), peas (Pisum sativum L.), lupins (Lupinus albus L.), and quinoa (Chenopodium quinoa Willd) are being isolated and characterized. The physical properties are being evaluated such as solubility, viscosity, elasticity, gel-forming, foaming and emulsifying properties, and coating characteristics. Chemical and enzymatic modification procedures are being developed for use by the food and non-food processing industries.
Development of such innovative products is encouraging as the industry is interested in certain specific properties of these fibers. For instance, agrofibers show some advantages in the reinforcement of composites over glass fibers which are currently used. The low wear factor, low brittleness and low irritation factor are of interest to operator and production equipment, the high elasticity modulus and the low brittleness allow the composite to be moulded after the production process, which is usually not feasible with glass-fiber reinforced composites. Biodegradability and incinerability of agrofibers enables easy disposal of wastes or used-up composites; glass-fiber reinforced composites are more and more causing problems in this respect. Agrofibers may be price-competitive with glass-fiber. The prices of short and long flax fibers and hemp bast fibers vary between 0.2 and 3 US$/kg, the price of E-glass-fiber is 3 to 4 US$/kg. This shows that a margin for improvement/modification of the agrofibers may even exist.
Multidisciplinary (basic) research that is carried out in order to realize the
novel applications includes the following topics:
Within each sowing date, only slight differences were found in the contents of the primary fatty acids with respect to harvest time (Fig. 2). This means that fatty acid yield is not dependent on harvest time. On the contrary, when thermal times after start of flowering were compared, differences of up to 20% in seed fatty acid content were observed between the various sowing dates. The date of sowing is much more critical than the date of harvest to maximize primary fatty acid yield. The relatively low effect of harvest date on primary fatty acid yield is agronomically important for growing these crops in climatologically unstable countries such as The Netherlands. Consequently, the yield of seeds can be considered as an important and easy harvest criterion.
Dedicated down-stream processing of specific fatty acids. The seed oil of Dimorphotheca pluvalis L. contains over 60% of the interesting, but highly reactive, dimorphophecolic acid (C 18:2, 9-OH) (Muuse et al. 1992). This fatty acid can be used in the production of polymers and coatings. Conventional production of fatty acids (by Colgate-Emery or Twitchell processes) will lead to impure products and/or a high degree of degradation and loss of reactive groups, especially in case of the labile dimorphecolic acid. Therefore, a method is needed to specifically and mildly isolate the desired fatty acid from the oil. Since the fatty acid was shown to be primarily located on the [[alpha]]-positions of the triglycerides, the use of bioreactors containing immobilized 1,3-specific lipases will show many advantages in processing such new industrial oils (Derksen et al. 1991; Muuse et al. 1992). A prudent choice of membrane in bioreactor construction may enable simultaneous hydrolysis of triglycerides and extraction of the desired reaction products, thus promoting favorable reaction kinetics as well as easy down-stream processing.
Fig. 2 schematically shows a membrane bioreactor system dedicated to processing Dimorphoteca oil. In the membrane module, Rhizopus javanicus lipase is immobilized on the lumen side of hydrophilic cellulose hollow-fibers, separating a water phase from an organic phase, as described by Pronk et al. (1988). Dilute Dimorphotheca oil (20% in hexane) is recirculated through the lumen of the reactor at 25°C. Triglycerides and liberated fatty acids mono-, and diglycerides were quantified (Muuse et al. 1992) by high-temperature capillary gas chromatography using octacosane and triheptadecanoin as internal standards. Dimorphecolic acid is liberated upon hydrolysis of Dimorphoteca oil in this membrane bioreactor system (Fig. 3). The initial reaction rate is high, but after 5 h the reaction rate decreases and hydrolysis runs at an equilibrium. As the lipases are immobilized onto the membrane and can remain active during a considerable period of time (reaction periods of over 300 h have been realized) multiple reuse of the enzyme is allowed.
The results show that lipases with 1,3-positional specificity can be employed for the production at mild conditions of unstable oxygenated fatty acids from new oil seed crops in pure form. Therefore, research is in progress to simultaneously hydrolyse the oil and recover the liberated dimorphecolic acid, thereby driving the hydrolysis reaction to completion. Such a system enables continuous processing of Dimorphoteca oil.
|Characteristic||Fiber flax||Fiber hemp||Jute||Sisal|
|Cell length [L](mm)||4-77||5-55||0.8-6||0.8-8|
|Cell width [D](mm)||0.005-0.076||0.01-0.051||0.005-0.025||0.007-0.047|
|Aspect ratio [L/D]||1000-2500||1000-1600||65-380||50-500|
|Specific gravity (kg/m3)||1500||1500||1500||1450|
|Tensile strength (GN/m2)z||1.0||0.7||1.0||0.53|
|Elasticity modules (GN/m2)||60||32||59||36|
|Break elongation (%)||2.5||2.2||1.5||2.0|
|Composition (% w/w)|
|Composition (% w/w)|
Fig. 1. Effect of sowing and harvest time on the yield of major (technical) fatty acids (% of dry seed weight) of four new oilseed crops: Crambe abyssinica, Euphorbia lagascae, Limnanthes alba, and Calendula officinalis. Time of seed development expressed as thermal time after start of flowering in degree (C) days.
|Fig. 2. Laboratory-scale hollow-fiber membrane bioreactor. Lipase (500 mg) immobilized on 1 m2 of cellulose hollow-fiber membrane. Reaction temperature 25°C.|