Melvyn F. Askew
Head of Agricultural and Rural Strategy Group, Central Science Laboratory, Sand Hutton, York, U.K.
Novel trends in investigations of Brassica napus
protein and its designation for non-food use
Nowe kierunki w badaniach białek rzepaku
i ich nieżywnościowe zastosowania
Key words: Brassica napus, oilseed rape, non-food uses, proteinThough a relatively new crop oilseed rape and associated canola species are now the world’s third most important vegetable oil and the only significant temperate oilseed in terms of tonnage.
Oil content varies around 40% by weight of seed. Whilst oil is usually extracted by expulsion followed by hexane extraction, alternatives based upon enzymatic processes or upon different solvents offer options and whilst the residue from the seed after oil extraction has a market as a feed, especially for ruminants, technologies exist to exploit metabolites from meal in different market places. Glucosinolates, sulphur compounds, offer some opportunities whilst proteins offer functionality in adhesives, plastics and other sectors, including potential replacements for methyl bromide.
A fundamental prioritisation of true value of rapeseed meal is essential if crop output value and potential is to be maximised.
Słowa kluczowe: rzepak, zastosowania nieżywnościowe, białko
Rzepak, mimo że jest stosunkowo nowym gatunkiem, a szczególnie jego odmiany podwójnie ulepszone, jest bardzo ważnym źródłem oleju roślinnego. Produkcja nasion rzepaku zajmuje trzecie miejsce wśród roślin oleistych w świecie, a jest najważniejsza w strefie klimatu umiarkowanego.
Zawartość oleju w nasionach waha się na poziomie około 40% wagowych. Olej ten jest zazwy-czaj wydobywany przez wytłaczanie, a następnie reszta jest ekstrahowana heksanem. Alternatywne metody opierają się na procesach enzymatycznych lub ekstrakcji różnymi rozpuszczalnikami. Pozos-tałość po ekstrakcji oleju z nasion jest sprzedawana jako pasza, szczególnie dla przeżuwaczy. Istnieją jednak technologie wykorzystania metabolitów ze śruty do różnych zastosowań. Glukozynolany, związki siarkowe oferują pewne możliwości, natomiast białka mogą funkcjonować jako substancje przy-lepne, kleje, plastyki oraz w innych zastosowaniach, włączając możliwość zastąpienia bromku metylu.
Podstawowym zadaniem jest ustalenie prawdziwej wartości śruty rzepakowej, jeżeli ma być maksymalizowana wartość dochodu z tej uprawy i jej potencjał.
Obecnie handlowe wykorzystanie białek pochodzących ze śruty rzepakowej może nienajlepiej oddawać ich wartość, szczególnie co do potencjału zastosowania w sektorze niespożywczym, które skądinąd jest możliwe.
Nowe „szlachetne” procedury ekstrakcji są prawdopodobnie lepiej dostosowane do zachowania białek i ich jakości w śrucie. Nie wiadomo jednak jak te procesy mogą wpływać na pierwotne i wtórne metabolity nasion lub śruty rzepakowej oraz jakie są koszty prowadzenia tych procesów.
Rynek i możliwości zbytu dla wielu potencjalnych produktów białkowych ze śruty rzepakowej są obecnie w dużym stopniu niewykorzystane.
Introduction
Whilst cereals (wheat, maize and rice) and potatoes form the four biggest crops within the world by production weight, the oilseeds are key elements in the sense of their value and the range of extra uses they provide both in the food and, potentially, in the non-food sectors. The world’s key oilseeds are palm, soya and rapeseed. Recent data or relative production quantities is shown in table 1.
Table 1 World production of major oilseeds — Światowa produkcja głównych roślin oleistych
Oilseed — Roślina oleista 1970 1980 1990 2000*
Castor — Olej rycynowy 0.4 0.5 0.5 0.8
Coconut — Orzech kokosowy 2.4 3.2 3.0 4.0
Cottonseed — Nasiona bawełny 2.5 3.2 4.0 4.0
Groundnut — Orzeszki ziemne 3.0 3.2 4.0 4.0
Linseed — Len 1.0 1.0 1.0 1.0 Olive — Oliwka 2.0 2.0 2.0 2.5 Palm† — Palma 2.0 4.5 13.0 22.0 Rape — Rzepak 2.0 4.0 9.0 15.0 Safflower — 0.2 0.3 0.3 0.3 Sesame — Sezam 1.0 1.0 1.0 1.0 Soya — Soja 6.0 15.0 16.0 30.0 Sunflower — Słonecznik 2.0 4.0 8.0 12.0 Subtotal — Łącznie 24.5 41.9 61.8 96.6
World total all vegetable oils
Wszystkie oleje spożywcze 35.0 60.0 80.0 * Estimate — Przewidywanie; † Palm and palm kernel oil — Olej z owoców i nasion palmy
Source: Weiss, Oilseed Crops (Second Edition) 2000.
Clearly the two palm oils and soya bean oil are not produced in mainstream quantities in the Northern Hemisphere and therefore for EU-25, the key opportunity is through the exploitation of the temperate oilseed, rapeseed.
Production of rapeseed in EU-15 during the period 2002 was 9,226,000 tonnes, which was 72% of the total oilseeds production in Europe. Total oilseeds production in Europe was 12,654,000 metric tonnes. The distribution of oilseeds crushing in Europe is shown in figure 1.
Oilseed rape (B. napus) has a thousand grain weight of approximately 4 up to 6 grams and is usually traded at a standard of 40% by weight of oil. The oil contains a range of different fatty acids, although the predominant ones are the so-called C18:1 and C18:2 oils. The tradition in the rapeseed industry has been to extract
undertaken with a purely mechanical process. This leaves what is a relatively high fat meal and that high fat meal is normally treated with hexane under conditions, which are not particularly suited to the further extraction of higher value metabolites. The residue after hexane extraction is normally referred to as defatted meal, although small amounts of lipid so remain in that meal. The meal itself is ideally suited to the feeding of ruminants, although there are some opportunities with smaller quantities of meal for feeding to some, but certainly not all, monogastrics.
Rapeseed in Europe
EU production (2002) — Produkcja w krajach Unii Europejskiej Total oilseeds — 12 654 000 tonnes
Ogółem produkcja roślin oleistych — 12 654 000 ton of which rapeseed: 9 226 000 t — 72% of the total production w tym rzepak: 9 226 000 t — 72% całkowitej produkcji roślin oleistych
25% 17% 51% 7% rapeseed rzepak sunflower słonecznik soya soja other inne
Fig. 1. Distribution of the oleaginous seeds crushing in EU — Struktura przerobu nasion
oleistych w Unii Europejskiej
Innovative oil extraction for an enhanced potential value
If it were possible to revise or redesign the methodologies whereby oil was extracted from oilseed rape then this would open up the opportunities to exploit other metabolites within the seed, or more correctly, the meal. This is outlined in figure 2.
The components of rapeseed meal are basically various forms of cellulose, protein accounting for some 40% by weight of the meal, a range of secondary metabolites, for example, glucosinolates and of course water. This is shown diagrammatically in Figure 3.
Fig. 2. Innovation oil extraction for an enhanced protein extraction from rapeseed — Innowacje w ekstrakcji oleju w celu ulepszenia białka z nasion rzepaku
Source: J. Gueguen et al
Potential uses of rapeseed meal proteins
A number of potential uses of rapeseed meal proteins have already been identified and some already tested. The uses are:
• Glues and adhesives • Foaming derivatives • Surfactants
• Antifungal agents (thiamins) — fumigants?
• Texture, viscosity, ‘mouth-feel’, appearance and aroma-stabilising agents • Antihypertension agents
• Food supplementation/fortification • Cosmetics
If the traditional oil extraction procedure outlined earlier in this paper was to be modified then there would be potential to exploit proteins to a greater extent than is the case at the moment. The techno-functional properties of proteins, 2 S albumins and 12 S cruciferins would not be degraded under the existing defatting procedures and therefore would become exploitable. In essence therefore we need to develop and test mild processes for oil extraction, which would allow this to occur. These would probably include dehulling, flaking, and cold extraction or, alternatively, enzyme based extractions. Examples are shown in figure 4.
If the processing procedures that are utilised in the extraction of lipids from rapeseed can be modified as suggested earlier then it will be possibly to modify proteins and peptides to generate functional molecules. These functional molecules would be focussed on particular marketing sectors and uses. See figure 5.
Fig. 5. Modification processes to proteins and peptides allowing generation of functional molecules Procesy modyfikacyjne procesów dla białka i peptydów pozwalająca na tworzenie cząsteczek funkcjonalnych
If these modifications were possible then considerable steps forward could be made in developing new markets. For example surface properties could be improved by chemical modification for example in acylation and sulfamidation. In this sort of situation then peptides from rapeseed proteins would actually behave more like soaps and detergents than proteins. This is shown in graphic form in figure 6.
Acylated peptides (5–6 AA) from rapeseed proteins — Acylowane peptydy z białek rzepakowych Chain grafted Wydzielony łańcuch Surface tension Napięcie powierzchniowe Foam characteristics Charakterystyka piany 0 min 8 min 18 min C8 C10 C12 C14 n.d. 43 42 34
Some acylated peptides behave more like soaps and detergents than like
proteins Niektóre acylowane peptydy zachowują się
bardziej jako mydła i detergenty niż jak
białka
γ: SDS: 44, Napin: 48
Fig. 6. Detergent properties of modified peptides — Własności detergentowe zmodyfikowanych peptydów
Conclusion
• Current commercial practise may not give best value for proteins in rapeseed meal, particularly for the non-food sector potential that these molecules would otherwise offer.
• Novel “gentle” extraction procedures would probably be more suited to maintaining proteins and protein quality in the meal, and that would be a step forward in terms of utilising those particular molecules. However what is unknown is what those processes might do to other primary and secondary metabolites in the rapeseed grain or meal and therefore what financial or other impact they may have.
• Markets and marking potential exist for many potential protein products from rapeseed meal and these are currently unexploited to any great extent. This is a weakness.
References
The European funded ENHANCE project N° QLK5-CT-1999-01442 — J. Gueguen; C. Schönweitzi, J. Evrard, Y. Popineau, C. Larre, H. Atterby, M.Q. Chaudhry, C. Malabat, S. Berot, J.P. Compoint, J.P. Douliez, H. Sorensen. Antihypertension — M.M. Must, J. Pedroche, J. Giron-Calle, M. Alaiz, F. Millan, J. Vioque and A. Natsch, C. Schäffer, A. Wäsahe.
