Reduction of Glucosinolate Content in Camelina sativa by Mechanical Heat-Pressing

Abstract

This experiment was undertaken to assess whether the heat effect during mechanical pressing of seeds of Camelina sativaL. Crantz permanently eliminates part of glucosinolates contained therein. The data indicate that the glucosinolates are lowered in the meal on average 31% compared to thecontrol defatted flourindependently from thelength ofthe extractiontime. GSL2 was the glucosinolate molecule more reduced by the mechanical heat-pressing(-36%) .

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* E-mail address: reggiani@ibba.cnr.it
Experiment Findings
Reduction of Glucosinolate Content in
Camelina sativa by Mechanical Heat-Pressing
Remo Reggiani*
Istituto di Biologia e Biotecnologia Agraria, CNR, Milano, Italy
.
ABSTRACT
This experiment was undertaken to assess whether the heat effect during mechanical
pressing of seeds of Camelina sativa L. Crantz permanently eliminates part of glucosinolates
contained therein. The data indicate that the glucosinolates are lowered in the meal on
average 31% compared to the control defatted flour independently from the length of the
extraction time. GSL2 was the glucosinolate molecule more reduced by the mechanical
heat-pressing (-36%).
Keywords: Camelina sativa, meal, seed crushing, oil, glucosinolates.
1. INTRODUCTION
Camelina (Camelina sativa L. Crantz), also known as gold of pleasure, has been grown in
Europe for centuries and, in the Iron and Bronze ages, was an important agricultural crop
[Russo & Reggiani, 2015]. It grows well in temperate climates and matures earlier than other
oilseed crops [Budin et al., 1995]. Moreover, camelina can be cultivated in semiarid regions
and saline soils. Camelina is an oilseed crop which has several agrotechnical benefits:
cultivation of the crop is simple and environmentally friendly, application of
pesticides/herbicides is not needed, a short growing season (85–100 days), the plant is
adaptable to marginal soils, it is less in need of water and has a higher cold-weather
tolerance [Budin et al., 1995; Zubr, 2003; Vollmann et al., 2007; Moser, 2010; Galasso et al.,
2010]. Thus, camelina has a lower production cost than other oilseed plants in environments
with particular climates [Budin et al., 1995]. Furthermore, camelina seed presents a really
important oil content (32-38%) [Colombini et al., 2012]. This has drawn attention to this plant
for the production of biodiesel but also for applications in the food industry being the oil rich
in omega-3 [Pecchia et al., 2014].
The evaluation of camelina meal as a potential ingredient in livestock rations is a critical
factor to further increase the economic value of the plant. The exploitation of this by-product
is a key factor to reduce costs and promote environmental sustainability. The meal is a good
source of protein (30-40% depending on the variety) for animal feed [Pecchia et al., 2014].
Camelina proteins have a favorable balance of amino acids and the meal is relatively low in
glucosinolates (18-36 mmol kg-1 dry weight) compared with many other crucifers, making this
meal potentially suitable for animal feed (Putnam et al., 1993; Schuster & Friedt, 1998;

* E-mail address: reggiani@ibba.cnr.it
Colombini et al., 2014). However, feeding trials in poultry showed that inclusion of camelina
meal at over 10% of the ration can affect egg production, feed consumption and egg yolk
weight (Cherian et al., 2009). Moreover, camelina meal >10% led to over 6% reduction in
egg total fat content (Cherian et al., 2009). In addition, 10% camelina meal led to significant
reduction in lipid oxidation products and an improvement in γ-tocopherol content and
antioxidant activity in meat. For this reason, the American Food and Drug Administration has
limited the inclusion of camelina meal in feed rations to 10% [Schill, 2010]. In order to
overcome this limit, a reduction of glucosinolates would be desirable.
Glucosinolates are β-thioglucoside N-hydroxysulfates with a side chain and sulfur linked β-
D-glucopyranose. In camelina, three main GSLs were identified named GSL1 (9-methyl-
sulfinyl-nonyl-GSL), GSL2 (10-methyl- sulfinyl-decyl-GSL) and GSL3 (11-methyl-sulfinyl-un-
decyl-GSL [Russo & Reggiani, 2012]. Their breakdown products isothiocyanates,
thiocyanates, nitriles and epithionitriles are responsible for toxicity like impairment of thyroid,
growth, fertility and reproduction, irritation of gastro-intestinal mucosa followed by local
necroses [EFSA, 2008].
Oil separation from seeds for biodiesel is accomplished by mechanical pressing, sometimes
followed by chemical extraction. Small biodiesel businesses will likely extract oil from seeds
using a mechanical method rather than a chemical method, which is expensive and
complicated [Herkes et al., 2015]. Most large commercial operations use a mild pressing
operation to extract 60-70% of the oil. Typically, seeds are heated for 15 to 20 minutes prior
to pressing [Herkes et al., 2015]. In canola, the heat applied before pressing has an effect on
the amount of glucosinolates remaining in the meal [Bell, 1984]. Another technique used is
that of heat during the pressing. In this brief report, we checked the glucosinolates content in
heat-pressed camelina meal in order to know whether, in this material, the content of
glucosinolates is actually lowered compared to a control flour and if, the glucosinolates
decrease, is due to their disappearance or to a slower release from the meal (by-passable
by a longer extraction time).
2. MATERIAL AND METHODS
Heat-pressed meal (HPM) of Camelina sativa L. variety Camelia was kindly gifted by Dr. A.
Agazzi and Panghea Natural and Chemical Innovation srl (Milan, Italy). This material
consisted of camelina seeds mechanically pressed at 70°C. As control for normal
glucosinolates content, seeds of Camelia were ground in a mortar and defatted with hexane.
The samples were prepared in triplicate.
On HPM and defatted flour (DF), glucosinolates were extracted with 70% hot ethanol.
Several extraction times were used with HPM (10 min, 1, 2.5, 5, 7.5 and 24h) while
glucosinolates in DF were extracted for 2.5h. After extraction, the samples were centrifuged
for 15 min at 15,000 rpm. Alcoholic extracts were adsorbed onto small DEAE-Sephadex A-
25 columns in acetate form (100 mg). The column was then washed twice with 1 mL of 20
mM sodium acetate at pH 4.0. Desulfation of GSLs was obtained by 50 µL of sulfatase
(500U) at 37˚C overnight. Desulfo-glucosinolates were eluted from the column with 1.0 mL of
ethanol and dried at 75˚C. The samples were resuspended in 200 µL ethanol before HPLC
analysis. Twenty µL of Desulfo-glucosinolates were analyzed by HPLC according to Russo
et al. [2014].

* E-mail address: reggiani@ibba.cnr.it
3. RESULTS AND DISCUSSION
HPM was subjected to various extraction times (10 min, 1, 2.5, 5, 7.5 and 24h) with 70% hot
ethanol in order to verify if glucosinolates are still present but more difficult to extract or if,
indeed, their content is lowered due to the heat-pressing. The content of GSL1, GSL2 and
GSL3 at different extraction times is shown in Table 1. As can be seen, an increase in the
glucosinolate content with increasing time of extraction is not evident but just data variability
among samples is observed. The mean content of glucosinolates in HPM was 17.77 mmol
kg-1 dry weight, which is 31% lower than that determined in DF. This decrease was mainly
due to the disappearance of GSL2 (-36%) which is the most abundant glucosinolate in
camelina.
Table 1. Level of glucosinolates in HPM at different extraction times (10 min, 1, 2.5, 5,
7.5 and 24h) and in DF of Camelina sativa variety Camelia. In parenthesis are shown
the % of decreases in glucosinolates in HPM respect to DF.
GSL1
*
GSL2
*
GSL3
*
Total GSL
*
HPM (10min) 3.57 12.52 3.45 19.54
HPM (1h)
2.98
10.65
2.89
16.51
HPM (2.5h)
3.54
11.98
3.31
18.83
HPM (5h)
3.25
11.37
3.09
17.70
HPM (7.5h)
2.93
11.47
2.86
17.26
HPM 24h)
3.16
10.67
2.94
16.77
Mean HPM 3.24±0.12 (-16%) 11.44±0.33 (-36%) 3.09±0.11 (-24%) 17.77±0.53 (-31%)
DF
3.86
±
0.24
17.76±0.22
4.06±0.16
25.69±0.72
*mmol kg-1 dry weight
Heat treatments make different antinutrients less available to extraction [Rehman and Shah,
2005]. For example, tannins and phytic acid contents were reduced by thermal heat
treatments by 33.1–45.7% and 28.0–51.6%, respectively [Rehman and Shah, 2005]. In
canola, the heat treatment of seeds before pressing reduced the glucosinolate content
[Herkes et al., 2015]. Here, It is shown that the mechanical heat-pressing reduced the
availability of glucosinolates in camelina by 31%. This experiment shows that, due to the
heat, glucosinolates are no longer extractable from the meal (if complexed or destroyed
does not matter) also increasing the extraction time. Heat treatments on camelina meal are
therefore useful to reduce the content of harmful substances (especially glucosinolates) in
order to increase the use of this material as feed for animal.
ACKNOWLEDGEMENTS
I am very grateful to Dr. A. Agazzi and Panghea Natural and Chemical Innovation srl (Milan,
Italy) for the kind gift of camelina meal.
REFERENCES
Bell JM. Nutrients and toxicants in rapeseed meal. J Anim Sci. 1984; 73:679-697.
Budin J, Breene W, Putnam D. Some compositional properties of camelina (Camelina sativa
L. Crantz) seeds and oils. J Am Oil Chem Soc 1995; 72:309–15.

* E-mail address: reggiani@ibba.cnr.it
Cherian G, Campbell A, Parker T. Egg quality and lipid composition of eggs from hens fed
Camelina sativa. J Appl Poultry Res. 2009;18:143-50.
Colombini S, Broderick GA, Galasso I, Martinelli T, Rapetti L, Russo R, Reggiani R.
Evaluation of Camelina sativa (L.) Meal as an Alternative Protein Source in Ruminant
Rations. J Sci Food Agric. 2014; 94:736-43.
European Food Safety Authority. Glucosinolates as Undesirable Substances in Animal Feed.
EFSA J. 2008; 590:1-76.
Galasso I, Caruso I, Martinelli T, Pecchia P, Reggiani R, Russo R, Mapelli S. Riscoperta la
Camelina sativa una valida alternativa per il biodiesel. L’Informatore Agrario (Suppl).
2012; 16:38–40.
Herkes J, Grubinger V, Schumacher J, Thompson J. Mechanical Extraction Processing
Technology for Biodiesel. Extension: Issue, Innovation, Impact. 2015. Accessed 11
December 2015. Available: http://articles.extension.org/pages/26911/mechanical-
extraction-processing-technology-for-biodiesel
Moser BR. Camelina (Camelina sativa L.) oil as a biofuels feedstock: Golden opportunity or
false hope? Lipid Techonol. 2010; 22:270–274.
Pecchia P, Russo R, Brambilla I, Reggiani R, Mapelli S. Biochemical Seed Traits of
Camelina sativa – An Emerging Oilseed Crop for Biofuel: Environmental and Genetic
Influences. J Crop Improv. 2014; 28(4):465-83.
Putnam DH, Budin JT, Field LA, Breene WM. Camelina: A promising low-input oilseed. In:
Janick J, Simon JE, editors. New crops: exploration, research, and commercialization.
Proceedings of the second national symposium, 314–322. New York: Wiley; 1993.
Rehman Z, Shah WH. Thermal heat processing effects on antinutrients, protein and starch
digestibility of food legumes. Food Chem. 2005; 327-31.
Russo R, Galasso I, Reggiani R. Variability in glucosinolate content among Camelina
species. Am J Plant Sci. 2014; 5:294-298.
Russo R, Reggiani R. Antinutritive Compounds in Twelve Camelina sativa Genotypes. Am J
Plant Sci. 2012; 3(10):1408-12.
Russo R, Reggiani R. Seed Protein in Camelina sativa (L.) Crantz var. Calena. Int J Plant
Soil Sci. 2015; 8(2):1-6.
Schuster A, Friedt W. Glucosinolate Content and Composition as Parameters of Quality of
Camelina Seed. Ind Crops Prod. 1998; 7(2-3):297-302.
Schill SR. Camelina Meal Approved for Feedlot Cattle. Biodiesel Magazine. 2010. Available:
http://www.biodieselmagazine.com/articles/3837/camelina-meal-approved-for-feedlot-
cattle
Vollmann J, Moritz T, Kargl C, Baumgartner S, Wagentristl H. Agronomic evaluation of
camelina genotypes selected for seed quality characteristics. Ind Crops Prod. 2007;
26:270–277.
Zubr J. Qualitative variation of Camelina sativa seed from different locations. Ind Crops
Prod. 2003; 17:161–169.