Effect of Seed Roasting on Canolol, Tocopherol ... - ACS Publications

Article

Subscriber access provided by FONDREN LIBRARY, RICE UNIVERSITY

Effect of seed roasting on canolol, tocopherol, phospholipid content, Maillard type reactions and oxidative stability of mustard and rapeseed oils Kshitij Shrestha, and Bruno De Meulenaer J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/jf500549t • Publication Date (Web): 02 Jun 2014 Downloaded from http://pubs.acs.org on June 8, 2014

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28

Journal of Agricultural and Food Chemistry

1

Effect of seed roasting on canolol, tocopherol,

2

phospholipid content, Maillard type reactions and

3

oxidative stability of mustard and rapeseed oils

4

Kshitij Shrestha1 and Bruno De Meulenaer*1

5

1

6

Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium

7

*

8

NutriFOODchem unit - Department of Food Safety and Food Quality (partner in

9

Food2Know)

NutriFOODchem Unit, Department of Food Safety and Food Quality, Faculty of Bioscience

Corresponding author: Prof. dr. ir. Bruno De Meulenaer

10

Faculty of Bioscience Engineering

11

Ghent University, Coupure links 653

12

B-9000, Ghent

13

Belgium

14

Email: [email protected]

15

Tel: + 32 9 264 61 66; Fax: + 32 9 264 62 15

16 17

Funding: Special Research Fund - BOF, Ghent University

1

ACS Paragon Plus Environment


Page 2 of 28

18

Abstract

19

This study was carried out to study the effect of roasting on different compositional

20

parameters and oil oxidative stability of three Brassica species (B. juncea (BJ), B. juncea var.

21

oriental (BJO) and B. napus (rapeseed, RS)). After 10 min of roasting at 165 oC, canolol

22

content of BJ, BJO and RS oil reached 297.8, 171.6 and 808.5 µg/g and, the phospholipid

23

phosphorus content reached 453.6, 342.6 and 224.2 µg/g oil, respectively. The BJ and BJO

24

seed showed more prominent browning reactions than RS, due to the presence of higher

25

amounts of reducing sugars, lysine, arginine; and the occurrence of Maillard type browning

26

reactions of phospholipids. The UV-visible spectra, fluorescence and pyrrole content showed

27

the presence of browning reaction products in the roasted seed oils. Roasting increased the

28

oxidative stability of all the varieties. Canolol formation could only partially explain for such

29

observation. Other roasting effects such as phospholipids extraction, Maillard type browning

30

reaction products etc were also responsible for that.

31

Keywords: 2,6-dimethoxy-4-vinylphenol (canolol), mustard, rapeseed, lipid oxidation, seed

32

roasting, phospholipid browning, Maillard type reactions

33

2


Page 3 of 28


34

Introduction

35

Seed roasting has been known to increase the oil oxidative stability of different seeds, such as

36

mustard (1), sesame (2), Pistacia terebinthus (3), pine nut (4), cashew (5), perilla (6), apricot

37

(7), pumpkin (8, 9), walnut (10), rapeseed (RS) (11) etc. However, there are considerable

38

differences in the manner roasting improves the oil oxidative stability of these seeds. For

39

instance, production of different radical scavengers, such as sesamol in sesame seed (2) and

40

canolol in RS (11-14) during seed roasting are considered to play an important role for such

41

phenomenon. In some cases, increased phospholipid extraction after seed roasting has also

42

been suggested (6, 9). In most of the cases, Maillard browning reactions between amino acids

43

and reducing sugars have been proposed as an important contributing factor for such

44

observation (1, 3-5, 8, 10, 11). These results suggest that roasting can have different effects in

45

different types of seeds. Hence, it is important to understand the roasting effects and the

46

manner it improves the oil oxidative stability on each type of seed, separately.

47

Mustard seeds are generally roasted before oil extraction, and the crude oil extracted using a

48

screw expeller, is consumed without refining in different south Asian countries such as India

49

and Nepal (1, 15). The traditional mustard and RS varieties contain high amounts of erucic

50

acid, while various low erucic RS varieties have also been developed by breeding practices

51

(14). Although a number of seed roasting experiments have been reported for RS (11, 12) and

52

mustard varieties (1, 11), a clear insight and in-depth understanding of how roasting improves

53

oxidative stability of these varieties are still lacking. For instance, all these studies consider

54

Maillard reactions to be partially responsible for increasing the oxidative stability of roasted

55

seed oil; however, none of them clearly demonstrates the occurrence of such reactions by

56

evaluating the loss of reducing sugars and amino acids, and by analyzing the browning 3



Page 4 of 28

57

reaction markers in the roasted seed oil. Moreover, the formation of canolol and its

58

contribution on the oxidative stability has been completely ignored in roasting experiments

59

carried out on high erucic mustard seed oil (1). Recently however, canolol formation during

60

roasting has also been confirmed in those varieties (14). Furthermore, most of the previous

61

studies have ignored the possibility of Maillard type browning reactions involving the amino

62

group containing phospholipid (e.g. phosphatidylethanolamine (PE)). Such browning reaction

63

products have been demonstrated to be more lipophilic compared to Maillard reaction

64

products between amino acids and reducing sugars (16). Hence, they are more likely to be

65

extracted with oil, and can contribute its antioxidative activity (17, 18). A correlation study

66

considering the effect of all these different factors on the oxidative stability of roasted

67

mustard seed oil has been published recently (18). It has provided a novel insight that the

68

presence of radical scavengers (such as canolol and tocopherol) could not solely explain the

69

very high oxidative stability of roasted mustard seed oil. Such observation has been shown to

70

be primarily linked with phospholipid content and the presence of lipophilic Maillard type

71

browning reaction products, in addition to canolol that is formed during roasting (18).

72

However, that study was carried out on roasted mustard seed oils collected from the market;

73

and hence, it does not clearly demonstrate how such antioxidative compounds are generated

74

during seed roasting and if there exist the difference in the roasting effect among different

75

mustard and RS varieties.

76

Therefore, the current study has been carried out to evaluate the seed roasting effect on

77

different compositional parameters and oil oxidative stability of different Brassica species.

78

The three species selected for the study were Brassica juncea (Indian mustard), Brassica

79

juncea var. oriental (oriental mustard) and Brassica napus (European rapeseed).

4


Page 5 of 28


80

Materials and methods

81

Materials and Reagents

82

The seeds of two high erucic acid mustard varieties (Brassica juncea (BJ) and Brassica

83

juncea var. oriental (BJO)) and a low erucic acid rapeseed (RS) variety (B. napus) were

84

collected from the local market of Ghent, Belgium. Tocopherol standard was obtained from

85

DSM (New Jersey, USA). Syringaldehyde and 1,2-dioleoyl-sn-glycero-3-

86

phosphoethanolamine were purchased from Sigma Aldrich (Steinheim, Germany).

87

Nonadecanoic acid was purchased from Fluka (Switzerland). The HPLC grade hexane was

88

bought from VWR International (Leuven, Belgium). Other reagents and solvents were of

89

analytical grade and obtained from reliable commercial sources.

90

Synthesis of canolol

91

Canolol was synthesized from syringaldehyde by condensation with malonic acid and then

92

double decarboxylation under microwave condition as described previously (14). The

93

ultraviolet, fluorescence, liquid chromatography-mass spectrometry and nuclear magnetic

94

resonance spectra were used to confirm the identity and purity of the synthesized compound

95

(14). The synthesized canolol was used as a standard for quantification.

96

Analytical methods

97

Fatty acid methyl esters were prepared using the boron trifluoride method (American Oil

98

Chemists Society, 1990) and were analyzed on a gas chromatograph using the method

99

described previously (18). Nonadecanoic acid was used as an internal standard for the

100

quantification. 5



Page 6 of 28

101

The analysis of the total amino acid profile of seed sample was carried out using the

102

previously described procedure (19) and included a full hydrolysis of the sample in acidic

103

conditions and a liquid chromatographic analysis using fluorescence detection after

104

derivatization. Thus tryptophan and cysteine were lost and glutamine and asparagine were

105

converted to glutamic and aspartic acid respectively. Tryptophan was separately analyzed

106

after basic hydrolysis followed by similar chromatographic conditions. The analysis of the

107

free amino acid content was carried out after their extraction from the ground seeds with 15

108

% trichloroacetic acid followed by similar chromatographic analysis, without acid hydrolysis.

109

Sarcosine was used as an internal standard to quantify proline. Norvaline was used as an

110

internal standard to quantify other amino acids.

111

Analysis of sugar content in the seed sample was carried out gas chromatographically after

112

aqueous extraction of the sugar and derivatisation via oximation and silylation using the

113

previously described procedure (20). Phenyl-β-D-glucopyranoside was used as an internal

114

standard for the quantification.

115

Tocopherol and canolol content of the oils were analyzed in a high pressure liquid

116

chromatograph using a fluorescence detector, after separation in a silica column as described

117

previously (14).

118

Peroxide value (PV) of oil was determined by using an iron based spectrophotometric method

119

(21). Calibration curve was constructed using a standard iron (III) chloride solution as

120

described in the same method. Calibration was done using six concentrations in duplicate in

121

the range of 5 to 30 µg of iron (III). The multiple R-squared value was more than 0.99 for the

122

calibration. Such calibration curve was constructed just before the measurement of the

123

peroxide value of the samples. 6


Page 7 of 28


124

Phospholipid phosphorus content of oil was analyzed spectrophotometrically after the

125

formation of a phospholipid phosphorus-molybdate complex as described before (18).

126

The pyrrolized phospholipid content of the oil samples was analyzed using a previously

127

described procedure (22). The absorbance of the Ehrlich adducts was measured at 512 nm

128

and the blank absorbance without Ehrlich reagent was subtracted during calculation. The

129

reported value of extinction coefficient of Ehrilich adducts (153000 M-1 cm-1) with 1-[1-(2-

130

hydroxyethyl)-1H-pyrrol-2-yl]propan-1-ol was used in the calculation (22).

131

UV-visible absorbance spectra of the oil solution in iso-octane (25 mg/mL) was measured

132

using a Cary 50 UV/Vis spectrophotometer (Varian) in a quartz cuvette. Fluorescence

133

(excitation at 350 nm and emission at 440 nm) of the same oil solution was additionally

134

measured using a Spectramax Gemini XS fluorescence spectrophotometer as described

135

previously (18). Fluorescence is expressed as the percentage fluorescence of 1 µM quinine

136

sulphate solution in 0.1 M H2SO4.

137

Experimental setup

138

Mustard and rapeseed were roasted in a beaker, which was dipped inside an oil bath

139

maintained at 180 oC as reported earlier (14). Briefly, 80 g seed sample was added to a heated

140

beaker placed on the oil bath (180 oC). The seed sample and heating oil were continuously

141

agitated with two electric mechanical stirrers. The temperature of seed sample and heating oil

142

was continuously monitored using Testo thermostat proves. The oil temperature was

143

maintained constant at 180 oC and seed roasting was carried out for 10, 20, 30, 45, 60 and 90

144

min. The seed temperature profile with time followed the equation T = 32.796 ln (t) + 89.422

7



Page 8 of 28

145

(R2 = 0.99) for the first 10 min of roasting, where T is the seed temperature (oC) and t is the

146

roasting time (min). Afterwards, seed temperature remained constant at 165 ± 3 oC.

147

The roasted and unroasted seeds were ground. The total amino acid profile was analyzed on

148

unroasted seed powder. The reducing sugar content and free amino acid profile was analyzed

149

both on unroasted and 10 min roasted seed powder.

150

The oil was extracted from unroasted and roasted seeds using petroleum ether (14).

151

Tocopherol, canolol, phospholipid and browning reaction markers (absorbance, fluorescence

152

and pyrrolized phospholipid content) were analyzed on unroasted and roasted seed oils. The

153

extracted oil (750 µL) was kept in a 1.5 mL loosely capped HPLC glass vial and stored at 104

154

o

155

at different time intervals. Both roasting and oxidation studies were carried out in

156

independent triplicate experiments.

157

Statistical analysis

158

All data are presented as mean values ± 95% confidence interval of mean based on three

159

independent experiments, unless otherwise stated. The logarithmic transformations of the

160

different data was done, whenever necessary, to have homoscedasticity before carrying out

161

the statistical analysis. ANOVA and post-hoc Tukey test were performed using TIBCO

162

Spotfire S+ 8.1 software. The significance level is p < 0.05, unless otherwise indicated.

C in order to accelerate the oxidation process. Oil oxidation was monitored by analyzing PV

163

8


Page 9 of 28


164

Results and discussion

165

Effect of roasting on different compositional parameters

166

Mustard and rapeseed roasting are known to form canolol by decarboxylation of sinapic acid

167

(11, 12, 14, 23, 24). Roasting of seed before oil extraction increased the canolol content of oil

168

in all the varieties (Table 1). The maximum canolol content of oil was reached during 10 to

169

20 min of seed roasting. Oil from 20 min roasted RS contained the highest amount of canolol,

170

which was 2.8 times higher compared to BJ seed oil and 4.9 times higher compared to BJO

171

seed oil, roasted for same time. Higher canolol formation in roasted RS compared to different

172

mustard seed varieties was also reported previously (14). Roasting for more than 20 min

173

gradually reduced the canolol content in all the varieties. The decrease in the canolol content

174

during longer roasting time was also reported previously (24). The canolol content of the

175

roasted rapeseed oil was reported in a similar range previously (23, 24).

176

The tocopherol content of the unroasted and roasted seed oil of different varieties is given in

177

Table 1. The α-tocopherol content in the unroasted RS oil was more than double the amount

178

present in both unroasted mustard seed oils. It remained stable during RS roasting, while a

179

significant gradual degradation was observed for both BJ and BJO mustard varieties. The γ-

180

tocopherol content in all the three varieties was quite comparable. Its degradation was

181

observed in all the varieties during 10 min of roasting. Afterwards, it remained constant in

182

RS, while slight degradation was observed during BJO roasting. The BJ seed oil showed a

183

gradual and the largest degradation in γ-tocopherol during longer roasting. The

184

plastochromanol-8 content remained relatively stable in the BJ seed oil during roasting. On

185

the other hand, a significant increment was observed in the BJO and RS oil during the first 10

9



Page 10 of 28

186

min of roasting. The disruption of matrix during roasting could be responsible for the

187

increased extractability. Longer roasting time had little effect in all the varieties studied.

188

The phospholipid phosphorus content of the unroasted seed oils, extracted using petroleum

189

ether, was in the range of 8 to 30 µg/g oil (Table 1). On the other hand, when the same

190

unroasted seed powder was extracted with a chloroform/methanol solvent mixture (2:1, v/v);

191

the phospholipid phosphorus content was 500 to 600 µg/g oil. Therefore, the lower

192

phospholipid content of unroasted seed oil was due to the poor extractability with petroleum

193

ether from the unroasted seed matrix. Roasting for 10 min significantly increased the oil

194

phospholipid content for all the varieties. This observation was similar to the increased

195

extractability of plastochromanol-8 after seed roasting. The increased phospholipid content of

196

the oil after seed roasting was also reported previously (9). Roasting for more than 10 min

197

showed a gradual decrease in the phospholipid phosphorus content in the oil of all the

198

varieties. The decrease in extractability could indicate its chemical modifications, for

199

instance, they could be covalently bound to matrix compounds.

200

Maillard reaction is one of the most well known nonenzymatic browning reactions in heat

201

treated food products. The possibility for such reactions during seed roasting was studied by

202

evaluating the changes in the amino acids and reducing sugars content. Among the free

203

amino acids, RS contained a significantly higher quantity of glutamate, histidine, alanine,

204

valine, isoleucine and lysine compared to both BJ and BJO mustard varieties (Table 2). On

205

the other hand, both BJ and BJO mustard varieties contained significantly higher quantity of

206

free arginine compared to RS. After 10 min of roasting, more than 85% of free amino acids

207

were lost, indicating the occurrence of Maillard reaction in all the varieties. The loss of

208

individual amino acid was quite comparable in all the varieties. Therefore, the formation of 10


Page 11 of 28


209

low molecular weight antioxidative compounds from such reactions could also be

210

comparable among those varieties. On the other hand, the total amino acids content (in fat

211

free dry matter (FFDM) basis) was higher in mustard varieties compared to that in RS (Table

212

3). Particularly notable were the presence of 30 to 40% higher arginine and 14 to 16% higher

213

lysine in mustard varieties compared to that in RS. Because of the presence of free amino

214

group, these amino acids are particularly responsible for the Maillard reactions involving

215

proteins. The formation of high molecular weight hydrophilic antioxidative compounds from

216

such reactions could be much more pronounced in mustard varieties compared to that in RS.

217

The effect of seed roasting on the sugar content was additionally evaluated in all the varieties

218

(Table 4). Both mustard varieties contained significantly higher quantity of glucose and

219

lower quantity of sucrose compared to RS before roasting. The fructose content of BJ

220

mustard seed was also higher compared to both BJO seed and RS. After 10 min of roasting,

221

the glucose content decreased significantly in all the varieties compared to the amount

222

present in the unroasted seed. The loss of glucose was around 4 times higher in both mustard

223

varieties compared to that in rapeseed. Moreover, the sucrose content of both mustard

224

varieties also decreased significantly, likely due to its hydrolysis into glucose and fructose.

225

The increase in sucrose content in rapeseed after seed roasting could possibly due to its

226

formation via the hydrolysis of stachyose and raffinose present in the matrix (25).

227

The ground seed meal of different varieties before and after 20 min roasting has been shown

228

in Figure 1. This picture illustrates that browning reactions during roasting were more

229

pronounced in mustard varieties compared to that in RS. This could be linked with the

230

presence of higher quantities of both reducing sugars and reactive amino acids (e.g. lysine,

231

arginine) in mustard varieties compared to that in RS.

11



Page 12 of 28

232

In addition to amino acids, the amino group containing phospholipid (e.g. PE) are also known

233

to take part in the Maillard type browning reactions with reducing sugars (17). Both types of

234

browning reactions could be expected to happen simultaneously in the seed however, their

235

extraction in the oil could be affected by their polarity differences. In a previous study, it was

236

shown that the amino group of PE was even more reactive with ribose than that of lysine

237

(16). These authors reported that, when the aqueous reaction mixture of PE, ribose and lysine

238

was extracted with chloroform/methanol (2:1, v/v) to have phase separation, the brown

239

compounds due to PE/ribose and lysine/ribose got separated into the organic and aqueous

240

phase, respectively (16). These observations showed that the lysine/ribose Maillard reaction

241

products are more hydrophilic, while the PE/ribose reaction system could produce lipophilic

242

Maillard type reaction products. The same extraction method was used to characterize the

243

brown compounds in the roasted seed oil. It was observed that the major brown compounds

244

of oil remained in the organic phase indicating that these brown compounds could be mainly

245

due to phospholipids browning compared to the reducing sugar amino acid Maillard reactions.

246

The possibility of such phospholipid browning reaction products was also reported previously

247

based on the high correlation observed between the phospholipid content, absorbance,

248

fluorescence and the pyrrolized phospholipid content in roasted mustard seed oil (18).

249

The changes in the browning reaction markers in the oil after seed roasting of different

250

varieties were further evaluated (Table 1). The absorbance of oil at 350 nm gradually

251

increased during roasting in all the varieties. The choice of this marker is based on the recent

252

report that oxidative stability of the roasted mustard seed oil is highly correlated at this

253

wavelength (18). The BJ seed oil showed the highest increment in the absorbance and

254

reached a maximum after 20 min of roasting, which was more than 3 times compared to that

255

of RS oil and more than 2 times compared to BJO seed oil, roasted for the same time. After 12


Page 13 of 28


256

45 min of roasting, the absorbance values of all the varieties remained almost constant. The

257

absorbance value after 45 min was comparable between BJ and BJO seed oil, and was around

258

double the amount compared to that of RS oil. To illustrate that more clearly, the changes in

259

the UV-visible absorbance spectra of oil after roasting for 10 and 90 min for all the varieties

260

are shown in Figure 2. It shows that the increase in the UV-visible absorbance due to

261

browning reactions within the 10 min of roasting was highest in BJ followed by BJO and

262

rapeseed oil. After 90 min of roasting, BJ and BJO seed oil showed similar UV-visible

263

absorbance spectra. On the other hand, the UV-visible absorbance spectra of roasted rapeseed

264

oil (even after 90 min of roasting) was lower than that of 10 min roasted BJ oil. This showed

265

that browning reactions were more prominent in BJ and BJO mustard varieties compared to

266

that in rapeseed variety. In addition, roasting increased the oil fluorescence (excitation 350

267

nm and emission 440 nm) in all the varieties (Table 1). However, fluorescence development

268

was comparable in all the varieties and could not differentiate the extent of browning

269

observed with the absorbance at 350 nm. Furthermore, the presence of the Maillard type

270

browning reaction products in the roasted seed oil was supported by the increment in the

271

pyrrolized phospholipid content after seed roasting in all the varieties (Table 1).

272

Oxidative stability of roasted seed oil of different varieties

273

The fatty acid compositions of all the oils are given in Table 5. Both mustard varieties were

274

rich in erucic acid, while the RS was rich in oleic acid. However, total saturated,

275

monounsaturated and polyunsaturated fatty acids content were comparable in all the varieties.

276

The oxidative stability of unroasted seed oil and roasted seed oil was evaluated by monitoring

277

the changes in the PV during accelerated oxidation at 104 oC (Figure 3). The previous study

278

showed that roasted mustard seed oil could have a very high oxidative stability with induction 13



Page 14 of 28

279

period more than 60 days during storage at 50 oC (18). Therefore, higher storage temperature

280

(104 oC) was chosen to accelerate the oxidation. The vials were loosely capped so as to

281

maintain the constant atmospheric oxygen concentration in the headspace. The experiment is

282

similar to the active oxygen method used for the evaluation of oxidative stability of oil at 100

283

o

284

peroxides could degrade at this temperature and the oil oxidation could be different from the

285

autoxidation, however, such effects could be similar in the oil samples with similar fatty acid

286

composition. Therefore, the results from this experiments should be taken as the relative

287

oxidative stability among the samples with similar fatty acid composition during accelerated

288

oxidation.

289

Roasting for 10 min significantly improved the oxidative stability of all the varieties

290

compared to their respective unroasted seed oil (Figure 3). Such increment in the oxidative

291

stability due to roasting was more prominent in BJ and BJO varieties compared to that in RS

292

variety. Roasting for longer time had a smaller additional effect.

293

Canolol is a potent antioxidant and is known to play an important role in the oxidative

294

stability of roasted rapeseed oil (11, 12). However, other factors in addition to canolol could

295

also be responsible for the increased oxidative stability. To evaluate the role of canolol alone,

296

oxidative stability was evaluated after the addition of canolol to the unroasted seed oil

297

equivalent to the amounts formed after 10 min roasting (Figure 2). In addition, oxidative

298

stability of unroasted rapeseed oil containing canolol equivalent to the amount in 10 min

299

roasted BJ seed oil was also evaluated. Canolol addition to the unroasted mustard seed (BJ

300

and BJO) could not increase their oxidative stability, while it showed significant protective

301

role in the rapeseed oil. In all the varieties, 10 min roasted seed oil was more stable compared

302

to their respective unroasted seed oil added with equivalent quantity of canolol. These

C by saturating the oil with oxygen, and monitoring the PV during storage. It is known that

14


Page 15 of 28


303

observation showed that canolol could play a significant role in increasing the oxidative

304

stability of roasted RS oil, however its formation alone could not be responsible for the

305

increased oxidative stability after seed roasting. Furthermore, even though BJ and BJO

306

varieties showed smaller increment in canolol during roasting compared to that in RS,

307

increment in the oxidative stability after roasting was more prominent in BJ and BJO

308

varieties compared to that in RS. This could be linked with other multiple effects of seed

309

roasting such as increased extraction of phospholipid, formation of antioxidants via Maillard

310

type reactions etc. Such roasting effects depend on the chemical composition of the seeds,

311

which could be different in the different varieties. In the current example, BJ and BJO

312

mustard seed showed stronger Maillard type browning reactions compared to RS variety.

313

Maillard type browning reaction products are known to have strong antioxidative activity (17,

314

26). Such browning reaction products could be responsible for the increased oxidative

315

stability of roasted mustard (BJ and BJO) seed oil in addition to the canolol formed during

316

the roasting. Further studies are required to isolate and identify the antioxidative compounds

317

formed during such reactions that can be used as a natural antioxidants in different food

318

products.

319

Abbreviations: PV peroxide value, BJ Brassica juncea, BJO B. juncea var. oriental, PE

320

phosphatidylethanolamine, RS rapeseed, FFDM fat free dry matter

321

ACKNOWLEDGEMENT

322

The study was financially supported by Special Research Fund - BOF, Ghent University,

323

which is gratefully acknowledged.

324

15



325

Page 16 of 28

Reference List

326 327 328 329

1. Vaidya, B.; Choe, E. Effects of seed roasting on tocopherols, carotenoids, and oxidation in mustard seed oil during heating. Journal of the American Oil Chemists' Society 2011, 88 (1), 83-90.

330 331 332

2. Lee, S. W.; Jeung, M. K.; Park, M. H.; Lee, S. Y.; Lee, J. Effects of roasting conditions of sesame seeds on the oxidative stability of pressed oil during thermal oxidation. Food Chemistry 2010, 118 (3), 681-685.

333 334 335

3. Durmaz, G.; Gokmen, V. Changes in oxidative stability, antioxidant capacity and phytochemical composition of Pistacia terebinthus oil with roasting. Food Chemistry 2011, 128 (2), 410-414.

336 337 338

4. Cai, L.; Cao, A.; Aisikaer, G.; Ying, T. Influence of kernel roasting on bioactive components and oxidative stability of pine nut oil. Eur. J. Lipid Sci. Technol. 2013, 115 (5), 556-563.

339 340

5. Chandrasekara, N.; Shahidi, F. Oxidative Stability of Cashew Oils from Raw and Roasted Nuts. J. Am. Oil Chem. Soc. 2011, 88 (8), 1197-1202.

341 342 343

6. Zhao, T.; Hong, S. I.; Lee, J.; Lee, J. S.; Kim, I. H. Impact of Roasting on the Chemical Composition and Oxidative Stability of Perilla Oil. Journal of Food Science 2012, 77 (12), C1273-C1278.

344 345 346

7. Durmaz, G.; Karabulut, I.; Topcu, A.; Asilturk, M.; Kutlu, T. Roasting-Related Changes in Oxidative Stability and Antioxidant Capacity of Apricot Kernel Oil. J. Am. Oil Chem. Soc. 2010, 87 (4), 401-409.

347 348 349

8. Nederal, S.; Skevin, D.; Kraljic, K.; Obranovic, M.; Papesa, S.; Bataljaku, A. Chemical Composition and Oxidative Stability of Roasted and Cold Pressed Pumpkin Seed Oils. J. Am. Oil Chem. Soc. 2012, 89 (9), 1763-1770.

350 351 352

9. Vujasinovic, V.; Djilas, S.; Dimic, E.; Basic, Z.; Radocaj, O. The effect of roasting on the chemical composition and oxidative stability of pumpkin oil. Eur. J. Lipid Sci. Technol. 2012, 114 (5), 568-574.

353 354 355

10. Vaidya, B.; Eun, J. B. Effect of roasting on oxidative and tocopherol stability of walnut oil during storage in the dark. Eur. J. Lipid Sci. Technol. 2013, 115 (3), 348-355.

356 357 358

11. Wijesundera, C.; Ceccato, C.; Fagan, P.; Shen, Z. Seed roasting improves the oxidative stability of canola (B. napus) and mustard (B. juncea) seed oils. Eur. J. Lipid Sci. Technol. 2008, 110 (4), 360-367.

16


Page 17 of 28


359 360 361

12. Koski, A.; Pekkarinen, S.; Hopia, A.; Wähälä, K.; Heinonen, M. Processing of rapeseed oil: effects on sinapic acid derivative content and oxidative stability. European Food Research and Technology 2003, 217 (2), 110-114.

362 363 364 365

13. Matthaus, B. Effect of Canolol on Oxidation of Edible Oils. In Canola and Rapeseed: Production, Processing, Food Quality, and Nutrition, Thiyam, U.; Eskin, M.; Mattaus, B., Eds.; CRC Press, Taylor & Francis Group: Boca Raton, 2012; pp 317-328.

366 367 368 369

14. Shrestha, K.; Stevens, C. V.; De Meulenaer, B. Isolation and identification of a potent radical scavenger (canolol) from roasted high erucic mustard seed oil from Nepal and its formation during roasting. J. Agric. Food Chem. 2012, 60 (30), 7506-7512.

370 371 372

15. Vaidya, B.; Choe, E. Stability of tocopherols and lutein in oil extracted from roasted or unroasted mustard seeds during the oil oxidation in the dark. Food Science and Biotechnology 2011, 20 (1), 193-199.

373 374 375

16. Zamora, R.; Nogales, F.; Hidalgo, F. J. Phospholipid oxidation and nonenzymatic browning development in phosphatidylethanolamine/ribose/lysine model systems. European Food Research and Technology 2005, 220 (5), 459-465.

376 377 378 379

17. Zamora, R.; León, M. M.; Hidalgo, F. J. Free radical-scavenging activity of nonenzymatically-browned phospholipids produced in the reaction between phosphatidylethanolamine and ribose in hydrophobic media. Food Chemistry 2011, 124 (4), 1490-1495.

380 381 382 383

18. Shrestha, K.; Gemechu, F. G.; De Meulenaer, B. A novel insight on the high oxidative stability of roasted mustard seed oil in relation to phospholipid, Maillard type reaction products, tocopherol and canolol content. Food Research International 2013, 54 (1), 587-594.

384 385 386

19. Kerkaert, B.; Mestdagh, F.; Cucu, T.; Shrestha, K.; Camp, J.; Meulenaer, B. The impact of photo-induced molecular changes of dairy proteins on their ACEinhibitory peptides and activity. Amino Acids 2012, 43 (2), 951-962.

387 388 389 390

20. De Wilde, T.; De Meulenaer, B.; Mestdagh, F.; Govaert, Y.; Vandeburie, S.; Ooghe, W.; Fraselle, S.; Demeulemeester, K.; Van Peteghem, C.; Calus, A.; Degroodt, J. M.; Verhe, R. Influence of Storage Practices on Acrylamide Formation during Potato Frying. J. Agric. Food Chem. 2005, 53 (16), 6550-6557.

391 392 393

21. Shantha, N. C.; Decker, E. A. Rapid, sensitive, iron-based spectrophotometric methods for determination of peroxide values of food lipids. J AOAC Int 1994, 77 (2), 421-424.

394 395 396

22. Zamora, R.; Olmo, C.; Navarro, J. L.; Hidalgo, F. J. Contribution of phospholipid pyrrolization to the color reversion produced during deodorization of poorly degummed vegetable oils. J. Agric. Food Chem. 2004, 52 (13), 4166-4171. 17



Page 18 of 28

397 398 399 400

23. Wakamatsu, D.; Morimura, S.; Sawa, T.; Kida, K.; Nakai, C.; Maeda, H. Isolation, identification, and structure of potent alkyl-peroxyl radical scavenger in crude canola oil, canolol. Bioscience, Biotechnology and Biochemistry 2005, 69 (8), 1568-1574.

401 402

24. Spielmeyer, A.; Wagner, A.; Jahreis, G. Influence of thermal treatment of rapeseed on the canolol content. Food Chemistry 2009, 112 (4), 944-948.

403 404

25. Shahidi, F. Canola and Rapeseed: production, chemistry, nutrition and processing technology; Van Nostrand Reinhold: New York, 1990.

405 406 407

26. Shrestha, K.; De Meulenaer, B. Antioxidant activity of Maillard type reaction products between phosphatidylethanolamine and glucose. Food Chemistry 2014, 161, 8-15.

408 409

18


Page 19 of 28


Figure captions Figure 1. Mustard (BJ and BJO) and rapeseed meal before and after 20 min of roasting Figure 2. Changes in the visible spectrum of the oil after roasting of B. juncea (A), B. juncea var oriental (B) and B. napus (rapeseed) (C) Figure 3. Changes in the PV of unroasted seed oil, roasted seed oil and canolol added unroasted seed oil of different varieties stored at 104 oC (

0 h,

9 h,

32 h and

98 h)

19



Page 20 of 28

Figure 1.

20


Page 21 of 28


Figure 2. 1.0

A

0.9 0.8

BJ 0

absorbance

0.7 BJ 10

0.6

BJ 90

0.5 0.4 0.3 0.2 0.1 0.0 300

350

400

450

500

550

wavelength (nm) 1.0

B

0.9 0.8

BJO 0

absorbance

0.7 BJO 10

0.6

BJO 90

0.5 0.4 0.3 0.2 0.1 0.0 300

350

400

450

500

550

wavelength (nm) 1.0

C

0.9 0.8

RS 0

absorbance

0.7 RS 10

0.6

RS 90

0.5 0.4 0.3 0.2 0.1 0.0 300

350

400

450

500

550

wavelength (nm)

21


ACS Paragon Plus Environment RS_roasted 90 min

RS_roasted 60 min

RS_roasted 45 min

RS_roasted 30 min

RS_roasted 20 min

RS_roasted 10 min

RS_unroasted + canolol 800 µg/g

RS_unroasted + canolol 300 µg/g

RS_unroasted

BJO_roasted 90 min

BJO_roasted 60 min

BJO_roasted 45 min

BJO_roasted 30 min

BJO_roasted 20 min

BJO_roasted 10 min

BJO_unroasted + canolol 170 µg/g

BJO_unroasted

BJ_roasted 90 min

BJ_roasted 60 min

BJ_roasted 45 min

BJ_roasted 30 min

BJ_roasted 20 min

BJ_roasted 10 min

BJ_unroasted + canolol 300 µg/g

BJ_unroasted

Peroxide value (meq oxygen/kg oil)

Journal of Agricultural and Food Chemistry Page 22 of 28

Figure 3.

50

45

40

35

30

25

20

15

10

5

0

22

Page 23 of 28


Tables Table 1. Effect of seed roasting on different compositional parameters and browning reaction markers of extracted oil variety

roasting time (min)

canolol (µg/g oil)

α-tocopherol (µg/g oil)

γ-tocopherol (µg/g oil)

plastochromanol8 (µg/g oil)

phospholipid phosphorus (µg/g)

absorbance (350 nm)

fluorescence1 (ex. 350 nm, em 440 nm)

pyrrole content (nmol/g)

BJ

unroasted

5.41 ± 0.01 a

89.56 ± 2.39 def

290.34 ± 2.36 hi

39.59 ± 1.43 hij

8.66 ± 1.81 a

0.03 ± 0.01 a

3.65 ± 0.19 a

6.97 ± 1.68 ab

BJ

10

297.76 ± 6.26 e

80.57 ± 0.99 cde

266.84 ± 2.16 efg

39.15 ± 0.81 hi

453.62 ± 51.65 k

0.56 ± 0.03 ghi

64.43 ± 1.34 efg

54.97 ± 4.64 c

BJ

20

301.19 ± 5.31 e

76.92 ± 2.02 cd

244.61 ± 17.93 d

38.16 ± 4.20 hi

319.23 ± 46.62 ijk

0.91 ± 0.13 k

56.71 ± 3.54 de

75.32 ± 6.87 efgh

BJ

30

255.31 ± 5.93 d

71.58 ± 1.89 bc

224.28 ± 3.79 c

36.63 ± 0.22 gh

175.54 ± 49.39 efgh

0.63 ± 0.02 hij

57.76 ± 3.19 de

86.45 ± 6.41 hi

BJ

45

234.56 ± 9.14 d

61.41 ± 5.57 b

221.74 ± 1.44 c

36.77 ± 0.69 hi

133.52 ± 35.91 def

0.63 ± 0.10 hij

64.57 ± 2.72 efg

65.04 ± 3.85 cde

BJ

60

181.82 ± 0.63 c

22.49 ± 1.81 a

200.09 ± 1.19 b

36.89 ± 0.60 hi

110.72 ± 30.13 de

0.70 ± 0.03 ij

71.34 ± 0.72 fghi

65.16 ± 4.43 cde

BJ

90

146.84 ± 12.39 b

12.96 ± 5.08 a

177.95 ± 11.47 a

32.99 ± 1.93 fg

117.74 ± 5.62 def

0.69 ± 0.01 ij

78.00 ± 2.73 ij

91.97 ± 5.66 ij

BJO

unroasted

5.06 ± 0.15 a

97.99 ± 0.82 f

358.49 ± 4.97 j

9.26 ± 0.25 b

15.66 ± 3.72 b

0.03 ± 0.01 a

3.51 ± 0.09 a

4.31 ± 1.50 a

BJO

10

171.64 ± 3.20 bc

89.72 ± 4.69 ef

295.40 ± 10.29 i

26.71 ± 0.88 c

342.57 ± 31.71 jk

0.26 ± 0.03 bc

42.72 ± 3.02 c

81.58 ± 2.44 fghi

BJO

20

174.32 ± 4.02 bc

87.30 ± 1.19 def

293.50 ± 1.57 i

27.61 ± 0.31 cd

271.75 ± 21.58 hijk

0.39 ± 0.02 cdef

43.62 ± 1.61 c

91.88 ± 2.05 ij

BJO

30

163.20 ± 1.25 bc

86.86 ± 0.58 def

291.26 ± 4.59 hi

29.50 ± 1.30 cdef

198.72 ± 21.46 fghi

0.52 ± 0.01 fgh

55.31 ± 1.87 d

89.02 ± 4.11 hi

BJO

45

154.23 ± 1.79 bc

85.65 ± 1.42 def

288.36 ± 4.23 hi

29.10 ± 1.13 cde

167.58 ± 46.28 efgh

0.65 ± 0.00 hij

67.41 ± 0.68 fgh

84.74 ± 2.36 ghi

BJO

60

157.98 ± 2.82 bc

85.42 ± 0.81 de

288.22 ± 2.06 hi

31.10 ± 0.14 def

128.29 ± 5.95 def

0.67 ± 0.00 ij

75.07 ± 2.51 hi

89.77 ± 0.89 hij

BJO

90

146.70 ± 0.49 b

76.61 ± 3.22 cd

283.36 ± 2.45 ghi

31.70 ± 0.80 ef

137.81 ± 41.53 defg

0.77 ± 0.09 jk

85.32 ± 1.73 j

172.31 ± 1.26 k

RS

unroasted

5.19 ± 0.09 a

214.89 ± 4.33 g

274.15 ± 3.81 fgh

1.80 ± 0.09 a

30.45 ± 9.38 c

0.04 ± 0.01 a

12.71 ± 0.28 b

1.92 ± 1.47 a

RS

10

808.48 ± 24.67 i

218.93 ± 14.31 gh

255.05 ± 14.61 de

40.29 ± 2.42 ij

224.15 ± 11.16 ghij

0.23 ± 0.09 b

68.90 ± 5.18 fgh

18.94 ± 9.64 b

RS

20

847.13 ± 22.30 j

222.79 ± 5.62 gh

258.10 ± 5.30 def

43.73 ± 0.77 jk

164.66 ± 19.28 efgh

0.27 ± 0.02 bcd

71.03 ± 1.17 fghi

60.12 ± 14.33 cd

RS

30

809.06 ± 4.22 i

224.49 ± 2.47 gh

260.62 ± 2.85 def

46.26 ± 0.98 kl

188.26 ± 47.47 fgh

0.45 ± 0.08 efg

68.96 ± 1.74 fgh

77.34 ± 1.56 efgh

RS

45

760.45 ± 31.19 h

229.81 ± 3.20 h

261.48 ± 2.61 def

48.01 ± 1.02 l

151.87 ± 12.68 efg

0.41 ± 0.02 defg

67.97 ± 0.71 fgh

71.36 ± 2.36 defg

RS

60

708.26 ± 15.97 g

225.77 ± 4.96 gh

257.19 ± 4.42 de

46.37 ± 0.58 kl

147.60 ± 39.54 defg

0.32 ± 0.11 bcde

63.54 ± 9.07 def

68.62 ± 5.30 cdef

RS

90

650.17 ± 13.83 f

227.06 ± 4.60 gh

257.06 ± 5.65 de

47.06 ± 1.14 kl

88.12 ± 4.96 d

0.36 ± 0.08 bcde

72.17 ± 3.00 ghi

102.20 ± 5.46 j

1

expressed as % of fluorescence of quinine sulphate solution (1 µM in 0.1 M H2SO4)

Values with different letters in a same column are significantly different (p < 0.05)

23



Page 24 of 28

Table 2. Free amino acids content (mg/100 g FFDM) of seeds before and after 10 min of roasting of different varieties BJ (unroasted)

BJO (unroasted)

RS (unroasted)

BJ (roasted 10 min)

BJO (roasted 10 min)

RS (roasted 10 min)

Aspartate

51.72 ± 1.12 d

92.18 ± 0.32 f

85.81 ± 1.74 e

10.23 ± 1.95 a

17.91 ± 0.93 b

25.96 ± 3.06 c

Glutamate

269.00 ± 3.35 b

259.75 ± 4.49 b

304.92 ± 8.12 c

15.11 ± 2.81 a

13.93 ± 0.64 a

23.19 ± 3.82 a

Asparagine

175.12 ± 1.93 e

100.69 ± 0.56 c

145.21 ± 4.04 d

17.76 ± 3.26 b

10.11 ± 0.68 a

21.64 ± 3.09 b

Serine

19.75 ± 1.34 c

42.58 ± 3.55 d

15.34 ± 2.95 c

4.46 ± 0.88 ab

8.88 ± 0.09 b

2.96 ± 0.32 a

Glutamine

6.99 ± 0.16 b

1.92 ± 3.75 a

7.54 ± 0.78 b

0.43 ± 0.07 a

0.36 ± 0.00 a

0.48 ± 0.15 a

Amino acids

Histidine

8.20 ± 0.25 b

9.52 ± 0.64 c

12.13 ± 0.47 d

1.59 ± 0.39 a

1.56 ± 0.14 a

1.58 ± 0.07 a

Glycine

6.35 ± 1.56 bc

12.23 ± 2.50 d

10.17 ± 2.56 cd

1.90 ± 0.37 a

2.99 ± 0.02 ab

3.04 ± 0.18 ab

Threonine

5.68 ± 0.15 b

8.90 ± 0.46 d

6.80 ± 0.32 c

0.91 ± 0.16 a

1.25 ± 0.05 a

1.34 ± 0.19 a

Arginine

28.11 ± 0.18 d

26.46 ± 0.16 c

22.34 ± 0.65 b

5.43 ± 1.03 a

4.14 ± 0.30 a

5.14 ± 0.65 a

Alanine

7.08 ± 0.41 b

15.82 ± 1.10 c

25.16 ± 0.63 d

2.74 ± 0.50 a

4.28 ± 0.29 a

8.65 ± 0.79 b

Tyrosine

4.33 ± 0.08 a

5.61 ± 0.32 b

5.84 ± 0.45 b

n. d.

n. d.

n. d.

Valine

7.82 ± 0.22 b

9.01 ± 0.54 c

11.73 ±0.61 d

0.57 ± 0.11 a

0.84 ± 0.05 a

1.39 ± 0.30 a

Methionine

1.62 ± 1.59 a

1.61 ± 1.57 a

0.64 ± 1.26 a

0.93 ± 0.11 a

1.17 ± 0.06 a

0.90 ± 0.00 a

Tryptophan

8.38 ± 0.23 b

15.71 ± 0.39 c

7.73 ± 0.57 b

0.65 ± 0.16 a

1.08 ± 0.14 a

1.08 ± 0.14 a

Phenylalanine

8.71 ± 0.06 c

15.46 ± 0.37 d

8.49 ± 0.43 c

1.83 ± 0.23 a

2.58 ± 0.14 b

2.26 ± 0.04 ab

Isoleucine

3.08 ± 0.09 c

4.14 ± 0.23 d

4.84 ± 0.22 e

0.14 ± 0.14 a

0.24 ± 0.02 ab

0.58 ± 0.10 b

Leucine

2.66 ± 0.19 b

5.00 ± 0.35 d

3.48 ± 0.53 c

0.08 ± 0.15 a

0.51 ± 0.04 a

0.45 ± 0.07 a

Lysine

6.99 ± 0.32 c

8.96 ± 0.35 d

11.51 ± 1.10 e

1.38 ± 0.21 a

1.24 ± 0.09 a

3.42 ± 0.58 b

Proline Total

3.47 ± 1.67 a

8.13 ± 0.21 b

8.46 ± 0.32 b

2.40 ± 0.27 a

2.83 ± 0.40 a

2.22 ± 0.36 a

625.07 ± 8.77 c

643.66 ± 10.26 c

698.14±15.31 d

68.55 ± 12.03 a

75.90 ± 2.54 a

106.28 ± 13.13 b

n. d. = not detected Values with different letters in a same row are significantly different (p < 0.05) 24


Page 25 of 28


Table 3. Total amino acids content (g/100 g FFDM) of unroasted seeds of different varieties Amino acids

BJ

BJO

RS

Aspartate

2.21 ± 0.04 c

2.07 ± 0.03 b

1.98 ± 0.03 a

Glutamate

6.39 ± 0.10 c

5.96 ± 0.05 b

4.73 ± 0.06 a

Serine

1.61 ± 0.05 c

1.51 ± 0.04 b

1.30 ± 0.02 a

Histidine

1.19 ± 0.02 c

1.09 ± 0.02 b

0.86 ± 0.02 a

Glycine

2.06 ± 0.04 c

1.94 ± 0.03 b

1.66 ± 0.03 a

Threonine

1.68 ± 0.02 c

1.59 ± 0.02 b

1.45 ± 0.02 a

Arginine

2.77 ± 0.04 c

2.59 ± 0.04 b

1.94 ± 0.03 a

Alanine

1.67 ± 0.03 c

1.57 ± 0.01 b

1.38 ± 0.02 a

Tyrosine

1.17 ± 0.03 c

1.08 ± 0.02 b

1.00 ± 0.02 a

Valine

1.84 ± 0.03 b

1.86 ± 0.02 b

1.61 ± 0.03 a

Methionine

0.55 ± 0.02 b

0.57 ± 0.05 b

0.46 ± 0.01 a

Tryptophan

0.43 ± 0.03 ab

0.45 ± 0.03 b

0.37 ± 0.04 a

Phenylalanine

1.68 ± 0.04 b

1.61 ± 0.04 b

1.32 ± 0.04 a

Isoleucine

1.69 ± 0.03 c

1.60 ± 0.02 b

1.37 ± 0.03 a

Leucine

2.71 ± 0.05 c

2.58 ± 0.05 b

2.18 ± 0.04 a

Lysine

2.25 ± 0.08 b

2.21 ± 0.07 b

1.94 ± 0.06 a

Proline

2.72 ± 0.03 c

2.57 ± 0.04 b

2.05 ± 0.03 a

Total

34.62 ± 0.59 c

32.85 ± 0.49 b

27.60 ± 0.47 a

Values with different letters in a same row are significantly different (p < 0.05)

25



Page 26 of 28

Table 4. Changes in the sugar composition (mg/g FFDM) in the seed after 10 min of roasting of different varieties roasting time (min)

fructose

glucose

sucrose

BJ

unroasted

6.70 ± 0.29 d

46.60 ± 1.92 c

51.70 ± 1.62 b

BJO

unroasted

3.80 ± 0.18 b

48.56 ± 2.58 c

62.77 ± 1.37 c

RS

unroasted

3.94 ± 0.27 b

12.43 ± 0.94 b

70.42 ± 2.27 d

BJ

10

5.99 ± 0.22 cd

3.51 ± 0.12 a

33.37 ± 2.85 a

BJO

10

5.16 ± 0.84 c

4.49 ± 0.48 a

48.95 ± 3.04 b

RS

10

1.07 ± 0.03 a

1.44 ± 0.25 a

84.74 ± 5.15 e

Varieties

Values with different letters in a same column are significantly different (p < 0.05)

26


Page 27 of 28


Table 5. Fatty acids composition of oil (g/100g oil) from different mustard and rapeseed varieties Fatty acid

BJ

BJO

RS

16:0

2.6

2.5

4.4

16:1

0.1

0.1

0.2

18:0

1.1

1.3

1.1

18:1

17.8

18.8

53.9

18:2

18.1

19.0

19.8

20:0

1.1

1.2

1.1

20:1

8.4

8.2

0.3

18:3

15.4

13.9

9.7

20:2

1.0

0.9

n. d.

22:0

0.2

0.3

n. d.

22:1

20.6

21.3

n. d.

24:1

1.2

1.2

n. d.

n. d. = not detected

27



Page 28 of 28

Table of contents graphics Total tocopherol (µg/g oil)

600 500 400 300 200

Juncea oriental Rapeseed

100 0 0

20

40

60

roasting time (min)

80

Canolol (µg/g oil)

900 800 700 600 500 400 300 200 100 0

Juncea oriental Rapeseed

0

20

40

60

80

roasting time (min)

28


Effect of Seed Roasting on Canolol, Tocopherol ... - ACS Publications

Recommend Documents