Article

Effects of Stir-Fry Cooking with Different Edible Oils on the Phytochemical Composition of Broccoli

CEBAS-CSIC, Food Science and Technology Dept., P.O. Box 164, 30100-Espinardo, Murcia, Spain.
Journal of Food Science (Impact Factor: 1.7). 02/2007; 72(1):S064-8. DOI: 10.1111/j.1750-3841.2006.00213.x
Source: PubMed

ABSTRACT

Numerous epidemiological studies indicate that Brassica vegetables in general and broccoli in particular protect humans against cancer; they are rich sources of glucosinolates and possess a high content on flavonoids, vitamins, and mineral nutrients. The contents of total intact glucosinolates, total phenolics, vitamin C, and minerals (potassium, sodium, calcium, magnesium, iron, manganese, zinc, and copper) in the edible portions of freshly harvested broccoli (florets), which was subjected to stir-frying treatments, were evaluated. In the present work, the stir-fry cooking experiments were carried out using different edible oils from plant origin (refined olive oil, extra virgin olive oil, sunflower oil, peanut oil, soyabean oil, and safflower oil) known and used worldwide. Results showed that during stir-frying, phenolics and vitamin C were more affected than glucosinolates and minerals. Stir-fry cooking with extra virgin olive, soybean, peanut, or safflower oil did not reduce the total glucosinolate content of the cooked broccoli compared with that of the uncooked sample. The vitamin C content of broccoli stir-fried with extra virgin olive or sunflower oil was similar to that of the uncooked sample, but greater than those samples stir-fried with other oils.

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Available from: Diego A. Moreno, Jan 20, 2014
S: Sensory & Nutritive Qualities of Food
Effects of Stir-Fry Cooking with Different
Edible Oils on the Phytochemical
Composition of Broccoli
DIEGO A. MORENO,CARMEN L
´
OPEZ-BERENGUER, AND CRISTINA GARC
´
ı
A-VIGUERA
ABSTRACT: Numerousepidemiologicalstudies indicate that Brassicavegetablesingeneralandbroccoliinparticular
protect humans against cancer; they are rich sources of glucosinolates and posses a high content on flavonoids,
vitamins, and mineral nutrients. The contents of total intact glucosinolates, total phenolics, vitamin C, and minerals
(potassium, sodium, calcium, magnesium, iron, manganese, zinc, and copper) in the edible portions of freshly
harvested broccoli (florets), which was subjected to stir-frying treatments, were evaluated. In the present work, the
stir-fry cooking experiments were carried out using different edible oils from plant origin (refined olive oil, extra
virgin olive oil, sunflower oil, peanut oil, soyabean oil, and safflower oil) known and used worldwide. Results showed
that during stir-frying, phenolics and vitamin Cwere moreaffected than glucosinolates andminerals. Stir-fry cooking
with extra virgin olive, soybean, peanut, or safflower oil did not reduce the total glucosinolate content of the cooked
broccoli compared with that of the uncooked sample. The vitamin C content of broccoli stir-fried with extra virgin
olive or sunflower oil was similar to that of the uncooked sample, but greater than those samples stir-fried with other
oils.
Keywords: Brassica oleracea, glucosinolate, minerals, phenolics, vitamin C
Introduction
B
rassica species are very rich in health-promoting phytochemi-
cals,including phenolic compounds,vitamin C, glucosinolates,
and minerals (Agte and others 2000; Vallejo and others 2003a, 2003b,
2003c; Anilakumar and others 2006). Food processing has the po-
tential to alter the nutrient quality of plant foods (Mosha and others
1995; Severi and others 1997; Vallejo and others 2002, 2003d). The
methods for broccoli and other cruciferous vegetables for prepara-
tion by means of conventional cooking such as boiling, steaming,
microwaving, and pressure cooking reduce the intake of important
potentiallyhealthprotective andpromotingphytochemicalssuch as
glucosinolates and phenolic compounds (McNaughton and Marks
2003; Vallejo and others 2003d; Verkerk and Dekker 2004).
The effect of cooking on glucosinolates has received a relatively
large amount of attention. Cooking reduces broccoli glucosinolate
levels by approximately 30% to 60%, depending on the method (for
example, conventional, microwave, high pressure), cooking inten-
sity (for example, temperature, time), and the type of compound
(Vallejo and others 2002, 2003d). On the other hand, total and in-
dividual glucosinolates measured in red cabbage after various mi-
crowave treatments showed higher levels of these compounds than
in the untreated vegetable (Verkerk and Dekker 2004).
Broccoli heads used to investigate the effect of the cooking treat-
ments on the texture and the antioxidant properties of this plant
food resulted in slight reductions in 2,2 diphenyl-1-picrylhydrazyl
(DPPH
+
) radical-scavenging activity with respect to fresh material
(Zhang and Hamauzu 2004; Lin and Chang 2005). On the contrary,
the phenolic content of broccoli was either reduced (Vallejo and
MS 20060377 Submitted 7/10/2006, Accepted 10/17/2006. Authors are with
C.E.B.A.S.–C.S.I.C., Food Science and Technology Dept., P.O. Box 164, 30100-
Espinardo, Murcia, Spain. Direct inquiries to author Moreno (E-mail:
dmoreno@cebas.csic.es).
others 2003d) or increased (Turkmen and others 2005) when steam-
ing or microwaving.
High-pressure boiling, steam cooking, microwaving, and low-
pressure boiling (conventional boiling) showed great differences in
their influence on the content of vitamin C in broccoli. Thus, clear
disadvantages were detected when cooking in a microwave due to
the high loss of vitamin C (40%). On the other hand, steaming had
minimal effects on vitamin C when compared to other cooking pro-
cesses (Vallejo and others 2002).
Concerning mineral composition of plant foods, it is well known
that these nutrients (sodium,potassium, calcium, magnesium,iron,
zinc, copper, manganese, and so on) are essential for human health,
and broccoli should be a mineral-rich plant food source (Huarte-
Mendicoa and others 1997; Severi and others 1997; Margen 2002;
Moreno and others 2006). The influence of common frying methods
(frying in an oven or in a pan deep frying) on the nutritive value of
vegetables revealed that after frying vegetable food, the content of
vitamins and minerals was nearly fully retained, while boiling and
steaming reduced the mineralcontent by25% to 50% (Petersen1993;
Schnepf and Driskell 1994; Bognar 1998).
Therefore, the purpose of the present paper was to evaluate the
influence of stir-fry cooking, using edible oils, on the phytochemical
composition (glucosinolates, phenolics, vitamin C, and minerals) of
freshly harvested broccoli inflorescences.
Materials and Methods
Broccoli
Freshly harvested commercial broccoli inflorescences (Brassica
oleracea L. cv. Nubia) were purchased from COATO (Totana, Murcia)
and sampled for 4 h before analysis. Broccoli heads were selected
at maturity or marketable stage (optimum quality heads of 130 ±
10 mm dia, 250 to 280 g wet basis; Vallejo and others 2003a), free from
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S: Sensory & Nutritive Qualities of Food
insect or mechanical damage. Inflorescences (36) were randomly se-
lected and transported to the laboratory, where the inedible parts
were removed using a sharp knife. The broccoli was cut into almost
equal small bite-sized pieces(edible florets, about 3 cm), mixed well,
and divided into portions (150 g). One portion was retained raw,
and others were cooked in triplicate with the different oils as de-
tailed ahead. Cookingparameters and conditions werepreliminarily
determined.
Processing treatments (stir-fry cooking)
Broccoli floret portions (150 g) were placed in the pan for stir-
frying once the ready-to-cook temperature of the corresponding
40 mL of edible oil was reached (ranging 125 to 140
C) in a fry-
ing pan (EU certified 22 cm non-stick ‘Silver’ Vitrex
TM
, Zaragoza,
Spain), and were cooked for 3 min 30 s.
Edible oils for cooking were obtained from different sources
(Table 1). Uncooked and stir-fried broccoli florets were frozen us-
ing liquid nitrogen and kept at 80
C, and then freeze-dried. The
material was subsequently ground into a fine powder and stored at
80
C for further phytochemical analysis. In all these treatments,
the cooking time was established previously by an informal testing
panel consisting of 5 trained people who decided the best conditions
for stir-fried broccoli regarding sensory parameters and the desir-
able relatively short duration when cooking cruciferous vegetables
from a health perspective (Vallejo and others 2002; Rungapamestry
and others 2006).
Glucosinolate extraction and analysis
A modified previously reported procedure (Vallejo and others
2002, 2003a; Bennett and others 2004) was used for extraction of
glucosinolates. In brief, each freeze-dried sample (50 mg) was ex-
tracted in 1.5 mL polypropylene-capped microcentrifuge tubes us-
ing 1500 µL of 70% aqueous methanol, heated at 70
C for 30 min
using a heating bath, with vortex mixing every 5 min, followed by
centrifugation (15 min, 17500 × g,4
C) to pellet insoluble mate-
rial. Subsamples (1000 µL) of each supernatant were taken. Solvent
was completely removed using a rotary evaporator. The dry material
was redissolved in 1000 µL of ultrapure water and filtrated (0.45 µm
Millex-HV, Millipore Corp., Bedford,Mass., U.S.A.) previous to HPLC
analysis. Each sample (20 µL) wasanalyzed ina Waters HPLC system
(Waters Cromatograf
´
ıa S.A., Barcelona, Spain)consisting ofa W600E
multisolvent delivery system, in-line degasser, W717plus Autosam-
pler, and a W2996 Photodiode Array Detector at 227 nm, using a
Table 1 --- Characteristics of the edible oils used in the experiments
Type of commercial edible oil Brand name, company, city, country Nutritional lipid composition
a
Refined olive oil Carbonel, SOS Cu ´etara SA, Madrid, Spain Saturated 13
monounsaturated 79
polyunsaturated 8
Extra virgin olive oil Olisone, LIDL Supermercados SA, Montcada i Rexac, Catalonia, Spain Saturated 14
monounsaturated 77
polyunsaturated 9
Sunflower oil Koipesol, SOS Cu´etara SA, Madrid, Spain Saturated 13
monounsaturated 27
polyunsaturated 60
Soyabean oil Soy oil, Spectrum Organic Products Inc., Petaluma, Calif., U.S.A. Saturated 14
monounsaturated 29
polyunsaturated 57
Peanut oil Planters, Kraft Foods Global Inc., Glenview, Ill., U.S.A. Saturated 12
mono and
polyunsaturated 88
Safflower oil Hollywood, The Hain Celestial Group, Inc., Melville, N.Y., U.S.A. Saturated 7
monounsaturated 79
polyunsaturated 14
a
Nutritional lipid composition in the label (g/100 g).
LiChrospher
100 RP18 column (25 cm × 0.4 cm, 5 µm particle size;
Merck KGaA, Darmstadt, Germany) with a LiChroCART
4-4 guard
column. The mobile phase was a mixture of water:formic acid (99:1)
(A) and acetonitrile (B). Glucosinolates were eluted off the column
in 35 min. The flow rate was 1 mL/min in a linear gradient starting
with 1% B reaching 20% B in 30 min and 1% B at 40 min (Bennett
and others 2004). Samples were then identified, using the previously
described intact glucosinolate LC-MS method, and quantified by
HPLC-DAD using sinigrin (sinigrin monohydrate from horseradish,
Sigma-Aldrich Chemie Gmbh, Steinheim, Germany) as standard.
Extraction and analysis of phenolic compounds
The extraction procedure has been previously described (Vallejo
and others 2003 c,d). Samples (20 µL) were analyzed on a Merck-
Hitachi liquid chromatograph equipped with a pump (L-6200) and
a UV-vis detector (L-7420) (Merck KgaA, Darmstadt, Germany).
Separations were achieved on a LiChroCart column (Merck KGaA,
ODS-18, 25 × 0.4 cm; 5 µm particle size). The mobile phase was
water:formic acid (95:5) (A) and methanol (B). The flow rate was
1 mL/min, and a linear gradient starting with 10% B, reaching 15%
B at 5 min, 30% B at 20 min, 50% B at 35 min, and 90% B at 40
min, was used. Chromatograms were recorded at 320 and 360 nm.
Caffeoyl-quinic acid derivatives were quantified as chlorogenic acid
(5-caffeoyl-quinic acid, Sigma, St. Louis, Mo., U.S.A.), flavonoids
as quercetin 3-rutinoside (Sigma), and sinapic acid derivatives as
sinapinic acid (Sigma).
Extraction and analysis of vitamin C and minerals
Ascorbic acid (AA) and dehydroascorbic acid (DHAA) contents
were determined according to Vallejo and others (2002, 2003c).
HPLC analysis was achieved after derivatization of DHAA into
the fluorophore 3-(1,2-dihydroxyethyl)furo[3,4-b]-quinoxaline-1-
one (DFQ), with 1,2-phenylenediamine dihydrochloride (OPDA).
Samples (20 µL) were analyzed with a Merck-Hitachi (Tokyo, Japan)
HPLC equipped with an L-4000 UV detector and an L-6000 pump.
Separations of DFQ and AA were achieved on a Kromasil 100 C-18
column (25 cm × 0.4 cm; 5 µm particle size; Tecnokroma, BCN,
Spain). The mobile phase was methanol:water (5:95) containing
5 mM cetrimide and 50 mM potassium dihydrogen phosphate at
pH 4.5. The flow rate was 0.9 mL/min, the detector wavelength was
initially set at 348 nm, and after elution of DFQ, it was manually
shifted to 261 nm for AA detection.
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S: Sensory & Nutritive Qualities of Food
Mineral analysis was carried out after HNO
3
-HClO
4
(2:1) acid
digestion of the material. Calcium, magnesium, potassium, iron,
manganese, zinc, and copper concentrations were determined by
ICP-spectrometry (IRIS Intrepid II XDL
; Thermo Electron Corp.,
Franklin Mass., U.S.A.) in a dilution with LaCl
3
+ CsCl of the extract
aliquot, as reported elsewhere.
Statistical analysis
All data were subjected to analysis of variance (ANOVA) using the
MS-DOS version of STATGRAPHICS Plus 7.0 version (StatPoint Inc.,
V.I., U.S.A.). The data shown are mean values (means ± SD) and the
significance of the differences was compared using the Duncans
Test, a multiple range test at 95% confidence level (P < 0.05).
Results and Discussion
Influence of stir-frying on glucosinolates
and phenolic compounds
The total intact glucosinolate contents (Figure 1) in stir-fried
broccoli florets were significantly reduced (P < 0.05) when using
refined olive oil (49% loss) and sunflower oil (37% loss) with respect
to the uncooked controls (43.22 mg/100 g wet basis), whereas the
concentration of these beneficial components remained almost un-
altered when using extra virgin olive, soybean, peanut, or safflower
oils.
Figure 1 --- Total intact glucosinolates
in broccoli inflorescences cooked
(stir-fried) with different edible oils.
Values are mean ±SD (n = 3). Means
followed by the same letter are not
significantly different at P < 0.05,
according to Duncan’s test.
Table 2 --- Phenolics in stir-fried broccoli using different oils
Compound (mg/100 g wet basis)
Treatment (oil) Caffeoyl-quinic acid derivatives Flavonoids Sinapic acid derivatives
Uncooked (control) 19.87 ± 4.75 118.78 ± 32.93 a(
) 7.54 ± 1.84 a(
∗∗
)
Rened olive oil 13.65 ± 1.86 57.28 ± 39.23 b 2.35 ± 1.11 c
Extra virgin olive oil 13.16 ± 3.10 59.47 ± 13.61 b 2.08 ± 0.38 c
Sunower oil 18.89 ± 4.35 73.60 ± 22.53 ab 3.33 ± 0.69 bc
Soybean oil 17.01 ± 4.38 81.94 ± 21.97 ab 4.50 ± 1.99 bc
Peanut oil 18.44 ± 4.69 93.37 ± 9.06 ab 5.33 ± 0.42 ab
Safower oil 16.82 ± 1.82 77.64 ± 7.35 ab 4.21 ± 0.91 bc
Results represents means ± standard deviation, n = 3. Values followed by a different lowercase letter are signicantly different from the uncooked control at
(
) P < 0.05 and (
∗∗
) P < 0.01, according to Duncans test.
Previous findings on cooking cruciferous vegetables (Vallejo and
others 2002; McNaughton and Marks2003; Verkerk and Dekker 2004;
Oerlemans and others 2006; Rungapamestry and others 2006) by
other conventional methods such as steaming, boiling, and mi-
crowaving also reported losses of glucosinolate content. The broc-
coli thermal breakdown and/or the enzymatic degradation at high
temperatures (stir-frying at 125 to 130
C on average) induced a
significant reduction of glucosinolates. However, depending on the
edible oil used, this degradation was different, but we could not
find any relationship between the cooking temperature (125
Cin
peanut oil; 130
C extra virgin and refined olive oils; 135 to 140
C
sunflower, soybean, and safflower oils) or the lipid composition of
the oils (Table 1) and the exerted effect on the glucosinolate levels
(Figure 1).
Regarding polyphenolic composition of broccoli florets, the data
in this study confirmed previously published data on profiling
caffeoyl-quinic acid derivatives, flavonoids, and sinapic acid deriva-
tives (Vallejo and others 2002, 2003d). No significant reductions
(P > 0.05) of the caffeoyl-quinic acid derivatives were observed for
broccoli after stir-frying (Table 2). Flavonoids, more sensitive to the
effects of cooking, as demonstrated by other authors (Vallejo and
others 2003d), suffereda significant (P < 0.05) reduction(50% to 52%
losses) when stir-frying broccoli florets with olive oils (refined and
extra virgin, Table 2). All treatments, except with peanut oil, reduced
the sinapic acid derivatives, but the range of losses varied as follows:
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S: Sensory & Nutritive Qualities of Food
< 40% (soybean oil), about 44% (safflower oil), about 55% (sun-
flower oil), <69% (extra virgin olive oil) about 70% (refined olive oil).
According to previous reports (Vallejoand others2003d; Turkmen
and others 2005), the high temperature conditions of the cook-
ing processes reduced the total phenols (flavonoids, sinapic, and
caffeoyl-quinic derivative contents). When refined and extra vir-
gin olive oils were used, the reductions of the total phenolics were
greater than during steaming (only 11% loss of total phenols), but
similar to the loss during high-pressure boiling (53% loss of total
phenols) and lower than in conventional-boiling or microwaving (
80% loss total phenols) (Vallejo and others 2002, 2003d). Other au-
thors have observed the increased or reduced phenolic content of
broccoli depending on the type of cooking method: boiling, steam-
ing, or microwaving (Turkmen and others 2005).
The cooking method used in the present experiment, stir-frying,
gave data on reduction of the flavonoids and sinapic acid deriva-
tives of broccoli depending on the oil used. Nonetheless, the effect
was completely independent of the cooking temperature but not
of the type of oil, since edible oils from olive origin demonstrated
a negative effect on flavonoids and sinapic acid derivatives. This
prompts future studies of the different cooking treatments (tem-
perature compared with oil quality and composition) on phyto-
chemicals in cooked green vegetables since the information is some-
how limited (Vallejo and others 2003d; Zhang and Hamauzu 2004;
Moreno and others 2006). The differences in the analysis extrac-
Figure 2 --- Vitamin C (ascorbic acid
+ dehydroascorbic acid) in broccoli
orets after stir-fried cooking with
different edible oils. Values are
mean ± SD (n = 3). Means followed
by the same letter are not
signicantly different at P < 0.01,
according to Duncans test.
Table 3 --- Minerals in stir-fried broccoli using different oils
(mg/100 g wet basis)
Treatments Iron Manganese Zinc Copper Potassium Sodium Calcium Magnesium
Uncooked 1.34 ± 0.04 c
0.44 ± .01 0.88 ± 0.06 0.34 ± 0.03 c
∗∗
399.91 ± 18.93 bc
∗∗
33.63 ± 2.69 45.09 ± 2.57 26.56 ± 1.62
Rened olive oil 1.79 ± 0.23 abc 0.42 ± 0.04 0.83 ± 0.09 0.74 ± 0.20 ab 345.33 ± 12.84 c 34.56 ± 0.47 41.98 ± 1.95 21.97 ± 0.17
Extra virgin 1.48 ± 0.28 bc 0.41 ± 0.06 0.83 ± 0.06 0.42 ± 0.07 bc 365.31 ± 19.16 bc 31.07 ± 3.16 34.68 ± 3.16 21.52 ± 2.29
olive oil
Sunower oil 2.02 ± 0.13 a 0.46 ± 0.06 0.97 ± 0.08 1.03 ± 0.21 a 369.35 ± 7.61 bc 33.36 ± 1.22 43.97 ± 0.66 24.36 ± 0.34
Soybean oil 1.42 ± 0.09 bc 0.35 ± 0.02 1.07 ± 0.12 0.41 ± 0.05 bc 409.71 ± 7.51 ab 34.40 ± 1.01 41.46 ± 1.90 21.93 ± 0.73
Peanut oil 1.89 ± 0.28 ab 0.45 ± 0.04 1.01 ± 0.13 0.36 ±. 012 c 407.18 ± 19.06 ab 31.95 ± 4.13 45.99 ± 4.38 25.53 ± 2.19
Safower oil 1.54 ± 0.06 abc 0.39 ± 0.02 1.03 ± 0.16 0.37 ± 0.03 c 459.49 ± 18.12 a 36.12 ± 2.94 42.66 ± 2.21 24.65 ± 0.71
Results represents means ± standard deviation, n = 3. Values followed by a different lowercase letter are signicantly different from the uncooked control at (
) P < 0.05 and
(
∗∗
) P < 0.01, according to Duncans test.
tion and the cooking methods could be also part of the reason for
such reductions, where boiling, baking, and frying resulted in sig-
nificant reductions of phenolics in cooked vegetables (McNaughton
and Marks 2003; Sahlin and others 2004).
Effect of stir-frying on vitamin C and minerals
Vitamin C (ascorbic acid+ dehydroascorbicacid) losses (Figure2)
were significant (P < 0.01), and considerably high for peanut oil,
safflower oil, and soybean oil (40% to 48% loss) or refined olive oil
(80% loss). The content of vitamin C of the uncooked florets was
similar to previously reported concentrations in different broccoli
cultivars and breeding lines (62 to 122 mg/100 g wet basis; Vallejo
and others 2003a, 2003d), but stir-fry cooking induced significant
losses, reaching levels below half of the dietary recommendations
(Recommended Dietary Allowance [RDA] per portion size, for US
population; Margen 2002).
None of the cooked samples showed significantly lower concen-
trations of mineral than the uncooked controls (Table 3). The con-
tent of these nutrients in the cooked florets was in accordance with
the RDA per portion size (for U.S. population, also used in Canada;
Margen 2002) for human nutrition: potassium, calcium, magne-
sium, sodium, and zinc (10%); manganese (45%); iron (15% to 25%
for men; 7% to 11% for women to age 50), and copper (38% to 110%).
The influence of mineral nutrients on fruits and vegetables in
the diet is crucial for human health and wellness, so, natural
Page 4
S: Sensory & Nutritive Qualities of Food
mineral-rich foods like green leafy vegetables should turn out to be
a better strategy for improving nutrition than adding low bioavail-
able elements in supplements or salts (Agte and others 2000). With
respect to minerals in stir-fried broccoli (Table 3), we could confirm
that broccoli is a good source of potassium, sodium, calcium, mag-
nesium, copper, iron, zinc, and manganese (Agte and others 2000;
Margen 2002) after being cooked.
Conclusions
T
he use of stir-frying as domestic or conventional cooking for
broccoli florets, rich in glucosinolates, phenolics, vitamins, and
minerals, revealed different degrees of retention for these health-
promotingcompounds.In terms of the effects of oil quality and com-
position on phytochemicals in cooked broccoli, we found a complex
response. During stir-frying with different edible oils from plant ori-
gin, phenolic composition (flavonoids and sinapic acid derivatives)
was affected by the type of oil used (refined and extra virgin olive oil
presented the highest losses), whereas the response of glucosino-
lates and vitamin C was different (refined olive oil showed highest
loss, but extra virgin olive oil showed a good level of retention), but
minerals were less affected. Further analysis should be carried out in
order to improve our knowledge about the potential for improving
the density of phytochemicals (glucosinolates and phenolics) and
micronutrients (vitamins and minerals) in processed food matrices,
and their respective absorption (bioavailability) to have an effect on
the human metabolism once ingested and digested.
Acknowledgments
The authors wish to thank the CICYT National Programme for the
financial support of this work (AGL2005-00650). Part of this work
was also funded by CSIC (Proyecto Intramural 200470E038). Carmen
L
´
opez-Berenguer was funded by a grant from Seneca Foundation
Comunidad Aut
´
onoma de la Regi
´
on de Murcia (Spain). Diego A.
Moreno thanks the European Social Fund (ESF) and the Spanish
Ministerio de Educaci
´
on y Ciencia for funding through a Ramon y
Cajal postdoctoral contract.
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    • "The decreases registered reached the 8 and 81% for extra virgin olive oil and refined olive oil, respectively. (Moreno et al., 2007b). Steaming, by the contrary, has been shown as the thermal cooking process that causes the lowest vitamin C loss in Brassica foods (Vallejo et al., 2002a; Volden et al., 2009; Francisco et al., 2010). "
    Full-text · Dataset · Feb 2014
    • "The decreases registered reached the 8 and 81% for extra virgin olive oil and refined olive oil, respectively. (Moreno et al., 2007b). Steaming, by the contrary, has been shown as the thermal cooking process that causes the lowest vitamin C loss in Brassica foods (Vallejo et al., 2002a; Volden et al., 2009; Francisco et al., 2010). "
    [Show abstract] [Hide abstract] ABSTRACT: Brassica genus includes known horticultural vegetables with major economical importance worldwide, and involves vegetables of economical importance being part of the diet and source of oils for industry in many countries. Brassicales own a broad array of health-promoting compounds, emphasized as healthy rich sources of vitamin C. The adequate management of pre- and postharvest factors including crop varieties, growth conditions, harvesting, handling, storage, and final consumer operations would lead to increase or preserve of the vitamin C content or reduced losses by interfering in the catalysis mechanisms that remains largely unknown, and should be reviewed. Likewise, the importance of the food matrix on the absorption and metabolism of vitamin C is closely related to the range of the health benefits attributed to its intake. However, less beneficial effects were derived when purified compounds were administered in comparison to the ingestion of horticultural products such as Brassicas, which entail a closely relation between this food matrix and the bioavailability of its content in vitamin C. This fact should be here also discussed. These vegetables of immature flowers or leaves are used as food stuffs all over the world and represent a considerable part of both western and non-Western diets, being inexpensive crops widely spread and reachable to all social levels, constituting an important source of dietary vitamin C, which may work synergistically with the wealth of bioactive compounds present in these foods.
    No preview · Article · Feb 2014 · Critical reviews in food science and nutrition
    • "ining around 36 % of the initial phenolic content. The lower temperature (54 °C) used in the vacuum boiling could be the reason for a lower cell disruption (Fig. 2) and consequently a lower lixiviation rate. Vitamin C The initial total vitamin C content (1,736.6 mg kg −1 fw) generally decreased after all cooking methods, except for frying (Fig. 3). Moreno et al. (2007) found that vitamin C of conventional Nubia broccoli did not decrease after stirfrying for 3 min and 3 s in extra virgin olive oil at 125– 140 °C. Vitamin C content dropped between 40 and 80 % when using soy, peanut, safflower and refined olive oil. The observed ascorbic acid retention after stir-frying with extra virgin olive oil may be"
    [Show abstract] [Hide abstract] ABSTRACT: The microbial, physical, sensory and nutritional quality of boiled (vacuum and conventional), steamed, pressure cooked, sous vide, microwaved (sous vide and conventional), deep-fried (vacuum and conventional) and grilled kailan-hybrid broccoli (Bimi®) after cooking was studied. Sous vide microwaving greatly decreased microbial counts, achieving very low psychrophilic and enterobacteria counts (1.1 and 0.2 log CFU g−1, respectively). Vacuum boiling and sous vide reduced the stem broccoli firmness by approximately 54–58 %, reaching a pleasant and moderate softening. Sous vide, grilling and steaming induced the lowest stem colour changes. Generally, all cooking treatments showed a good overall sensory quality. The total phenolic content (1,148 mg CAE kg−1 fw) usually increased after cooking, with microwave and grilled treatments registering the highest increases up to 2-fold. Commonly, the total antioxidant capacity (296.6 mg AAE kg−1 fw) increased after cooking by sous vide, microwaving and frying treatments registering the highest increments, by approximately 3.6-fold. Generally, the cooking process reduced the initial vitamin C content, with vacuum and conventional boiling showing the lowest and highest losses with 27 and 62 %, respectively, while vacuum deep frying preserved the initial value (1,737 mg kg−1 fw). As a main conclusion, the studied grilling and vacuum-based cooking treatments resulted in better microbial quality, colour, stem firmness and sensory quality than the remaining ones. This maintained or even improved the total antioxidant content of the new kailan-hybrid broccoli studied.
    No preview · Article · Aug 2012 · Food and Bioprocess Technology
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