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Food Science and Technology International
DOI: 10.1177/1082013203009002006
2003; 9; 101Food Science and Technology InternationalH. Dogan and M. V. Karwe
Physicochemical Properties of Quinoa Extrudates
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Physicochemical Properties of Quinoa Extrudates
H. Dog an1 andM.V. Karwe2,*
1TUBITAK Marmara Research Center, Food Science and Technology Research Institute,P.O. Box 21, Gebze/Kocaeli, 41470, Turkey
2Food Science Department, Rutgers University, 65 Dudley Road, New Brunswick, NJ, 08901 USA
Response surface methodology (RSM) was used to analyse the effect of temperature, screw speed, and
feed moisture content on physicochemical properties of quinoa extrudates. A three-level, three-variable,
Box-Behnken design of experiments was used. The experiments were run at 1624% feed moisture content,
130170C temperature, and 250500 rpm screw speed with a fixed feed rate of 300 g/min. Second order
polynomials were used to model the extruder response and extrudate properties as a function of process
variables. Responses were most affected by changes in feed moisture content and temperature, and to a
lesser extent by screw speed. Calculated specific mechanical energy (SME) values ranged between 170
402 kJ/kg which were lower than those observed for other cereals, most likely due to high (7.2%) fat
content of quinoa. High levels of feed moisture alone, and in combination with high temperature, resulted
in poor expansion. The best product, characterised by maximum expansion, minimum density, high degree
of gelatinization and low water solubility index, was obtained at 16% feed moisture content, 130 C die
temperature, and 375 rpm screw speed, which corresponds to high SME input. It was demonstrated that
the pseudo-cereal quinoa can be used to make novel, healthy, extruded, snack-type food products.
Key Words: quinoa, extrusion cooking, physico-chemical properties
INTRODUCTION
Quinoa (Chenopodium quinoa Willd.) is a disc shaped
small seed that looks like a cross between sesame seed
and millet. It is a crop that has been grown in South
American countries for centuries and has many poten-
tially beneficial properties such as resistance to cold
(Becker and Hanners, 1990; Coulter and Lorenz, 1991a;
Prakash et al., 1993). It can be grown in poor soil and athigh altitude (Ng et al., 1994). The edible seed of the
quinoa plant has been called both a pseudo-cereal and a
pseudo-oilseed because of its unique nutritional profile.
It has been recently identified to have promising
potential to overcome worlds food shortage (Ahamed
et al., 1996). The seeds have protein quality comparable
to that of whole dry milk in terms of balanced amino
acid composition (Ng et al., 1994). Quinoa protein is
rich in lysine, methionine and cysteine (Becker and
Hanners, 1990). Thus, it is a good complement for
legumes, which are often low in methionine and
cysteine. Some types of wheat come close to matching
protein content of quinoa, but cereals such as corn andrice generally have less than half the protein content of
quinoa. In addition, quinoa is a relatively good source
of vitamin E, and several of the B vitamins (Ruales and
Nair, 1993; Ahamed et al., 1996). It also has desirable
fatty acid composition, and high levels of calcium, iron
and phosphorous (Ruales and Nair, 1993; Przybylsk
et al., 1994) which make it a unique food source.
The Aztecs and Incas credited quinoa with medicina
properties including lowering blood cholesterol, improv-
ing glucose tolerance and reducing insulin requirements
(Guzman-Maldonado and Paredes-Lopez, 1998). In
recent years, scientific information supporting the
health benefits of quinoa has accumulated (Guzman
Maldonado and Paredes-Lopez, 1998). Quinoa contains
significant amounts of flavonoids and phenolic acids
and a number of structurally diverse saponins (Ridout
et al., 1991; Gee et al., 1993; Ng et al., 1994
Masterbroek et al., 2000). Saponins can help lower
cholesterol blood levels, inhibit growth of cancer cells
eliminate digestive toxins, and strengthen the immune
system (Arditi et al., 2000). Phenolic derivatives act as
natural antimicrobial agents. They have been proven to
be very good antioxidants, scavenging free radicals and
providing metal chelating activities. Polyphenols havebeen implicated in health benefits, such as prevention of
cancer and cardiovascular diseases.
This unique added chemical composition makes
quinoa an ideal candidate to be further studied for
establishing it as a functional food. Processing o
traditional grains like quinoa into products that deliver
nutritive as well as physiologically active components
represents a major opportunity for food processors
catering to the health-food market.
Extensive studies on extrusion processing of cereals
such as corn and wheat, to generate ready-to-ea
*To whom correspondence should be sent(e-mail: [email protected]).Received 11 July 2002; revised 18 December 2002.
Food Sci Tech Int 2003;9(2):010114 2003Sage PublicationsISSN: 1082-0132DOI: 10.1177/108201303033940
101at UNIV DE SAO PAULO BIBLIOTECA on September 25, 2009http://fst.sagepub.comDownloaded from
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breakfast cereals and snacks, have been carried out
(Chinnaswamy and Hanna, 1990; Case et al., 1992; Cai
and Diosady, 1993; Guha et al., 1997). The only study
reported in literature on extrusion of quinoa (Coulter
and Lorenz, 1991a, b) is about the nutritional, sensory
and physical characteristics of quinoa-corn grit blends
(up to 30 : 70 ratio) extruded at 1525% feed moisture
content, 100150C, 100200 rpm screw speed, and at1 : 1 and 3 : 1 compression ratios on a Brabender
Plasticorder single-screw extruder. Although the pro-
ducts extruded at 15% moisture content and a 3 : 1
compression ratio had a greater expansion, lower
density and lower shear strength, addition of quinoa
to corn grit resulted in a general decrease in product
quality and an increase in extrusion rate under all
processing conditions.
In our research we focused on the investigation of
processability of quinoa flour by twin-screw extrusion
and the evaluation of physicochemical properties of
extruded quinoa in comparison to unprocessed grains.
This paper treats the effect of feed moisture content,die temperature, and screw speed on process and
product responses during twin-screw extrusion of
quinoa flour.
MATERIALS AND METHODS
Material
Quinoa seeds (Chenopodium quinoa Willd) were
obtained from Quinoa Corporation (Torrance, CA)
and milled into flour using a Fitz Mill (Model D).
Proximate Analysis
For the proximate composition analysis of quinoa
flour the following methods were used (AACC, 1984).
Moisture: oven drying at 103C (method no. 4415A).
Ash: calcination at 550C (method no. 0801)
Lipids: defatting in a soxhlet apparatus with petro-
leum ether (method no. 3010)
Protein: micro Kjeldahl (N 6.25) (method no. 4613)
CHOfiber: by the difference.
Amylose content was determined by the method
proposed by Chrastil (1987). The method is based on
spectrophotometric measurement of the intensity of blue
color formed due to complex formation between
amylose and iodine.
Extrusion
Extrusion experiments were carried out on a twin-
screw extruder (ZSK-30, from Krupp Werner &
Pfleiderer, Ramsey, New Jersey). The extruder has two
co-rotating, self-wiping screws (30.7 mm diameter,
4.7 mm channel depth, and 878mm processing length;
L/D 28.6) in a steel barrel with five zones. Each zone is
heated by resistive electric heaters and the temperature of
each zone can be controlled independently. The screw
configuration used in extrusion experiments consisted of
forward conveying elements, mild mixing elements,
kneading elements and reverse elements (Table 1). Die
pressure was measured using a Dynisco pressure trans-
ducer (TPT463E, Dynisco, Sharon, MA). The die had
two circular orifices (3 mm diameter, 5 mm long). Quinoa
flour was metered into the feed section of the extruder
with a volumetric feeder (K-Tron Corp., Pitman, NJ).
Water was injected into the feed section of the extruder
immediately after the feed port using a triple action
piston pump (US Electric Co., Milford, CT). Both the
feeder and the pump were calibrated prior to extrusion
runs to determine the set points required for desired massflow rates of quinoa flour and water, respectively.
Throughput or the total mass flow rate (flour water)
was kept constant at 300 g/min for all experiments.
Temperatures at zones I, II, and III were set to room
temperature, 80 and 120C, respectively, while the
temperatures at zones IV and V were adjusted such that
the desired die temperatures could be maintained.
Table 1. Screw configuration used for quinoa extrusion.
Extrusion zones*
Feed zone
(84mm)
Zone I
(196mm)
Zone II
(210mm)
Zone III
(178mm)
Zone IV
(98mm)
Zone V
(84mm)
Die zone
(28mm)SK 42/42 42/21 T 28/28 28/14 20/10 KB 45/5/14 14/14
SK 42/42 42/42 28/28 KB 45/5/14 20/10 KB 45/5/14 LH 14/14
42/42 IGEL 42 20/20 KB 45/5/20 14/14
42/21 28/28 20/20 20/10 LH 14/14
IGEL 42 28/28 20/20 20/10 14/14
28/28 KB 45/5/28 20/20 20/10 14/14
28/14 20/20 14/14
28/14 KB 45/5/20 14/14
20/10 LH
20/10
20/10
*IGEL: mild kneading element. KB: kneading block. LH: left handed (reverse) element. SK: feed element.T: transition element.
102 H. DOGAN AND M.V. KARWE
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Experimental Design
Response surface methodology was used to investi-
gate the effects of extrusion conditions on the product
and process responses of quinoa. Results from pre-
liminary trials were used to select suitable extruder
operating window. The independent variables con-
sidered in this study were feed moisture content(1624% w.b.), die temperature (130170C), and
screw speed (250500 rpm). A three-variable, three-
level, Box-Behnken design (Table 2) was employed to
determine the extrusion conditions. Experiments were
randomized in order to minimize the systematic bias in
the observed responses due to extraneous factors.
Preparation of Samples
Samples were collected under steady state conditions
of pressure, torque and temperature. Immediately after
extrusion, extrudates were cooled, packed into glass jars,
flushed with nitrogen gas, sealed and kept refrigerated(5C) until analysis.
Process Responses
The ZSK-30 extruder is equipped with a torque
indicator which shows % torque which is proportional
to the current drawn by the drive motor. A reading
of 100% torque corresponds to the max allowable
torque of 172 Nm. The specific mechanical energy
(SME) was calculated from the measured torque reading
as follows (Godavarti and Karwe, 1997):
SME kJ=kg
Total torque (%) Friction torque (%) N 9:1
100 500mf
1
The drive motor has a rated power of 9.1 kW at a
rated screw speed of 500 rpm. The friction torque was
measured with screws attached to the drive and the
barrel empty.
The determination of specific energy delivered
(SED) to the extrudate is based on the energy balance
(Figure 1) between the inlet and just before the exit at
the die of the extruder under steady state conditionscomputed from the following equations,
mfCpiTi QH QC ME mfCpo Tp 2
QH QC
mf
ME
mf Cpo Tp CpiTi 3
SME and SED were measured from experimenta
conditions and STE was calculated from Equation (4).
STE SME SED 4
Negative value of specific thermal energy (STE)
indicates net cooling at the barrel.
Product Responses
Extrudate samples used for determination of the
degree of gelatinization (DG), water solubility index
(WSI), and water absorption index (WAI), were dried at
45
C overnight to 45% moisture. Dried samples wereground and passed through 28-mesh sieve (590mm
opening), and the flour samples were placed in glass
jars and sealed. The method proposed by Birch and
Priesty (1973) was used for determination of the DG
The method was based on the monitoring of the
complexation of iodine with amylose released due to
starch gelatinization. The results reported are the mean
of five measurements for each extrudate sample.
Water solubility index and water absorption index of
both unprocessed quinoa and extrudate samples were
determined by the method of Anderson et al. (1969) with
Table 2. Experimental design for extrusion of quinoa.
Coded Levels Actual Levels
X1 X2 X3 M(% wb) T(C) S (rpm)
1 1 0 24 170 375
1 1 0 24 130 375
1 1 0 16 170 375
1 1 0 16 130 375
0 1 1 20 170 500
0 1 1 20 170 250
0 1 1 20 130 500
0 1 1 20 130 250
1 0 1 24 150 500
1 0 1 24 150 250
1 0 1 16 150 500
1 0 1 16 150 250
0 0 0 20 150 375
0 0 0 20 150 375
0 0 0 20 150 375Figure 1. Schematic diagram showing the barrel oextruder and various energy flows.
Quinoa Extrudates 103
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some modifications. WSI was calculated as follows:
WSI g water soluble matter
g dry sample 5
For the calculation of WAI the total solids in the
original sample were corrected for the loss of solubles inthe supernatant and WAI was expressed as,
WAI g water absorbed
g dry sample 1 soluble fraction 6
Product density (e) was measured by volumetric
displacement method as described by Hicsasmaz and
Clayton (1993). Glass beads of 0.5 mm diameter
(Biospec Products, Inc., Bartlesville, OK) were used as
displacement medium. Density of glass beads was
determined as 1550 kg/m3, then the density of extrudates
was calculated as
e We
Wgbgb 7
The e values were obtained from five random
samples for each extrusion condition, with three
replications.
The sectional expansion index (SEI) of extrudate was
measured as the ratio of the diameter of the extrudate to
that of the die. The extrudate diameter was measured
with a digital Vernier caliper and the results were
expressed as the average of hundred measurements on
each condition. The longitudinal (LEI) and volumetric
expansion (VEI) indices were calculated according to
Alvarez-Martinez et al. (1988).
Textural properties of extrudates were measured using
TA-XT2 texture analyser (Stable Micro Systems, UK).
A three-point bend rig with a support length (bridge) of
30mm and a rounded plate probe (15 mm 5mm,
D 5 mm) exerting force in the middle of bridge were
used to test extrudates in the bend mode (Zasypkin and
Lee, 1998). The test speed was 2 mm/s and the full load
scale was 50 kg. Data were processed with an XT-RA
Dimension software package (Stable Micro Systems,Haslemere, Surrey, UK). The hardness of dry extrudates
was measured as the peak force offered by the sample
during cutting. Breaking strength (N/mm2) was calcu-
lated as the peak breaking force (N) divided by the
cross-sectional area (mm2) calculated for each extrudate
sample. The reported values are the averages of 15
measurements.
The color of ground unprocessed quinoa and
extrudate samples was measured in triplicate using
Minolta Chroma Meter (CR-210) in terms of Hunter
Lab values (L,a,b), where L represents lightness with 0
for dark and 100 for bright, a represents the extent of
green colour in the range from 100 to 0 and red in the
range 0 to 100, b quantifies blue colour in the range
from 100 to 0 and yellow in the range from 0 to 100.
The total colour change (E) was then calculated as
Effiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffiffiffiffiffiffiL 2 a 2 b 2
q 8
where L LL0, ia aa0, and b bb0; the
subscript 0 indicates initial colour values before
processing.
Analysis of Data
Process responses (SME, SED, STE, SME/SED) and
product responses (iE, e, WAI, WSI, DG, SEI, LEI,
VEI, hardness and breaking strength) obtained as a
result of the proposed experimental design were
subjected to regression analysis in order to assess theeffects of feed moisture content, extrusion temperature
and screw speed. Second-order polynomials of the form
yi b0 X3i1
biXi X3i1
X3ji
bijXiXj 9
were fitted to the independent variables and were
computed by using SAS (version 8.1) statistical package,
where Xi, XiXi and XiXj are linear, quadratic, and
interaction effect of the input variables which influence
the response y, respectively, and b0, bi, and bij are themodel constants to be determined. All crosscorrelations
between the process and product responses themselves
were also assessed. The response surface plots for these
models were plotted as a function of two variables, while
keeping the third variable constant at its intermediate
value.
RESULTS AND DISCUSSION
Composition of grain could vary with variety and
growing conditions, even though experimental results forcomposition (Table 3) agreed with previous data (Becker
and Hanners, 1990; Coulter and Lorenz, 1990; Guzman-
Maldano and Paredes-Lopez, 1998; Koziol, 1992;
Prakash et al., 1993; Ruales and Nair, 1993). The
quinoa seeds used in this study have high crude protein,
crude fat and ash than common cereals, such as rice and
corn. Extrudates of widely different physical structure
were obtained by twin-screw extrusion of quinoa flour at
differentcombinations ofprocessingparameters (Table2).
Regression analyses of the physicochemical properties of
quinoa extrudates (Table 4) indicated that all the second
104 H. DOGAN AND M.V. KARWE
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order polynomial models correlated well with the mea-
sured data and were statistically significant (p < 0.05).
Process Responses
Calculated SME values ranged between 170 and
402 kJ/kg. The regression analysis results (Table 4)
revealed that temperature (T), feed moisture content
(M) and screw speed (S) had linear and significant
(p
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Table 4. Results of regression analysis (calculated on coded levels where all independent variables a
Levels
Degree of
Geltn
Density
(kg/m3)
Sectional
Expansion
Index
Longitudinal
Expansion
Index
Volumetric
Expansion
Index
Water
Solubility
Index
(g/g)
Water
Absorption
Index
(g/g) iE
Hardness
(N)
Breaking
Strength
(N/mm2)
Spe
Mecha
Ene
(kJ/
C 0.781*** 246.7*** 2.75*** 0.630** 4.78*** 0.202*** 6.03*** 21.35*** 3.62*** 0.068*** 258.
M 0.046*** 88.1*** 0.43*** 0.090ns 1.67*** 0.025*** 0.57*** 1.88*** 0.19ns 0.041*** 37.9
T 0.058*** 30.4*** 0.73*** 0.650*** 0.99** 0.017*** 0.14** 0.84** 1.04*** 0.028*** 59.3
S 0.034*** 38.0*** 0.15* 0.010ns 0.61ns 0.021*** 0.20*** 0.53ns 0.17ns 0.016** 51.
M M 0.033** 57.9*** 0.24** 0.296ns 0.33ns 0.026*** 0.33*** 1.49** 0.46* 0.017* 15.6
T T 0.037*** 34.6** 0.39*** 0.711** 0.96ns 0.031*** 0.15* 2.67*** 0.62** 0.021** 23.
S S 0.041*** 38.2** 0.04ns
0.364ns
0.77ns
0.009** 0.19** 0.25ns
0.34ns
0.001ns
9.M T 0.015ns 4.0ns 0.17ns 0.218ns 0.92ns 0.002ns 0.53*** 0.10ns 0.07ns 0.017* 11.
M S 0.015ns 18.8ns 0.10ns 0.038ns 0.05ns 0.003ns 0.02ns 0.76ns 0.32ns 0.006ns 9.
T S 0.009ns 26.8** 0.02ns 0.098ns 0.66ns 0.011** 0.06ns 0.10ns 0.15ns 0.004ns 7.
R2 0.98 0.98 0.98 0.90 0.89 0.99 0.98 0.96 0.94 0.97 0.
F 28.28 28.68 24.65 5.25 4.59 102.6 27.13 13.97 9.48 16.14 21.
Sig. F 0.001 0.001 0.001 0.041 0.052 0.000 0.001 0.005 0.012 0.003 0.
C: model constant; M , Tand S: linear effects of moisture content, die temperature and screw speed, respectively. M M, T Tand S S: quadratic effects of moistrespectively;.M T, M S and T S: interaction effects of moisture content and die temperature, moisture content and screw speed, and die temperature and screw**significant at p
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(T), screw speed (S) and moisture (M), and the
quadratic effects of screw speed (S S) and tempera-
ture (T T) had the highest impact, significant at
p
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In general, low feed moisture and high product
temperature have been found to increase the DG in
extrusion of starchy materials (Bhattacharya and
Hanna, 1987; Cai and Diosady, 1993). However, in the
presence of lipids, extrusion temperature required for
maximum DG was in the intermediate range. Lower
temperatures compensated for the decrease in melt
viscosity due to lipids (Dog an, 2000). In high lipidcontaining cereals like quinoa, excessive feed moisture
acts as a secondary lubricant which prevents the
achievement of appropriate development or cooking of
dough by shear induced disruption. In this study, DG
was found to be highly correlated (0.81, p
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decreased with increasing temperature (Figure 5), which
can be explained by the negative effect of temperature
on the elasticity of extrusion cooked melts (Launay and
Lisch, 1983). This result is in agreement also with the
work of Ilo et al. (1999). On the other hand, longitudinal
expansion appeared to be extensively favored by lower
melt viscosity at higher temperature and higher moisture
level (Figure 6).Volumetric expansion index, the multiplication pro-
duct of SEI and LEI, was affected only by feed moisture
content (p
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giving a minimum value at about 140C die tempera-
ture, 19.1% feed moisture, and 425 rpm screw speed.
The mechanical properties of extruded products can
be described either by compressive deformation or by
breaking strength (Colonna et al., 1989). Breaking
strength is the measure of the strength of cell wall
which is expected to affect the texture and sensory
crispiness of the extruded product (Chen et al., 1991).Breaking strength was found to be highly correlated
with SEI (0.85,p
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feed moisture content due to the fact that high thermal
and mechanical energy inputs favour starch dextriniza-
tion (Figure 9). Low WSI values were observed at
intermediate to low temperature levels at all processing
conditions. The increase in WSI with increasing
temperature was consistent with the results reported
for oat extrudates (Singh and Smith, 1997). The
WSI decreased with the increase in moisture. Similareffects of decreasing moisture on WSI have been
reported earlier for starch, maize grits, wheat and pea
flour (Della Valle et al., 1994; Kirby et al., 1988).
Minimum WSI of 0.186 g/g was achieved at 18.3% feed
moisture content, 140C die temperature, and 192 rpm
screw speed.
The poor correlation between WSI and most of the
process and product responses (Table 5) may be
explained by the fact that WSI includes the opposing
effects of starch dextrinization and the molecular level
interactions between degraded components, which may
not be favoured at the same condition. An increase in
the amount of dextrinized starch during extrusion
cooking results in an increase in WSI. However
molecular interactions between degraded starch, pro
tein, and lipid components, which in turn lead to anincrease in molecular weight, may decrease the solubi-
lity, thus WSI. Moreover, according to the mode
proposed by Gomez and Aguilera (1984) for starch
degradation during extrusion cooking, three pure states
i.e., raw, gelatinized, and dextrinized, of starch exis
together. Due to different states in which starch is found
in extrudates, some granules may be underprocessed
while some others may be overprocessed or dextrinized
According to the same model, dextrinization can be
considered to take place together with or right after
adequate gelatinization. According to our experimental
results, thermal and mechanical input seemed to be
enough for sufficient starch gelatinization but not severeenough to favour starch dextrinization. SME values
were not high enough to cause dextrinization, which in
turn increases WSI. This is also evident by the high
correlation coefficient between SME and DG (0.81
p 0.10).
Water absorption index depends on the availability of
hydrophilic groups and on the gel formation capacity of
the macromolecules (Gomez and Aguilera, 1983). It is a
measure of damaged starch together with protein
denaturation and new macromolecular complex forma-
tions. WAI of extrudates ranged between 4.45 and
6.72 g/g which was significantly higher than that o
(1.69g/g) unprocessed quinoa. The regression analysis
(Table 4) showed that the linear effect of feed moisture
content (M), and the interaction effect of die tempera-
ture and moisture content (T M) were highly sig
nificant on WAI. Singh and Smith (1997) reported an
increase in WAI with the increase in moisture and
temperature during extrusion of oats, which is in
agreement with our experimental results (Figure 10)
WAI had poor correlations with almost all process and
product responses except product density (Table 5). This
is an expected result since it includes the effect of starch
gelatinization, protein denaturation and molecular levelcrosslinking reactions which are not always favoured at
the same conditions.
Colour
Colour is an important quality parameter since i
reflects the extent of chemical reactions and degree of
cooking or degradation that take place during extrusion
cooking. In this study, E represents the total colour
difference compared to the colour of unprocessed
quinoa. Higher E means darker products with more
Figure 9. Effect of feed moisture content, die tem-perature and screw speed on water solubility index(WSI, g soluble matter/g dry sample).
Quinoa Extrudates 111
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intense yellow and red colour. The total colour change
in extruded products ranged between 15.5 and 23.7
(Table 4). Quadratic effect of temperature (T T) and
the linear effect of feed moisture content (M) were
found to have the highest contribution to total colour
change. Low feed moisture content and high tempera-
ture increased the total colour change possibly due toincreased extent of browning reactions under this
condition (Figure 11). Although, the screw speed was
not a significant parameter (Table 4), at low screw
speeds a slight increase in colour change observed due to
longer residence times which might increase the extent of
chemical reactions.
In summary, because the high lipid and low amylose
contents, extrusion cooking of quinoa required proces-
sing conditions that provide high shear environ-
ment indicated by high SME values which disrupts
starch granules. Extrusion cooking conditions that
produced quinoa products with desirable expansion
characteristics were at low moisture, low temperature
and medium screw speed within the range of our process
variables.
NOMENCLATURE
Cp heat capacity (kJ/kg.K)
LEI longitudinal expansion index (dimensionless)
ME rate of mechanical energy input (dissipa-
tion) (W)
mf total mass flow rate (kg/s)
N screw speed (rpm)
QC rate of energy removal by the cooling sys-
tem (W)
QH rate of heat generation (W)
SED specific energy delivered (kJ/kg)
SEI sectional expansion index (dimensionless)
Figure 10. Effect of feed moisture content, dietemperature and screw speed on water absorptionindex (WAI, g H2O/g dry sample).
Figure 11. Effect of feed moisture content, die
temperature and screw speed on total color change(E).
112 H. DOGAN AND M.V. KARWE
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SME specific mechanical energy (kJ/kg)
STE specific thermal energy (kJ/kg)
Ti inlet temperature of the product (C)
To outlet temperature of the product (C)
Td die temperature or product temperature (C)
VEI volumetric expansion index (dimensionless)
WAI water absorption index (g water absorbed/g dry
sample)We weight of extrudate (kg)
Wgb weight of glass beads displaced by the extru-
dates (kg)
WSI water solubility index (g water soluble matter/g
dry sample)
E total colour change
e density of extrudate (kg/m3)
gb density of glass beads (kg/m3)
ACKNOWLEDGEMENTS
This is publication No. D 01544-01-01 of the NewJersey Agricultural Experiment Station supported by
State funds and the Center for Advanced Food
Technology (CAFT). The Center for Advanced Food
Technology is a New Jersey Commission on Science
and Technology Center. Author H. Dog an acknowl-
edges the financial support from TUBITAK Marmara
Research Center, Food Science and Technology Res-
earch Institute, Turkey.
REFERENCES
AACC (American Association of Cereal Chemists, 1984).AACC Approved Methods. Vol. II. Minneapolis,Minnesota: AACC.
Ahamed N.T., Singhal R.S., Kulkarni P.R. and Pal M.(1996). Physicochemical and functional properties ofChenopodium quinoa starch. Carbohydrate Polymers 31:99103.
Akdog an H. (1996). Pressure, torque, and energy responseof a twin screw extruder at high moisture contents. FoodResearch International29: 423429.
Alvarez-Martinez L., Kodury K.P. and Harper J.M.(1988). A general method for expansion of extrudedproducts.Journal of Food Science 53: 609615.
Anderson R.A., Conway H.F., Pfeifer V.F. and GriffinL.E.J. (1969). Gelatinization of corn grits by roll-andextrusion cooking. Cereal Science Today 14: 412.
Arditi T., Meredith T. and Flowerman P. (2000). Renewedinterest in soy isoflavonoids and saponins. Cereal FoodsWorld45: 414417.
Atwell A., Patrick B.M., Johnson L.A. and Glass R.W.(1982). Characterization of quinoa starch. CerealChemistry 60: 911.
Becker R. and Hanners G.D. (1990). Compositional andnutritional evaluation of quinoa whole grain flour and
mill fractions. Lebensmittel-Wissenschaft und-Technologie-Food Science and Technology23: 441444.
Bhattacharya M. and Hanna M.A. (1987). Kinetics ostarch gelatinization during extrusion cooking.Journal ofFood Science 52: 764766.
Bhattacharya S. and Choudhury G.S. (1994). Twin-screwextrusion of rice flour: effect of extruder length-to-
diameter ratio and barrel temperature on extrusionparameters and product characteristics. Journal of FoodProcessing and Preservation 18: 389406.
Bhattacharya S. (1997). Twin-screw extrusion of rice-greengram blend: extrusion and extrudate characteristicsJournal of Food Engineering 32: 8399.
Birch G.G. and Priesty R.J. (1973). Degree of gelatinizationof cooked rice. Starch-Staerke 25: 98103.
Cai W. and Diosady L.L. (1993). Model for gelatinizationof wheat starch in a twin-screw extruder. Journal of FoodScience58: 872887.
Case S.E., Hamann D.D. and Schwartz S.J. (1992). Effectof starch gelatinization on physical properties oextruded wheat-and corn-based products. CereaChemistry 69: 401404.
Chavez-Jauregui M.E., Silva M.P. and Areas J.A.G(2000). Extrusion cooking process for amaranth
Journal of Food Science 65: 10091015.
Chen J., Serafin F.L., Pandya R.N. and Daun H. (1991)Effects of extrusion conditions on sensory properties ofcorn meal extrudates.Journal of Food Science 56: 8489
Chinnaswamy R. and Hanna M.A. (1990). Macromolecularand functional properties of native and extrusion cookedcorn starches.Cereal Chemistry 67: 490499.
Chrastil J. (1987). Improved calorimetric determination ofamylose in starch or flour. Carbohydrate Research 159154158.
Colonna P., Tayeb J. and Mercier C. (1989). Extrusioncooking of starch and starchy products. In: Mercier C.P. Linko and J. M. Harper (eds), Extrusion CookingMinneapolis, Minnesota: AACC. pp. 247319.
Coulter L.A. and Lorenz K. (1990). Quinoa: compositionnutritional value, food applications. Lebensmittel-Wissenschaft und Technologie-Food Science andTechnology23: 203207.
Coulter L.A. and Lorenz K. (1991a). Extruded corn grits-quinoa blends: I. Proximate composition, nutritionaproperties and sensory evaluation. Journal of FoodProcessing and Preservation 15: 231242.
Coulter L.A. and Lorenz K. (1991b). Extruded corn grits-
quinoa blends: II. Physical characteristics of extrudedproducts.Journal of Food Processing and Preservation15231242.
Della Valle G., Kozlowski A., Colonna P. and Tayeb J(1989). Starch transformations estimated by the energybalance on a twin-screw extruder. LebensmitteWisensachft und Technologie 22: 279286.
Della Valle G., Oullien L. and Geuguen J. (1994)Relationships between processing conditions and starchand protein modifications during extrusion cooking ofpea flour.Journal of the Science Food and Agriculture 64509517.
Quinoa Extrudates 113
at UNIV DE SAO PAULO BIBLIOTECA on September 25, 2009http://fst.sagepub.comDownloaded from
http://fst.sagepub.com/http://fst.sagepub.com/http://fst.sagepub.com/http://fst.sagepub.com/8/12/2019 Propiedades Fisico Quimicas Quinoa
15/15
Della Valle, G., Colonna P. and Patria A. (1996). Influenceof amylose content on the viscous behavior of low hyd-rated molten starches.Journal of Rheology 40: 347262.
Della Valle G., Vergnes B., Colonna O. and Patria A.(1997). Relations between rheological properties ofmolten starches and their expansion behavior in extru-sion.Journal of Food Engineering 31: 277296.
Dogan H. (2000). The effect of component interactions onthe structural and functional properties of legume extru-dates. Ph.D. Thesis, Middle East Technical University,Ankara-Turkey.
Faubion J.M. and Hoseney R.C. (1982). High temperatureshort time cooking of wheat starch and flour I. Effect ofmoisture and flour type on extrudate properties. CerealChemistry 59: 529533.
Gee J.M., Price K.R., Ridout C.L., Wortley G.M., HurrelR.F. and Johnson I.T. (1993). Saponins of quinoa:Effects of processing on their abundance in quinoaproducts and their biological effects on intestinalmucosal tissue. Journal of the Science of Food andAgriculture63: 201209.
Ghiasi K., Hoseney R.C. and Varriano-Marston E. (1983).Effects of flour components and dough ingredients onstarch gelatinization. Cereal Chemistry 60: 5861.
Godavarti S. and Karwe M.V. (1997). Determination ofspecific mechanical energy distribution on a twin-screwextruder. Journal of Agricultural Engineering Research67: 277287.
Gomez M.H. and Aguilera J.M. (1983). Changes in thestarch fraction during extrusion cooking of corn. Journalof Food Science 48: 378381.
Gomez M.H. and Aguilera J.M. (1984). A physicochemicalmodel for extrusion of starch.Journal of Food Science49:4043, 63.
Guha M, Ali S.Z. and Bhattacharya S. (1997). Twin-screwextrusion of rice flour without a die: Effect ofbarrel temperature and screw speed on extrusion andextrudate characteristics.Journal of Food Engineering32:251267.
Guzman-Maldonado S.H. and Paredes-Lopez O. (1998).Functional products of plants indigenous to LatinAmerica: Amaranth, quinoa, common beans and bota-nicals. In: Mazza G. (ed), Functional Foods: Biochemicaland Processing Aspects. Lancaster: TechnomicPublishing Company. pp. 293328.
Hic sasmaz Z. and Clayton J.T. (1993). Characterization ofthe pore structure of starch based food materials. FoodStructure 11: 115132.
Ilo S., Liu Y. and Berghofer E. (1999). Extrusion cookingof rice flour and amaranth blends. Lebensmittel-Wissenschaft und Technologie Food Science and
Technology32: 7988.
Kirby, A.R., Ollett A.L., Parker R. and Smith A.C. (1988).An experimental study of screw configuration effects inthe twin-screw extrusion cooking of maize grits.Journalof Food Engineering 8: 247272.
Kokini J.L., Lai L.S. and Chedid L.L. (1992). Effect ofstarch structure on starch rheological properties. FoodTechnology46: 124139.
Kokini J.L. (1993). The effect of processing history onchemical changes in single- and twin-screw extruders.Trends in Food Science and Technology 4: 324329.
Koziol M.J. (1992). Chemical composition and nutritionalevaluation of quinoa (Chenopodium quinoa Willd).Journal of Food Composition and Analysis 5: 3568.
Lai L.S. and Kokini J.L. (1990). The effect of extrusion
operation conditions on the on-line apparent viscosity of98% amylopectin and 70% amylose corn starches duringextrusion. Journal of Rheology 34: 12451266.
Launay B. and Lisch J.M. (1983). Twin-screw extrusioncooking of starches: Flow behavior of starch pastes,expansion and mechanical properties of extrudates.Journal of Food Engineering 2: 259280.
Martinez-Serna M.D. and Villota R. (1992). Reactivity,functionality and extrusion performance of native andchemically modified whey proteins. In: Kokini J.L., HoC.T. and Karwe M.V. (ed.), Food Extrusion Science andTechnology. New York: Marcel Dekker, Inc. pp. 387415.
Masterbroek H.D., Limburg H., Gilles T. and MarvinH.J.P. (2000). Occurrence of sapogenins in leaves and
seeds of quinoa (Chenopodium quinoa Willd). Journal ofthe Science of Food and Agriculture 80: 152156.
Ng K.G., Price K.R. and Fenwick G.R. (1994). A TLCMethod for the analysis of quinoa saponins. FoodChemistry 49: 311315.
Padmanabhan M. and Bhattacharya M. (1989). Extrudateexpansion during extrusion cooking of foods. CerealFoods World34: 945949.
Prakash D., Nath P. and Pal M. (1993). Composition,variation of nutritional contents in leaves, seed protein,fat and fatty acid profile ofChenopodiumspecies.Journalof the Science of Food and Agriculture 62: 203205.
Przybylski R., Chauhan G.S. and Eskin N.A.M. (1994).
Characterization of quinoa (Chenopodium quinoa) lipids.Food Chemistry 51: 187192.
Qian J.Y. and Kuhn M. (1999). Characterization ofAmaranthus cruentus and Chenopodium quinoa starch.Starch-Staerke 51: 116120.
Ridout C.L., Price K.R., DuPont M.S., Parker M.L. andFenwick G.R. (1991). Quinoa saponins Analysis andpreliminary investigations into the effects of reduction byprocessing.Journal of the Science of Food Agriculture 54:165176.
Ruales J. and Nair B.M. (1993). Content of fat, vitaminsand minerals in quinoa (Chenopodium quinoa Willd)seeds. Food Chemistry 48: 131136.
Singh N. and Smith A.C. (1997). A comparison of wheatstarch, whole wheat meal and oat flour in the extrusioncooking process. Journal of Food Engineering 34: 1532.
Wang S.S., Chiang W.C., Zheng X., Zhao B., Yeh A. andCho M.H. (1992). Application of an energy equivalentconcept to the study of the kinetics of starch conversionduring extrusion. In: Kokini J.L., Ho C.T. and KarweM.V. (eds),Food Extrusion Science and Technology. NewYork: Marcel Dekker, Inc. pp. 165176.
Zasypkin D.V. and Lee T.-C. (1998). Extrusion of soybeanand wheat flour as affected by moisture content. Journalof Food Science 63: 10581061.
114 H. DOGAN AND M.V. KARWE