Gluten-free couscous preparation: Traditional procedure description and technological feasibility for three rice-leguminous supplemented formulae

Tags: raw material, Traditional procedure, Hard Wheat Couscous, semolina, technological feasibility, distilled water, Journal of Food, Agriculture & Environment, Granulometry, dry couscous, fine particles, GFC, Algeria, field bean, HWS, Mentouri de Constantine, Wheat Semolina, coarse grains, Granulometry distribution, Mohammed Nasreddine Zidoune Laboratoire de Nutrition, Institut de la Nutrition, pea, Technologies Agro-Alimentaires, Chickpea, HWC, gluten free couscous, gluten-free products, hard wheat, Swelling index, Rice-Chickpea Couscous
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Journal of Food, Agriculture & Environment Vol.6(2) : 105-112. 2008
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Gluten-free couscous preparation: Traditional procedure description and technological feasibility for three rice-leguminous supplemented formulae Leila Benatallah *, Abdelnacer Agli and Mohammed Nasreddine Zidoune Laboratoire de Nutrition et Technologie Alimentaire (L.N.T.A.), Institut de la Nutrition, de l'Alimentation et des Technologies Agro-Alimentaires (I.N.A.T.A.A.), Universitй Mentouri de Constantine, 25000, Algйrie. *e-mail: [email protected], [email protected],[email protected]
Received 18 January 2008, accepted 7 April 2008. Abstract Technological feasibility to obtain gluten-free couscous based on rice-leguminous supplementation was studied. Cereal-leguminous of 2/1 weight/ weight ratio was chosen to supplement semolina of rice (Oryza sativa) with each of chickpea (Cicer arietinum) or proteaginous pea (Pisum arvense) or field bean (Vicia faba). A traditional procedure, widely held in Constantine region (North East of Algeria), was described and tested to approach manual manufacturing feasibility for the three formulae comparatively to a control couscous made with wheat semolina (Triticum durum vulgare). The three gluten-free products and the control one were compared on the basis of productivity, granulometry, swelling, disintegration level and structure. Feasibility was confirmed for the three formulae, and comparison of the obtained products in accordance with tasters preference placed the Rice-Field bean Couscous (RFC) as best after the Hard Wheat Couscous (HWC), followed by the Rice-Chickpea Couscous (RCC) and the Rice-Proteaginous pea Couscous RPC. Key words: Traditional preparation, gluten-free couscous, Celiac Disease, rice supplementation, chickpea, proteaginous pea, field beans, technological feasibility.
Introduction Low diversity and availability of gluten-free products and the wish of the population concerned by celiac disease 1 to find appropriated and traditional products on the Algerian market constitute our fundamental arguments to propose formulae for Gluten-Free Couscous (GFC). Couscous is one of the most ancient diet prepared and consumed in African countries. In North Africa, it is made from barley and durum wheat semolina 2, 3, whereas in West Africa, sorghum, millet, maize and other flours are used 4, 5. Chickpea, proteaginous pea and field bean seeds were chosen to supplement rice aiming to offer a better balance in amino-acids6 with more diversification and possibilities to obtain gluten-free couscous. Technological feasibility was approached by testing a traditional procedure practised in the North Eeast of Algeria (Constantine region). After description of the procedure, the different couscous samples were appreciated according to their granulometry, productivity, structure and capacity of swelling and disintegration. Sensorial analysis approaching stickiness, firmness, colour and odour permits to complete the comparison. Materials and Methods raw material and formulation: Seeds utilized were as follows: bleached long rice (Oryza sativa japonica) of Thai origin of Basmati variety, field bean (Vicia faba minor) of Sidi Aпch variety, chickpea (Cicer arietinum) of FLIP-90-13C-G1 variety and Abbreviations: GFC = Gluten-Free Couscous, RFF = Rice-Field bean Formula, RCF = Rice-Chickpea Formula, RPF = Rice-Proteaginous pea Formula, RFC = Rice-Field bean Couscous, RPC = Rice-Proteaginous pea Couscous, RCC = Rice-Chickpea Couscous, HWC = Hard Wheat Couscous, Fs/Cs = The ratio Fine semolina (Fs)/Coarse semolina(Cs), PDC = Productivity of Dry Couscous.
proteaginous pea (Pisum arvense) of Messire G2 variety. The three leguminous seeds were produced by the Institut Technologique des Grandes Cultures (I.TG.C.), Guelma, Algeria. All seeds were milled using a grinder stack (UMA- MG E3 type, Rouiba, Algeria). The field bean seeds were at first crushed and manually degermed. Our semolina control was prepared by ERIAD-society from a mixture of unspecified varieties of hard wheat (Triticum durum). The granulometry of milled raw material was obtained by sieving through sieves of 1000, 800, 630 and 500 µm standardised mesh opening. According to the three announced leguminous, the three following formulae were prepared and studied: Rice-Field bean Formula (RFF), Rice-Proteaginous pea Formula (RPF) and RiceChickpea Formula (RCF) to obtain three types of GFC: Rice-Field bean Couscous (RFC), Rice-Proteaginous pea Couscous (RPC), Rice-Chickpea Couscous (RCC). According to our traditional procedure and before formulation, two fractions were separated from each milled material: coarse semolina (Cs>500 µm) and fine semolina (Fs500 µm). For formulation, rice and leguminous were mixed at the two levels of granulometry (Cs & Fs) separately in a ratio of 2/1 (w/w). Two corresponding fractions (coarse and fine) were necessary to start the procedure of manufacturing. The couscous control made with hard wheat semolina (HWC) permits to compare levels of technological feasibility.
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Traditional utensils used for preparing couscous: Traditional
utensils used to manufacture couscous are shown in Fig. 1.
A couscous-cooker composed by two compartments: a steam
generator using boiling of water and above it, a couscous
container or steam receiver named "keskess" where heat treatment
occurs. Operations of rolling for aggregating semolina are realized
in a large wooden dish called "guessвa". Four different sieves
named "dekkak", "reffad", "meвaoudi" and "sekkat" are utilized a
bb
in sieving or sizing operations and correspond respectively to
500, 1000, 1130 and 1280 µm mesh opening.
Chemical analysis: Characterization of milled Raw Materials was
carried out according to standards of AFNOR: moisture 7a by
drying in a drying-room at 130°C until constant weight, ash 7b,c by
mineralization at 900°C for wheat and rice and at 550°C for
leguminous until constant weight, total lipids 7d by extraction in
the hexane and total nitrogen 7e (NT) using Kjeldahl method.
c
d
A factor of 5.7 was used to convert the NT into total proteins 8.
Results of characterization are the average of six trials.
Traditional procedure of manufacturing couscous: In traditional preparation, women in the region of Constantine city prepare the couscous by hands using the utensils presented in Fig. 1a. The procedure described in Fig. 2 and tested in this work is that practised in the region of Constantine city. Usually, quantities of semolina and couscous produced are those satisfying daily or yearly needs of a family and exceed the amount of semolina considered in the present study. Contrary to the quantities showed in photos (Fig. 1), the procedure tested here starts with a quantity of 500 g of coarse semolina (>500 µm) steam precooked in "keskess" for 8 min at 95°C. This heat treatment may prepare the semolina and permits to foresee better productivities. However, the fraction of large particles up to 1130 µm resulting from this precooking preparation is after emoting and cooling (Fig. 1b) eliminated as a "meвaoudi" sieve reject. The semolina undergoes then the first operation of rolling in the "guessвa" with progressive adjunction of amounts of salted water. This beginning of rolling step aims to hydrate and prepare the semolina particles to aggregation which will occur in the "guessвa" along the other steps. For the HWC, the Fine semolina/Coarse semolina (Fs/Cs) weight ratio is generally about 2 to 2.5. So, for our study, we chose the 2.5 ratio to apply it to the GFC manufacturing. Hydration is at first homogenized by circular movement with fingers as shown in Fig. 1c. During the following steps, rolling is carried out with all the parts of the hands (fingers and palms) applying a slight pressure on the particles in a "to and fro" movement like a glass wiper (Fig. 1d). After each step of rolling, aggregation and resulting couscous grain must be controlled by sieving (Fig. 1e) or sizing (Fig. 1f) with appropriate sieves. Sizing consists to force all the particles to pass through the sieve by moving and pressing them with hand. Sizing decreases from 1280 µm (sekkat sieve) to 1130 µm (meвaoudi sieve) (Fig. 2). When aggregate size is 1130 µm, fine semolina (500 µm) is progressively added for rolling in the "guessвa". Hydration is pursued by progressive and intermittent salted water addition and rolling. Sieving occurs at last to recover rolled couscous grain up to 1000 µm which must be steam cooked (95°C, 8 min). Fine couscous (<1000 µm) obtained is recycled by rolling in the "guessвa". To control possible large grains formation due to the static heat treatment and swelling in
e
ff
Figure 1. Utensils and unit operations of couscous preparation according to the traditional procedure of Constantine region. a: steam-cooker, sieves and guesвa; b: Emoting; c: Circular homogenizing movement; d: "to and fro" aggregating movement; e: Sieving process; f: Sizing process.
"keskess", a sizing operation with "sekkat" sieve (1280 µm) is practised before drying under shade and natural air convection. Granulometry of dry couscous (500-1000 µm) is at last controlled by sieving on the dekkak (500 µm) to eliminate fine particles. Couscous productivity: Productivity in Dry Couscous (PDC) is calculated as follows: PDC = [mass of dry couscousЧ100] / [mass of coarse and fine semolina used]. Couscous granulometry: Granulometry of particles can be seen at each sieving step of the procedure. Granulometry of raw material is obtained by sieving the grinding products through seven sieves of 1000, 800, 630, 500, 160, 100 and 50 µm mesh opening. Granulometry of final couscous is obtained by sieving dry products of each formula through four sieves of 1000, 800, 630 and 500 µm mesh opening. Determination of Swelling Index (SI): In graduated test tubes distilled water (initial volume V ) was added to 20 g of dry i couscous. After closing the tubes, successive turn up was done in order to hydrate all couscous grains. Those adhering on the wall were rinsed by few ml of distilled water. Then tubes were placed in a Marie-bath at 25°C. Final couscous volume (Vf) was noted after 5, 10, 20, 30, 40, 50 and 60 min. Swelling index (SI) is given according following equation: SI (%) = 100Ч(Vf - Vi)/ Vi .
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Sensory appreciation: Our cooked
couscous samples were appreciated by
a test of classification by rank Friedman
test 9. This consists in presenting to a
jury of 10 tasters, 5 g of each
manufactured couscous, coded A, B, C
and D, couscous control included. The
tasters have to classify these 4 samples
in increasing intensity from 1 to 10,
according to the following descriptors:
stickyness, firmness under the tooth,
colour and odour of the couscous. This
evaluation test was done on steam
cooked couscous without sauce. For
each descriptor, the general comparison
of all tested samples was realised with
calculation of Friedman value F = 12/
(JP(P+1)(
R12
+
R22
+...+
R
2 P
)-3J(P+1)),
where J number of tasters, P number of
samples, ....... sum of rank attributed to
the P samples for the J tasters.
data analysis: Statistical Analysis was carried out with StatView 5th version (Abacus Concepts TM, Berkeley, USA) and XLSTAT 7th version: Chi 2 test for comparing percentage, slope test to the comparison of two linear correlations, ANOVA test for comparing means, Bonferroni/Dunn test to compare individual groups of means, simple linear correlation to approach THE RELATIONSHIP between quantitative variables and Pearson Correlation test to test association between several quantitative variables. The level of significance was fixed at 0.05.
Results and Discussion
Couscous composition: The
composition of the couscous was
approached only from those of the
formulae intended to the rolling which
Figure 2. Traditional procedure of couscous manufacturing according to the North East Algerian preparation.
themselves were obtained by calculation from the general chemical composition
of the raw material. Table 1 shows major components of each
Determination of disintegration degree (DD): After steam ingredient concerned by couscous manufacturing and calculated
cooking (8 min at 95°C), 10 g of each couscous was covered by 50 levels resulting from the considered supplementation. Rice which
ml of distilled water at 25°C. Above the bed of couscous, a magnetic is the base of our formulae presented the lowest amount in proteins
bar stirred the suspension for 5 min at a constant speed. (66 g kg-1). Among the used leguminous, field bean seeds were
Disintegration was approached by recovering fine particles the richest in proteins (p<0.0001) and in total carbohydrates
through a 630 µm sieve and drying at 100°C until constant mass. (p<0.0001). Calculation based on the 2/1 ratio used showed
Loss of matter was expressed by the disintegration degree (DD): enhancement and amelioration in protein levels of formulae due DD(%) = (DEЧ50)Ч100/DM, where DE = dry extract determined at to leguminous presence. As a result of supplementation, all the
100°C (g) and DM dry mass of couscous (g).
formulae may ameliorate the amino acid balance and enhance the
amounts of protein content in this rice-based product (couscous).
Structure observation: The rolled grains of couscous were Additionally to the advantage of the Amino Acids balance as
observed using a digital camera (FUJIFILM, FinePix E900, 9Mega shown by Hamdaoui et al.10, for the chickpea-couscous
Pixels) coupled to a magnifying binocular (PARALUX, XTB 01). supplementation, iron requirements are improved. The RF formula
Journal of Food, Agriculture & Environment, Vol.6 (2), April 2008
107
Table 1. Major components of raw materials (g kg-1 of raw matter).
(n = 6)
Humidity
Protein
Fat
Ash
Total carbohydrates*
Raw material :
Hard wheat
147.3 r 2.2
132.5 r 2
3.3 r 0.8
9.8 r 1.4
694.3
Rice
131.5 r 0.6
66.0 r 1.6
5.6 r 0.9
2.9 r 0.8
790.3
Proteaginous pea 116.3 r 1.8
223.5 r 0.8
3.5 r 1.5
27.9 r 3.2
497.0
Chickpea
107.7 r 1.1
248.8 r 5.8
22.1 r 2.5
34.4 r 2.9
554.9
Field bean
119.2 r 6.1
309.0 r 5.2
3.1 r 0.3
24.3 r 2.9
625.3
Formulae** or corresponding couscous :
RPF
126.4 r 0.05
118.5 r 8
4.90 r 0.5
11.2 r 1.3
739.0
RCF
123.5 r 0.05
127.0 r 1
1.11 r 1.1
13.4 r 0.7
725.0
RFF
127.4 r 0.19
147.0 r 2
0.47 r 0.6
10.0 r 1.1
710.9
*Carbohydrates values obtained by difference, **: Values obtained by calculation according to 2/3 (wt) rice and 1/3 (wt) leguminous, n = number of trials,
RPF = Rice-Proteaginous pea Formula, RCF = Rice-Chickpea Formula, RFF = Rice-Field bean Formula.
may offer most proteins (147 g kg-1). For RPF and RCF, no significant difference in the rates of protein was noted (118.5 and 127 g kg-1 respectively). Ash in RPF and RCF seemed slightly higher and may contain more minerals than the RFF because of the presence of the husks. Lipid content may be higher in the formula containing chickpea (11.1 g kg-1) which is the richest ingredient (22.1 g kg-1). Composition of formulae as calculated and showed in Table 1 must, however, be reviewed considering the final and true repartition or ratio of the two types of semolina particles (rice and leguminous) aggregated in the final couscous obtained. Despite these differences in distribution ratio or supplementation level in the final couscous, the amino acid balance remains relatively significant. Quantification of this distribution is necessary to appreciate the efficiency of supplementation for each proposed formula or couscous. Couscous granulometry Case of formulae: Granulometry estimated separately before formulation for each raw material is shown in Fig. 3. Coarser semolina (>500 µm) is noted for the hard wheat against finer semolina (500 µm) for the milled rice and leguminous. This difference may be partly due to that leguminous seeds present difference in friability and were milled with non-cylindrical grinders.
This difference is also a very important factor which may influence the level of feasibility and so final couscous productivity. Changing these proportions in granulometry distribution may be very interesting to study in future investigation. We tried to fabricate couscous from milled products where granulometry distribution differs from the usual wheat semolina. We can deduce from Fig. 3 that the coarse semolina (>500) used from each raw material in the beginning of the procedure of manufacturing presents some differences in size distribution. For example, in the large interval of the defined coarse semolina (500-1000 µm), the most coarse fraction (630-1000 µm) represents about 11% in the proteaginous pea and in the control semolina, 3.8% and only 1.5% in the rice and field bean respectively but more than 23% in the case of chickpea. These differences and those concerning the ratio of fine to coarse semolina (Fs/Cs) (cf mass balance and productivity) needed for a good aggregation deserve a most complete and detailed study to control the effect of granulometric factor. Technological feasibility approached in the present work attempts to answer how the rice and leguminous milled material do permit aggregation and particles development along the steps of rolling process according to the traditional diagram described. Answers recorded in this paper may be seen through distribution of the different dry couscous obtained, productivity, structure observation and disintegration degree.
800-1000 µm 630-800 µm 500-630 µm
160-500 µm 100-160 µm 50-100 µm
%
96
98.4
100
88.9
88.4
90
76.6 80
70
60
50
40
30 20 9.8 10 1.2 0 HWS
3.4 0.1 RS
0.5 1 FS
15.2 8.3 CS
7.2 4.4 PS
Coarse Semolina
100 87.7 90
80
70
60
50
40
30
20
11.2
10
1
0 HWS
97.6
96
59.5 50 45.5
31.1
19.4
9.3
4
0.9
0
RS
FS
CS
Fine Semolina
4.4 PS
Figure 3. Granulometry of raw material. HWS = Hard Wheat Semolina, RS = Rice Semolina, FS = Field bean Semolina, CS = Chickpea Semolina, PS = Proteaginous pea Semolina.
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Case of produced couscous: Granulometry distribution (Fig. 4) shows more likeness between the three dried GFC and distinguish them from the HWC by the presence of more fine grain fractions (500-630 µm). This may indicate more difficulties to aggregate particles of the three formulae. Granulometric class of 500-800 µm reaches about 69 to 74% of the total dry GFC against only 44% in the control couscous. So, the RFC is the only one which presents more coarse grains with about 30% of the 800-1000 µm fraction. This occurs despite the lower amount (1.5%) of larger grain fraction (630-1000 µm) in its starting coarse semolina. So, higher levels of this fraction in the starting coarse semolina (23.36 and 11.55%) respectively for chickpea and proteaginous pea do not permit a better level of aggregation and size development as shown with the formula containing field bean. Our results show that yielding more couscous is not dependent only on the presence of high proportions of intermediate and coarse starting semolina particles as found by Debbouz et al. 11. In addition to this, differences in productivity between all the types of manufactured couscous make up the fact that the relationship granulometrysize development (or particle formation) is not simple and may include other parameters and specific techno-functional properties of each ingredient of the formulae. The highest amount of protein in the RFF may have not been the only important factor. Mass balance of the manufacture indicates that also the amount of fine semolina included in addition to the coarse one used in the beginning of the procedure can have an influence.
Mass balance and productivity: Mass balance deduced as a mean of three manufacturing tests permits to evaluate the proposed traditional diagram and distinguish technological feasibility and productivity for each proposed formula. Productivity noted for
% 100
800 1000 8µ0m0-1000 µm630 860300-µ8m00 µm 550000-663300µµmm
90
80
70
60 55.78
50
40
39.95
30
20
48.98
47.69
48.52
30.4 26.89 24.96 25.42 25.85 20.43
10 0 PDC :
4.27 HWC 82%
RFC 67%
RCC 61%
RPC 40.7%
Figure 4. Granulometry distribution of the manufactured couscous. PDC = Productivity of Dry Couscous, RFC = Rice-Field bean Couscous, RPC = Rice-Proteaginous pea Couscous, RCC = Rice-Chickpea Couscous.
the control made with hard wheat (82%) is the highest one (Table 2). It reveals that the traditional diagram permits a loss of about 18% of raw wheat semolina. Usually, in household habits, this fraction does not constitute a true loss because it is not excessive and can be incorporated for other food preparations. The loss in raw material is higher in the GFC obtained and shows significant differences between the three products (p<0.0001). On the other hand, the initial quantity of fine semolina was not completely consumed for the HWC (1048.85 g), what gives a ratio Fs/Cs of 2.1 instead of 2.5 as expected. In the case of the GFC, all of fine semolina was consumed, what lets think that the report Fs/ Cs in the case of the proposed formulae must be revised. This lets suppose that the GFC requires a higher ratio Fs/Cs. This deserves to be clarified in future investigations. Mass balance shows that the total quantity of salted water used in the manufacturing of the RPC is significantly superior to those used for RFC and RCC as well as for the HWC (p<0.0001). The total salted water used in the manufacturing of RCC and RFC was identical. As our first aim is to compare levels of technological feasibility for the formulae proposed to diversifying gluten-free foods, improvements required in Industrial process have not been discussed in this paper. According to the traditional diagram of Constantine region (Algeria) tested here, our results can insure population concerned by celiac disease that diversification with better nutritive levels is accessible. Couscous productivities noted for all the three formulae (RFC 67.28%, RCC 60.83% and RPC 40.71%) are significantly (p<0.0001) lower than for the HWC (83.03%). Despite the need of investigation to improve the mass balance level of feasibility remains, however, satisfactory. Productivity values express the ability of leguminous and rice particles to aggregate for constituting couscous grains under rolling conditions. Difficulty to aggregate the different ingredients of the supplemented formulae appears to be higher in the case of RPC. This is indicated by a loss of about 60% of raw material against about 40 and 33% loss of RCC and RFC respectively. Couscous structure observation: Views of individual coarse semolinas and the resulting formulae used when starting the manufacturing procedure are shown in Fig. 5. While hard wheat and rice semolinas show a vitreous and salient aspect, leguminous semolinas seem to be more floury with more round edge of fragments. An intensified yellow colour is noted for the chickpea and the proteaginous pea more than for the field bean. In formulae, we can see the domination of the white colour on the yellow one expressing the 2/1 ratio used in the rice-leguminous supplementation (Fig. 5). The rolling operation along the steps of the procedure did not give spherical grains such as imagined considering the movement of them in the "guessвa". For all the types of couscous, grains present a micro-relief with asperities corresponding to particles of
Table 2. Mass balance of couscous manufacturing according to the traditional diagram.
(n = 3)
HWC
RFC
RCC
RPC
Coarse semolina (g)
500
500
500
500
Fine semolina
1048.85 r 0.54
1250
1250
1250
Salted water (g)
525.29 r 0.61 516.37 r 0.39 517.88 r 0.19 725.66 r 1.52
Dry couscous (g)
1270.61 r 1.15 1177.57 r 0.48 1064.58r 0.51 712.56 r 0.44
Productivity (%)
82.03
67.28
60.83
40.71
n = number of manufacturing, HWC = Hard Wheat Couscous, RPC = Rice-Proteaginous pea Couscous, RFC = Rice-Field bean Couscous, RCC
= Rice-Chickpea Couscous.
Journal of Food, Agriculture & Environment, Vol.6 (2), April 2008
109
HWS
FS
RFF
RS 500 µm
500 µm
500 µm RPF
500 µm
PS
CS
RCF
Figure 5. Aspect of individual coarse semolinas and resulting formulae: HWS = Hard Wheat Semolina, FS = Field bean Semolina, PS = Proteaginous pea Semolina, CS = Chickpea Semolina, RS = Rice Semolina, RFF = Rice-Field bean Formula, RPF = Rice-Proteaginous pea Formula, RCF = Rice-Chickpea Formula.
fine semolina attached to the surface of the biggest particles (coarse semolina). The HWC and the RFC seem having more homogeneous and smoothness aspect in structure grains contrarily to RPC and RCC (Fig. 6). As the RFC is quantitatively the richest GFC in proteins (P < 0.0001), a determining role may be attributed to these proteins. The good adhesion occurring during preparation of the RFC caused a strong positive correlation (p<0.0001) between couscous productivity and the levels of proteins of the formulae. For hard wheat couscous, several authors 12, 13 underlined the importance of the content of proteins in the culinary quality. However, the qualitative aspect of these proteins must be taken in consideration. The role of starch in the good behaviour of the grains must be included. Heat treatment applied to coarse semolina and final couscous may beget a partial gelatinization of starch which possibly needs ameliorations.
HWC
RFC
RPC
500µm RCC
500µm
500µm
500µm
Figure 6. Aspect of dried gluten free couscous compared to the control of hard wheat. HWC = Hard Wheat Couscous, RFC = Rice Field bean Couscous, RPC = Rice Proteaginous pea Couscous, RCC = RiceChickpea Couscous.
Fold of swelling
Swelling index (SI): Swelling in water at 25°C of the dried couscous obtained seems to begin stabilisation at about 5 to 20 min after immersion and contact (Fig. 7). While the GFC stop swelling at a level about 80% (SI = 80), the HWC after 5 min continues and reach an SI about 135%. Compared to the initial volume of the dried couscous, this result reveals that the control couscous may swell until 2.3 fold and the GFC can only reach about 1.8 fold. The swelling phenomenon results from absorbing different amounts of water by the constituents of the different couscous grains. In the present conditions, the constituents of HWC seem to absorb water and swell to a higher level than those of the GFC. This could be explained by the presence of gluten in the HWC and its absence in three studied types of couscous. In the same way, Debbouz and Donelly 14 found that the homemade hard wheat couscous from strong gluten cultivars had higher SI than did couscous made from weak gluten cultivars. The SI values indicate and distinguish behaviour of compared couscous in simplified experimental conditions. In reality, couscous swells during steam cooking operation before consumption. It occurs in the traditional "keskess" as a result of combined heat treatment and steam absorption operations. In the other hand, results obtained by Ounane et al. 3 on cooked couscous showed no correlation between the couscous swelling and the total lipid content but a negative impact of free lipid on cooked couscous and dough swelling 15 by masking the sites of hydrophilic groups involved in water molecule fixation. Our results concerning not cooked couscous show that total lipid concentration in GFC is significantly higher (p<0.001) than in HWC. This observation could fit with those of Ounane et al.3.
SI%
2.4 140
2.2 120
2 100
1.8 80
1.6 60 40 1.4
HWC RPPC
RFBC RCPC
20 1.2
0 0 0 5 10 15 20 25 30 35 40 45 50 55 60
Time (min)
Figure 7. Swelling Index (SI) of the manufactured couscous. HWC = Hard Wheat Couscous, RFC = Rice-Field bean Couscous, RPC = RiceProteaginous pea Couscous, RCC = Rice-Chickpea Couscous.
Disintegration degree (DD): According to Guezlane et al.16, during cooking amylose diffuses from the couscous surface which is responsible for particle disintegration. Amounts of fine particles (<630 µm) lost in stirred water at 25°C from steam-cooked couscous reveals (Fig. 8) that the GFC presents higher levels (p<0.01) of DD (2.9-3.65%) than the control (1.73%). The high relatively levels of DD remain interesting compared to those recorded in the literature 12, 17 (4.62-6.16%) for the traditional wheat couscous. This seems to converge in general to the recorded differences in couscous productivity but values of the GFC DD do not coincide with the granulometry distribution of the dried grain of each couscous. So the RFC which has about 20% of 500-630 µm grain
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Journal of Food, Agriculture & Environment, Vol.6 (2), April 2008
Sticky
3.36.565
8
7
RCC
HWC
RCC
6
RFC
RPC
3.31.313
5
4
RFC
3
2.92.9
2
1
RPC 1.17.373
Odour
0
Firmness
0
1
2
3
4
Figure 8. GFC and HWC disintegration in water at 25°C. HWC = Hard Wheat Couscous, RFC = Rice-Field bean Couscous, RPC = RiceProteaginous pea Couscous, RCC = Rice-Chickpea Couscous.
Colour
fraction and the better productivity (67%) presents more disintegration than the RPC which contains 25% of the same class of grain size with only 40% of productivity. Sensorial appreciation of the GFC: The Friedman test of classification by rank allows the arrangement of the tested samples (GFC and HWC) for each descriptor. This classification is represented in Fig. 9. Calculation of the F value of Friedman for each descriptor shows a significant difference between all the tested samples (p < 0.01). The differences between the three GFC and the HWC are more significant for stickiness and colour than for odour and firmness descriptors. The GFC appears more sticky and coloured in general than the control. For the stickiness criterion, all the studied GFC showed a lower quality with regard to the HWC which seems to be largely least sticky followed by the RFC, RCC and then the RPC. Colour intensity of the GFC increased with the following order: RFC, RCC and RPC. The superiority in colour of the GFC is caused by the most intense coloration of each leguminous despite their low proportion in the proposed formulae. The GFC seems to be slightly less firm accordingly to the following increasing order: RFC, RCC and RPC. Odour descriptor classified the RCC as the least odorous couscous. The RFC and RPC appear, however, having higher odour intensity than the HWC (control). The RFC also brought nearer to the HWC by its stickiness and colour. The RPC brought together by firmness and odour to the HWC. RPC-HWC similarities in firmness seem to be corroborated by the results of DD classification. Comparison based on the bringing together of the GFC to the HWC classify the studied formulae as follows: RCF in the second position, RPF in the first one with regard to firmness and odour and RFF also in the first position but according to stickiness and colour. However, as the differences in firmness and odour intensities are smaller than those in stickiness and colour, the RPF cannot take the first position. Preference of tasters confirmed this and classified the three GFC with the RFC as the best couscous after the HWC followed by RCC and RPC. In popular traditions, sauces, milk or other accompaniment are often added to couscous during or just before its consumption. These express different preferences and may permit more acceptance despite the differences noted between the studied GFC.
Figure 9. Friedman rank classification of different manufactured couscous. HWC = Hard Wheat Couscous, RFC = Rice-Field bean Couscous, RPC = Rice-Proteaginous pea Couscous, RCC = RiceChickpea Couscous. Conclusions Through one of the traditional tested procedures of the North East of Algeria, GFC production shows a relative good technological feasibility. This feasibility is accompanied with the cereal-leguminous supplementation advantage and the possibility to offer to housewives and industrials the possibility to increase the availability and diversity of their gluten-free products to the celiac population. The RFF presents the best productivity of the GFC. This productivity remains, however, satisfactory, but is less than for the HWC. The easiness of aggregating different ingredients from the RFF is indicated by the presence of the highest coarse couscous grains fraction in the RFC. This couscous formula appears to have more similarities in aspect with regard to the control. Its grains seem to have more homogeneous and smoothness aspect contrarily to the RCC and the RPC. Considering results of Friedman rank classification which was confirmed by the tasters preferences, the arrangement of the GFC placed the RFC as the best couscous after the HWC followed by the RCC and RPC. Acknowledgement We would like to thank I.T.G.C. of Guelma for supplying us by known variety of leguminous. References 1Benatallah, Le., Zidoune, M. N. and Agli, A. 2004. La maladie coeliaque: Cas recensйs de 1998 а 2003 et diйtйtique associйe а Jijel, Batna et Khenchela. Colloque ADELF-EPIBIO: Epidйmiologie et prise de dйcision en santй publique. Santй Publique & Sciences Sociales. Oran, 10:88-89. 2Kaup, S. M. and Walker, C. E. 1986. Couscous in North Africa. Cereal Food World 31:179-182. 3Ounane, G., Cuq, B., Abecassis, J., Yesli, A. and Ounane, S. M. 2006. Effect of physicochemical charachteristics and lipid distribution in Algerian durum wheat semolinas on the technological quality of couscous. Cereal Chem. 83:377-384.
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4Galiba, M., Rooney, L. W., Waniska, R. D. and Miller, F. R. 1987. The Preparation of sorghum and millet couscous in West Africa. Cereal Food World 32:878-884. 5Aboubacar, A. and Hamaker, B. R. 1999. Physicochemical properties of flours that relate to sorghum couscous quality. Cereal Chem. 76:308-318. 6FAO 1982. Les graines de lйgumineuses dans l'alimentation humaine. FAO, Etudes Alimentation et Nutrition 20, Rome, 152 p. 7AFNOR 1991. a) Norme AFNOR NF V 03-707- cйrйales et produits cйrйaliers : Dйtermination de la teneur en eau, mйthodes de rйfйrence pratique (juin 1989), b) Norme AFNOR NF V 03-720- cйrйales et produits cйrйaliers : Dйtermination des cendres, Mйthodes par minйralisation а 900°C (dйcembre 1981), c) Norme AFNOR NF V 03760- cйrйales, lйgumineuses et produits dйrivйs : Dйtermination des cendres, Mйthode par minйralisation а 550°C (dйcembre 1981), d) Norme AFNOR NF V 03-713- cйrйales et produits cйrйaliers : Dйtermination de la teneur en matiиres grasses totales (fйvrier 1984), e) Norme AFNOR NF V 03-050- cйrйales et produits cйrйaliers : Directives gйnйrales pour le dosage de l'azote avec minйralisation selon la mйthode de Kjeldahl (septembre 1970), In Recueil de normes franзaises : Contrфle de la qualitй des produits alimentaires, Cйrйales et produits cйrйaliers, AFNOR/DGCCRF, 3иme йdition, Paris, 360 p. 8Barr, C., Beau, M. F., Belly, J. M., Bocquet, A., Bris, V., Delplancke, D., Fisher, J., Foucher, C., Gabillard, M., Hoffmann, D., Kern, F., Leblanc, M. P., Lebras, A., Lebrun, J., Mahaut, B. et Martin, G. 1995. Contrфle de la qualitй des cйrйales et protйagineux. guide pratique. Editions ITCF, Nancy, France, 253 p. 9Anonymous 1995. Contrфle de la qualitй des produits alimentaires. Recueil de normes franзaises. 5иme йdition, AFNOR, Paris, 400 p. 10Hamdaoui, M., Doghri, T. and Tritar, B. 1992. Bioavailability of iron from a traditional Tunisian meal with chickpeas fed to healthy rats. Ann. Nutr. Metab. 36:135-140. 11Debbouz, A., Dick, J. W. and Donnelly, B. J. 1994. Influence of raw material on couscous quality. Cereal Foods World 39:213-236. 12Guezlane, L., Selselet-Attou, G. et Senator, A. 1986. Etude comparйe de couscous de fabrication industrielle et artisanale. Industries des Cйrйales 43:25-9. 13Elias, E. M. 1995. Durum wheat products. In Di Fonzo, N., Kaan, F. and Nachit, M. (eds). Durum Wheat Quality in the Mediterranean Region. Options Mйditйrranйennes. Sйrie A: Sйminaires mйditйrranйens, Zaragoza, 17-19 November 1993, 22, CIHEAM/ICARDA/CIMMYT, Zaragoza, pp. 23-31. 14Debbouz, A. and Donnelly, B. J. 1996. Process effect on couscous quality. Cereal Chem. 73:668-671. 15Addo, K. and Pomeranz, Y. 1992. Effects of lipids and emulsifiers on alveograph charachteristics. Cereal Chem. 69:6-12. 16Guezlane, L., Colonna, P. and Abecassis, J. 1998. Effet du traitement hydrothermique du couscous de blй sur les modifications physiques de l'amidon. Ann. INA El Harrach 19:62-81. 17Yettou, N., Guezlane, L. et Ounane, G. 2000. Mise au point d'une mйthode instrumentale d'йvaluation de la dйlitescence du couscous du blй dur. Actes du premier symposium international sur la filiиre blй: Symposium blй 2000, enjeux et stratйgies. Alger 7-9 fйvrier 2000, OAIC 2000, 348 p.
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