Eur Food Res Technol (2007) 225:205–213
DOI 10.1007/s00217-006-0405-y
ORIGINAL PAPER
Development of gluten-free fresh egg pasta analogues
containing buckwheat
Cristina Alamprese · Ernestina Casiraghi ·
M. Ambrogina Pagani
Received: 28 April 2006 / Revised: 6 June 2006 / Accepted: 8 June 2006 / Published online: 23 June 2006
C Springer-Verlag 2006
Abstract To improve the use of common buckwheat
(Fagopyrum esculentum), characterized by interesting nutritional properties, it could be used in pasta formulations.
In particular, as buckwheat is devoid of the gluten-forming
proteins, it might be an ingredient for celiac patient food.
The aim of this study was to develop both fresh egg pastas integrated with buckwheat and fresh egg pasta analogues classifiable as gluten-free, based on buckwheat and
rice flours. Matter loss in the cooking water and weight increase during cooking of buckwheat pasta were higher than
those of a reference sample made of common wheat flour.
As buckwheat integration increased, sample break strain
was significantly lower, as a result of the progressive reduction in gluten content. In the production of gluten-free
pasta analogues, wheat flour was substituted with rice flour,
precooked rice flour or pregelatinized rice starch. Since
samples containing precooked rice flour gave the best results, in terms of workability, break strain and weight increase during cooking, they were also produced on an industrial scale. Industrial gluten-free fresh egg pasta analogues were tougher and less deformable in comparison
with the laboratory-produced samples. These results were
determined by the presence of the double thermal pasteurisation treatment, which allows to obtain a better structure
of the product, showing also a lower matter loss during
cooking.
C. Alamprese () · E. Casiraghi · M. A. Pagani
DiSTAM, Dipartimento di Scienze e Tecnologie Alimentari e
Microbiologiche, University of Milan,
Via Celoria 2,
20133 Milan, Italy
e-mail: cristina.alamprese@unimi.it
Tel.: +39-02-50316625
Fax: +39-02-50316632
Keywords Buckwheat . Cooking behaviour . Fagopyrum
esculentum . Fresh egg pasta . Gluten-free . Pasta
analogues . Rice
Introduction
Although common buckwheat (Fagopyrum esculentum) is
characterized by interesting nutritional properties, such as
the presence of proteins of a high biological value, natural antioxidants, minerals, vitamins (especially those of the
B group) and dietary fibre [1–3], relatively low quantities
of it are consumed by human beings especially in western
countries. One of the best ways to promote the use of this
pseudocereal would appear to be its introduction into formulations for mass consumer goods, such as pasta. More
specifically, as buckwheat is devoid of the proteins of which
gluten is composed [4], one interesting use might be in the
production of foods for people with celiac disease, i.e. for
those subjects who suffer from gluten intolerance.
Indeed there is an increasing demand for these products, as
celiac disease is one of the most common food intolerances,
with an incidence of one case every 100–500 people in the
European population [5]. The illness presents with a typical
lesion of the mucosa of the proximal small intestine, causing
chronic inflammation and the progressive disappearance of
the villi, leading to the malabsorption of several important
nutrients including iron, folic acid, calcium and fat-soluble
vitamins. The only effective treatment for celiac disease is a
strict adherence to a gluten-free diet throughout the patient’s
lifetime which, in time, results in clinical and mucosal recovery [6].
Experimental tests have been carried out to produce dried
pasta containing up to 30–50% buckwheat and other pseudocereals flour and bran [7–9]. These brought out a certain
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206
Table 1 Sample identification
code (ratio between flours used)
and formulation (%)
Eur Food Res Technol (2007) 225:205–213
Sample
Wheat
Buckwheat
Rice
Egg
Water
F100
B40-F60
B60-F40
B60-R40
B60-RS40
B60-PR40
B60-R40-Md
B60-PR40-Md
B60-PR40-Md
72.4
43.5
28.9
–
–
–
–
–
–
–
28.9
43.5
40.0
40.0
37.9
40.0
37.9
37.9
–
–
–
26.8a
26.8b
25.3c
26.8a
25.3c
25.3c
20.1
20.1
20.1
30.0
30.0
29.8
30.0
29.8
29.8
7.5
7.5
7.5
3.2
3.2
7.0
3.2
7.0
7.0
F, common wheat flour; B, dehulled buckwheat flour; R, rice flour; PR, precooked rice flour; RS, pregelatinised
rice starch.
a
Rice flour.
b
Pregelatinised rice starch.
c
Precooked rice flour.
d
Produced adding 0.5% Methocel Food Grade.
degree of fragility in pasta structure, with much more leaching of organic matter into the cooking water compared with
pasta based on durum wheat semolina as a consequence of the
lack of a continuous and regular gluten network. Moreover,
buckwheat dough exhibits a higher susceptibility to Maillard
reactions during pasta drying [10], given its high concentration of lysine and reducing sugars [11]. On the other hand,
the cooking quality of pasta containing non-traditional ingredients is generally improved by drying at high or ultrahigh
temperatures [12–14].
Using buckwheat in fresh pasta brings some advantages,
as this product allows the problems associated with the drying phase to be avoided. Pasteurisation of pasta and the possibility of using egg as ingredient can, moreover, help to give
a structure to the product. It is well known that egg proteins,
especially albumen proteins, form a reticule which can guarantee a cohesive mass, with a good consistency, achieved by
thermal denaturation, even in the absence of gluten. Fresh
pasta is also interesting from the commercial point of view,
due to its continuously expanding market and the absence of
analogues products that celiac subjects can consume.
The aim of this study was to develop two different types of
products: fresh pastas containing wheat and buckwheat flour
and fresh pasta analogues classifiable as gluten-free, based
on buckwheat and rice flours. Besides the laboratory production, the most successful formulations were also produced
on an industrial scale, in order to evaluate their feasibility
and to study the structuring effects of thermal pasteurisation
treatments.
r F: commercial wheat flour
r B: dehulled buckwheat flour (Molino Filippini, Teglio,
Sondrio, Italy)
r R: rice flour Remyflo R 200 (Remy Industries, Leuven,
Belgium)
r PR: precooked rice flour R 150 P (Remy Industries)
r RS: pregelatinised rice starch FG-P (Remy Industries)
r M: Methocel Food Grade (Dow Chemical Company, Midland, USA), a methylcellulose based additive
r grade A eggs
r commercial pasteurised whole egg product
The production of fresh egg pasta analogues on
laboratory scale
The experimental pasta samples were produced in sheets for
lasagna, using an automatic plant for the production of fresh,
retail-manufactured pasta (P. Nuova, La Monferrina, Asti,
Italy). The mixing phase lasted for approximately 15 min.
The crumbly dough (1.5 kg) was then fed through the pasta
rolling machine to smooth and firm it, and fed another four
times between the rollers, at the maximum setting, to give
the pasta a good shape and texture. Finally, the pasta thus
obtained was rolled into sheets of approximately 1 mm thick.
Eight different formulations of fresh pasta analogues were
made in duplicate. All presented results are the average of the
two technological trials. Table 1 shows sample identification
code and formulation. Identification code represents the ratio
between flours used.
Materials and methods
The industrial production of fresh egg pasta analogues
Materials
Formulations B60-F40, B60-PR40 and B60-PR40-M were
also industrially produced in a pasta factory; industrial samples were identified as I-F40, I-PR40 and I-PR40-M, respectively.
For the production of fresh pasta analogues, the following
raw materials were used:
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Eur Food Res Technol (2007) 225:205–213
The flours were weighed and blended. The liquid ingredients (water and pasteurised whole egg) were then added
and mixed in. The crumbly dough obtained was transferred
to a kneading machine, worked for 10 min and finally cut
into large pieces and transferred to the rolling machine, obtaining rolls of 5 mm thick dough sheets. These were then
fed through the calibration rollers, which reduced the thickness to approximately 1 mm. The pasta sheet thus obtained
was transported by a conveyor belt to an injected steam pasteuriser. The loose product was pasteurised at 95 ◦ C for about
1 min. The pasta sheet was air cooled and, at the pasteuriser
exit, cut with a blade and packed in trays. The packs underwent a second pasteurisation treatment, carried out in an
air circulation chamber, at a temperature of approximately
93 ◦ C for 70 min.
Moisture
Moisture content of the pasta and wheat products was determined by a gravimetric method according to the Italian
“Metodi Ufficiali di Analisi dei Cereali” [15]. Moisture content of whole egg products was determined according to the
AOAC Official Method 925.30 [16]. Results are the average
of two determinations and are expressed as g/100 g.
Protein and lipid content
Total nitrogen content of the pasta and wheat products was
evaluated according to AOAC Official Method 920.87 [16].
Protein content was calculated using cereal conversion factor
5.7.
Lipid content of the pasta was determined according to
the Italian “Metodi Ufficiali di Analisi dei Cereali” [15] and
expressed as ether extract.
Protein and lipid analyses were performed in duplicate
and results are expressed as g/100 g d.m.
Total starch content
The total starch content of the different flour samples was
determined enzymatically using the “Total Starch Assay
Kit” by Megazyme International Ireland Ltd. (Bray Business
Park, Bray, Co. Wicklow, Ireland). Results are the average
of four determinations and are expressed as g/100 g d.m.
Damaged starch content
Starch damage was measured enzymatically using the
“Starch Damage Assay Kit” by Megazyme International Ireland Ltd. (Bray Business Park, Bray, Co. Wicklow, Ireland).
Results are the average of four determinations and are given
as g/100 g d.m.
207
Viscoamylographic test
This analysis was performed by using a Micro ViscoAmylograph (Brabender OHG, Duisburg, Germany). A water suspension of flour (14 g at 14% moisture in 100 ml
distilled water) was evaluated under constant conditions (stirring: 250 min−1 , sensitivity: 300 cm gf ) according to the following time-temperature profile: the suspension was heated
from 50 to 95 ◦ C with a temperature gradient of 6 ◦ C/min;
the sample was then maintained at 95 ◦ C for 5 min (first
holding period); the paste was then cooled down to 50 ◦ C
at 6 ◦ C/min and held at this temperature for 5 min (second
holding period). For the characterization of the pasting properties of the sample, the following parameters were taken
from the curves: beginning of gelatinisation (“pasting” time
and temperature), maximum viscosity, breakdown (defined
as the difference between the maximum viscosity and the
viscosity at the end of the first holding period), setback (defined as the difference between the viscosity at the end of
the cooling period and the viscosity at the end of the first
holding period).
Cooking tests
Cooking tests were performed under standard conditions:
four sheets of pasta (20 cm × 10 cm) were laid in a
lasagna cooking device made of perforated stainless steel
plates placed one on top of the other. The cooking device was dipped in 1500 ml of boiling natural spring water
(pasta/water ratio ca. 1/10) with no salt added. After 3 or
6 min of cooking (according to the thickness of the sheets),
the cooking device was extracted from the water and the
pasta sheets were left to drain for 2 min. Only the three
upper sheets of cooked pasta were considered for analysis.
Weight increase
Pasta weight increase due to cooking was evaluated on the
sheet of pasta set in the top position in the cooking device,
weighing pasta before and after cooking. Weight increase
was expressed as a percentage of the raw pasta weight and
represents the average of four cooking trials.
Matter loss
Matter loss of the pasta during cooking was evaluated by
determining the dry matter content of the cooking water
left, after restoring it to the initial volume by adding natural
spring water. Dry matter was determined on 25 ml of cooking
water, previously evaporated and then desiccated to constant
weight in an oven at 105 ◦ C. Results, expressed as grams
of matter loss/100 g pasta d.m., represent the average of
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Eur Food Res Technol (2007) 225:205–213
Results and discussion
Characterization of flours
Fig. 1 Load–displacement curve example, with construction lines
used for calculations
four determinations, carried out on the water of two different
cooking tests.
Rheological tests
Tensile tests were performed on both raw and cooked pasta,
using an Instron Universal Testing Machine 4301 (Instron
Ltd., High Wycombe, UK) supported by Series IX Automated Material Testing software (Instron Co., 1998). Analyses were carried out at room temperature with a constant
cross-head speed of 20 mm/min. Pasta samples were “dog
bone” shaped and clamped at the ends by adjustable grips.
For each sample at least six replicates were carried out. The
Young modulus (MPa), an index of pasta hardness, was calculated on the linear part of the tensile curve as the ratio
between tensile stress and relative deformation. Break strain
(%) was obtained by calculating the ratio between maximum
extensibility (break displacement) and initial sample length.
Break load (N) was also determined, as an index of pasta
toughness. Figure 1 shows an example of load–displacement
curve, with construction lines used for calculations.
During analyses, pasta samples were kept in airtight
polystyrene boxes to avoid moisture loss.
Statistical analysis
One-way ANOVA was carried out using Systat 5.03 software
for Windows (Systat Inc., USA).
Table 2 Moisture, protein,
starch content and amount of
damaged starch of the flours
used (F, common wheat; B,
dehulled buckwheat; R, rice;
PR, precooked rice; RS,
pregelatinised rice starch)
d.m., dry matter.
a
Figure provided by the supplier.
Springer
Table 2 shows moisture, protein and starch content and the
amount of damaged starch of the flours.
B and F had the highest moisture content. Instead, moisture levels proved to be particularly low in the case of PR.
The protein content of the flours was in line with expected
values: highest in B, followed by F; intermediate in R and
PR; close to zero in RS.
The starch content in sample RS was obviously the highest, far higher than those of the other flours. The starch content of F, R and RP was over 75%, being on average higher
in rice flours. As expected, the percentage of damaged starch
(assessed on the basis of its susceptibility to enzymatic hydrolysis), proved to be high, 90% of total starch quotas, in
the flours which had undergone precooking treatments. Consequently, on viscoamilograph testing (Fig. 2), samples PR
and RS also had breakdown values (821 and 712 BU, respectively) decidedly higher than F (251 BU) and R (429 BU)
and much lower setback values (respectively 277, 177, 537
and 668 BU). PR and RS had a very high initial viscosity, as
is shown by the curves in Fig. 2A, with RS (937 BU) reaching the maximum viscosity, while sample PR was not much
lower than this (855 BU as against 1020 BU). This result can
be ascribed to the high water absorption capacity of the gelatinised starch granules [17]. The viscosity of the system then
dropped considerably and very rapidly. The low setback values of PR and RS indicate that the starch contained in these
samples retrograded less during cooling. Viscoamilographic
tracings for F and R showed a similar trend, but the values for
maximum viscosity and final viscosity for R (954 and 1069
BU, respectively) proved to be higher than the corresponding
values for F (697 and 978 BU, respectively).
In the case of sample B, the viscoamilographic tracing
(Fig. 2B) was very different from those of the other flours
under examination. The time required for pasting was comparable with the times recorded for samples F and R. Sample
B reached maximum viscosity (1059 BU) at the end of the
period during which temperature was maintained at 95 ◦ C
and there was no subsequent reduction in viscosity. During
cooling, retrogradation caused the viscosity to reach a level
of over 1500 BU, higher than the respective value for the
Sample
Moisture (g/100 g)
Protein (g/100 g d.m.)
Total starch (g/100 g d.m.)
F
B
R
PR
RS
14.6a
14.3 ± 0.1
10.7 ± 0.2
4.8 ± 0.1
8.4 ± 0.1
12.0 ± 0.1
13.6 ± 0.2
7.5 ± 0.2
7.2 ± 0.2
0.4 ± 0.1
76.5 ± 1.1
69.4 ± 0.5
77.2 ± 1.0
79.8 ± 1.4
90.1 ± 1.8
Damaged starch
(g/100 g d.m.)
5.0 ± 0.1
0.8 ± 0.1
13.0 ± 0.1
72.6 ± 1.1
83.5 ± 1.8
Eur Food Res Technol (2007) 225:205–213
209
Laboratory-produced fresh egg pasta analogues
Fig. 2 Viscoamilographic tracings of the flours used. R, rice flour;
PR, precooked rice flour; RS, pregelatinised rice starch; B, dehulled
buckwheat flour; F, commercial wheat flour
other non-pretreated flours (F and R). The particular pasting
behaviour of buckwheat has been already observed by other
Authors [18–21] and in an our previous work [22]. It could
be explained by the peculiar conformation of starch granules,
that are very small (1–7 µm), regular and clearly grouped
in cellular structures [22], and the higher amylose content
and water-binding capacity of buckwheat starch [19]. Moreover, Zheng et al. [20] reported that the stable viscosity of
buckwheat on heating could be a result of the rigidity of its
granules.
Table 3 Gross composition
and cooking behaviour of
laboratory-produced fresh egg
pasta analogues (see Table 1 for
sample identification)
d.m., dry matter.
∗
P<0.05; ∗∗ P < 0.01; n.s., not
significant, in reference with
F100.
†
P<0.05; ‡ P<0.01; N.S., not
significant, in reference with
B60-F40.
The aim of this first part of the study was to verify whether
it would be possible to formulate a fresh pasta analogue,
with acceptable cooking behaviour, containing high levels
of buckwheat (samples B40-F60 and B60-F40) and whether,
at the highest level of integration, it would be possible to
replace all the wheat flour with other gluten-free flours, so
as to obtain a product classifiable as gluten-free. Rice flours,
were chosen to replace the wheat flour, being neutral-tasting
ingredients that would have a positive effect on the sensory
profile of a product characterized by ingredients with such
a distinct and typical taste, as buckwheat and egg. In two
of the gluten-free samples the additive Methocel Food-grade
was used for improving the structure of the doughs (samples
B60-R40-M and B60-PR40-M). Actually, methylcellulose,
being an hydrocolloid, is able to control both the rheology
and texture of aqueous systems; gum use has been reported
as gluten substitutes in the formulation of gluten-free breads
[23, 24].
Table 3 reports the gross composition and the cooking
behaviour of the samples of fresh egg pasta produced in the
laboratory, compared with the reference sample F100. For
sample identification see Table 1. As regards composition,
it should be noted that the two samples of fresh pasta integrated with buckwheat (B40-F60 and B60-F40) showed
no basic differences compared with the reference sample
made with common wheat flour (F100) apart from the higher
lipid content, due to dehulled buckwheat flour (fat content
2.7 g/100 g – figure provided by the supplier). In order to
obtain a workable dough, the samples of gluten-free fresh
pasta were produced with a moisture and egg content higher
than those of the reference and integrated pastas. Actually,
hydration level often has to be adjusted to obtain a proper
consistency in dough containing non-traditional ingredients
[9]. The higher lipid content of the gluten-free samples is
due both to the presence of the dehulled buckwheat flour and
to the greater quantity of egg in the dough (30% vs. 20%).
Finally, it should be noted that sample B60-RS40 had a lower
protein content, owing to the presence of the rice starch, as
this flour is almost completely devoid of proteins.
Sample
Moisture
(g/100 g)
Protein
(g/100 g d.m.)
Lipid
(g/100 g d.m.)
Matter loss
(g/100 g d.m.)
Weight increase
(%)
F100
B40-F60
B60-F40
B60-R40
B60-RS40
B60-PR40
B60-R40-M
B60-PR40-M
30.8 ± 0.9
31.0 ± 0.7
30.9 ± 0.6
33.2 ± 0.4
32.9 ± 0.1
34.5 ± 0.5
33.0 ± 0.5
35.3 ± 0.1
14.7 ± 0.1
14.6 ± 0.6
14.4 ± 0.6
13.7 ± 0.1
11.7 ± 0.3
14.3 ± 0.1
14.1 ± 0.3
14.3 ± 0.4
3.9 ± 0.3
4.4 ± 0.4
4.8 ± 0.7
5.5 ± 0.4
5.4 ± 0.2
5.5 ± 0.8
6.0 ± 0.7
5.4 ± 1.0
2.58 ± 0.06
3.13 ± 0.12∗
3.03 ± 0.83 n.s
3.77 ± 0.16 N.S
4.10 ± 0.05 N.S
3.65 ± 0.03 N.S
3.53 ± 0.13 N.S
3.46 ± 0.53 N.S
39.21 ± 2.13
55.05 ± 0.17∗∗
57.59 ± 2.35∗
56.62 ± 2.08 N.S
46.45 ± 2.60†
41.20 ± 0.03‡
55.46 ± 0.89 N.S
42.89 ± 0.50†
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210
Table 4 Break load and break
strain of F100 sample and
laboratory-produced fresh egg
pasta analogues, both before and
after cooking (see Table 1 for
sample identification)
Eur Food Res Technol (2007) 225:205–213
Sample
F100
B40-F60
B60-F40
∗
Raw pasta
Break load (N)
Break strain (%)
Cooked pasta
Break load (N)
Break strain (%)
1.08 ± 0.06
0.48 ± 0.06∗∗
0.61 ± 0.03∗∗
67.83 ± 6.61
35.85 ± 8.02∗
20.31 ± 1.70∗∗
3.24 ± 0.02
1.75 ± 0.24∗
1.44 ± 0.22∗∗
84.71 ± 8.48
41.66 ± 5.57∗
29.10 ± 3.42∗
P<0.05; ∗∗ P<0.01, in reference with F100.
During pasta production all the sheets were rolled to a
thickness of approximately 1 mm. The only exceptions were
samples B60-R40 and B60-R40-M which, during lamination, showed a tendency to break and “fray”, making difficult
to produce sheets of the usual thickness. For these samples
the final pasta sheets were approximately 1.2 mm and, consequently, the optimal cooking time (corresponding to the
disappearance of the white central core of the lasagna sheet)
was 6 min instead of 3 min.
Matter loss in the cooking water was higher in the samples
containing buckwheat, as compared with F100. According
to Steadman et al. [1] buckwheat bran contains 12% soluble
dietary fibre; part of it leaches out of the pasta during cooking
[9]. All the gluten-free samples showed high levels of matter
loss, owing both to the presence of buckwheat and to the poor
structuring capacity of the rice flours. The sample produced
with rice starch (B60-RS40) scored particularly high, due to
the presence of a greater quantity of starch and the absence
of a well-structured protein reticule, hindering the excessive
swelling of the starch granules and the consequent dispersion
of organic substance in the cooking water. The addition of
Methocel to the product had no effect on this.
The samples containing buckwheat flour had a significantly (P>95%) greater weight increase during cooking than
those of the reference sample. This probably depended on
various factors: the high non-starch polysaccharide content
of buckwheat which is known to have a high water absorption
[25]; the greater egg content [26]; the unusual conformation
of buckwheat starch granules, which are smaller, with a more
irregular structure, and contain more amorphous areas than
those of wheat; and the disruption in the protein matrix,
promoting water absorption [9, 27, 28].
Table 4 reports the results of the tensile tests carried out
on sample F100 and on the samples of fresh egg pasta integrated with buckwheat, both before and after cooking. Break
load of the raw pasta sheets for the two samples integrated
with buckwheat flour proved to be significantly (P>99%)
lower than those of the reference. As buckwheat integration
increased, there was also a significant reduction in sample
break strain, which was more contained (47% less) in the
case of formulation B40-F60 and particularly evident in the
case of formulation B60-F40 (70% lower). These results are
consistent with the progressive reduction in gluten content
and, consequently, with a distinct loss of elastic properties
in the dough. Fibre components too have an important effect
on the mechanical properties of the sheets, owing to their
capacity to bind water and interrupt the continuity of the
gluten reticule [9].
After cooking, F100 still had a break load and a break
strain significantly (P>95%) higher than the samples integrated with buckwheat flour. These last samples were similar
to one another in terms of break load.
Figure 3 shows the results of the tensile stress tests conducted on the samples of fresh gluten-free pasta, both before and after cooking. Data are discussed with reference
to the formulation containing the greatest quantity of buckwheat (B60-F40), since gluten-free samples contain 60% of
dehulled buckwheat and other gluten-free flours. The horizontal lines in the graphs of Fig. 2 thus represent the average
value obtained for sample B60-F40. As regards the raw pasta
Fig. 3 Break load and break strain of the samples of laboratoryproduced fresh gluten-free pasta, both before and after cooking. The
horizontal lines represent the average value obtained for raw (- - -) and
cooked (—) sample B60-F40. ∗∗ P<0.01; ∗ P<0.05, N.S., not significant, in reference with B60-F40
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Eur Food Res Technol (2007) 225:205–213
sheets, the break load of the samples containing rice flour
(B60-R40 and B60-R40-M) proved to be similar to the reference, whereas for all the other samples it proved to be significantly (P>95%) higher. Samples B60-PR40 and B60-PR40M were found to be more similar to the reference B60-F40 in
terms of deformability, whereas the samples containing rice
flour proved to be the least deformable. Sample B60-RS40
was considerably different from all the others showing higher
deformability. Together, the values of the rheological parameters indicate that the sheets of sample B60-RS40 were rather
poorly structured and, when subjected to the mechanical action of the dynamometer, they tended to “fray”, opposing a
very low resistance. After cooking, the samples containing
rice flour, with and without additive, proved to be significantly (P>95%) more resistant to breaking compared to the
reference B60-F40, showing higher figures for break load.
Instead, the differences noted between sample B60-RS40
and all the others in terms of break strain were reduced and
no longer proved significant, due to protein denaturation in
cooking.
In conclusion, the behaviour of the products containing
rice starch on the tensile test was very different from the
reference B60-F40; samples produced with rice flour were
similar to the reference B60-F40, although they were difficult to work. Samples containing precooked rice flour proved
to be more similar to the reference B60-F40 both as regards
workability and break strain; moreover, they showed a limited weight increase after cooking, similar to that of sample
F100.
Industrial samples of fresh egg pasta analogues
The laboratory-made fresh pasta analogues which had given
the best results were also produced on an industrial scale.
More specifically, we chose to produce the formulation of
pasta integrated with 60% of buckwheat (a sample which
we labelled I-F40) and the gluten-free formulation containing precooked rice flour, both with and without methylcellulose (samples I-PR40 and I-PR40-M). The aim of this
phase of the study was to evaluate the difficulties that might
arise in the industrial production of gluten-free formulations and, above all, to assess whether the thermal pasteurisation treatment would be able to improve the structural characteristics of the product and its behaviour during
cooking.
During the rolling and calibration phases in the industrial plants, the doughs tended to break, especially during
transportation of the sheets on the conveyor belt. Only the
product containing precooked rice flour and added methylcellulose (I-PR40-M) presented no problems, proving to be
very elastic and similar in its behaviour to a conventional
formulation based on common wheat flour. The presence of
211
Table 5 Cooking behaviour of industrially produced fresh egg pasta
analogues and commercial samples (mean data) [29]
Sample
Matter loss (g/100 g
d.m.)
Weight increase (%)
I-F40
I-PR40
I-PR40-M
Commercial
4.52 ± 0.12
4.33 ± 0.14
3.70 ± 0.04
3.43 ± 0.80
72.80 ± 4.81
70.36 ± 2.76
71.52 ± 2.73
42.33 ± 16.86
I-F40, I-PR40 and I-PR40-M are formulated as B60-F40, B60-PR40
and B60-PR40-M, respectively (see Table 1). d.m., dry matter.
the additive, which at a laboratory level seemed not to influence the characteristics of the pasta to any great extent,
proved to be effective in the industrial product, probably due
to the presence of a texturing kneading phase.
As regards the composition of the industrial samples,
the fat content was between 4.06 and 5.36 g/100 g d.m.,
with the highest values for the gluten-free samples (I-PR40
and I-PR40-M), and the protein content fell between 13.87
and 15.21 g/100 g d.m. The two heat treatments of the industrial cycle reduced moisture content of the samples as
compared with the corresponding laboratory-made samples
(from 33.6 to 30.4% moisture, on average). Besides, a longer
exposure of doughs to air takes place during the industrial
process.
The industrially produced sheets were thicker than the
laboratory samples (1.2 mm on average) and this was why
the best cooking time proved to be 6 min instead of 3 min.
Table 5 shows results relating to the cooking behaviour of the
industrial samples. For comparison, the mean data relating to
commercial samples of fresh egg pasta analysed in a previous
study have been included [29].
The matter loss for all industrially produced samples
was higher than the mean for the commercial samples.
The presence of methylcellulose did however reduce the
amount of matter loss, making sample I-PR40-M significantly (P>95%) different from I-PR40.
The formulations containing buckwheat absorbed a high
quantity of water during cooking, rendering them highly
different from the averages data for commercial samples.
However, these results were partly justified by the greater
thickness of the sheets, which took longer to cook.
In Fig. 4 the results of the tensile tests carried out on
industrial samples are illustrated. In these cases too, the
horizontal lines refer to mean figures for the commercial
samples previously analysed, taken as a reference. The raw
samples containing buckwheat proved to be less deformable
(lower break strain) and tougher (higher break load)
compared with the mean figures for the commercial samples
of fresh egg pasta. After cooking, these samples remain
less deformable than the commercial ones and become
less tough. This behaviour is due to the lack of gluten and,
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Eur Food Res Technol (2007) 225:205–213
Fig. 4 Break load and break strain of industrially produced fresh pasta analogues, both before and after cooking. The horizontal lines represent
the average value obtained for raw (- - -) and cooked (—) commercial fresh egg pasta samples [29]
consequently, to the fact that the dough is less elastic and
less compact after cooking. However, considering the wide
variability in the characteristics of commercial products, we
should stress that the parameters measured for the samples
containing buckwheat do still fall within the range of values
observed for the commercial samples [29].
The presence of precooked rice flour led to an increase
in break load for the raw pasta sheets and a reduction in the
break strain for the cooked sheets, as compared with sample
I-F40.
The comparison between the raw industrial samples and
those produced in the laboratory brought out the fact that the
former were less deformable and also tougher, these results
being determined by the presence of the double thermal pasteurisation treatment the industrial pasta underwent. Indeed,
as pasteurisations of the pasta sheets causes denaturation
of the proteins, it promotes the formation of a more compact protein reticule, giving rise to a product which offers
greater resistance to the application of tensile forces [30].
After cooking the differences between the products are reduced, owing to further denaturation of the protein and to
the effect of the absorbed water.
So, this second part of the study showed that fresh glutenfree pasta can be industrially produced, especially if methylcellulose based additives are employed to make the dough
more workable. Moreover, the thermal pasteurisation treatment which packaged fresh pasta normally undergoes allows
to obtain a better structure of the product, characterized by a
lower matter loss during cooking.
Conclusions
In conclusion, this work shows new possibilities to produce
gluten-free fresh egg pasta analogues, thus expanding celiac
products market. The use of 30% egg in pasta formulation
allows the production of well-structured gluten-free fresh
pasta analogues, with improved nutritional properties, due to
considerable buckwheat content. Moreover, product texturisation appears to be enhanced both by the use of precooked
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rice flour and methylcellulose and by pasteurisation thermal
treatments. In particular, the presence of gum allows a better
dough workability during rolling on industrial plants.
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