Effects of Drying Process on the
Physicochemical Properties of Nopal
Cladodes at Different Maturity Stages
Margarita Contreras-Padilla, Elsa
Gutiérrez-Cortez, María del Carmen
Valderrama-Bravo, Isela Rojas-Molina,
Diego Germán Espinosa-Arbeláez, et al.
Plant Foods for Human Nutrition
ISSN 0921-9668
Plant Foods Hum Nutr
DOI 10.1007/s11130-011-0265-x
1 23
Your article is protected by copyright and
all rights are held exclusively by Springer
Science+Business Media, LLC. This e-offprint
is for personal use only and shall not be selfarchived in electronic repositories. If you
wish to self-archive your work, please use the
accepted author’s version for posting to your
own website or your institution’s repository.
You may further deposit the accepted author’s
version on a funder’s repository at a funder’s
request, provided it is not made publicly
available until 12 months after publication.
1 23
Author's personal copy
Plant Foods Hum Nutr
DOI 10.1007/s11130-011-0265-x
ORIGINAL PAPER
Effects of Drying Process on the Physicochemical
Properties of Nopal Cladodes at Different Maturity Stages
Margarita Contreras-Padilla & Elsa Gutiérrez-Cortez &
María del Carmen Valderrama-Bravo & Isela Rojas-Molina &
Diego Germán Espinosa-Arbeláez & Raúl Suárez-Vargas &
Mario Enrique Rodríguez-García
# Springer Science+Business Media, LLC 2011
Abstract Chemical proximate analysis was done in order to
determine the changes of nutritional characteristics of nopal
powders from three different maturity stages 50, 100, and
150 days and obtained by three different drying processes:
freeze dried, forced air oven, and tunnel. Results indicate that
nopal powder obtained by the process of freeze dried retains
higher contents of protein, soluble fiber, and fat than the other
two processes. Also, freeze dried process had less effect on
color hue variable. No changes were observed in insoluble
fiber content, chroma and lightness with the three different
drying processes. Furthermore, the soluble fibers decreased
M. Contreras-Padilla (*) : M. d. C. Valderrama-Bravo
División de Investigación y Posgrado, Facultad de Ingeniería,
Universidad Autónoma de Querétaro,
Cerro de las campanas s/n,
C.P. 76010 Querétaro, Qro, México
e-mail: [email protected]
E. Gutiérrez-Cortez : M. d. C. Valderrama-Bravo :
R. Suárez-Vargas
Laboratorio Experimental Multidisciplinario LEM-A. Ingeniería
en Alimentos, Departamento de Ingeniería y Tecnología,
Facultad de Estudios Superiores Cuautitlán,
Universidad Nacional Autónoma de México,
Av. 1 de mayo s/n,
Cuautitlán Izcalli C.P.54740 Edo. de México, México
I. Rojas-Molina
Facultad de Ciencias Naturales, Licenciatura en Nutrición
Universidad Autónoma de Querétaro,
Av. de las Ciencias s/n,
C.P. 76230 Querétaro, Qro, México
D. G. Espinosa-Arbeláez : M. E. Rodríguez-García
Departamento de Nanotecnología, Centro de Física
Aplicada y Tecnología Avanzada,
Universidad Nacional Autónoma de México,
Campus Juriquilla No. 3001, Juriquilla,
C.P. 76230 Querétaro, Qro, A.P.1-1010, México
with the age of nopal while insoluble fibers and ash content
shows an opposite trend. In addition, the luminosity and hue
values did not show differences among the maturity stages
studied. The high content of dietary fibers of nopal pad
powder could to be an interesting source of these important
components for human diets and also could be used in food,
cosmetics and pharmaceutical industry.
Keywords Drying . Nopal cladodes . Nutritional
characteristics . Opuntia ficus-indica . Physicochemical
properties
Introduction
The Opuntia ficus-indica is a family of plants that are
drought tolerant and can be cultivated in arid and semiarid
regions. Nopal pads (or cladodes) have played an important
role in the Mexican people’s diet and have been used since
prehispanic times. Young cladodes are eaten as a vegetable
mainly in Mexico and in South of USA. Saenz [1] reported
that a potential source of dietary fiber can be found in the
nopal due to its high levels of total fiber. It was found that
the nopal has a higher concentration of calcium and dietary
fiber in more maturity stages than young cladodes [2, 3].
The β-carotene and lutein levels were higher in nopal pads
than in other vegetables [4, 5]. Contreras-Padilla et al. [6]
found a low concentration of calcium oxalate in nopal
cladodes for all maturity stages studied. Scientific studies
have reported positive medical effects of nopal, such as:
diuretic, antinflammatory, analgesic, antiulcerous, antihyperglycemic, and hypercholesterolemic [7–9]. Applications
in the food industry have found that the inclusion of 4% of
nopal powder improves rheological properties and increases
the calcium content at level of traditional nixtamalized corn
Author's personal copy
Plant Foods Hum Nutr
flour [10]. However, nopal pads are prone to rapid
microbiological decay, because of their high water content
and low pH, consequently limiting fresh marketing. It is
important to keep in mind that older nopal cladodes are not
consumed and thus, do not have commercial value which
represents an economical loss for farmers. Therefore, postharvest technology is crucial to maintain their quality and in to
maximize storage life for human consumption.
Drying and grinding processes produce powder forms of
material that have several important advantages, such as: it is
easy to store and to transport because it is lightweight, and this
also extends the shelf-life of the product. Some studies were
done regarding the kinetics of drying of nopal [11–14] and
others on the impact of drying processes on textural
properties [13] and antioxidant components [15, 16]. However, it is necessary to conduct further studies on the effect on
the nutritional components and physicochemical parameters
due to the drying process in order to obtain products with
appropriate nutritional quality for human consumption.
The objective of this research was to investigate the effects
of three different drying processes: forced air oven drying,
freeze-drying, and tunnel drying on the physicochemical and
nutritional attributes of nopal pads in three different maturity
stages.
initial environmental conditions during the drying process
were 39% HR and 30 °C. The cladodes were cut into squares
of 2×2 cm for the forced air and tunnel process and thickness
used was 0.44, 0.65 and 1.045 cm for the different maturity
stages, 50, 100 and 150 days, respectively. All the samples
were cut to half their original thickness. A forced air oven has
a fan and a series of resistors that permits the heated air to
move through the trays. Tunnel dryers heat the air which
travels through the sections containing product.
Force Air Drying
The cladodes pieces were placed on stainless steel trays in
order to be dried in a force air oven (BG model E102 USA).
The drying heat conditions were 50 °C with air flow rate of
1.4 m/s. The amount of nopal pads used was 5 kg and the total
drying time was 12 h.
Freeze Dried
The nopal pads were blended in order to obtain a puree mixture
which was frozen in an ultra freezer for 24 h at −50 °C. Then
the samples were freeze dried using a freeze zone Labconco
equipment with 130×10−3 mbars vacuum and a temperature
of −46 °C for 4 days. The amount of nopal used for each
sample was 1 kg.
Materials and Methods
Tunnel Drying
Sample Preparation
Nopal pads of Opuntia ficus-indica var. redonda, from the
experimental field located in Silao, Gto., Mexico, were
cultivated during a period of six months and were harvested
during May–June 2010. The variety redonda, at present, is
cultivated in Guanajuato by a group of producers for human
consumption in diverse forms, such as powder, strip,
dehydrated cube, spicy, salty, and frozen nopal. Also, some
producers are interested in exporting this material. In order to
discern the age of cladodes, these were marked and dated
during the sprouting, and harvested in three different ages:
50, 100, 150 days. Each sample consisted of 50 kg of nopal
pads which were collected from several plants in the same
sampling areas but at different maturity stages. All the
samples were harvested between 11 am and 12 pm. Once
collected, the cladodes were washed with distilled water and
disinfected using commercial 10% sodium hypochlorite
solution in order to eliminate microorganisms. Then the
spines were manually removed.
Nopal pieces were placed on stainless steel trays and put
into the drying tunnel (Didacta Italia, IC106D). The drying
heat conditions were 70 °C and air flow rate of 2.14 m/s.
The drying time was 9 h. The amount of each sample was
0.5 kg. The dried pieces were ground using a Pulvex 200
(Mexico) equipment. The grinding feed rate was 10 g/s.
The screen output restriction of mill was 0.8 mm.
Chemical Proximate Analysis of the Nopal Powder and pH
Determination
Moisture content was determined using the 934.01 method,
nitrogen content using the Kjeldahl method (2001.11), fat
content by 920.39 method, ash content by 942.05 method,
finally soluble and insoluble dietary fibers were determined
according to the 991.42 and 993.19 AOAC Official
Methods [17]. Also, the pH values of the nopal powders
were determined according to method 44–19 from AACC
[18] using a Oakton pH 1,100 series.
Drying and Grinding Process
Color Analysis of the Nopal Powder
The initial average moisture of the cladodes was 92.2% for
50 days, 91.9% for 100 days, and 91.8% for 150 days. The
The system used to measure the color was CIELAB. The
GretagMacbeth color eye 7,000 spectrophotometer was
Author's personal copy
Plant Foods Hum Nutr
Table 1 Dimensions and
weight of nopal pads at 50,
100 and 150 days of maturity
Maturity (days)
50
100
150
Average
% CV
Average
% CV
Average
% CV
used with the IQC color program. The results were reported
as hue (hº), chroma (C*) and lightness (L*) values.
Differential Scanning Calorimetric (DSC) Analysis
The soluble and insoluble fiber were analyzed, with 94 and
95% purity of lyophilized nopal, respectively, obtained
according to the AOAC and used as references. DSC
analysis was carried out in a Q100 TA Instruments
calorimeter. The samples were placed in aluminum hermetic sealed pans, and were stabilized at room temperature for
15 min, then heated in a ramp at 10 °C/min. Enthalpy and
temperature calibrations were performed using pure indium
(99.99%).
Weight (g)
Length (cm)
Width (cm)
Thickness (cm)
202.355±1.393
0.69
405.785±4.335
1.068
602.305±1.009
0.17
19.22±0.217
1.13
22.12±0.453
2.07
28.22±0.425
1.51
10.556±0.221
2.1
13.228±0.623
4.71
16.72±0.248
1.49
0.88±0.013
1.47
1.292±0.126
9.814
2.09±0.165
7.9
air drying, tunnel drying and freeze dried, and the maturity
stage of cladodes which were 50, 100, and 150 days. The
Tukey test for mean comparison was used (P<0.05). The
Statgraphics XV ® software was used.
Results and Discussion
Table 1 shows the weight, length, width, and thickness of
20 nopal pads at 50, 100, and 150 days of maturity with a
Statistical Analysis
All analytical experiments were conducted in triplicate. The
experiments were carried out using bifactorial analysis (3×3)
where the two factors were: drying process which were forced
Fig. 1 DSC thermogram for soluble and insoluble fiber of nopal pads
Fig. 2 Effects of drying process and maturity on protein (a), ash (b), and
moisture (c) content of nopal powder. Different letter indicate statistical
differences (p<0.05). Average moisture content of samples analyzed (in
parenthesis in g/100g d.m.) for freeze dried, 50 d (4.3), 100 d (4.22),
150 d (4.25); for forced air oven 50 d (5.55), 100 d (5.38), 150 d (5.41)
and for tunnel 50 d (5.95), 100 d (5.73), 150 d (5.58)
Author's personal copy
Plant Foods Hum Nutr
coefficient of variation less than 10%, which represents
nopal pads with homogeneous physical characteristics.
Figure 1 shows the thermograms of insoluble and soluble
fiber. These thermograms provide information related to the
endothermic or exothermic processes that results from the
heat treatment. According to this figure, the range of
temperatures between 50 to 70 °C have no changes in the
chemical composition of fiber; which means that this range
can be used for the forced air oven and for the tunnel drying.
For insoluble fiber, the endothermic peaks located at 100 °C
(A) correspond to loss of water in lignin [19] and the peaks
located at 284 °C (C) and 340 °C (D) are associated with
hemicellulose and cellulose degradation. These results agree
to those found by Tsujiyama and Miyamori [20]. Moreover,
two endothermic peaks were found for soluble fiber, a
transition located at 122 °C (E) associated with mucilage
[21] and the transition found at 215 °C (F) is related to the
cross linking process of carbohydrates.
The kinetic drying obtained for these processes follow
the same behaviors of results reported for other authors [11,
12, 14]. The protein content showed a significant statistical
difference between treatments (Fig. 2a) for both maturity
stages and types of drying processes used (P<0.05). In all
the stages of maturity, the protein content was greater for
freeze dried samples. The minor concentration of protein
can be explained as follows: 1) some reactions between
Fig. 3 Effects of drying process
and age on insoluble fiber (a),
soluble fiber (b), fat content (c),
and pH value (d) of nopal
powder. Different letter indicate
statistical differences (p<0.05).
Average moisture content of
samples analyzed (in parenthesis
in g/100g d.m.) for freeze dried,
50 d (4.3), 100 d (4.22), 150 d
(4.25); for forced air oven 50 d
(5.55), 100 d (5.38), 150 d (5.41)
and for tunnel 50 d (5.95), 100 d
(5.76), 150 d (5.58)
carbohydrates and proteins occur during drying process that
produces volatile compounds [22, 23] and 2) the moisture
content of the lyophilized samples was lower than the other
dehydrated samples obtained by the forced air and tunnel;
therefore, this condition triggers and apparent major
concentration of protein in lyophilized samples. The ash
content for all the samples studied, in all maturity stages,
demonstrated a statistical difference for the drying processes (P<0.05). The difference was found for freeze dried
process (Fig. 2c) because the nopal powder in this process
had less moisture (around 4%) than the samples for the
other two process which was approximately 5.5%. This
result was inherent to the lyophilized process that removes
more moisture. The environmental conditions were the
same, because the different drying processes for a specific
stage of maturity were performed at the same time.
Therefore, the differences were found reliable to the drying
process. In the case of moisture, the three drying processes
had significant differences; therefore, the drying process
had an important impact on the final moisture of the
samples (Fig. 2c).
The insoluble fiber was significantly different but only
for maturity factor (P<0.05), and it increases with age
(Fig. 3a). Similar results were reported by other authors [2,
3]. For insoluble fiber, no degradation was observed in any
of the three different drying processes. These results concur
Author's personal copy
Plant Foods Hum Nutr
with the DSC analysis of insoluble fiber. The soluble
dietary fibers were significantly different for both, maturity
and drying process (Fig. 3b). The content of soluble fiber
decreases with age. These results agree with other authors
[2, 3]. The different content of soluble fiber observed from
the result of the different drying processes was due to the
degradation of this fiber during the dehydration process.
The freeze dried samples had a higher content of soluble
fiber for all maturity stages; therefore, this process had less
effect on this compound. León-Martinez et al. [24] found a
glass transition temperature of the mucilage at 45 °C. Their
results explain the degradation observed on the soluble
fiber during the drying processes of tunnel and forced air
oven. Mucilage is part of the soluble fiber (around 93%)
[25]. The importance of the dietary fiber lies in the fact that
it has interesting physiological and beneficial effects in the
human body [1, 9, 26]. In addition dietary fibers can be
used in order to modify textures and to improve the stability
of the food during production and storage [27].
Results indicate that the fat content decreased with age
and that the drying processes had a great influence on the
final content (P<0.05) (Fig. 3c). The freeze dried samples
had the greatest fat content in comparison with the other
dried samples. This is because some fat components
produce volatile compounds due to the heat treatment
during drying [28]; also apparently there is major concentration of fat in lyophilized samples due to its minor
moisture content. The content of fat is very low, which this
is an advantage if the powders are considered as low fat
products. The nopal powders show a low pH, similar results
were found by Ayadi et al. [29], this is due to the fact that
these kinds of plants have crassulacean acid metabolism
that produces acids as part of the metabolic cycle [30] such
as malic acid, citric acid, and oxalic acids [8]. The data only
indicate statistical differences for drying process (Fig. 3d).
Freeze dried samples had significantly different values of pH.
A possible explanation is the concentration effect because
moisture was smaller.
L* shows a high level, 75; therefore, the samples are
light (Fig. 4a). Also, none of the factors have a statistically
significant effect on Lightness (P<0.05). Consequently, this
attribute was not influenced by the drying process or
maturity stage. C* values indicate that samples are pale
(Fig. 4b). The results indicate that for those of 150 days of
age were paler than the other age groups, except for freeze
dried samples. This can be explained by considering that
cladodes at this maturity stage could more sensitive to heat
treatment and had a slight deterioration of chlorophylls. h°
showed values of approximately 90°–98° which is a green–
yellow tonality (Fig. 4c). The h° data shows that freeze
dried samples were greener than the samples using the other
dryers. These results indicate that the forced air oven and
tunnel affect the color of the nopal powder giving a yellow
Fig. 4 Effects of drying process and maturity on color values of hue (a),
chroma (b) and luminosity (c) of nopal powder. Different letter indicate
statistical differences (p<0.05). Average moisture content of samples
analyzed (in parenthesis in g/100g d.m.) for freeze dried, 50 d (4.3), 100
d (4.22), 150 d (4.25); for forced air oven 50 d (5.55), 100 d (5.38), 150
d (5.41) and for tunnel 50 d (5.95), 100 d (5.76), 150 d (5.58)
tonality. Then, freeze dried process had less effect on this
variable. The data of the three parameters evaluated show
that the color of nopal powder was pale green with high
lightness. Similar results were reported [1, 29]. The major
components present in the nopal powder are: ash, soluble,
and insoluble dietary fibers. These results agree with the
finding of Saenz [1], Rodriguez-Garcia et al. [2],
Hernandez-Urbiola et al. [3], and Ayadi [29].
Conclusions
The samples obtained by different drying process showed
different effects regarding the chemical content; color and pH.
These values were directly influenced by the process, mainly
by the heat treatment. The results are important to consider in
order to select the appropriate equipment for the drying
process. The samples obtained by freeze dried process were
evaluated as the best, because they retained the highest content
of the nutrients studied and the color was greener than the
other samples. The best maturity stage, which could be used
Author's personal copy
Plant Foods Hum Nutr
for human diet, is cladodes of 100 days of maturity. This is
because the content of protein is slight higher, also the soluble
and insoluble fiber have an intermediate content that might
give the beneficial effect of both fibers. High levels of dietary
fibers indicate that nopal powder could be an interesting
source for these important components in the human diet. In
addition nopal powder could become one of the main ways to
consume cladodes in many countries around the world. It
could prove to be useful not only in the food industry, but also
in the cosmetics and pharmaceutical as raw material for the
preparation of products of these industries.
Acknowledgements We would like to thank C.P. Luis Lorenz for his
invaluable cooperation in his farm (NOPALZIN) and Marlene Meza for
the technical English revision of this article.
References
1. Saenz HC (1997) Cladodes: A source of dietary fiber. J Prof
Assoc Cactus Dev 2:117–123
2. Rodríguez-García ME, De Lira C, Hernández-Becerra E, CornejoVillegas MA, Palacios-Fonseca AJ, Rojas-Molina I, Reynoso R,
Quintero LC, Del Real A, Zepeda TA (2007) Physicochemical
characterization of prickly pads and dry vacuum prickly pads
powders as a function of the maturation. Plant Foods Hum Nutr
62:107–112
3. Hernández-Urbiola MI, Contreras-Padilla M, Pérez-Torrero E,
Hernández-Quevedo G, Rojas-Molina JI, Cortes ME, RodríguezGarcía ME (2010) Study of nutritional composition of nopal
(Opuntia ficus-indica cv. redonda) at different maturity stages.
Open Nutr J 4:11–16
4. Betancourt-Domínguez MA, Hernández-Pérez T, García-Saucedo
P, Cruz-Hernández A, Paredes-López O (2006) Physico-chemical
changes in cladodes (nopalitos) from cultivated and wild cacti
(Opuntia spp.). Plant Foods Hum Nutr 61:115–119
5. Hernández-Pérez T, Mejía-Centeno J, Cruz-Hernández A, ParedesLópez O (2009) Biochemical and nutritional characterization of three
prickly pear species with different ripening behavior and nutraceutical value of nopalitos. Acta Hort (ISHS) 841:515–518
6. Contreras-Padilla M, Pérez-Torrero E, Hernández-Urbiola MI,
Hernández-Quevedo G, Del Real A, Rivera-Muñoz EM, RodríguezGarcía ME (2011) Evaluation of oxalates and calcium in nopal pads
(Opuntia ficus-indica var. redonda) at different maturity stages. J
Food Compos Anal 24:38–43
7. Galati EM, Tripodo MM, Trovato A, Miceli N, Monforte MT (2002)
Biological effect of Opuntia ficus-indica (L.) Mill. (Cactaceae)
waste matter note I: Diuretic activity. J Ethnopharmacol 79:17–21
8. Stintzing FC, Carle R (2005) Cactus stems (Opuntia spp.): A
review on their chemistry, technology, and uses. Mol Nutr Food
Res 49:175–194
9. Feugang JM, Konarski P, Zou D, Stintzing FC, Zou C (2006)
Nutritional and medicinal use of cactus pear (Opuntia spp)
cladodes and fruits. Front Biosci 11:2574–2589
10. Cornejo-Villegas MA, Acosta-Osorio AA, Rojas-Molina I, GutiérrezCortéz E, Quiroga MA, Gaytán M, Herrera G, Rodríguez-García ME
(2010) Study of the physicochemical and pasting properties of instant
corn flour added with calcium and fibers from nopal powder. J Food
Eng 96:401–409
11. Lahsasni S, Kouhilaz M, Mahrouz M, Ait Mohamed L, Agorram B
(2004) Characteristic drying curve and mathematical modeling of
thin-layer solar drying of prickly pear cladode (Opuntia ficus-indica).
J Food Process Eng 27:103–117
12. Touil A, Chemkhi S, Zagrouba F (2010) Modelling of the drying
kinetics of Opuntia ficus-indica fruits and cladodes. Int J Food
Eng 6(2):11
13. Medina-Torres L, Gallegos-Infante JA, Gonzalez-Laredo RF,
Rocha-Guzman NE (2008) Drying kinetics of nopal (Opuntia
ficus-indica) using three different methods and their effect on their
mechanical properties. Food Sci Technol-Leb 41:1183–1188
14. López R, de Ita A, Vaca M (2009) Drying of prickly pear cactus
cladodes (Opuntia ficus-indica) in a forced convection tunnel.
Energ Convers Manage 50:2119–2126
15. Gallegos-Infante JA, Rocha-Guzman NE, Gonzalez-Laredo RF,
Reynoso-Camacho R, Medina-Torres L, Cervantes-Cardozo V
(2009) Effect of air flow rate on the polyphenols content and
antioxidant capacity of convective dried cactus pear cladodes
(Opuntia ficus-indica). Int J Food Sci Nutr 60:80–87
16. Medina-Torres L, Vernon-Carter EJ, Gallegos-Infante JA, RochaGuzman NE, Herrera-Valencia EE, Calderas F, Jiménez-Alvarado
R (2011) Study of the antioxidant properties of extracts obtained
from nopal cactus (Opuntia ficus-indica) cladodes after convective
drying. J Sci Food Agric 91:1001–1005
17. AOAC (2000) Official Methods of Analysis, 17th edn. Gaithersburg,
MD: Association of Official Analytical Chemists
18. AACC (2000) Approved methods 08–01, 30–25, 46–13 and 44–
19. St. Paul, MN: American Association of Cereal Chemists
19. Popescu C-M, Cazacu G, Singurel GH, Vasile C (2006) Study of
the process of the water desorption from lignins. Rom J Phys
51:277–283
20. Tsujiyama S, Miyamori A (2000) Assignment of DSC thermograms of wood and its components. Thermochim Acta 351:177–
181
21. Ahuja M, Kumar S, Yadav M (2010) Evaluation of mimosa seed
mucilage as bucoadhesive polymer. Yakugaku Zasshi 130:937–
944
22. Finot PA, Aeschbacher HU, Hurrel RF, Liardon R (1990) The
Maillard Reaction in Food Processing, Human Nutrition and
Physiology. Birka user Verlag, Boston
23. Martins SIFS, Jongen WMF, van Boekel MJS (2001) A review of
maillard reaction in food and implications to kinetic modeling.
Trends Food Sci Tech 11:364–373
24. León-Martínez FM, Méndez-Lagunas LL, Rodríguez-Ramírez J
(2010) Spray drying of nopal mucilage (Opuntia ficus-indica):
Effects on powder properties and characterization. Carbohyd
Polym 81:864–870
25. Saenz C, Sepulveda E, Matsuhiro B (2004) Opuntia spp
mucilage’s: A functional component with industrial perspectives.
J Arid Environ 57:275–290
26. Bensadon S, Hervert-Hernández D, Sáyago-Ayerdi SG, Goñi I
(2010) By-products of Opuntia ficus-indica as a source of
antioxidant dietary fiber. Plant Foods Hum Nutr 65:210–216
27. Thebaudin JY, Lefebvre AC, Harrington M, Bourgeois CM (1997)
Dietary fibres: Nutritional and technological interest. Trend Food
Sci Tech 8:41–48
28. Nawar WW (1984) Chemical changes in lipids produced by
thermal processing. J Chem Educ 61(4):299–302
29. Ayadi MA, Abdelmaksoud W, Ennouri M, Attia H (2009) Cladodes
from Opuntia ficus-indica as a source of dietary fiber: Effect on
dough characteristics and cake making. Ind Crops Prod 30:40–47
30. Cushman JC, Bohnert HJ (1999) Crassulacean acid metabolism:
Molecular genetics. Annu Rev Plant Physiol 50:305–332