Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.11, n.2, p.137-142, 2009
ISSN 1517-8595
137
THE PROCESSING AND CHARACTERIZATION OF RED CHILI PEPPER JAM
Felipe Richter Reis1, Bogdan Demczuk Júnior1 , Sonia Mara Macari2 , Maria Lucia
Masson3
ABSTRACT
Red pepper fruit does not have a high added value. Thus, the use of this fruit in the preparation
of a jelly is a way of adding value to it. In this study, a process of evaporation was used to make
jam from red chili pepper fruit after which a comprehensive characterization of the final product
was obtained. Evaporation was carried out under direct fire at atmospheric pressure. The
changes in the solution concentration were well fitted by means of an exponential model.
During evaporation, the solution boiling point rose up, which most commonly occurs during
food evaporation. The jam formulation was (w/w): 100:50:1:0.08 parts of red chili peppers juice
(0.2 °Brix), sucrose, pectin and citric acid, respectively. The jam presented the following
characteristic: pH of 2.7; soluble solids content of 75°Brix; gel deformation of 3.57%; water
activity of 0.71; viscosity of 972.86 mm2/s; lightness of 19.54; redness of 7.75; yellowness of
17.39; hue angle of 65.97 (orange); and average sensory score of 7.73. No syneresis was
observed after 180 days of storage. Results suggest that the final product from the evaporation
of the red chili pepper fruit makes a high quality jam considering its physical-chemical
properties, sensory properties and physical stability. This study can be used to design a process
to manufacture red chili pepper jam.
Keywords: red chili pepper, jam, evaporation.
PROCESSAMENTO E CARACTERIZAÇÃO DE GELÉIA DE PIMENTA VERMELHA
RESUMO
Frutos de pimenta vermelha não apresentam um alto valor agregado. Sendo assim, o uso destes
frutos no preparo de uma geléia é uma forma de adicioná-los valor. Neste estudo, um processo
de evaporação foi empregado para produzir uma geléia a partir de frutos de pimenta vermelha e
uma abrangente caracterização do produto final foi realizada. A evaporação foi efetuada sob
fogo direto à pressão atmosférica. A variação da concentração da solução de alimentação foi
bem ajustada por um modelo exponencial, e o ponto de ebulição da solução aumentou durante o
processo de evaporação, o que é um comportamento tipicamente observado quando se
evaporam alimentos líquidos. A formulação da geléia foi (em m/m): 100:50:1:0,08 partes de
suco de pimenta vermelha à 0,2 °Brix, sacarose, pectina, e ácido cítrico, respectivamente. A
geléia apresentou pH de 2,7, teor de sólidos solúveis de 75 °Brix, deformação do gel de 3,57%,
atividade de água de 0,71, viscosidade cinemática de 972,86 mm2/s, luminosidade de 19,54,
tonalidade vermelha de 7,75, tonalidade amarela de 17,39, ângulo de tom de 65,97 (laranja), e
escore sensorial médio de 7,73. Não foi observada sinérese do produto após 180 dias de
armazenamento à temperatura ambiente. Os resultados permitem afirmar que o produto final da
evaporação de frutos de pimenta vermelha é uma geléia de alta qualidade no que tange a
caraterísticas físico-químicas, sensoriais e de estabilidade física. Os dados gerados podem ser
utilizados para delinear um processo de produção de geléia de pimenta vermelha.
Palavras-chave: pimenta vermelha, geléia, evaporação.
Protocolo 110.006 de 15/10/2009
1
Eng. de Alimentos, M.Sc, doutorando, Programa de Pós-Graduação em Tecnologia de Alimentos, Depto. de Engenharia Química, UFPR,
Caixa Postal 19011, CEP 81531-990, Curitiba-PR, (00XX41) 33613232, [email protected]; [email protected].
2
Eng. de Alimentos, M.Sc. [email protected].
3
Eng. Química, D.S., Professora do Programa de Pós-Graduação em Tecnologia de Alimentos, Depto. de Engenharia Química, UFPR,
(00XX41) 33613232, [email protected].
138
Processing and characterization of red chili pepper jam
Reis et al.
MATERIALS AND METHODS
INTRODUCTION
Chili peppers, which are fruits of the
plants from the Capsicum genus are one of the
200 primary commodities (Food and
Agriculture Organization of the United Nations,
2007). Brazil is an important center of
domesticated species of the Capsicum genus,
where a wide diversity of C. annuum var.
annuum, C. baccatum var. pendulum, C.
frutescens e C. Chinense can be found. Fruits of
the plant named Capsicum baccatum, from the
pendulum variety, are typically elongated and
finger-shaped, presenting a size of 7 x 1-1.5 cm
(length x width), low pungency and aroma and
red color (Sudré et al., 2005; Embrapa, 2008).
As many other fruits, red chili peppers present
high water contents.
Evaporation is a unit operation that is
used for the partial removal of water from
liquid foods by boiling. The concentration of
solids achieved by evaporation, due to a
difference in volatility between water (solvent)
and solute, reduces water activity, such as in
jams, and hence helps in preservation (Sharma
et al., 2000). The concentration of diluted
solutes in the heated solution is an important
parameter to be studied when carrying out the
concentration of liquid foods by evaporation
(Ordóñez, 2005).
The gel observed in good jams is
obtained when special conditions of solids and
pectin concentration and pH are achieved
(Cecchi, 2003). Some fruits do not present an
adequate amount of pectin in order to promote
gelification. In this case it is necessary to add
pectin to the jam. According to Jackix (1988),
the optimum amount of pectin to be added to
promote gelification is around 1% (w/w), the
pH must be between 2.6 and 3.4 and the solids
concentration between 68 and 76°Brix.
The economic importance of chili
peppers is remarkable. In addition, their
perishability is high and their added-value is
low. Thus, it is important to find ways to
improve their shelf life and add them value.
This research reports a study of evaporation
process in order to obtain red chili peppers jam
and some of its chemical, physical and sensory
characteristics.
Materials
Red chili peppers (pendulum variety)
and sucrose (Nova América, Tarumã, Brazil)
were acquired in the local market. Citric pectin
was acquired from SP Labor (Presidente
Prudente, Brazil) and citric acid was acquired
from Labsynth (Diadema, Brazil). All reagents
were of analytical grade. The potable water
used in the jam formulation was tap water.
Methods
Raw peppers were washed, separated
from their stems, weighed, ground and
homogenized with water (1:1 w/w) for 1 minute
in a food-processor (Philips do Brasil, São
Paulo, Brazil). The homogenized was heated in
an aluminum pan at 70°C for 10 minutes under
direct fire to boost the aqueous extraction of
pepper solids. The biggest solids were then
removed by means of a plastic sieve model
12506 (Jolly, São Paulo, Brazil). The juice
concentration was measured by means of a
standardized Abbe refractometer. The juice was
then diluted with water at the concentration of
0.2 °Brix.
Sucrose was mixed with the diluted
juice and the solution was transferred to an
aluminum kettle and evaporated at atmospheric
pressure (91.325 Pa at Curitiba, Brazil) under
direct fire. The solution concentration and
temperature were measured at 10 minutes
intervals during the evaporation treatment.
Since evaporation is a water removal operation,
an exponential mathematical model was fitted
to the experimental data in order to find the
respective equation that described the process
and the value of the determination coefficient or
R2. At 40 minutes of evaporation the solution
was added with the pectin. When the jam
concentration reached the range suggested by
previous studies, the evaporation was
interrupted. The pH was measured and adjusted
with citric acid until it reached a value within
the range recommended by other authors
(Jackix, 1988).
Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.11, n.2, p.137-142, 2009
Processing and characterization of red chili pepper jam
The jam was packed at 104°C in glass flasks
which were turned upside down during three
minutes for pasteurization. Part of the jam
(sample A) was analyzed and other part (sample
B) was stored for 180 days to verify the
occurrence of syneresis. The gel deformity after
cooling was evaluated by filling three flasks
which presented flat bottoms with hot jam.
After cooling to around 21°C, the jam was
removed from the flasks and the gel height was
measured and compared to the height of the
flask using equation 1, which gives a parameter
we called gel deformation, as follows:
Gel deformation % = 100 – [(GH/FH) x100]
(equation 1)
In such equation, GH corresponds to the gel
height and FH corresponds to the flask height.
The jam kinematic viscosity was measured at
95 °C by means of a CT 52 capillary viscometer
(Schott Geräte, Mainz, Germany). The glass
capillary used had a 1.26 mm internal diameter.
Kinematic viscosity was given by equation 2,
showed below.
v=K.t
(equation 2)
In such equation, v corresponds to the
kinematic viscosity (mm2/s), K is a capillarydependent constant and t (s) is the time required
for the liquid to flow through a standardized
section of the glass capillary. Water activity
(Aw) was measured at 21°C by means of a
Pawkit water activity meter (Decagon Devices,
Pullman, United States). Color was measured
by means of a MiniScan XE PLus portable
reflectance spectrophotometer (HunterLab,
Reston, United States) and expressed as
parameters of the CIE L*a*b* and CIE L*C*h*
scales (Comission Internationale de l’Eclairage,
1986). The sensory acceptability of the final
product was evaluated by 26 assessors who
previously reported to like piquant foodstuffs.
The panel used a structured hedonic scale in
which “1” corresponded to “dislike extremely”
and “9” corresponded to “like extremely”
(Meilgard et al., 1987). Each assessor
received an approximately 15g jam sample and
a cream cracker biscuit and was required to
Reis et al.
139
evaluate the sample by eating it pure and also
mixed with the biscuit.
RESULTS AND DISCUSSION
The formulation suggested by us for
preparing red chili peppers jam is showed in
Table 1.
Table 1: Chili peppers jam formulation
Ingredients
Parts (in weight)
Chilly juice*
100.00
Sucrose
50.00
Pectin
1.00
Citric acid
0.08
*Soluble solids content: 0.2 °Brix.
The amount of pectin added followed
the directions provided by Jackix (1988). The
amount of citric acid added was that necessary
to promote gelification. Sugar was added in
order to provide our jam with the characteristic
sensory attributes of jams, such as sweetness
and gelified texture. The experimental data
were in good agreement (R2 = 0.98) with the
exponential model (figure 1), as expected and
observed before for unit operations of water
removal (Velic et al., 2004). The evaporation
was interrupted at 80 minutes of process, when
the desired soluble solids content was achieved.
Table 2 shows the variation in jam solution
temperature during the evaporation process.
Boiling started at 50 minutes of process. There
was an increase of 7°C in the jam boiling point,
which can be justified by the fact that, as the
food concentration rises, larger amounts of heat
are necessary to remove water from food. Such
behavior is attributed to stronger physical and
chemical interactions between water and food
solids at such conditions (Palanimuthu &
Chattopadhyay,
1993;
Kaleemullah
&
Kailappan, 2005).
Table 3 shows some chemical and
physical characteristics of the red chili peppers
jam. The mechanical shocks which may take
place during transportation can cause breaking
of the gel and, in that way, impair its
appearance.
Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.11, n.2, p.137-142, 2009
140
Processing and characterization of red chili pepper jam
Reis et al.
Figure 1 – Changes in feed solution concentration along with the time of evaporation.
Table 2 – Changes in feed solution temperature along with the time of evaporation.
Jam temperature (°C)
Evaporation time (min)
21.4
0
74.0
10
90.0
20
94.0
30
96.0
40
97.0
50 (beginning of boiling)
97.0
60
100.0
70
104.0
80
A low gel deformation, like the one
observed in this study, suggests that the jam is
relatively shock-resistant. The red chili peppers
jam presented a very low water activity, as
expected. Most yeasts, molds and bacteria do
not survive at low water activities, which are
correlated with a long shelf life (Beuchat,
1981). Food rheological properties, such as
viscosity, are useful for designing, choosing
and operating equipments such as pumps and
shaking systems (Vidal et al., 2004). The red
chili peppers jam kinematic viscosity is also
showed in table 3. The jam color was found to
be darkened (low L* value), reddish (positive
a* value) and yellowish (positive b* value).
The mixture of red and yellow hues yields the
orange hue, which is the red chili peppers jam
hue (h*) as expressed in the polar L*C*h*
space. Such hue can be attributed to the
carotenoids contained in peppers, while low
lightness is typically correlated with the
products of caramelization and Maillard
reactions (Deepa et al., 2007). After 180 days of
storage, it was not observed syneresis in the
jam, which confirms a high stability of the gel.
Figure 2 shows the distribution of the
scores provided by the sensory panel when
evaluating the red chili peppers jam. It was
observed that the majority of the assessors gave
high scores (“8”) to the jam. Such result means
Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.11, n.2, p.137-142, 2009
Processing and characterization of red chili pepper jam
that most of the assessors “like very much” the
jam as expressed by hedonic rating. A score of
“7” is the minimum numeric limit for
acceptance of an evaluated food (Meilgard et
141
Reis et al.
al., 1987) and the average score of our jam was
above seven (7.73), i.e., the product was well
accepted by consumers.
Table 3 - Chemical and physical characteristics of red chili peppers jam
Parameters
Values
pH
2.70
Soluble solids (°Brix)
74.00
Gel deformation (%)
3.57
Aw (at 21°C)
0.71
Viscosity (mm2/s at 95°C)
972.86
Lightness (L*)
Redness (a*)
Yellowness (b*)
Hue angle (h*)
Syneresis after 180 days of storage
19.54
7.75
17.39
65.97
None
10
9
8
7
6
Number of assessors
5
4
3
2
1
0
6
7
8
9
Hedonic score
Figure 2 – Sensory profile of red chili pepper jam.
Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.11, n.2, p.137-142, 2009
142
Processing and characterization of red chili pepper jam
CONCLUSIONS
Evaporation of a 0.2 °Brix juice made
from red chili peppers fruits and added with
sucrose, pectin and citric acid generated a high
quality jam. This can be concluded on the basis
of the characteristic sensory properties, physical
chemical parameters and stability to storage
observed in the final product. An exponential
model successfully fitted (R2 = 0.98) the
changes in feed solution water content,
suggesting that the unit operation studied is a
typical water removal operation. Once a process
was suggested and process parameters were
generated, this study can be used as a reference
to obtain red chili pepper jam, helping to add
value to this relevant food commodity.
ACKNOWLEDGMENTS
The authors thank CAPES and CNPq for the
financial support.
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