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Aceh Int. J. Sci. Technol., 7(2): 138-143
August 2018
doi: 10.13170/aijst.7.2.8964
138
Analysis of Parameter Roasting on Color and Peanuts Roasted Taste
Silvi Ariyanti1*, Chandrasa Soekardi2 and M. Sobron Yamin Lubis3
1Industrial Engineering Study Program of Mercubuana University, Jakarta, Indonesia
2Mechanical Engineering Study Program of Mercubuana University, Jakarta, Indonesia
3Mechanical Engineering Study Program of Tarumanagara University, Jakarta, Indonesia
*Corresponding Author Email: silvi.ariyanti@mercubuana.ac.id
Received : Nopember 20, 2017
Accepted : August 21, 2018
Online : August 31, 2018
Abstract - The purpose of this study is to determine the optimum temperature of roasting, optimal rotation speed of tube
and roasting time, to produce roasted peanuts with good taste and good colour. The research method is experimental using
a Completely Randomized Design (CRD) with three factors of temperature, rotation and time. And analyzed using Anova
method and Multiple Linear Regression. Temperature consists of five variables, namely 80oC, 85oC, 90oC, 95oC and 100oC.
For rotations speed consists of 30, 35, 40 and 45 RPM. Variable of roasting time consists of four roasting times of 10, 15,
20 and 25 minutes. The numbers of data were 80 experiments. With three observation parameters namely moisture
containing, color and aroma. It can be concluded that the temperature 95oC is the optimal roasting temperature; the optimal
rotation speed is 40 RPM and 25 minutes for each roasting time. With the variable values mentioned, roasted bean products
contain a fairly good taste, good moisture and good colour.
Keywords: roasting temperature, rotation speed, optimal roasting, peanut
Introduction
Peanuts as one of the commodities of food crops have a high nutritional value and delicious taste. Peanuts
can be used for food, forage and cooking oil. In addition, peanuts can be processed into roasted beans. Peanut
is one of the most widely used legumes due to its nutrition and taste (Francisco and Maria, 2008). As a food,
peanuts have certain compounds that are indispensable for the body's organs for survival, especially protein,
carbohydrate and fat content (Susanto and Saneto, 1994). Due to their health-beneficial ingredients the
consumption of nuts can contribute to a healthy diet (Schlörmann et al. 2015)
Roasting is a relatively fast drying process. Peanut water content will decrease from 0.5% to 5%. This
reduction in water content is accompanied by the discharge of oil from the cotyledon surface. This peanut oil
comes out through the cytoplasm so that the cytoplasm becomes free of oil (Indrasti, 2003). Roasting done
evenly to get a uniform color of all nuts. Fatty acid compositions were not affected by roasting. Temperature
problems should be well controlled, because the lower temperatures will cause raw peanut smelt. The higher
temperatures will cause scorched (Indrasti, 2003).
The flavor and color of roasted peanuts have a strong impact on consumer acceptance (Lykomitros et.al,
2016). In order to be able to know the effect of roasting parameters on the taste and color of beans, the sensoric
test should be performed. The color sensoric test was performed using a hedonic test by random sampling and
given to ten panelists to be observed with a specific code. The parameters observed were roasted peanut color
(Manurung, 2013). During peanut roasting, pyrazine compounds correlate highly with roasted flavor and aroma.
Although roast color measurement is used to predict roasted flavor in peanuts, there are known variations
between roast color and flavor development among genotypes (Baker et al. 2003). The control system was tested
on a pilot-scale roaster and it successfully maintained roasted peanut colour within an acceptable range despite
disturbances in roaster bed depth, roasting air temperature and colour setpoint (Davidson et al. 1999).
Aceh International Journal of Science and Technology
ISSN: p-2088-9860; e-2503-2398
Journal homepage: http://jurnal.unsyiah.ac.id/aijst
Aceh Int. J. Sci. Technol., 7(2): 138-143
August 2018
doi: 10.13170/aijst.7.2.8964
139
The results of research by Dimitrios et.al (2016) it is found that the selection of raw materials is the key
factor to develop the taste, but processing method is also significantly increase the roasted color of oeanutes to
darken and reduce sweetness. It also affects the color and profile of fatty acids. Chemical characteristics and
fatty acid composition of the extracted oils were determined (Megahed, 2001).
The roasting process is not optimal and has not produced good quality products, due to the lack of precise
roasting speed and roasting time. Roasted beans produce varying surface colors at different temperature / time
combinations. Substantially, variations in chemical and physical properties will be related to the product quality
(Xiaolei et al, 2018 and Mcdaniel, 2012). Proper roasting process is very important for the development of taste,
color, and texture of the final product (Lasekan, 2014).
The roasting of peanuts was carried out using two pieces of cauldron and two stoves. During the roasting
process, peanuts must be continuously stirred by a man power by using both their right and left hands. This is
done because if the worker stops stirring because of exhaustion, the peanut will have burnt. This event often
occurs which results in a bitter taste of the roasted beans. Such errors lead to poor quality of roasted peanut.
Figure 1 Peanuts Roasting Machine
Based on the above problems, a prototype roasting machine to help small and medium-sized enterprises
to increase the productivity in roasting peanuts is introduced by reducing processing time and helping to clean
the epidermis on roasted beans (Figure 1). This peanut roasting machine has been equipped with rotary reader
screen, temperature controller and timer. Some grills are used including manually operated externally heated
rotating drums (Olawale, 2014). Important components of this machine are the feed hopper, roasting chamber,
drain outlet, main driver, speed reduction mechanism and main support and 2 Hp electric motor (Adesoji et.al,
2017).
Roasting was carried by using a roasting machine. The working principle of this roasting machine is as
follows: first, the tube is heated and rotated with an electric motor. After the temperature of the tube is ready
for roasting, the peanuts are put into the tube, then the peanuts are roasted and then the peanuts will fall into
tempering.
Based on the above considerations, a research on peanut roasting using a designed roasting machine was
conducted. The purpose of this study is to determine the optimal temperature, rotation speed of tube and
roasting time which produced good quality of roasted peanuts in order to produce taste and color of peanuts’
favoured meet with consumers’ expectation.
Materials and Methods
The materials used in this study were peanuts and liquid gas for the stove. The tools used in this study
were peanut a roasting machine, a digital scale, a gas stove and a camera. The data used consists of a tube
rotation speed, heating temperature and roasting time. Parameters observed were sensoric analysis related to
the colour, moisture content and organoleptic preference for peanut flavor. This experiment was used a
Completely Randomized Design (CRD) with three factors and analyzed using Analisis of Variance (ANOVA)
and Multiple Linear Regression. The experiment was carried out with three factors of roasting temperature,
Aceh Int. J. Sci. Technol., 7(2): 138-143
August 2018
doi: 10.13170/aijst.7.2.8964
140
rotation speed and roasting time. Roasting temperature consists of five variables; namely 800C, 850C, 900C, 950C
and 1000C. Rotation speed consists of 30, 35, 40 and 45 rotations per minute. For a roasting time consists of
four types of roasting times 10, 15, 20 and 25 minutes. The amount of experimental combination consists of 80
experiments.
Results and Discussion
Moisture Contains Test
From the ANOVA analysis it was found that there was a significant effect of temperature, rotation, and
time simultaneously on the water content which is shown in the regression model as follows:
Y = 96.992-0.136X1 + 0.202X2-0.095X3 (1)
Y is moisture content, X1 is roating temperature, X2 is rotation speed and X3 is roasting time. The
temperature value has a negative correlation value, meaning that the temperature increases will be followed by
a decrease in the percentage value of moisture or vice versa. While the rotation value (X2) has a positive
relationship, which means that the higher the rotation speed, will be followed by an increase in the percentage
of moisture. Roasting time (X3) also has a negative value which means that the higher the percentage of moisture
will be followed by a decrease in roasting time and vice versa. The results obtained proved that the roasting
temperature and time were the main factors affecting the moisture content (Karim et.al, 2011). The lower
percentage of moisture content will be better for the durability of roasted beans.
From the correlation value obtained R-value of 0.924 shows that there is a very strong relationship
between time, rotation and temperature to moisture content and from the value of R Square shows that the
time, rotation and temperature affect 85.5% of the percentage of moisture. Figure 2 shows the effect on roasting
temperature, rotation and time. It can be concluded that the lowest yield was found at a temperature of 95-
100oC, rotation 30 minutes and roasting time for 25 minutes.
Figure 2 the Effect of Moisture Contains on Time, Temperature and Roration
Testing of Taste
From the results of ANOVA analysis on the effect of time, tube rotation speed and roasting temperature
on peanuts flavor by respondent were found to have no significant effect. Likewise, with the correlation analysis
performed the R value of 0.226 shows that there is a weak relationship to the taste of nuts with time, rotation
and temperature. From the results of testing the regression coefficient partially with the t distribution found
that the roasting temperature and tube rotation speed have a significant effect on nut taste, but the roasting time
has non- significant effect on nut taste. Descriptive sensory analyses on these same roasted nuts samples showed
that optimal balance of important flavor characteristics such as roasted peanut, dark roast, and sweet had distinct
roast temperature and time requirements (Smyth et al. 1998). The excessive heat increased negative flavour
components such as bitter.
Aceh Int. J. Sci. Technol., 7(2): 138-143
August 2018
doi: 10.13170/aijst.7.2.8964
141
Figure 3 The Effect of Temperature, Rotation and Time on Bean Flavor
From Figure 3 it can be seen that the effect of temperature on the average flavour variation shows that
at a temperature of 95oC the taste of the bean is most preferred the taste of bean are crispy and resultserred
aroma. Rotation speed of 40 per minute results in the most preferred taste. 15 minutes roasting time produces
the most preferred bean flavour.
Colour Testing
From the results of ANOVA analysis on the effect of time, rotation and temperature of the roasting, the
results showed that all three had a significant effect on the colour of the roasted peanut. From the results of
multiple regressions analysis, it was obtained the equation:
Y= -4,993+0,074X1-0,004X2+0,0036X3 (3)
Y is the colour of the roasted peanuts, X1 is the temperature, X2 is the rotation and X3 is the time. The
model above shows that the temperature and roasting time have a positive effect on the peanuts temperature.
While the rotation has a negative influence on of the roasted peanuts. From the results of the correlation test it
is obtained that the R-value of 0.825. It shows that there is a strong relationship to the colour of peanuts that
have been roasted to temperature, rotation and time. From the R Square value shows that the time, rotation and
temperature affect 68.1% of the roasted peanuts colour and and 31.9% of the peanuts colour is influenced by
other factors.
Figure 4 The Effect of Temperature, Rotation and Time on Colour of Roasted Peanuts
From the partial test results at roasting temperature, it was found that the temperature had a significant
effect, the rotation had no significant effect and the roasting time partially had a significant effect on the roasted
Aceh Int. J. Sci. Technol., 7(2): 138-143
August 2018
doi: 10.13170/aijst.7.2.8964
142
colour. From figure 4, it can be seen that the best colours are darkish brown, which is present at roasting
temperature of 95-100oC, while the time and rotation is significantly influenced by the roasted bean colour.
Table 2 Comparison of Statistical Analysis Results
Moisture content
Anova
Regression
Correlation
Distribution t
The best value
Temperature
significant
effect
Negative
very strong
Significant effect
95o-100oC
Rotation
Positive
Non-significant effect
30 rpm
Time
Negative
Significant effect
25 minutes
Taste of Nuts
Anava
Regression
Correlation
Distribution t
The best value
Temperature
Non-
significant
effect
Positive
Poor
Significant effect
95oC
Rotation
Positive
Significant effect
40 rpm
Time
Positive
Non- Significant effect
15 minutes
Color
Anava
Regression
Correlation
Distribution t
The best value
Temperature
significant
effect
Positive
very strong
take effect
95o-100oC
Rotation
Negative
Non- Significant effect
Non- Significant effect
Time
Positive
Significant effect
Non- Significant effect
From Table for a temperature of 95oC, it provides good moisture, colour and taste. For rotations of 40
per minute that have significant effect, from the analysis of ANOVA it has a significant and positive correlation
effect. For the roasting time in Table 2, the best value is 25 minutes produce good peanut flavour. The roasting
process within an appropriate temperature range and time feature improved texture, more attractive colour, as
well as more favourable taste and flavor (Kita and Figiel, 2007).
Conclusion
Temperature of 95oC is optimal rotation temperature; optimal rotation speed is 40 rpm and 25 minutes
roasting period for roasting peanut. The roasted peanuts have a quite dry moisture content and resulted in a
good taste and colour.
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