Tối ưu hóa các yếu tố ảnh hưởng đến quá trình sản xuất sirô sim (Rhodomyrtus tomentosa) để có hàm lượng anthocyanin cao

t germinate. Consequently, it is only 
necessary to inactivate molds and yeasts. This 
can be done at much lower temperatures, with 
the result that the F0-values are very low, since 
the lethal rate at a temperature of 80◦C is 7.76 
× 10−5 min−1. A more practical unit for 
quantifying the lethal effect of this type of 
process is the pasteurization unit PU 
(Holdsworth and Simpson 2007) given by 
dt10=PU
t
0
z
)TT(
z
T
ref
ref 

 [7] 
Where t is the time, T is temperature of the 
product, Tref is the reference temperature, z is 
the thermal destruction rate analogous. In this 
study, with the pH = 3, the Sim syrup has to 
achieve the PU-value higher than 5 min using 
the Tref = 85oC and z = 8.3oC (Ly Nguyen Binh 
and Nguyen Nhat Minh Phuong, 2011; 
Weemaes, 1997). 
2.5. Statistical analysis 
Response surface methodology (RSM) is an 
effective statistical method based on a 
multivariate non-linear model, and has been 
widely used for optimizing complex process 
variables (Mundra et al., 2007). Using 
Statgraphics 15, RSM was used to describe and 
optimize the extraction of anthocyanins from 
Sim crudes. 
3. RESULTS AND DISCUSSION 
3.1. Composition of Sim fruit 
In this study, the sugar content (27.23%), 
the total acid (0.76%) and pectin (2.76%) of 
whole sim fruit from Mang Den, Kom Tum was 
higher those from Phu Quoc, Kien Giang 
(Nguyen Thi Ngoc Ngan, 2009). The contents 
were different due to effect of growing 
conditions. However, the anthocyanin concent 
(75.46mg/100g) in whole sim fruit from Mang 
Den, Kom Tum was lower than that 
(160mg/100g) from Thai Nguyen and Hai Duong 
(Lai Thi Ngoc Ha et al., 2013). Beside of 
growing conditions, the method analysis might 
contribute to the difference of anthocynin 
concentration. 
Table 1. Composition (/100g dry weight) 
of Sim fruit 
Composition Content 
Sugar (g) 
Total acid (g) 
Pectin (g) 
Anthocyanin (mg) 
27.23 ± 0.25 
0.76 ± 0.01 
2.76 ± 0.07 
75.46 ± 0.73 
Optimization of factors to affect syrup production from "sim" fruit (Thodomyrtus tomentosa) (Mang Den, Kontum) 
for high anthocyanin concentration and good quality 
102 
3.2. Optimization of concentration of 
pectinase, temperature and time for 
extraction of Sim juice. 
Extraction is an important step to gain high 
yield of juice containing high concentration of 
soluble solid concentration and high 
concentration of anthocyanins. However, Sim 
crudes with high concentration of pectin are too 
turbid and viscous which is difficult to filter and 
collect juice. Using pectinase to break down 
pectin in the cell wall of fruit, the filtrate would 
have more yield (Nadeem, 2009), high 
concentrations of soluble solid and 
anthocyanins. 
Optimization of pectinase concentration, 
temperature and time for yield in the filtrate 
The surface response shows effects of 
temperature, time and pectinase enzyme on the 
yield of the filtrate (Figure 1). 
There was significant difference of the 
filtrate yields between different pectinase 
concentration, temperature and time. When the 
incubation temperature increased upto 40oC, 
the filtrate yield increased. Then the yield went 
down when the temperature was higher 40oC. 
This could be explained that the pectinase 
enzyme hydrolyzed pectin of the fruit cell wall 
to release more juice and reduced the viscous of 
the crudes to improve filterability (Nguyen 
Trong Can et al., 1998; Viquez et al., 1981). It is 
also reported that pectinase enzyme breaks 
down the link between pectin and cellulose of 
the cells and tissues to release the soluble 
substrates (sugar, acid, vitamin and 
anthocyanin) resulting increase of the yield. It 
was found that the hydrolysis of pectin could 
increase the extraction yield 10% more than the 
control (Wolfbrother, 2011). 
The response surface could be fitted and 
described by the model with R2=0.97 as shown 
below: 
Yield = H (%) = - 105.90 + 7.16X + 0.54Y + 
171.85Z - 0,09X2 – 0.01XY – 0.01Y2 - 717.04Z2 [8] 
Where, X is temperature (oC), Y is time 
(min), Z is pectinase concentration (%). 
The optimal extraction conditions for the 
filtrate yield (62.3%) was pectinase enzyme of 
0.1% at temperature of 40oC for 60 minutes. 
Nguyen Thi Ngoc Ngan (2009) reported the 
highest filtrate yield of sim crude from Phu 
Quoc was obtained when treated with pectinase 
concentration (0.8%) for 5 hours while the 
filtrate yield of was only 59.17% when sim 
crudes was treated with pectinase concentrate 
(0.6%) for 60 minutes. 
Chauhan and Gupta (2004), and Le Viet 
Man et al. (2010) have emphasized the 
acceptance of any model with R2 > 0.75. 
Therefore, the R2 of this model and the following 
models were higher than 0.75 which was 
acceptable. Shahadan and Abdullah (1995) 
found that use of 0.04% pectinase enzyme 
(Pectinex Ultra SP-L, Novozymes A/S, 
Denmark) at 300C with pH 3.4 was effective to 
reduce viscosity and improve filterability in the 
preparation of clarified banana juice. 
Figure 1. Response surface plots 
of the yield of the filtrate affected 
by incubation temperature and time 
Using the Eq.[8], the values of yield were 
predicted from pectinase concentration, 
temperature and time. Figure 2 shows that the 
predicted yield and actual yield had high 
correlation coefficient of 0.95. It means that the 
model (Eq.[8]) could be used to describe the 
yield as a function of pectinase concentration, 
temperature and time in the extraction process. 
Nhân Minh Trí, Nguyễn Minh Thủy, Phạm Thị Kim Quyên 
103 
Figure 2. Relationship between the actual and predicted yields 
Optimization of pectinase concentration, 
temperature and time for transmittance of the 
filtrate 
The surface response shows effect of 
temperature, time and pectinase enzyme on the 
transmittance of the filtrate (Figure 3). 
It is known that fruit juice contains a lot of 
substrates including pectins and protein which 
cause viscosity and stupidity of juice. The 
Pectinex can have pectinase and protease which 
break down the pectin and protein molecules to 
decrease viscosity and stupidity in fruit juice 
(Hoang Kim Anh, 2007). The filtration of fruit 
juice will be efficient, if the juice is pretreated 
with pectinase (Le Ngoc Tu, 2003) 
There were significant differences of the 
transmittance of filtrate between different 
pectinase concentration, temperature and time. 
When the incubation temperature increased 
upto 40oC, the transmittance of the filtrate 
increased. Fruit juices contain colloids that are 
mainly polysaccharides (pectin, cellulose, 
hemicellulose, lignin and starch), protein, 
tannin and metals (Vaillant et al., 2001). The 
major problem is that the presence of pectin 
causes cloudiness during the preparation of 
fruit juices. The pectinase hydrolyses pectin and 
separate the complexes of pectin–protein 
resulting in flocculation of pectin and protein. 
Many studies reported that pectinase enzyme 
Figure 3. Response surface plots of the transmittance 
of the filtrate affected by incubation temperature and time 
Optimization of factors to affect syrup production from "sim" fruit (Thodomyrtus tomentosa) (Mang Den, Kontum) 
for high anthocyanin concentration and good quality 
104 
was used for clarification of fruit juices 
(Kashyap et al., 2001; Lee et al., 2001). 
The response surface could be fitted and 
described by the model with R2=0.78 as shown 
below: 
Transmittance = -230.26 + 9.47X + 1.07Y + 
612.65Z – 0.12X2 – 0.01Y2 – 1.01YZ – 2382.96Z2 [9] 
Where, X is temperature (oC), Y is time 
(min), Z is pectinase concentration (%). 
The optimal extraction conditions for the 
transmittance (38.3%) of the filtrate was 
pectinase enzyme of 0.1% at temperature of 
40oC for 60 or 80 minutes. 
Optimization of pectinase concentration, 
temperature and time for anthocyanin 
concentration in the filtrate 
The surface response shows effect of 
temperature, time and pectinase enzyme on 
anthocyanin concentration in the filtrate 
(Figure 4). 
There were significant differences of the 
anthocyanin concentrations of filtrate between 
different pectinase concentration, temperature 
and time. When the incubation temperature 
increased upto 40oC, the anthocyanin 
concentrations of the filtrate increased. 
The concentration of anthocyanin 
increased with concentration of pectinase 
enzyme. It is known that pectinase can be 
helpful to extract colorants (e.g., anthocyanin), 
tannin and other soluble solids (sugar and 
acid) to enhance the quality of juice (Le Ngoc 
Tu, 2003; Hoang Kim Anh, 2007; Tadakittisarn 
et al., 2007; Liu et al., 2012). 
The response surface could be fitted and 
described by the model with R2=0.81 as shown 
below: 
Anthocyanin = -313.06 + 15.25X + 1.25Y + 
503.07Z - 0,19X2 - 0,01Y2 – 1971.41Z2 [10] 
Where, X is temperature (oC), Y is time 
(min), Z is pectinase concentration (%). 
The optimal conditions for anthocyanin 
concentration (68.52 mg/L ) in the filtrate 
extracted from the whole sim fruit was 
pectinase enzyme of 0.1% at temperature of 
40oC for 60 minutes. Liu et al. (2012) found that 
the optimal conditions for extracting 
anthocyanins from the fruit skin of downy rose-
myrtle (sim fruit) were 64.38 °C, 116.88 min, 
15.7:1 liquid-solid ratio, with the corresponding 
anthocyanin content = 4.345 mg/g. The reasons 
can be that they studied the skin of sim fruit 
which contains higher content of anthocyanin.
Figure 4. Response surface plots of the anthocyanin concentration 
of the filtrate affected by incubation temperature and time 
Nhân Minh Trí, Nguyễn Minh Thủy, Phạm Thị Kim Quyên 
105 
3.3. Effects of pasteurization on quality of 
syrup and loss of anthocyanin 
3.3.1. Effects of pasteurization on safety 
Food in the cans or bottles has to be sterilized 
or pasteurized to inactivate enzymes and 
microorganisms for safety and preservation 
(Nguyen Trong Can and Nguyen Thi Le Ha, 2009). 
The sim syrup with the pH of 3.6 was treated 
thermally with the Tref = 85oC and z = 8.3oC (Ly 
Nguyen Binh and Nguyen Nhat Minh Phuong, 
2011; Weemaes, 1997). The temperature profiles of 
Sim syrup heated at 85oC shown on Figure 5 are 
representative for pasteurization of all samples in 
this study. These temperature profiles of Sim syrup 
of the same heating temperature (85oC) were 
heated at different holding times. 
The temperature profiles at 80, 85 and 90oC 
were used to calculate PU-values of 
pasteurization process (PU = PUcoming up + 
PUholding + PUcooling) using [Eq.7]. The PU-values 
and total microbial counts of the pasteurized 
Sim syrup are shown in Table 2. 
The longer holding times were, the higher 
PU-values and the lower total counts were. If 
the Sim syrups were pasteurized at 85 ÷ 90oC 
for 2 ÷ 6, the PU-values would be 7.8 ÷ 40 
higher PU-value = 5 (Ly Nguyen Binh and 
Nguyen Nhat Minh Phuong, 2011; Weemaes, 
1997) and the sim syrups would be safe with the 
total microbial count = 0. However, the higher 
PU-values were the more loss of anthocyanin 
and the lower sensory values. 
Figure 5. Temperature profiles of Sim syrup pasteurized 
at heating temperature of 85oC with holding times for 2, 4 and 6 minutes 
Table 2. Effects of pasteurization on PU-values with z = 8.3 & Tref = 85oC 
and total microbial counts 
Product temperatures 
(oC) 
Holding times (min) 
 2 4 6 
PU-value CFU/g PU-value CFU/g PU-value CFU/g 
80 1.86 8.2x10
1 2.21 9.4x102 3.15 5.0x101 
85 7.82 5.7x101 9.18 - 11.07 - 
90 20.98 - 33.06 - 40.33 - 
Note: ‘-‘, no microbial counts. 
Optimization of factors to affect syrup production from "sim" fruit (Thodomyrtus tomentosa) (Mang Den, Kontum) 
for high anthocyanin concentration and good quality 
106 
3.3.2. Effects of pasteurization on loss of 
anthocyanin 
Pasteurization improves the safety and the 
shelf life of Sim syrup product. However, 
anthocyanin is degradable due to heat treatment 
during pasteurization. Anthocyanins degrade 
easily to form unacceptable browning compounds 
during thermal process (Torskangerpoll and 
Andersen, 2005; Liu et al., 2013). 
The thermal process for Sim syrup was applied 
at 85oC for 4 min to obtain PU858.3 = 9 min, no total 
microbial counts and high sensory values. The PU858.3 
= 9.18 min for sim syrup with pH = 3.5 meets 
requirement for the juice product (Holdsworth and 
Simpson, 2007; Weemaes, 1997). If the product is 
heated with lower PU858.3 = 9.18 min, the product will 
not be safe. If the product is heated with higher PU858.3 
= 9.18 min, the overcooking will cause high loss of 
anthocyanin and high waste of electricity and time. 
Figure 6. Change of anthocyanin concentration with temperature 
and time during pasteurization 
4. CONCLUSION 
Pretreatment of Sim crudes by pectinase 
could be described by models for yield, 
transmittance and anthocyanin concentration in 
the filtrate as a function of pectinase 
concentration, temperature and time. They 
could be optimized by using pectinase enzyme 
0.1 % at temperature 40oC for 60 minutes to 
have the highest yield (62.93%), clarity (38.3%, 
T) and anthocyanin concentration (68.52 mg/L) 
in the Sim extract. Sim syrup was pasteurized 
at temperature 85oC with holding time of 4 min 
to have PU-value = 9.18 min, high safety and 
high anthocyanin concentration retained in the 
Sim fruit syrup. This product is a natural and 
nutritious fruit drink containing high energy, 
vitamins, and anthocyanin which is able to 
prevent chronic, and diabetes, cardiovascular 
disease and cancer. Production of sim syrup 
utilizeingthe wild fruit for new food product 
development is helpful to increase income for 
famers living in the highlands. 
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