Proceeding of 2013 International Seminar on Climate Change and Food Security ISCCFS 2013
Palembang, South Sumatra -Indonesia, 24-25 October,2013
126
2. Materials and Methods
2.1. Materials
The materials used in the experiments were
batik
rice
Ciherang
variety. The chemical agents used in proximate analysis were in analytical grade. The equipments were analytical balance Ohaus, texture
analyzer LFRA 1500, Brookfield, USA, chromameter Minolta, HPLC, oven Memmert, spectrophotometer Jenway 6305, muffle furnace 1400 Barnstead Thermolyne.
2.2. Methods
The research included two phases, namely: 1 sampling of
batik
rice, 2 analysis of physical, chemical, sensory and functional characteristics of
batik
rice. All analysis on
batik
rice would be also carried out in milled ordinary rice. It was intended to compare the changes that occur in
batik
rice with ordinary rice. The physical properties of the samples were analyzed for the grain dimension and color intensity.
Chemical properties were analyzed for the levels of protein, thiamin, essential amino acids, and antioxidant activity. Analysis of crude protein and antioxidant activity [9] were conducted in the laboratory of
Chemistry of Agricultural Product, Faculty of Agriculture, Sriwijaya University. Amino acid analysis was carried out by using High Performance Liquid Chromatography HPLC at the Integrated Laboratory of
Bogor Agriculture Institution in Bogor, and thiamin analysis by using HPLC at the laboratory of Saraswanti Indo Genetech, Bogor. The grain dimension was measured by using calipers.
The texture analysis was carried out on cooked rice which was cooked in a rice cooker at the ratio between rice and water of 1:3. The specification of texture analyzer‘s probe was TA 39 with 2mm of
diameter, 20mm of length, flat end made of
stainless steel
. The colour intensity was measured by chromameter for the attributes of
L
lightness,
C
chroma,
h
hue,
a
redness,
b
yellowness. The sensory evaluation of paired comparison test was selected for cooked milled
batik
rice. Cooked milled ordinary rice was used as standard in the paired comparison test.
3. Results and Discussion
3.1 Physical Properties of Batik Rice
The physical properties of
batik
rice grain were observed for the rice grain dimensions length, width, and thickness, colour intensity and texture analysis. The average of water content on rice grain was around
12 ww. Rice grains are not completely spherical or cylindrical. The longest side of a rice grain was considered
as length of the rice grain. The greatest side of a rice grain‘s center was considered as width, while the shortest si
de of a rice grain‘s center was assumed as thickness. The results of rice grain dimension are presented in Figure 1.
Fig. 1: Rice grain dimension
9.32 9.32
6.51 6.67
2.28 2.33
1.84 1.85
1.6 1.99
1.54 1.56
2 4
6 8
10 12
Ordinary rough rice Batik rough rice Ordinary milled rice
Milled batik rice L
en g
th ,
w id
th o
r th
ick n
ess
m m
Length Width
Thickness
Proceeding of 2013 International Seminar on Climate Change and Food Security ISCCFS 2013
Palembang, South Sumatra -Indonesia, 24-25 October,2013
127 Figure 1 shows that the length, width and thickness of
batik
rice grain both rough and milled rice tend to be larger than ordinary rice.
Ciherang
rice variety was classified as long rice grain due to the ratio of length and width was more than 3. The ratio between length and width of both rough
batik
and ordinary rice were 4.09 and 4.00, respectively, while the ratio between length and width of milled
batik
and ordinary rice were 3.54 and 3.61, respectively.
Color analysis was carried out by using the CIELAB system, and
LCH
color scale. CIELAB color space set in cube form shape of a cube.
L
axis starting from the top down top to bottom with
a
maximum value of 100 indicating perfect reflecting diffuser is indicated as a white, and a value of zero indicates the color black. Axes
a
and
b
have no numerical limits. Positive
a
indicates red, and negative
a
is green. Positive value of
b
is yellow and negative
b
is blue. In this study, the color of ordinary rice grain sample was considered as standard. The results of color intensity for milled
batik
and ordinary rice grains are presented in Table 1.
Table 1. Colour intensity of milled
batik
and ordinary rice grains No.
Colour components Milled ordinary rice
Milled
batik
rice 1.
L Lightness
, 69.90 ± 1.87
72.23 ± 2.85 2.
C Chroma
, 12.00 ± 0.20
11.57 ± 0.67 3.
h Hue
,
o
77.83 ± 0.49 79.27 ± 1.63
4.
a
2.43 ± 0.15 2.23 ± 0.35
5.
b
11.27 ± 0.67 11.77 ± 0.25
Lipase is the primary enzyme that resulted in hydrolysis of triglycerides into glycerol and fatty acids. Lipase significantly increased free fatty acids in brown rice due to lipid hydrolysis [10], wherein the lipase
activity is affected by moisture, temperature, pH, time and water activity [11][12]. The activity of lipase enzyme increased at the temperature of 40
o
C, then its activity would decrease after reaching the temperature of 60
o
C [13]. The humidity in the stack of wet rough rice grains was high and its temperature might reach 40°C, and this condition could support the occurrence of such lipase activity.
Texture analysis showed that the texture of cooked
batik
rice 29 gf was higher than that of cooked ordinary rice 20.67gf. It might be due to aleurone on the surface of milled
batik
rice disrupting water penetration into the rice endosperm during cooking, so it resulted in harder texture in cooked milled
batik
rice. Higher degree of milling resulted in easier water absorption into the rice endosperm when cooking rice [14]. Higher milling degree means more aleurones were brushed off during milling that could be indicated
by whiter milled rice. In addition, it might result in softer texture in cooked rice [14].
3.2. Chemical Characteristics of
