15 5000g, 10 min. The supernatant was then decanted and washed with 50 ethanol twice to remove
the digested starch. The sediment was solubillized in 2 ml of 2 M KOH in an ice bath, neutralized with 8 ml sodium acetate 1.2 M and the RS was hydrolyzed to glucose with of amyloglucosidase
0.1 ml, 3300 Uml for 20 min. The glucose oxidase peroxidase reaction was used to measure glucose released from the digested and resistant starches. Absorbance was read at 510 nm after a 20
min incubation period at 50
o
C. Starch fractions were calculated as follows: Resistant starch
= ∆E x F x 10.30.1 x 11000 x 100W x 162180 = ∆E x FW x 9.27
Non-resistant starch =
∆E x F x 1000.1 x 11000 x 100W x 162180 =
∆E x FW x 90 Total starch
= Resistant starch + Non-resistant starch Where,
∆E = absorbance reaction read against the reagent blank
F = conversion from absorbance to microgram the absorbance obtained for 100 μg of
D-glucose in the GOPOD reaction is determin ed, and F = 100 μg of D-glucose
divided by the GOPOD absorbance for this 100 μg of D-glucose. 1000.1 = volume correction 0.1 ml taken from 100 ml
11000 = conversion from micrograms to milligrams
W = dry weight of sample analyzed
= “as is” weight x [100-moisture content100] 100W
= factor to present RS as a percentage of sample weight 162180 = factor to convert from free D-glucose, as determined, to anhydro-D-glucose as
occurs in starch 10.30.1 = volume correction 0.1 ml taken from 10.3 ml for samples containing 0-10 RS
where the incubation solution is not diluted and the final volume is ~ 10.3 ml
3.3.7 Granular Morphology
Samples were magnified from 500 to 5000 X under SEM. Detector SE1 was used with acceleration potential of 5.00 kV during micrography using SEM.
3.3.8 Thermal Properties
Samples of approximately 3 gram were weighed into aluminium pans followed by addition of 6 μl of water. The pans containing mixtures were then hermetically sealed to prevent moisture loss and
equilibrated at ambient temperature for 2 h. Samples which have been equilibrated were heated from 10
o
C to 120
o
C at a rate of 10
o
Cmin using differential scaning calorimeter DSC. The onset temperature T
o
, peak temperature T
p
, conclusion temperature T
c
, the gelatinization enthalpy
change ΔH were also calculated and expressed as joule per gram sample Jg.
3.3.9 Pasting Properties
Paste viscosity was determined by using rapid visco analyzer RVA. A programmed heating and cooling cycle was used where the samples were held at 50
o
C for 1 min, heated to 95
o
C at 6
o
Cmin, and held at 95
o
C for 2.7 min, prior to cooling from 95 to 50
o
C at 6
o
Cmin and holding at 50
16
o
C for 2 min. Parameters recorded were pasting temperature, peak viscosity, final viscosity viscosity at 50
o
C, breakdown viscosity peak-trough viscosity, and setback viscosity final-trough viscosity.
3.3.10 Textural Properties
Textural properties were analyzed by using texture analyzer TA. Sample was sliced to smaller size 6x6x1 cm. Texture profile analysis was conducted under condition of 100 mmmin
pretest speed, 50 mmmin test speed, 100 mmmin post test speed, 20 strain, P36R probe, with weight calibration as follows; return distance of 30 mm and return speed of 10 mmsec.
3.3.11 Color Properties
The ColorQuest XE HunterLab, Hunter Associates Laboratory Inc., Virginia-USA based on CIE system L, a, b was used to investigate the color of rice cake and pea cake. The instrument
was calibrated each time before its use using area view of 0.375 RSINRSEX, light tab reflectant and white tile reflectant.
3.3.12 Statistical Analysis
Results were expressed as mean of values ± standard deviation of independent determinations. Analysis of variance and comparison of means using Duncan`s test p
≤0.05 were performed using the statistical software SPSS 16.0 for windows, SPSS Inc., Chicago, USA.
17
IV. RESULT AND DISCUSSION
4.1 PRELIMINARY RESEARCH
4.1.1 Chemical Composition
Table 1 summarizes the analytical results for the chemical composition of pea flour, rice flour, and sticky rice flour involving moisture content, ash content, protein, and crude fat content. Pea flour,
rice flour, and sticky rice flour possessed moisture content of 7.73 , 11.30 , and 9.77 , respectively. The moisture content of pea flour was in range 7.7-9.1 with those reported by other
authors Naguleswaran and Vasanthan, 2010;
Chung et al., 2008, whereas for rice flours ranged from 6.10-12.52 Dias et al., 2010;
Tavares, 2010; Liu et al., 2006; Chun and Yoo, 2004 and moisture
content of 10.05 for sticky rice flour was reported by Zhu et al., 2010. The difference in moisture content among them was mainly due to the difference in manufacturing.
In term of ash content, pea flour 2.86 was the highest followed by rice flour 0.38 and sticky rice flour 0.17 , respectively. Range of ash content for pea flours 2.24-3.73 , rice flours
0.40-0.72 , and sticky rice flour 0.16-0.29 were reported by Dias et al., 2010; Naguleswaran and Vasanthan 2010; Petitot et al. 2010; Singh et al. 2010; Sung et al. 2008; Maninder et al.
2007; Latha et al. 2002; Lumdubwong and Seib 2000.
Table 1. Chemical composition of raw materials Sample
Moisture Ash
Protein Crude fat
Pea flour 7.68
2.83 21.84
0.80 Rice flour RF
11.21 0.39
7.21 0.41
Sticky rice flour SRF 10.37
0.18 6.12
0.29 The reported crude fat content of pea flours were 0.80-0.99 Naguleswaran and Vasanthan,
2010, which were near to the crude fat content determined in this study. However the crude fat content of rice flour 0.41 and sticky rice flour 0.29 were markedly lower than those reported
by Dias et al. 2010 and Latha et al. 2002, for rice flour 0.87-0.90 and Sung et al. 2008, for sticky rice flour 0.45-0.94 . The flours might be previously defatted Maninder et al., 2007.
Protein content of 21.84 , 7.20 , and 6.12 were observed during analysis for pea flour, rice flour, and sticky rice flour, respectively. Other results in protein content analysis by another
authors were 21.4-26.8 for pea flour, 6.93-8.11 for rice flour, and 6.35-8.85 for sticky rice flour Naguleswaran and Vasanthan, 2010; Petitot et al., 2010; Tavares et al., 2010; Chung et al.,
2008; Sung et al., 2008; Maninder et al., 2007; Chun and Yoo, 2004. Protein contents in legume grains range from 17 to 40 , contrasting with 7-13 of cereals, and being equal to the proteins
contents of meats 18-25 Genovese and Lajolo, 2001 in Costa et al., 2006. Hence, legume seeds including pea, are of prime importance in human nutrition due to their high protein content and are
better known as a rich source of protein rather than rice Singh, et al., 2004.
