dark at 25°C for 5 days. To calculate the number of microbial total aerobic bacteria or total yeast mold, formula below was used:
N = C
aver
x rinse solution volume where:
N = Number of colonies per cup cfucup
C
aver
= Average of all colonies on two plates, Askar and Treptow, 1993.
2.6. Physical analysis
2.6.1. Measurement of pH value
pH-meter Docu-pH
+
meter model Sartorius was used to measure pH value. Before used, the calibration was carried out by buffered-water with pH value 4, 7,
and 10.
2.6.2. Water Activity aW
Water activity of sample was measured five replication using AquaLab® Model Series3. The weight of sample that was used for one measurement
approximately about 2 – 3 grams. Before measuring the sample, calibration of the
equipment was done by using distillated water for the maximum value.
2.6.3. Color Measurement
Miniscan XE Plus® Model No.450-L was used to measure the color of sample in 0, 3, and 6 days. This instrument defines color numerically in terms of
its lightness or ―L‖ value, ―a‖ value for greenness - and redness + and ―b‖ value blueness - and yellowness + Illuminant D65 and 10 Observer were used
in the active view option. The weight of sample that was used for analysis was 25 gram for each replicates. Each sample was measured ten replicates.
2.6.4. Direct Observation
Direct observation was conducted by the researcher for detecting all physical changes that make the product was not appropriate anymore. In this
observation, the visible growth of yeast and moulds was became the major concern. On the 0, 3
rd
, and 6
th
day, all the food samples was observed to check the changes in odor, physical appearance, and the presence of slimy surface.
2.7. Statistical analysis
Experimental data were processed by multivariate ANOVA and Tukey as post-hoc analysis with statistical significance at 95. Analysis was conducted by
using SPSS software SPSS Student Version 16.0 for windows Priyatno, 2011.
