16 which including moisture content, ash content, equivalent weight, methoxyl levels, galacturonic content,
and degree of esterification.
1. Moisture content
The moisture content of the material will affect the shelf life of the material. The high moisture content in the material causes of vulnerability to microbial activity. As an effort to extend the shelf life,
pectin was dried up to a certain limit of moisture content. Drying at low temperature aims to minimize degradation of pectin.
In this study, drying of samples was conducted in hot air oven with temperature 40 °C for 8 hours. The moisture content of the resulted pectin ranged from 9.58-11.83. Moisture content of the samples
was still inside the range of values that are allowed by The Council of European Communities 1998 that the moisture content of pectin should not more than 12. The relationship between extraction time and
microwave power to the moisture content of pectin can be seen in Figure 10. The moisture content of the resulted pectin would lower with increasing microwave power and the length of extraction time.
Figure 10. The relationship between microwave power and extraction time to moisture content The highest moisture content of pectin obtained at the extraction with microwave power of 800 W
for 3 minutes was 11.83. It was almost the same with moisture content of pectin with microwave power of 600 W for 3 minutes which was 11.75. While the lowest moisture content obtained in the treatment of
extraction microwave power of 800 W for 7 minutes was 9.58. This suggests that the interaction between temperature and extraction time significantly affect the moisture content of pectin. Results of
analysis of variance showed that extraction time and interaction between microwave power and extraction time significantly affected the moisture content of pectin, but the microwave power was not significantly
affect the moisture content of pectin Appendix 2b. The higher microwave power and the longer extraction time will increase the amount of water which
evaporates during the extraction process thus simplifying the drying process and resulted in the low levels of moisture content inside the pectin. The higher microwave power and longer duration of extraction
would able to hydrolyze pectin polymers so that the molecular chains become shorter. The shorter the chain of pectin polymer will further made drying process easier because the content of water trapped
inside the lower than long chain pectin. But, it can be used as a reference when the temperature and time of drying in the oven is fully controlled. With the oven temperature and drying time are the same in each
sample, it will show the influence of microwave power and extraction time on moisture content produced. The moisture content of extracted pectin is affected by drying rate of wet pectin and storage
condition. Drying process of all the wet pectin was subjected on hot air oven with temperature of 40
o
C for 8 hours. Ranganna 1977 suggested that drying should be done in low pressure so the pectin is not
harmed. Measuring the moisture content of pectin is important to determine actual yield of pectin. If the drying rate is low, the yield obtained is seen higher than actually are.
a a
a b
b c
5 6
7 8
9 10
11 12
13
600 800
M oi
st ur
e co
nt en
t
Microwave Power Watt 3 min
5 min 7 min
17
2. Ash content
