6 pure N
2
or N
2
and CO
2
in ratio of 1 : 9; temperature 37
o
C, pH 6-7.5, medium flushed with oxygen-free nitrogen gas Zigova Sturdik 2000.
D. SWEET POTATO
Sweet potato is classified into Planatae kingdom, Spermatophyta division, Angiospermae subdivision, Concolvulales ordo, Convolvulacea family, Ipomoea genus, Ipomoea batatas species.
Sweet potato can grow in tropical and sub-tropical climate and it has characteristics such as thin bark, variation shape, contains fiber in variation amount depend on the variety Mucthadi dan Sugiyono,
1989. The stem is yellow, green, or orange, whereas the root is long and round. The leaf has round shaped with serration or wavy in the leaf side. The color of flower is white and has bell shaped, but
most of it does not has flower. Sweet potatos is divided into two groups, sweet potato which has soft corm because contains more water and sweet potato which has hard corm because contains more
starch Lingga et al. 1989. Sweet potato can be consumed directly or processed further become sweet potato flour or sweet potato starch. Table 2 shows starch content in several variety of sweet potato.
Table 2. Starch Content in Sweet Potato Variety
Starch Content Jago
Sukuh Sari
Boko Kidal
31 31
32 32
33 Source : Departemen Pertanian 2009
Sweet potato has many advantages such as short period harvest, good adaptation in the lack of soil, and can be alternative food in the crop failure or disaster area. Because has good adaptation,
sweet potato plays important role as a source of food in Asia and Pacific region. At about 94 total production of sweet potato around the world is produced from this region. Production of sweet potato
is predicted about 98.6 milions ton a year. Indonesia is the second country, after China, which produce the most sweet potato in the world Christian, 2005. Table 3 shows the total production of sweet
potato in Indonesia. Table 3. Total Production of Sweet Potato in Indonesia
Year Production ton
2005 2006
2007 2008
2009 1.856.969
1.854.238 1.886.852
1.880.977 2.057.913
Source : Departemen Pertanian 2009 One of sweet potato variety is Jago. This variety is semi-compact plant, has productivity until
25-30 tonha, and it can be harvested in 4-4.5 months. It has round shape corm, short stem, white bark and flesh and also resistant with boleng pest. This variety has high yields, high starch content, and
suitable to be used in flour and starch production. Figure 1 shows jago variety of sweet potato.
7 Figure 1. Jago Sweet Potato
8
III. MATERIAL AND METHOD
A. MATERIALS AND EQUIPMENTS 1. MATERIALS
