2 or stored. Resistant starch, on the other hand, resists digestion and passes through to the large intestine
where it acts like dietary fiber. In large intestine, resistant starch fermented by microorganism resulting SCFA. Prevoius research showed that dominant microflora in human intestinal was
Clostridium, Eubacterium, and Fusobacterium that include butyrate producing species. Sweet potato Ipomoea batatas is one of staple food in Indonesia because contains high
carbohydrate level as energy source. Sweet potato can be consumed directly as food or processed further become sweet potato flour or sweet potato starch. Unfortunately, utilization of sweet potato is
not optimum, however Indonesia is the biggest country which produce sweet potato in the after China. Total production of sweet potato was 2.057.913 ton per year. High carbohydrate level is correlated to
high starch level, so it can be utilized as resistant starch source. In recent years, a considerable number of studies have focused on the importance of type 3 resistant starch RS as a substrate for colonic
fermentation. Thus, sweet potato is very potential to develop as resistant starch source.
B. OBJECTIVE
The objective of the research were to study short chain fatty acid profile produced by Clostridium butiricum BCC B2571 during fermentation of type 3 resistant starch of sweet potato and
to determine the effect of concentration of resistant starch to the SCFA formation by Clostridium butiricum BCC B2571.
.
3
II. LITERATURE REVIEW
A. SHORT CHAIN FATTY ACID SCFA
Human colonic bacteria ferment resistant starch RS and non-starch polysaccharides NSP,
major components of dietary fiber to short chain fatty acids SCFA, mainly acetate, propionate, and butyrate. Polymer substrate will be hydrolized into monomer like glucose, galactose, xylose, which
then fermented through glycolisis pathway into pyruvate acid. These pyruvate acid is changed into short chain fatty acid and gases.
Short chain fatty acid is an organic fatty acid with 1 until 6 carbon atoms and is the principal anion which arise from bacterial fermentation of polysaccharide, oligosaccharide, proteins, peptide,
and glycoprotein precursors in the colon Cumming et al. 1991. The primary end products beside SCFA are gases CO
2
, CH
4
, and H
2
and heat. The general reaction of SCFA production and overall stoichiometry has been summarized for a hexose as follows :
59 C
6
H
12
O
6
+ 38 H
2
O → 60 CH
3
COOH acetate + 22 CH
3
CH
2
COOH propinonic + 18 CH
3
CH
2
CH
2
COOH butyrate + 96 CO
2
+ 268 H
+
+ Heat. The production of SCFA is determined by many factors, including the numbers and types
of microflora present in the colon Roberfroid. 2005, substrate source Cook and Sellin, 1998, gut transit time, hexose availability, enzyme production by bacteria, and amount of carbohydrate.
Fermentation involves a variety of reactions and metabolic processes in the anaerobic microbial breakdown of organic matter, yielding metabolizable energy for microbial growth and maintenance
and other metabolic end product for host use. Various population data show that SCFA production in order of acetatepropionatebutyrate in a molar ratio of approximately 60:20:20 or 3:1:1, respectively
in the proximal and distal colon Topping and Clifton. 2001. In ruminants and other herbivores, SCFA are absorbed and transported via the portal vein to
the liver and it can be used as for maintanance, growth, and lypogenesis. The fraction not absorbed is distributed to the other body organs and tissues for metabolism. The SCFA produced by fermentation
have a very important effect on the host by locally providing energy to the epithelial cells of the colon, decreasing the pH, improving the absorption of calcium, iron and magnesium and beneficial
influences of the glucose and lipid metabolism in the liver. Acetic acid C
2
H
4
OH is an organic acid which is colorless and gives vinegar sour taste. Acetate acid is absorbed and metabolized in liver, muscle, and brain tissue. Acetic acid is utilized by
the liver where it is converted into Acetyl-CoA, which can act as a precursor for lipogenesis, but also stimulates gluconeogenesis Remesy et al.1992. Low concentrations of acetic acid can also be
detected in venous blood in peripheral tissues Scheppach et al. 1991. Propionic acid is a clear, colorless liquid with a slightly sweetish odor. It has CH
3
CH
2
COOH chemical formula. Propionic acid is mainly metabolized in the liver and has been shown to inhibit gluconeogenis and increase
glycolysis in rat hepatocytes. It has also been proposed that propionic acid may lower plasma cholesterol concentrations by inhibiting hepatic cholesterogenesis. Butyric acid is a carboxylic acid
with the structural formula CH
3
CH
2
CH
2
-COOH and a product of anaerobic fermentation. Butyric acid is metabolized in colon ephitalium cell, it has role to regulate cell growth so it can maintain mucose
cell and can reduce tumor cell proliferation. Butyrate is the main fuel for the colonocytes and thus exerts a trophic effect. Butyrate also appears to reduce cell differentiation and stimulate apoptosis in
tumour cell lines Douglas et al. 2006. Furthermore, it also regulates gene expression leading to anti-
4 inflammatory and anti-carcinogenic effects Hamer et al., 2008. Total SCFA and regional differences
in SCFA concentration are implicated in colon desease, especially in cancer and gastrointestinal disorders. Therefore, an increased SCFA production and higher delivery of SCFA distally, especially
butyrate, may have a role in prevention these desease.
B. RESISTANT STARCH
