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
Starch is a major reserve polysaccharide in plants. It is found in high levels in roots, tubers, cereal grains and legumes and is present as intracellular granules with different sizes and shapes
depending on the starch source. In the diet of mankind and many animals, it is one of the most
important carbohydrates. It consists mainly of two glucose polymers: amylose and amylopectin.
Resistant starch RS is defined as starch and products of starch degradation that cannot be absorbed in the small intestine of healthy individuals and, hence, might be fermented in the colon
Haralampu, 2000. There are four types of RS. Type I RS1 represents physically inaccessible starch, which is locked in the plant cell walls of some foodstuffs, such as partially milled grains, seeds
and legumes. Type II RS2 is native granular starch found in food containing uncooked starch, such as bananas, raw potatoes and beans. Type III resistant starch RS3 is made up of retrograded starch or
crystalline non-granular starch, like the starch found in cooked and cooled potatoes, bread crust, cornflakes and retrograded, high-amylose maize starch. Type IV RS4 refers to specific chemically
and thermally modified or repolymerized starches Englyst et al.,1992. Table 2 shows classification of resistant starch.
RS is not digested in the small intestine, because of that it has a lower energy content than digestible carbohydrates. The consequence of significant amounts of RS reaching the large intestine is
the potential for fermentation by colonic micro-organisms. Short chain fatty acids SCFA produced in response to fermentation of RS are thought to be responsible for much of the intestinal and systemic
effects reported for this fiber. Englyst et al. 1992. Some factors associated with RS formation during these processes are the physical state of the food material whole or ground water content, pH,
heating temperature and time, feed composition, number of heating or cooling cycles, freezing methods slow vs rapid and drying Cummings, 1987.
Table 1. Resistant Starch Classification Class Description
Example of
Source RS1
Starch that escapes digestion in the small intestine due to physical protection by the food mixture i.e.,
hull, shell, seed casing Whole grains, seeds, legumes
RS2 Raw starch granules ungelatinized with compact
structure which limits accessibility of digestive enzymes
Green banana, raw potato, high- amylose corn starch, raw whole
grain flours RS3
Retrograded starch in which parts of the starch chain can crystallize into components that are less
digestible. Most often, this occurs by cooking and cooling starch containing food
Cooked and cooled starch - corn, potato, rice, pasta
RS4 Not found naturally in foods. Starch that has been
chemically modified to introduce bonds that are not digestible by human enzymes.
Does not occur in nature. Ingredient source of modified
produced from wheat and tapioca are available
Source : Englyst et al. 1992
5 Some benefits of resistant starch are the slow hydrolysis of RS makes it useful for the slow
release of glucose, which can be especially useful in controlling glycaemic plasma responses, increase faecal bulk, lower faecal pH, and increase excretion of butyrate and acetate Philip et al. 1995.
Besides physiological benefits in human, RS has been reported to have potential as a unique ingredient that can yield high-quality foods. For example, application tests of RS showed
improvement of crispiness and expansion in certain products and better mouthfeel, colour and flavour as compared with products produced with traditional, insoluble fibres.
The process of making resistant starch is consisted of gelatinizing a slurry of the starch, treating the gelatinized starch with a debranching enzyme, deactivating the enzyme, cooling and
isolating the starch product Schmiedel et al., 2003. Gelatinization process is purposed to make debranching enzyme easier to hydrolize
α-1,6 glicosidic bond. Cooling process will stimulate retrogradation which form crystalline structures. The crystalline structure of granules may cause
starch to be resistant to enzyme hydrolysis. Starch product can be isolated by hot air dyring, freeze drying, and spray drying.
Pullulanase pullulan 6-glucanohydrolase, EC 3.2.1.41, an important debranching enzyme in starch processing, can cleave
α-1,6 linkages in pullulan, amylopectin and other related polysaccharides Lin et al. 2006. Debranching of amylopectin will provide an increased opportunity
to molecule alignment or aggregation, to form crystalline structures, and is, hence, helpful in RS formation. The pullulanase enzyme preferably reacts with a pH from 4.5 to 5.5 at temperature of 40°C
to 60°C. Berry 1986 reported a substantially increased RS3 content during monitoring the debranching effect of pullulanase on potato amylopectin, and attributed this effect to an increase in
linear starch chains resulting from debranching.
C. Clostridium butyricum
