Effect Of Sweet Potato Resistant Starch On The Absorption Of Minerals In Wistar Rats

Resistant starch is defined as the sum of starch and products of starch degradation not absorbed in the small intestine of healthy individuals. It not only has physiological functions similar to dietary fiber, but also unique functional properties. In this study, with sweet potato starch as materials, the optimal parameters for preparation of resistant starch (RS) was investigated, and the effect of RS on the minerals absorption in wistar rats, the results indicated:1) For these factors in resistant starch preparation, the subsequence of importance was starch concentration > cooking temperature > pH > retrogradation time > retrogradation temperature. With the starch concentration 30%, pH 6.0, heated at 120℃ for 60 minutes, then retrograded at 4℃ for 96 hours, the original starch yield of 23.4% RS.2) The RS have no bad effect on ability to growth and viscera. The RS can enhanced feces production and the water holding capacity of feces in wistar rats with 6.1% RS provided in diets, preventing constipation.3) The RS from sweet potato can significantly enhance the calcium, magnesium absorption in wistar rats when 6.1% RS is provided, and the serum magnesium is significantly larger than the control.4) The RS from sweet potato can significantly enhance the iron, zinc absorption in wistar rats when 10.8% RS is provided, and the serum zinc is significantly larger than the control.5) The mechanism of enhancing absorption of minerals is that these RS is fermented in ileum and cecum, producing many short chain fatty acid, These fatty acid can increase the concentration of soluble minerals of calcium, magnesium, iron, zinc and raised their absorption at the bottom of ileum ,cecum and colon.6)The RS from sweet potato can accelerate the discharge of lead in feces, when the content of RS is 6.1%,the discharge of lead is 91.5%, and RS is 10.8%,the discharge of lead is 96.4%.7)The mechanism of discharge of lead in feces includes two theories :The one is that RS can accelerate the dissolve of calcium, iron and zinc in intestine, to inhibit the lead absorption competitively, and the good nutrition of calcium, iron and zinc can accelerate the discharge of lead in tissues ; The other is that RS has absorption effect on lead, It can absorb the lead in feed and facilitate the lead expelling from bile to reach the cecum which can be fermented and combined with protein to vent.