Studies On Extraction, Purification And Functionality Of The Polysaccharides And The Technology Of The Functional Food Of Yam

The enzyme browning of yam and the extraction, purification, molecular weight mensuration, moncsaccharide composition and the functionality of yam polysaccharide was studied. The functional yam beverage and instant yam powder were made also. On the basis of the determination of the optimum pH value, optimum temperature of the activity of polyphenol oxidase from yam and the effect of different color-keeping methods on yam and polyphenol oxidase from it, the optimum color-keeping condition of yam was obtained as followed: dose of Sodium sulfite, 0.25%, dose of Citric acid 0.25%, dose of Sodium chloride, 1.5%, yam was directly dipped in color-keeping solution. With the orthogonal design L₉(3³), the optimum extracting condition of yam powder was confirmed as followed: extracting temperature, 40℃, extracting time, 3.5hour, 1:8 of ratio of yam powder to water. The method of removal of protein, 10% Trichloroacetic acid(TCA) precipitation precipitation, was obtained after the effects of Sevag precipitation method(precipitation times also) and TCA (concentration of TCA also) on the removal of protein from yam were studied. The yam crude polysaccharide(YP) was got after extracting yam powder, ethanol precipitation, removal of amylum with α-amylase, removal of protein with 10% content of TCA and gliding-water dialysis. The yam crude polysaccharide(MYP) was got after ethanol precipitation of mucus, removal of amylum with α-amylase, removal of protein with 10% content of TCA and gliding-water dialysis. One neutral fraction and two conjoint acidic fractions were isolated after DEAE-cellulose column chromatogramphy. The neutral fraction and the larger acidic one were collected and named as YPa &YPc respectively. YPa was separated into two fractions by SephadexG-200 gel column chromatogramphy, which shows that YPa is not pure. The larger one was collected and concentrated into 1/5 of ratio of volume of original solution, which was named as YPa-I. Only one peak was observed after YPc flowing through SephadexG-200 gel column, which shows that YPc is pure. The molecular weight of YPa-I(42931) and YPc(54979) were determined with the method of Gel filtration and which are 31796.97 & 48762.05 respectivelywith the method of HPLC. By means of GC, the monosaccharide composition of YPa and YPo were measured. The component of YPa consists of arobinose, mannose and glucose. The component of YPc consists of xylose, glucose, galactose, fructose and some rhamnose, arobiriose and mannose. The solution of YPa and YPc were scanned by Ultraviolet spectrophotometry. The result shows that both YPa and YPc have no absorbance between the range from 260nm to 280nm. The inhibiting effect of yam polysaccharide on a -amylase was studied, the results shows that yam polysaccharide(YP, MYP, YPc) inhibits a -amylase activity in a certain extent. The relationship between inhibiting effect and yam polysaccharide concentration is positive correlation, which shows that the polysaccharide content of yam have relevance to the hypoglycemic functionality of yam. The result of scavenging O2 shows the component which scavenge O2 may be the Polysaccharide-protein complex or other active composition. The significant ability of yam polysaccharide to scavenge OH was observed in the experiment. Furthermore, yam functional beverage and instant yam powder were made. With the gyrating regression design of the stability of yam functional beverage, the optimum radio of multiplex stabilizer was obtained as followed: radio of xanthan gum. 0.5361 %o, radio of CMC, O.2443%o, radio of pectin, 0.2196/oo, and the optimum pH value is 4.05.