IgY was separated from a hen's egg yolk that was immunized with Helicobacter pyroli. The anti-H. pyroli IgY activity at acidic pH and the suppressive effect of polyol on acid-induced inactivation of IgY were investigated. Sorbitol and xylitol were used as polyols. IgY was quite stable at pH 5-7. Irreversible inactivation of IgY was observed at pH below 4, and proceeded rapidly at pH below 3. The acid stability of IgY was enhanced in the presence of 30% sorbitol or above. In a 50% aqueous sorbitol solution, an acid-induced inactivation was almost completely suppressed at pH 3. However, the improvement of IgY activity was not observed in the aqueous xylitol solution. IgY showed almost the same activity as native IgY when sucrose was substituted for sorbitol. On the other hand, the xylitol replacement with sucrose did not enhance the acid stability of IgY. The acid-induced inactivation of IgY was related to tryptophyl fluorescence. Fluorescence emission spectra suggested that structural changes near the tryptophan residues may occur under acidic conditions. An increase in sorbitol concentration induced a blue shift. The fluorescence emission of IgY in a 50% sorbitol solution had a peak at 330 nm, which was the same emission peak that was exhibited by native IgY. Sorbitol could, therefore, be used as a good stabilizer of IgY under acidic conditions.

Anti-oxidant activities of ethanol extracts from whole and hulled mung bean starches (WMS and HMS) isolated using distilled water, and gels (WMSG and HMSG) were investigated. Total chlorophyll contents of WMS and WMSG were 4.61 and 2.14 μg/mL, respectively. WMS at 0.29 mg of gallic acid/g of MS and 0.54 mg of quercetin/g of MS had higher total phenolic compounds and flavonoid contents than HMS at 0.11 mg of gallic acid/g of MS and 0.28 mg of quercetin/g of MS. Total phenolic contents of WMSG and HMSG increased by 2.14x and 1.64x, respectively. Total flavonoid contents decreased by 0.98x and 0.57x. The 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt radical scavenging activities and reducing powers of WMS and WMSG were higher than for HMS and HMSG. made using WMS exhibits increased anti-oxidant activities of gels and is a good food for improvement in health functionality.