찰 옥수수전분의 Sodium Trimetaphosphate 가교에 미치는 Xanthan과 Dry-heating의 효과
Effect of Dry-Heating with Xanthan on Cross-Linking of Waxy aize Starch with Sodium Trimetahoshate
찰옥수수 전분페이스트 Dry-heating;
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Effects of xanthan and dry heating on the paste viscosity and clarity (light transmittance) of the starch in a buffer solution (pH7.0, 0.1M sodium phosphate) were examined. Waxy maize starch was impregnated with xanthan(1.0% based on starch) and a mixture(99:1) of sodium trimetaphosphate(STMP) and sodium tripolyphosphate(STPP) in water, and the mixture was dry-heated at 130℃ for 2∼4 hr. Dispersing starch with the phosphate salts itself made significant change in the pasting viscogram of waxy maize starch. Impregnating of xanthan decreased peak viscosity and reduced breakdown resulted in a high final viscosity, which indicated that the cross-linking of starch was enhanced. With reaction pH increased from 8.0 to 9.0, the cross-linking was accelerated because the light transmittance of the starch paste was decreased. Therefore the cross-linking effect of waxy maize starch using phosphate salts was raised by xanthan at alkaline pH. Shear stabilization in viscogram also proved that cross-linking was accelerated by xanthan. By dry heating, peak viscosity of waxy maize starch increased at pH8.0 and swelling of the granules significantly decreased at pH9.0. Dry heated waxy maize starch also showed reduction of paste clarity. By dry heating with xanthan and salt-mixture, waxy maize starch was more effectively cross-linked. This dry heating process with xanthan can be a useful alternative to chemical cross-linking for starch with no by-product and simplicity. The digestibility of the dry-heat treated waxy maize starches was measured as rapidly digestible starch(RDS), slowly digestible starch(SDS), and resistant starch(RS) fractions. SDS and RDS contents were not different among the samples. But the amount of RS was increased by the dry-heating with xanthan. Those cross-linked starches only with salt mixture contained significant levels(15.24∼28.24%) of resistant starch, and dry heating with xanthan further increased the RS content. RDS, SDS, and RS contents were not significantly related to pasting properties. Light transmittance is highly related to SDS and RS with R2 value of 0.62 and 0.67, respectively. As heating time was increased, RDS content was increased and SDS decreased. Waxy maize starch dry-heat treated with xanthan and salt-mixture improved native waxy maize starch pasting properties and enhanced RS content. The dry heating process in the presence of xanthan is useful cross-linking process for starch with RS increase.