Study On The Strength Of The Starch Hydrogels Affected By The Modification Of Starch

Since starch is the primary component of the food, its unique properties as a hydrocolioid in the food processing are important for the food characteristics. As the rising of the living level, it is not only concern the food ingredients but also its texture characteristics for the consumers. Apparently, the traditional processing of the starch need modified to satisfy the developmental demand. This research is focus on the effects of the starch processing on the strength of the starch hydrogel.The strength of starch hydrogel from different plant resources was analyzed, and its measurement method which was simple and feasible was set up. The effects of concentrations, pH value, aging time, gelation time and additives on starch hydrogel were studied. The effect of modified methods including acidification, oxidation and esterification was also discussed. The research results would provide the data reference for producing starch food.The research results of native starches showed that there were great differences between the starches from different plant resources on their properties because of their different structure. Compared to corn starch, cassava starch, the strength of potato starch gel was much stronger, because there was hydrophilic phosphoric acid group in the potato starch which improved the affinity between starch molecular and water. Otherwise, the hydrogel strength of oxidized starch was stronger than that of native starch with the same intrinsic viscosity of which was gotten from acid-treated starch.The research results of oxidation starch indicated that as the oxidation levels increased the gel strength decreased, the wet structure loosened and the ability of keeping water decreased. The starch gel wouldn't be formed when oxidation exceeded some extend. The result also showed that the gel strength of oxidized starch is some stronger than that of the native starch with the same intrinsic viscosity.The research result of phosphates starch implied that phosphates starch gel exist the strongest strength at its DS was 0.92%. The strength of phosphates starch hydrogel increased, due to there was hydrophilic phosphoric acid group in the potato starch which improved the affinity between starch molecular and water.The strengths of the starch hydro gels which were added with some additives were studied. The effects of some factors on the strength of starch hydrogel such as the starch concentration, the pH value of the system, the aging time of hydrogel and the metal ionic concentration were determined. The results made clear that when controlled the starch concentration as 15%, the additive amount of gelatin as 2.0%, or the additive amount of sodium alginate as 1.5%, the aging time of hydrogel was 7 days, the pH value of the system as 6 to 7, the ionic of calcium concentration as 1.0%, the hydrogel strength reached the highest value. Meanwhile, it is clear that the Gelatin and Sodium alginate have a great enhance on the hydrogel strength of the starch.