Corn Starch Lab Report

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Results and discussion Previous analysis were performed to stablish the impact of pH and temperature on the enzymatic reactionand to select suitable reaction conditions for the enzymatic modification of corn starch. The level of hydrolysis induced by CGTaseat 95 ºC was rather low, indicating that the enzymatic activity onto the starch granules did not affect significantly the maximum viscosity of the corn starch (Fig. 1). Enzymatic activity was mainly revealed during the cooling stage of the RVA analysis, resulting in high starch hydrolysis (50 ºC) in the pHs range of 4.0 to 7.0, with two maxima observed at pHs 4.0 and 6.0. Those pHs were selected to perform further enzymatic modification of corn starch. 3.1 Microstructure of the starch No changes in granule size and shape and no holes were visible in C4 and C6 (Fig. 2a and b), and surfaces appeared smooth without any…show more content…
The ANOVA indicated a significant effect of the pH on the paste clarity, related to the compounds leached out, which was higher when treated at pH 6.0.The iodine binding value, thus the amount of amylose leached to the supernatant, after thermal treatment at 50 ºC was greater for samples soaked at pH 4.0 for some time. The solubility index (SI) value was significantly (P < 0.05) enhanced due to enzymatic treatment and the time of treatment. SI determines the amount of solid compounds leached when breaking intermolecular bonds between amylose and amylopectin. Despite the enzymatic activity at both pHs, the amylose released was low, likely due to interaction between amylose-amylose and/or amylose-amylopectin [18] or reduction in granular swelling [19]. In fact, enzymatically treated corn starches showed significantly lower swelling capacity (SC), thus less amount of water was absorbed by these starches. This suggests that enzymatic treatment modified the granular integrity of the starch affecting its swelling

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