Changes of pasting and gelling properties of potato, normal corn and waxy corn starch blends

• Main Authors: Yu-Tsung Lee, 李昱宗
• Other Authors: 呂廷璋
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/rn8ey3

碩士 === 國立臺灣大學 === 食品科技研究所 === 106 === Native starch exists in granule form, which needs to be heated in solution to make it swell and gelatinize, and form gel. There are many factors that would affect the properties of pasting and gelling of starch, including its source, composition, thermal property, concentration and so on. Blended starch is commonly used in food industry to impart desired properties. This study aims to understand of pasting and gelling properties of blended starch. This study used three pure starches with different amylose contents and pasting properties Native potato starch (PS) and thin-boiling potato starch (TBP) were blended with normal corn (NCS), waxy corn starch (WCS) and their thin-boiling modified starch, thin-boiling normal corn (TBC) and thin-boiling waxy corn (TBW) at different ratios (100/0, 75/25, 50/50, 25/75 and 0/100.). Native/ thin-boiling potato starch blends were used as control. The results showed that PS/TBP decreased linearly with decreased PS ratio, while PS/WCS, PS/NCS, PS/TBC and PS/TBW did otherwise Using differential thermal analysis (DSC), it was found that starch with lower gelatinization temperature delayed the gelatinization temperature of starch with higher gelatinization temperature in blended starch. Pasting properties- final viscosity (FV) and setback have significant differences compared with PS/TBP group, which indicated that there was obvious interaction of blended starch during cooling procedure. The correlated factors of TBP blended group (TBP/WCS, TBP/NCS, TBP/TBC, and TBP/TBW) also show linearity, which mean that starch high swelling power will affect the pasting viscosity in the blended system. In addition, PS/WCS and PS/TBW show double peaks under 50/50 blended ratio. Yet the peak viscosity at the high temperature is proved to be native potato starch instead of waxy corn starch. Low shear dynamic rheometer was used to observe swelling property of the blended starch. There was no observed linear relationship between dynamic modulus and blend ratio in PS/TBP group. The reason for this might be because starch granules are not easily broken in a low shear environment. Maximum gel firmness was observed for PS/TBC=50/50, which might indicate that leached out amylose and intact starch granule are most stable at this ratio. In summary, considering amylose content, solubility index and swelling power, swelling power has the greatest impact on pasting properties of the blended starch. On the other hand, leached-out amylose and intact starch granules had the greatest impact on gel firmness.