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Trends in Applied Sciences Research
  Year: 2007 | Volume: 2 | Issue: 2 | Page No.: 103-114
DOI: 10.3923/tasr.2007.103.114
 
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Preparation of High Degree Substituted Acetylated Acid Modified Rice Starches, Intermediate Degree Substituted Derivatives of Rice Starch and Zein Proteins and Preparation of Biodegradable Films (Part II)

Vasudeva Singh, Seiichiro Isobe, Hiroshi Okadome and Ken'ichi Ohtsubo

Abstract:
Starches from Indica, Japonica and Japonica waxy rices were acid modified by treatment at 50°C for 1 h. These were acetylated using acetic anhydride and 11% sodium hydroxide added as 50% aqueous solution for 1 h. These starches were then combined with zein and chemically modified by acetylation for a period of 30 min as before. All acid modified and acetylated starches showed almost the same content of acetyl and same degree of substitution (DS), with acetyl percentage being around 39.5 and DS around 2.4. Starch-zein acetylated one showed almost the same range of acetyl percentage and DS, the values being around 27% and 1.35, respectively. All these modified products dissolved easily in dimethyl formamide. Acid modified and acetylated starches were combined with zein protein after dissolution in the above solvent separately and after mixing, their films were prepared. In a similar way, films were also prepared from starch-zein acetylated products. Among the native starches, japonica waxy showed the highest glass transition temperature (Tg) (~ 232°C) followed by japonica non-waxy (224°C) and the lowest by indica (213°C). Difference in specific heat capacity before and after Tg increased in general from native to acid modified one and acid modified one to acid modified starches cum acetylated one. However the melting points were in the reverse order compared to Tg. Among the acid modified and acetylated ones, the melting point of Indica starch was the highest (~320°C). Glass transition temperature increased to a greater extent acid in modified starches and acetylated japonica waxy starches. Crude corn zein showed three characterstic peaks in DSC thermogram. It had the highest Tg (~258°C) and highest melting point (~306°C) but lowest Cp. After acetylation of starch and zein, all DSC parameters increased along with their respective starch zein mixture values. Decomposition temperature was the highest in japonica-zein acetylated one. Zein showed only endothermic peak. Acetylated japonica-waxy and zein showed the highest heat holding capacity among the three zein starch acetylated ones.
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How to cite this article:

Vasudeva Singh, Seiichiro Isobe, Hiroshi Okadome and Ken'ichi Ohtsubo, 2007. Preparation of High Degree Substituted Acetylated Acid Modified Rice Starches, Intermediate Degree Substituted Derivatives of Rice Starch and Zein Proteins and Preparation of Biodegradable Films (Part II). Trends in Applied Sciences Research, 2: 103-114.

DOI: 10.3923/tasr.2007.103.114

URL: https://scialert.net/abstract/?doi=tasr.2007.103.114

COMMENTS
07 June, 2012
Prof. Symon M. Mahungu:
How can I access the full paper. It will be very useful for a PhD student am supervising. How was the degree of substitution determined(The formula used)?
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