Modification of wheat starch with succinic acid/acetic anhydride and azelaic acid/acetic anhydride mixtures I. Thermophysical and pasting properties

The aim of this research was to investigate the influence of modification with succinic acid/acetic anhydride and azelaic acid/acetic anhydride mixtures on thermophysical and pasting properties of wheat starch. Starch was isolated from two wheat varieties and modified with mixtures of succinic acid and acetic anhydride, and azelaic acid and acetic anhydride in 4, 6 and 8 % (w/w). Thermophysical, pasting properties, swelling power, solubility and amylose content of modified starches were determined. The results showed that modifications with mixtures of afore mentioned dicarboxylic acids with acetic anhydride decreased gelatinisation and pasting temperatures. Gelatinisation enthalpy of Golubica starch increased, while of Srpanjka starch decreased by modifications. Retrogradation after 7 and 14 day-storage at 4 °C decreased after modifications of both starches. Maximum, hot and cold paste viscosity of both starches increased, while stability during shearing at high temperatures decreased. % setback of starches modified with azelaic acid/acetic anhydride mixture decreased. Swelling power and solubility of both starches increased by both modifications.

Optimization of Hydroxyropylation Conditions and Property of Acid-Modified Hydroxypropyl Pueraria Lobata Starch

In order to improve the property of pueraria lobata starch, and enlarge application fields of pueraria lobata starch, this study involved in the optimization of determining parameters in hydroxyropylation conditions and the property of acid-modified hydroxypropyl pueraria lobata starch with low substitution degree (DS).Characterizations were carried out by analyzing the spectrum of the thermograms of differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The fludity was used for characterizing the degree of acid hydrolysis. The substitution degree was measured by the spectrophotometric method. The optimized hydroxyropylation conditions were as follows: reaction temperature 40°C, reaction time 18h, amount of sodium hydroxide 1.2%, amount of anhydrous sodium sulfate 12%, respectively. The properties such as the transparency, freeze-thaw stability, blue value, swelling power, retrogradation, acid and alkali resistance of acid-modified hydroxypropyl pueraria lobata starch were compared with those of pueraria lobata starch and acid-modified pueraria lobata starch. It was shown that acid hydrolysis and hydroxyropylation increased the decomposition temperature, but reduced the enthalpy value from the thermal analysis.