Effect of citric acid esterification conditions on the properties of the obtained resistant starch

Abstract

This study was aimed at comparing selected properties of starch citrate obtained from native or retrogrades of potato starch at various temperatures (100, 130 or 160°C) and at various doses of reactant (10, 20 or 40 g per 100 g). Higher susceptibility to esterification was demonstrated for retrograded starch, whereas the degree of esterification of the produced esters varied considerably (1.4 to 10.0 g per 100 g preparation) and was increasing along with increasing roasting temperature and dose of citric acid. The process of pasting occurred only in the esters obtained at a temperature of 100°C, which resulted in a significant decrease in swelling power and solubility in water of the citrates produced at higher temperatures. The resultant starch citrates were characterised by significant resistance to amylolysis (ranging from 22 to 100 g per 100 g). There was observed an increase in starch resistance along with the increase in the acid dose and roasting temperature. All analysed properties of starch citrates were not correlated with the degree of esterification, but appeared to depend on the roasting, which may point to a significant effect of this factor on the mechanism of starch cross-linking with citric acid.

Effects of Heating Temperatures and Acid Concentrations on Physicochemical Properties and Starch Digestibility of Citric Acid Esterified Tapioca Starches

“…Temperatures and acid concentrations significantly affected the DS of the citrate esterified tapioca starch. The quantity of bound citric acid increased along with the increasing temperatures and acid concentrations, similar trends to those reported previously . In this study, the increasing rate of DS at high temperatures was more pronounced than that at the lower temperatures.…”

“…The transitional enthalpy of the citrate samples was found to be lower than that of native starch and it reduced gradually when a higher temperature and acid concentration were applied. This suggests that the samples were incapable of gelatinization, possibly due to high cross‐linking of amylopectin chains that inhibited macromolecular mobility of water into molecule's interior . Similar results were reported for citrate maize starches and rice or pea starches .…”

“…The quantity of bound citric acid increased along with the increasing temperatures and acid concentrations, similar trends to those reported previously. [4,14,15] In this study, the increasing rate of DS at high temperatures was more pronounced than that at the lower temperatures. When using acid concentration at 10-50 g/100 g, the DS increased from 0.06 to 1.28 g/100 g at 100 C, while it increased from 0.08 to 1.87 at 140 C. At the same temperature, the DS markedly increased when the acid concentration increased from 10 to 30 g/100 g, but only slightly increased when the acid concentration was further increased to 50 g/100 g. However, the DS of citrate tapioca starch was previously reported to increase when the acid concentration was 10-30 g/100 g, and decrease when the acid concentration was further increased to 40 g/ 100 g (modification at 130 C).…”

“…Esterification conducted at lower temperature, e.g., 100 °C in this study, led to starch citrates that could be gelatinized. Previous report suggested that this capability did not depend on the DS but on the heating temperature. Citrate starches with similar DS heated at various temperatures were found to be extremely different in thermal properties.…”

“…[2,3] The health-promoting significance of RS becomes lead to the search for novel methods of producing RS that could be used as food additives. [4] The main portion of starch could be chemically modified by degradation, substitution, or cross-bonding, [5] with esterification being one of the most important chemical modification methods for starch. Acetic, citric, and formic acids have been often used for chemical modification of starch.…”