Effect of gum arabic on freeze-thaw stability, pasting and rheological properties of tapioca starch and its derivatives

Effect of gum arabic (GA) on swelling power (SP), solubility index (SI), freeze-thaw stability, pasting and rheological properties of native, anionic and cationic tapioca starch (TS, ATS and CTS) was studied. It was found that SP and SI of TS, ATS and CTS were reduced by GA and the extent followed the order: CTS > TS > ATS. This may be due to attractive interactions between oppositely charged molecules occurring when anionic GA encountered positively charged CTS. Addition of GA decreased setback (SB) values of ATS but had no effect on CTS (p < 0.05). All the three starch-GA mixtures exhibited lower peak viscosities (PVs) compared with their controls. The extent of the decrease in PV caused by GA addition followed the order: ATS > TS > CTS. For ATS-GA mixtures, the decrease of PV can be interpreted by the repelling force between ATS and GA. Furthermore, GA played an accelerative effect on syneresis of CTS, an inhibiting effect on syneresis of ATS and almost no effect on syneresis of TS. Rheological studies showed that all starch and starch-GA gels were classified as typical weak gels. The storage modulus (G') of TS and CTS could be enhanced by GA, while G' of ATS-GA paste was weakened by GA. The foregoing data indicated that the effect of GA on physical properties of starch depended on its charge. (C) 2015 Elsevier Ltd. All rights reserved.