EFFECTS OF PHOSPHATES ON THE PASTING PROPERTIES OF RICE FLOUR FROM WAXY AND NON‐WAXY VARIETIES

Abstract

ABSTRACTThe objective of this study was to investigate the effects of phosphates on the pasting properties of rice flour. Taisen 2 and Taisen waxy 2 (TSW2) were selected as rice material. Different phosphates including sodium phosphate dibasic, sodium tripolyphosphate and sodium trimetaphosphate were added to the rice flour at 0.1, 0.2 and 0.5% (w/w, dry basis) levels and cooked in Rapid Visco Analyser at 95C for 12.5 min. Results showed that the addition of the phosphates significantly (P < 0.05) changed pasting properties that relate to the native rice flour. Addition of phosphates significantly (P < 0.05) decreased overall viscosities (except for breakdown) of the non‐waxy rice flour compared with those of the control. Hardness and adhesiveness of the non‐waxy rice flour gel was also significantly (P < 0.05) reduced with addition of the phosphates. For waxy rice flour, TSW2 showed a significant (P < 0.05) decrease in overall viscosity parameters compared with the control due to addition of phosphates. The texture of waxy and non‐waxy rice flour gel was different with the addition of phosphates.PRACTICAL APPLICATIONSRice flour is widely used in the rice food industry. Phosphates are widely used in traditional rice products, i.e., rice noodle, rice vermicelli and bamboo‐leaves‐wrapped alkaline waxy rice dumpling (alkaline tsong‐tsu) to improve pasting properties and texture of these products. The use of phosphates in tsong‐tsu has replaced the illegal uses of borax for the improvement of pasting properties and texture of the product. Rice flour is usually used along with other ingredients such as salts, sugar, lipids, emulsifiers and phosphates. The presence of phosphates may cause interactions with other food ingredients and influence the rice flour pasting properties and rice product texture differently. Because very little information on this area is available, the effects of phosphates on the pasting behaviors and texture of rice flour need to be examined. Such investigations are of importance to rice food industries and especially to the rice consuming peoples.