Functional Properties of Glutinous Rice Flour by Dry-Heat Treatment

Yang Qin,Jinmiao Cao,Qingjie Sun,Chengzhen Liu,Suisui Jiang,Liu Xiong,Dafeng Hui

doi:10.1371/journal.pone.0160371

Abstract

Glutinous rice flour (GRF) and glutinous rice starch (GRS) were modified by dry-heat treatment and their rheological, thermal properties and freeze-thaw stability were evaluated. Compared with the native GRF and GRS, the water-holding ability of modified GRF and GRS were enhanced. Both the onset and peak temperatures of the modified samples increased while the endothermic enthalpy change decreased significantly (p < 0.05). Meanwhile, dry heating remarkably increased the apparent viscosities of both GRF and GRS. Importantly, compared with GRS samples, the storage modulus (G') and loss modulus (G") values of modified GRF increased more greatly and the tanδ values decreased more remarkably, indicating that the dry-heat treatment showed more impact on the GRF and a higher viscoelasticity compared with GRS. Our results suggest the dry-heat treatment of GRF is a more effective method than that of GRS, which omits the complex and tedious process for purifying GRS, and thereby has more practical applications in the food industry.

Highlights

Rice starch is one of the important commercial cereal starches
glutinous rice flour (GRF) within the retort pouch was dried in a hot air oven at 45°C until the moisture content reduced to 7.0%, and the dried GRF passed through a 100-mesh screen
Dry-heat treatment played an important role in the rheological, thermal properties and freezethaw stability of GRF and glutinous rice starch (GRS)

Summary

Introduction

Because of the unique physiochemical properties (such as small granules, low allergenicity, and increased freeze—thaw stability of pastes), rice starch has been applied as cosmetic dusting powder, photographic paper powder, food thickener, and excipient for pharmaceutical tablets [1,2]. The close conjunction between the starch granules and surrounding protein matrix results in difficult isolation of rice starch. Glutinous rice flour (GRF) has been widely used in both novel and traditional foods such as sweet soup balls, infant foods, puffed grains and gluten free products [3,4] due to the soft, high sticky nature and digestible carbohydrates after cooking [5]. GRF is rich in protein, mineral substances, and vitamins, and is more nutritious than glutinous rice starch (GRS).

Objectives

Methods

Results

Conclusion