The physicochemical and thermal properties of unripe glutinous rice flour and application in gluten-free noodle

Abstract

The physicochemical and thermal properties of unripe glutinous rice flour (UGRF) and its potential application in rice noodles were evaluated in this study. UGRF showed dramatically higher protein content (10.57%) compared to glutinous rice flour (GRF) but was lower in amylose content. The lower peak (1647.67 cP), breakdown (661.00 cP), final viscosity (1208.33 cP), and setback viscosity (218.67 cP) were observed in UGRF (p<0.05). Therefore, the solubility, swelling power, and water absorption capacity of UGRF were higher than in glutinous rice flour. The onset, peak, final temperature, and especially gelatinization enthalpy was significantly different (p<0.05) compared to glutinous rice flour. Flour formulas for gluten-free noodle preparation were made by substituting glutinous rice flour and tapioca flour with UGRF from 0-20% (by total flour weight). The pasting properties of flour mixtures were significantly decreased with increased UGRF content. The gluten-free noodle containing 5-20% of UGRF showed a low cooking loss, high cooking weight, high maximum load, reflection at yield, and also a green-yellow colour. The porous structure of dried gluten-free noodles was increased with an increase in UGRF content, which affects the stickiness and springiness of noodles. The addition of 5-10% of UGRF showed the most appropriate properties of making gluten-free noodles with good cooking and textural properties including overall acceptance from consumers and can be used as a healthy ingredient in a variety of noodles.