Effect of hydroxypropyl methylcellulose, protein and fat on predicted glycemic index and antioxidant property of gluten‐free bread from rice flour

Abstract

Due to the lack of gluten, hydroxypropyl methylcellulose (HPMC), whey protein concentrate (WPC) and soy protein isolate (SPI) were fortified (4 g/100 g flour) into gluten‐free bread made from rice flour. The heteropolymer structure of HPMC and protein covered starch granules, resulting in a decrease in predicted glycemic index (pGI) of bread from 84.08 to 67.20–71.04. Addition of butter reduced the pGI to 73.55. By changing the baking mode from hot air baking to microwave baking and microwave‐hot air baking, the pGI was reduced from 73.55 to 70.51–70.81 (p ≤ 0.05). With addition of HPMC or/ and protein, the gluten‐free bread exhibited stronger inhibition of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radicals than the wheat bread. Therefore, starch digestibility of the gluten‐free bread was mainly reduced by mixture of HPMC, proteins and butter in the dough recipe. Addition of HPMC and WPC further benefited the improvement of antioxidant activity by DPPH assay. Practical applications The finding of this research was the technique to manipulate GI and antioxidant activity in the rice‐flour bread by microwave assisted baking process and addition of HPMC, WPC and butter. The outcome of this research could increase health benefit of gluten‐free bread from rice flour, in terms of slow starch digestion and high antioxidant activity.

Insights into Recent Updates on Factors and Technologies That Modulate the Glycemic Index of Rice and Its Products

“…The use of HPMC and whey protein additionally enhanced the enhancement of antioxidant activity, as assessed by the DPPH experiment. [112] Instant rice White rice with different amylose content was cooked at different conditions [cooking temperature (82-90 • C), water: rice ratio (1.0-1.9-fold)].…”

Comparison of the effect of hydroxyl propyl methyl cellulose, pectin, and concentrated raisin juice on gluten‐free bread based on rice and foxtail millet flour

“…A study has shown that the addition of 1% HPMC leads to an improvement in the internal structure of bread and an increase in the level of porosity in GF bread based on rice and buckwheat flour (Baldino et al., 2018 ). In previous studies, the effects of HPMC on properties of GF bread from rice flour (Srikanlaya et al., 2022 ), different starch sources (rice flour or maize starch) (Belorio & Gómez, 2020 ), and potato starch (Chen et al., 2023 ) were studied. Pectin is another gum suggested for GF bread in which polysaccharide is derived from citrus peel or apple pomace.…”