Evaluation of rice bread quality

Bread height and volume were measured by the method of Jung et al. (2016). For a seed replacement method for bread volume, millet seeds were used. A 1.5-L plastic container was filled with millet to determine the density (mL/g) of millet used for converting a weight into a volume. After a loaf of bread was placed in a container full of millet, the weight of the millet pushed out of the container was measured, and the volume (mL) of the bread was calculated based on the calculated density. Each measurement was performed in duplicate.

The color of the crumb of bread was measured as L* (lightness), a* (redness), b* (yellowness) values using a colorimeter (CR-20, Minolta, Co., Tokyo, Japan). Measurements were performed in five replicates.

The bread firmness was measured using a Texture Analyzer (Brookfield CT3, Middleboro, MA, USA) according to the AACC Approved Method 74-09.01 (2010). The measurement conditions were set as follows: Mode: Measure force in compression, Pretest speed: 2.0 mm/s, Test speed: 2.0 mm/s, Posttest speed: 5.0 mm/s, Probe: 1.27 cm ball, Penetration distance: 15 mm. One loaf of bread was cut from the center into 3 pieces with 2 cm thickness. One piece was used for a fresh sample (0 day), the remaining 2 pieces were sealed in an aluminum foil package capable of avoiding moisture loss during storage, and placed in a refrigerator. Measurement of firmness during storage was performed on days 1 and 4 of storage after baking. Three loaves were used for the firmness measurement.

The moisture content of the bread samples was measured using the AACC Approved Method 44-15.02 (2010). About 2 g of pre-weighed bread crumb in a weighing container was placed in a hot-air drying oven (FO 600-M, Jeio Tech, Daejeon, Korea) at 130 °C for exactly 1 h, and cooled at room temperature for 30 min. The moisture content of the bread was calculated from the reduction in weight during drying.