JIA-2019-11

2655 Ji-Eun Kim et al. Journal of Integrative Agriculture 2019, 18(11): 2652–2663 Co., Ltd., Seoul, Korea). After the dough sheeting, the dough was rounded to a dome shape of 5.5 cm height and proofed for 15 min in a proofing cabinet (32°C, 85% relative humidity). The proofed dough was steamed for 15 min for KSSB and for 20 min for NSCSB and cooled for 15 min at 24°C before analysis. 2.5. Quality evaluation of steamed bread Quality of two types of steamed bread was evaluated according to the method described by Ma and Baik (2016). Steamed bread was cooled for 15 min at 24°C after preparation and then was weighed with an analytical balance. Diameter and height of steamed bread was measured, and volume of steamed bread was determined with the rapeseed displacement method. Both surface and crumb colors of steamed bread were determined with a colorimeter (CM-2002, Minolta Camera, Osaka, Japan) using an 11-mm measurement aperture. Whiteness index was calculated according to Nguimbou et al . (2012). Hardness of crumb was determined with a TA-XT2 Texture Analyser (Stable Micro Systems, England) according to the method described by Ma and Baik (2016). A 28-mm thick, horizontal-cut slice of steamed bread was obtained from the center part of steamed bread with an electric knife. The slice was placed on a flat metal plate and compressed to 50% of its original thickness at a speed of 1.0 mm s –1 using a 3.6-cm diameter cylindrical acrylic probe; the compression was paused for 4 s after 50% compression, and then the probe was returned to its initial position. The force required to compress 50% of a steamed bread slice and the force after the 4 s pause with 50% compression were recorded as peak force 1 (P1) and compression force 2 (P2), respectively. Stress relaxation was calculated from the two compression forces (P1 and P2) with the following eq.: Stress relaxation=(P1–P2)/ P1×100, according to the method described by Ma and Baik (2016). 2.6. Statistical analysis Statistical analysis of the data was performed by R free software (The R Project for Statistical Computing, R version 3.4.4 from https://www.r-project.org ) using Fisher’s least significant difference procedure (LSD), analysis of variance (ANOVA), and Pearson’s correlation coefficient. Sources of variation in the model were considered to be fixed effects. Regression equation was formulated with the optimum model excluding non-significant variations based on the highest R 2 value. All measurements were performed at least in triplicate and all were averaged. 3. Results 3.1. Flour characteristics Flour characteristics and allelic variations of 11 Korean wheat cultivars were summarized in Table 1 (Appendix A for each Korean wheat cultivar), Table 2 and Fig. 2. Range of ash and damaged starch content, averages of particle size and whiteness index of flour were 0.37–0.47%, 2.8–9.0%, 54.4–85.8 μm and 85.6–89.6, and ranges of protein content, SDS sedimentation volume based on constant flour and protein weight (SDSSF and SDSSP) were 8.5–16.3%, 23.0–78.5 mL and 17.5–55.5 mL, respectively. Particle size of flour, damaged starch and protein content, and SDSSF of six Korean wheat cultivars with hard kernel texture, carrying Pina-D1b or Pinb-D1b alleles (80.2 μm, 7.0%, 12.1%, 54.7 mL, respectively), were higher than those of five Korean wheat cultivars with soft kernel texture, carrying Pina-D1a and Pinb-D1a alleles (62.0 μm, 4.1%, 10.0%, 33.1 mL, respectively). Average of particle size of flour and damaged starch content of Korean wheat cultivars carrying Table 1 Flour characteristics of 11 Korean wheat cultivars Characteristics Korean wheat cultivars Physico-chemical properties of flour Ash (%) 0.41±0.03 (0.37–0.47) Average particle size (μm) 71.9±11.8 (54.4–85.8) Damaged starch (%) 5.7±2.1 (2.8–9.0) Whiteness index of flour 87.8±1.2 (85.6–89.6) Protein (%) 11.1±2.1 (8.5–16.3) SDS-sedimentation volume with flour (mL) 1) 44.9±17.2 (23.0–78.5) SDS-sedimentation volume with protein (mL) 2) 38.2±9.7 (17.5–55.5) Solvent retention capacity Distilled water 59.8±5.1 (53.6–66.7) 5% sodium carbonate 76.7±3.8 (69.9–82.7) 5% lactic acid 112.0±17.2 (93.6–157.2) 50% sucrose 108.2±9.4 (96.1–119.9) Dough rheology Water absorption of Mixograph (%) 60.2±2.7 (57.8–67.0) Mixing time of Mixograph (min) 2.9±0.9 (1.6–5.0) Maximum height of dough (mm) 12.3±3.9 (6.0–20.3) Pasting properties of starch Amylose (%) 27.4±1.0 (25.8–29.0) Peak viscosity (BU) 101.7±27.9 (71.7–160.3) Holding strength (BU) 64.3±19.2 (39.3–102.7) Final viscosity (BU) 224.8±47.3 (163.7–339.7) Breakdown (BU) 37.4±16.2 (20.3–73.7) Setback (BU) 160.5±34.1 (111.7–237.0) 1) Sodium dodecyl sulfate (SDS) sedimentation test conducted on a constant flour weight (3 g). 2) SDS sedimentation test conducted on a constant protein weight (300 mg). Data are average±standard deviation, ranges from Korean wheat cultivars described within parentheses.