Table 4.
Identified flavonoid and phenolic acid compounds from an optimized extract of red and brown rice bran with information of retention time, wavelength, and linear regression parameters.
| Flavonoids and Phenolic Acids | Rice Bran | tr (min) | λ (nm) | Calibration Equation * | R 2 | LOD | LOQ | |
|---|---|---|---|---|---|---|---|---|
| Red | Brown | |||||||
| Catechin | 4.26 ± 0.34 a | 2.14 ± 0.16 b | 3.82 ± 0.02 | 280 | (0.138 ± 0.005)x + (−0.086 ± 0.040) | 0.993 | 0.55 | 1.68 |
| Quercetin | 5.16 ± 0.48 a | 1.65 ± 0.10 b | 9.52 ± 0.02 | 360 | (0.085 ± 0.001)x + (−0.112 ± 0.021) | 0.992 | 1.14 | 3.52 |
| Myricetin | 7.55 ± 0.45 a | 4.41 ± 0.24 b | 11.47 ± 0.01 | 360 | (0.060 ± 0.001)x + (−0.086 ± 0.036) | 0.994 | 0.82 | 2.51 |
| Luteolin | 6.47 ± 0.27 a | 1.08 ± 0.10 b | 14.65 ± 0.02 | 360 | (0.147 ± 0.002)x + (−0.101 ± 0.005) | 0.995 | 1.09 | 3.29 |
| Apigenin | 11.63 ± 0.69 a | 7.69 ± 0.51 b | 18.04 ± 0.03 | 360 | (0.029 ± 0.001)x + (−0.041 ± 0.015) | 0.986 | 1.10 | 3.32 |
| Cinnamic acid | 6.03 ± 0.38 a | ND | 10.22 ± 0.02 | 320 | (0.158 ± 0.004)x + (−0.123 ± 0.073) | 0.993 | 0.93 | 2.84 |
| Syringic acid | 6.23 ± 0.37 a | 7.15 ± 0.36 b | 15.60 ± 0.03 | 280 | (0.017 ± 0.001)x + (−0.044 ± 0.005) | 0.990 | 1.18 | 3.62 |
| p-coumaric acid | 8.16 ± 0.49 a | 7.94 ± 0.53 a | 15.83 ± 0.03 | 320 | (0.251 ± 0.005)x + (−0.117 ± 0.004) | 0.995 | 1.16 | 3.54 |
| Ferulic acid | 5.56 ± 0.26 a | 5.12 ± 0.44 a | 17.04 ± 0.01 | 320 | (0.055 ± 0.004)x + (−0.096 ± 0.028) | 0.991 | 0.91 | 2.75 |
| Protocatechuic acid | 2.04 ± 0.11 a | 1.60 ± 0.12 b | 18.01 ± 0.03 | 320 | (0.068 ± 0.007)x + (−0.054 ± 0.064) | 0.998 | 1.10 | 3.37 |
a, b Data were the mean ± standard deviation of triplicate measurements. Different superscript lower case letters in each row indicated significant difference at p < 0.05 (Duncan’s test). ND: not detected; *: n = 3; tr: retention time; λ: wavelength; LOD: limit of detection; LOQ: limit of quantification.