pH values of bleaching medium | Whitening time (min.) and values of walnut meal peroxide index (mmol/g oil) | ||||
0 min. | 10 min. | 20 min. | 30 min. | 60 min. | |
pH-10 | 4.71 ± 0.30 | 4.79 ± 0.33 | 4.83 ± 0.33 | 4.85 ± 0.33 | 4.91 ± 0.34 |
pH-7 | 4.75 ± 0.33 | 4.78 ± 0.33 | 4.79 ± 0.33 | 4.86 ± 0.34 | |
pH-3 | 4.73 ± 0.33 | 4.76 ± 0.33 | 4.77 ± 0.33 | 4.87 ± 0.34 |