Table 4. Phenolic metabolism of walnut kernels coated with gum arabic enriched with γ-aminobutyric acid (GABA) during storage at 20 °C for 18 weeks.
| Phenolics metabolism | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| w(gum arabic)/% | c(GABA)/mM | t/week |
w(total phenolics as GAE)/ (mg/g) |
DPPH• scavenging capacity/% | PAL activity/ (μmol/mg∙ h) |
PPO activity/ (U/mg) |
|||||
| 0 | (54.4±0.9) | (65.5±0.9) | (62.4±1.1) | (9.1±0.8) | |||||||
| 0 | 0 | 6 | (35.7±0.8)bcd | (52.1±0.2)cd | (36.8±0.8)d | (12.8±0.7)ef | |||||
| 12 | (26.9±0.6)ef | (42.1±0.3)f | (22.3±0.3)g | (28.1±1.3)c | |||||||
| 18 | (19.4±1.5)f | (35.9±0.3)g | (17.9±0.2)h | (66.1±1.3)a | |||||||
| 0 | 1 | 6 | (41.0±1.9)b | (55.7±0.3)b | (41.9±0.3)c | (11.0±1.8)f | |||||
| 12 | (33.0±1.8)cde | (49.2±0.3)d | (36.1±0.4)d | (16.9±1.1)e | |||||||
| 18 | (29.6±1.3)de | (45.9±0.6)e | (28.9±0.4)f | (37.6±0.2)b | |||||||
| 10 | 0 | 6 | (38.2±1.3)bc | (54.9±0.6)b | (45.9±0.4)b | (11.3±0.1)f | |||||
| 12 | (28.1±0.6)e | (50.4±0.9)cd | (38.2±0.2)d | (14.6±0.2)ef | |||||||
| 18 | (20.3±0.9)f | (45.3±0.3)e | (30.7±0.4)ef | (31.9±0.1)c | |||||||
| 5 | 0.1 | 6 | (52.6±0.6)ef | (60.2±1.5)a | (57.4±1.6)a | (9.5±0.2)f | |||||
| 12 | (48.2±0.6)a | (55.6±0.4)b | (44.9±0.9)b | (11.4±0.1)f | |||||||
| 18 | (39.1±0.6) bc | (53.1±0.6)bc | (32.1±0.3)e | (22.7±0.3)d | |||||||
| Significant | df | ||||||||||
| Time | 2 | ** | ** | ** | ** | ||||||
| Treatment | 3 | ** | ** | ** | ** | ||||||
| T×T | 6 | ns | ** | ** | ** | ||||||
| CV | - | 7.39 | 2.15 | 2.92 | 7.52 | ||||||
Data are presented as mean value±standard error of three replications. Different letters indicate significant differences at p=0.05. * and **Significance at p=0.05 and 0.01, respectively. GAE=galllic acid equivalents, PAL=phenylalanine ammonia-lyase, PPO=polyphenol oxidase