Table 4.
Changes of phenolic acids, vitamin C, and DPPH scavenging activity in fresh and cooked sweet potato (Poongwonmi) leaves
| Compound | Before cooking | Conventional blanching | Microwave blanching | ||
|---|---|---|---|---|---|
| Amount | Loss (%) | Amount | Loss (%) | ||
| Phenolic acids (mg/100 g FW) | |||||
| ChA | 138.25 ± 7.24a | 31.54 ± 5.52b | 77.2 | 16.76 ± 4.90c | 87.9 |
| 4,5-diCQA | 101.13 ± 10.58a | 76.70 ± 12.70ab | 24.2 | 55.09 ± 19.84b | 45.5 |
| 3,5-diCQA | 421.16 ± 26.06a | 112.20 ± 26.96b | 73.4 | 82.61 ± 6.22b | 80.4 |
| 3,4-diCQA | 43.99 ± 2.50a | 34.78 ± 5.35b | 20.9 | N.D. | 100.0 |
| Sum1 | 704.52 ± 46.29a | 255.22 ± 48.92b | 63.8 | 154.46 ± 30.78c | 78.1 |
| Vitamin C (mg/100 g FW) | 71.69 ± 3.43 | N.D. | 100.0 | N.D. | 100.0 |
| DPPH radical scavenging activity (EC50, mg/mL) | 0.13 ± 0.00c | 0.34 ± 0.04b | 0.44 ± 0.03a | ||
ChA chlorogenic acid; 4,5-diCQA 4,5-dicaffeoylquinic acid; 3,5-diCQA 3,5-dicaffeoylquinic acid; 3,4-diCQA 3,4-dicaffeoylquinic acid. N.D. not detected, FW fresh weight
1Total amount of ChA, 4,5-diCQA, 3,5-diCQA, and 3,4-diCQA
a–dValues with different letters in a row are significantly different (P < 0.05). Each value is expressed as mean ± standard deviation (n = 3)