The results
indicated that TCC reached the maximum after boiling cilantro, Thai basil leaves, and
sweet potato leaves for 10 minutes, 5 minutes, and 5 minutes, respectively, and choy sum
remained almost unchanged after 30 minutes of boiling. Boiling cilantro and choy sum had
a negative effect on their TPC, whereas there was a significant increase in TPC of Thai basil
leaf and sweet potato leaf at 1 minute and 5 minutes of boiling, respectively. During water
cooking, TAC of the vegetables did not demonstrate a consistent trend. However, TCC was
a vital contributor to %IP, whereas TPC showed a strong association with TEAC. Our
findings suggest that a boiling time of 5 minutes would be better for preserving or
enhancing TCC and TPC as well as revealing a higher %IP, TEAC, or metal-chelating effect
for the four vegetables investigated in this study.