Taste characteristics, volatile components, sensory properties, and antioxidant activity of fresh onion (Allium cepa L.) leaves

Abstract

Taste characteristics of fresh onion leaves The concentrations of taste components in the Welsh and fresh onion leaves are presented in Table 1. Lower Brix levels, lower fructose, sucrose, and total sugar concentrations, and a lower degree of sweetness were found in fresh onion leaves (p < 0.05) than in Welsh onion leaves. The concentrations of L-tartaric, L-malic, citric, succinic, and fumaric acids were lower in fresh onion leaves than in Welsh onion leaves (p < 0.05). In fresh onion leaves, the concentrations of L-aspartate, L-serine, glycine, L-histidine, L-arginine, L-alanine, L-proline, L-tyrosine, L-valine, L-methionine, L-cystine, L-isoleucine, L-leucine, and total free amino acids were lower than in Welsh onion leaves, whereas L-glutamate was higher (p < 0.05). The 5'-guanylate concentration in fresh onion leaves was higher than that in Welsh onion leaves (p < 0.05). The taste responses to the Welsh and fresh onion leaves are shown in Fig. 1. A lower level of initial taste astringency-A was observed in fresh onion leaves than in Welsh onion leaves (p < 0.05). The value of astringency-A correlated positively with the concentrations of L-aspartate, L-arginine, L-threonine, L-alanine, L-valine, L-methionine, L-isoleucine, L-leucine, and total free amino acids (r = 0.661–0.733, p < 0.05).