Assessment of different blanching strategies on quality characteristics and bioactive constituents of Toona sinensis

Toona sinensis is a seasonal woody vegetable with unique flavor and high nutritional values. However, the shorter edible period and quite difficult in fresh-keeping limited its further utilization. To solve these problems, the optimal blanching times of three blanching methods (i.e., hot water blanching (HWB), steam blanching (SMB) and microwave blanching (MWB) were first determined by peroxidase and polyphenol oxidase inactivation, and the quality of the blanched Toona sinensis were further evaluated. The results indicated that the characteristics of Toona sinensis (i.e., color, bioactive constituents, antioxidant activity and aroma) were better retained after HWB treatment. Conversely, MWB showed the highest retention of crude protein and amino acids (except for glycine and methionine). Notably, the obvious uptrends of 3 individual phenol compounds (gallic acid, quercertin and kaempferol) were observed under all blanching treatments. The lowest loss of characteristic aroma in Toona sinensis (i.e., 2-Mercapto-3,4-dimethyl-2,3-dihydrothiophene) was observed in HWB than the rest two methods. Moreover, five biomarkers of volatile compounds (i.e., 2-hexenal, 3,4-dimethyl-thiophene, caryophyllene, β -selinene, γ -gurjunene) were identified in all blanched Toona sinensis samples. Additionally, the characteristic aroma components in each kind of blanching treatment had been found, which can be used to distinguish the blanching types of Toona sinensis products. • Comparative quantitative evaluation of HWB, SMB, and MWB was performed. • The better green of Toona sinensis retained under all blanching treatments. • Microwave blanching led to higher nutrient retention than HWB and SMB. • The higher retention of bioactive constituents and characteristic aroma in HWB.