Enzymatic hydrolysis and auto-isomerization during β-glucosidase treatment improve the aroma of instant white tea infusion

Abstract

The aroma changes in instant white tea resulting from β-glucosidase treatment was investigated by quantitative descriptive analysis (QDA), gas chromatography-mass spectrometry (GC-MS), odour activity value analysis (OAV), aroma reconstruction and omission tests. The grassy, floral and sweet notes increased significantly (P < 0.05), and the roasted note decreased significantly (P < 0.05) upon β-glucosidase treatment. Quantitative analysis showed that the concentrations of benzaldehyde, benzeneacetaldehyde, (Z)-3-hexen-1-ol, linalool, phenylethyl alcohol, cis-linalool oxide, trans-linalool oxide, hexanol, hotrienol and (E)-2-hexen-1-ol increased significantly (P < 0.05) after treatment; however, (Z)-3-hexen-1-ol isomerized to (E)-2-hexen-1-ol. OAV analysis, aroma reconstruction and the omission test showed that the grassy, floral and sweet notes increased as the (Z)-3-hexen-1-ol, cis/trans-linalool oxide and benzeneacetaldehyde increased, whereas the roasted note declined under the same conditions. The enzymatic hydrolysis of glycosidic precursors and the auto-isomerization of volatile compounds provide new information for understanding how β-glucosidase treatment improves the aroma of tea products.

Keywords: (E)-2-(2-Pentenyl)-furan (PubChem CID: 5369957); (E)-2-Hexen-1-ol (PubChem CID: 5318042); (E)-β-Ionone (PubChem CID: 638014); (Z)-3-Hexen-1-ol (PubChem CID: 5281167); 1-Ethyl-1H-pyrrole (PubChem CID: 185226); 1-Ethyl-1H-pyrrole-2-carboxaldehyde (PubChem CID: 579338); 2,4-Ditert-butylphenol (PubChem CID: 6911); 2-Ethyl-furan (PubChem CID: 18554); 2-Methyl-butanal (PubChem CID: 7284); 2-Methyl-furan (PubChem CID: 10797); 2-Methyl-propanal (PubChem CID: 6561); 2-Pentyl-furan (PubChem CID: 19602); 3-Methyl-butanal (PubChem CID: 11552); Aroma reconstruction and omission test; Benzaldehyde (PubChem CID: 240); Benzeneacetaldehyde (PubChem CID: 998); Cis-limonene oxide (PubChem CID: 6452061); Cis-linalool oxide (PubChem CID: 6428573); Dihydroactinidiolide (PubChem CID: 6432173); Dimethyl sulphide (PubChem CID: 1068); GC–MS; Hexanol (PubChem CID: 8103); Hotrienol (PubChem CID: 5366264); Instant white tea; Limonene (PubChem CID: 440917); Linalool (PubChem CID: 6549); OAV; Phenylethyl alcohol (PubChem CID: 6054); Safranal (PubChem CID: 61041); Trans-linalool oxide (PubChem CID: 6432254); Volatile compounds; β-Glucosidase.