Effects of electric field treatments on phenol compounds of brandy aging in oak barrels

• Application of electric field treatment of 1 kV/cm speeded up brandy maturation.
• Electric field treatment enhanced extraction of phenols from oak wood.
• Smaller size of barrel was in favor of phenol extraction from oak wood.
• Electric field treatment played a much more intensive impact than barrel size.
• Kinetic model of oak phenol compounds extracted by brandy was established.

The effects of applying an electric field (EF) treatment with 1 kV/cm (50 Hz) on brandy stored in 5-L and 2-L oak barrels, respectively, for over 14 months to simulate the natural aging process were investigated in this paper, as compared with brandy sample naturally aged in 225-L oak barrels. Results demonstrated that the content of phenol compounds in brandy such as tannins, total phenols as well as volatile phenols were significantly increased after treatment by EF, with tannin concentration of the brandy treated by EF being 54.4% and 43.9% higher than those of the control brandy after 14 months of maturation in 5-Land 2-L barrels, respectively. On the other hand, the chromatic aberration of the brandy treated by EF for 14 months was 19.2% and 24.9% higher than the control in 5-L and 2-L barrels, respectively. It was also demonstrated that the EF treated samples in 5-L barrels for 7 months and in 2-L barrels for 5 months exceeded the content of tannins of those naturally aged for 12 months in 225-L oak barrels used in the brandy industry.Ten kinds of phenol compounds were identified, which could be divided into three categories based on clustering analysis, and the kinetic model of oak phenol compounds extracted by brandy demonstrated that EF treatment played a positive role in accelerating the extraction of phenol compounds and its effect was more significant than the size of barrel.The current study demonstrated that application of EF treatment directly on oak barrel is a promising and feasible technology to speed up brandy maturation.Industrial relevanceThe current study demonstrated that application of electric field treatment directly on oak barrels is a promising and feasible technology to speed up brandy maturation for the industry.