The antioxidant properties of methanolic extracts (PM) from the fruit of Prunus mume after liquor manufacturing were determined in a chicken breast meat system. When PM was added to chicken breast meat, 2-thiobarbituric acid-reactive substances (TBARS) value at day 3 was decreased by about $25\%$ compared to control meat without PM. PM did not significantly affect the color of chicken meat compared to the control. The amounts of volatile aldehydes and hydrocarbons were decreased by the addition of PM. Hexanal was the predominant volatile compound in the control, accounting for the majority of total volatiles; PM reduced the amount of hexanal to $81\%$of that in the control meat at 3 days.