FIGURE 2.

Time course of discoloration of the wounded surface of roots stored at 6 and 12°C. Roots were wounded by abrading the root surface with a wire brush 2 h after harvest and were subsequently stored at 94% relative humidity. Red discoloration is presumed to be due to oxidation of phenolic compounds to o-quinones by polyphenol oxidase. Gray to black discoloration is presumed to be due to reaction of o-quinones to form melanin. Pictures are representative of the coloration observed for five individual roots.